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communal ownership vs governmental ownership
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When something seems to go wrong with the environment, people often accept that the government should take charge to protect it from people without asking is central control any better? There was a time when population was low and conservation wasn't really on people's minds. Like in Nepal. Big mountains, Big cats, and diverse forests that people used for firewood and animal feed. But as population began to rise, deforestation started to become bigger problems. So in 1957 the government took control of the forests to try and stop people from using them so much. The plan: was to put it all under government ownership, take inventories of all the trees, find out how much can uses and require people to have a permit to take anything from the forests. Then they imprisoned or fined those who broke the rules. Good plan? No. Bad plan. Bad government. You see, even though it wasn't in writing the locals considered the forests their own property and they managed it themselves. While conservation wasn't a big issue, in some places like the mountainous regions where growth is slow, they had to work together to closely control how much they took and how often. Other villages might make sure things were distributed to people evenly. These institutions most likely weren't adapted for the new demand on the forests. But after nationalization, most of the communes that used to operate were basically split up since they didn't feel they owned the forests anymore. What came after was no longer a matter of trying to work together, but competing against each other. You see, to get firewood or animal feed, they needed a permit. But the permit offices were scattered and could take days to get to. So most just risked the consequences and took products illegally. And Nepal is made up of thousands of forests scattered over difficult terrain. Monitoring of the new rules turned out to be basically impossible. There fear of enforcement, but most illegal activity went unpunished and people generally took what they wanted. Most people held some private land of their own for agriculture and trees. But under the new laws, the government could take private land if they felt it was necessary. For example: any land left unused for longer than 2 years could be taken by the government. But just letting the land rest like this was a common regenerative practice. Why should they lose their land for taking care of it. So clearly rules like this need to be changed. But to change a rule, they would need to travel to a forest office, convince them that the rule needs to be changed. Carry that on to another level of government where a bunch of people in suits can deliberate. And if that's all successful, then they need to communicate the change to the millions of people in the secluded places all over the country. This is way too much work to change 1 rule. But really, it's indicative of the inefficiency of the whole plan. So it was all ultimately a failure. After government control, the people didn't work, they couldn't work together because the forests weren't technically theirs to manage and deforestation actually accelerated. It wasn't that the government was incompetent, or evil. It's just, to implement the plan, they needed to decide who could use it, when, how much, monitor everything and make sure all the information on all these things was accurately. And each forest and each community would need different considerations. It's...expensive. And the people won't think it's fair when an outsider comes in to try and claim the resource, even with good intentions. And outsiders typically won't understand as much or care as much about a resource as those who work with and rely on it. They're just too disconnected from the resource. And the further away you look at someone or something from, the more you'll overlook the way they really are. You might think one group of people are inherently sensible and another are inherently incompetent. You'll be forced to work from theory, assumptions and models like the tragedy of the commons and the prisoners dilemma. Models like these are nice because they can explain different situations all over the world. But their just metaphors that can tell you maybe 1 or 2 things. Take this picture.... that I drew. It represents a person. You can use it to describe a person in different situations. But it doesn't really tell you anything about real people. We would have to accept a lot of assumptions to use it literally, like people are 2 dimensional faceless anorexics.... with no hands or genitals. We have to make a lot of assumptions to make these models work too. And when policy makers assume that these assumptions are true in real situations, they run into problems. So we need a different approach. Let's check out here. Alanya Turkey. In the 1970s the fishery wasn't doing great. There were too many fishermen chasing fewer and fewer fish People invested in boats and fishing equipment but there were so many people fishing that there was no guarantee they would catch enough fish to make their money back. So people would fight, physically, over the good fishing spots. So the local fishing cooperative developed a system to make it fair. The whole area was split up into fishing spots such that fishing in one spot wouldn't block the migration of fish to the next spot. Every year, a list is produced of all the licensed fishers and they are randomly assigned to a spot. Then every day from september to january each fisher moves east to the next location. From January to May, when the fish migration switches direction, they switch the direction of the cycle to ensure everyone gets a fair chance. Monitoring people's compliance with the rules came about naturally from the rotation system. Everybody knows where they're supposed to be and if someone is in your spot, you'll know right away. Monitoring like this is almost free. And they carry out the the punishment themselves too. If they need to they can cut a fishermen's nets or kick them out of the system. But because most people understand the system is beneficial to everyone, they usually they just need to give them a warning. And most everyone just follows the rules. And rules are easier to change because those who make the rules, are those who follow them. If they meet somewhere in town, everyone gets a chance to bring up issues, and everybody hears them. Communication this way cheap and quick. So the people of Alanya were able to create their own institution to use the resource in a fair way. It's not that the government shouldn't have any hand in the resource. It's just ultimately, resource management isn't done in a board room by legislatures. But by foresters and fishermen, those who work with the resource in the field. So the management needs to be receptive to them in some way. That's why these institutions are best adapted case by case. Sweeping statements about who should do what or about how the environment can be helped, are not very helpful. This strategy that failed in Nepal, actually works OK in other places like Canada. But most Canadians don't heat their homes with wood or use forest products for fodder. So the permits go out to large companies rather than hundreds of thousands of individuals. Also the population of Canada, is about the same as Nepal. In 1978 the Nepal government started working with the communities allowing them to own and manage the forests. They began growing back and people's livelihood improved. ... Grands banks cod was one of the biggest populations on the planet. So what happened. Well it turned out, Cod was made of meat. And because of advances in technology, Cod catch reached record levels. The researchers and local fishermen warned of the declines in population. So why didn't it stop? The way the system was set up, the department....
Posted by: irarmy on Nov 1, 2014
People often feel that the government should be in charge of natural resources because the environment belongs to us all and the government represents the people. While there's no single way for renewable resource ownership, people tend towards government control a little too often. It can hurt instead of help.
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Mathematical Problems in Engineering / 2015 / Article
AbstractIntroductionPreliminariesRelated WorkConclusionsAcknowledgmentsReferencesCopyright
Research Article | Open Access
Volume 2015 |Article ID 150512 | https://doi.org/10.1155/2015/150512
Siyu Lin, Hao Wu, "Bloom Filter-Based Secure Data Forwarding in Large-Scale Cyber-Physical Systems", Mathematical Problems in Engineering, vol. 2015, Article ID 150512, 12 pages, 2015. https://doi.org/10.1155/2015/150512
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Bloom Filter-Based Secure Data Forwarding in Large-Scale Cyber-Physical Systems
Siyu Lin 1,2 and Hao Wu2
1School of Electronic and Information Engineering, Beijing Jiaotong University, No. 3 Shang Yuan Cun, Haidian District, Beijing 100044, China
2State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, No. 3 Shang Yuan Cun, Haidian District, Beijing 100044, China
Academic Editor: Yang Tang
Received24 Sep 2014
Accepted19 Mar 2015
Published08 Apr 2015
Cyber-physical systems (CPSs) connect with the physical world via communication networks, which significantly increases security risks of CPSs. To secure the sensitive data, secure forwarding is an essential component of CPSs. However, CPSs require high dimensional multiattribute and multilevel security requirements due to the significantly increased system scale and diversity, and hence impose high demand on the secure forwarding information query and storage. To tackle these challenges, we propose a practical secure data forwarding scheme for CPSs. Considering the limited storage capability and computational power of entities, we adopt bloom filter to store the secure forwarding information for each entity, which can achieve well balance between the storage consumption and query delay. Furthermore, a novel link-based bloom filter construction method is designed to reduce false positive rate during bloom filter construction. Finally, the effects of false positive rate on the performance of bloom filter-based secure forwarding with different routing policies are discussed.
Over the past few years, the cyber-physical systems (CPSs) have attracted considerable attention due to their wide applications in various areas such as power grids [1], intelligent transportation systems [2], and aerospace systems [3]. Communication networks are the connecting links between CPSs and physical world. To defend the attacks from the external and internal of networks destroying the data exchange or stealing data, the CPSs need a secure data forwarding scheme to achieve an end-to-end protection for sensitive data [4].
The forwarders can alter, drop, and delay existing packets, thus sensitive data packets should only be forwarded by the entities that have secure forwarding capabilities. On one hand, CPSs could be large-scale systems including many different types of devices and data, such as smart grid systems; they require different security levels (e.g., high, medium, and low) on different security attributes (e.g., integrity, confidentiality, and availability) [5–7]. The high dimensional multiattribute and multilevel security requirements require efficient secure forwarding capability management and evaluations. On the other hand, the ever increased system scales of CPSs and diverse secure forwarding policies significantly increase the amount of secure forwarding information, which introduces the secure information storage and query problem to the entities which have limited storage capability and computational power (such as embedded devices in CPSs).
Bloom filters can achieve space-efficient storage with constant query delay, which have been applied in many applications [8]. In this paper, we propose a novel secure data forwarding scheme for large-scale CPSs that achieves well balance between the space-efficiency and query delay based on the bloom filters. Compared with traditional secure data forwarding schemes, the proposed scheme improves the space-efficiency while achieving a comparable query delay. However, bloom filters suffer from the false positive issues, which are especially undesirable for the secure forwarding information management and evaluation. A link-based bloom filter construction method is further proposed to reduce the possibility of secure forwarding policies violation caused by the false positive issue.
Specifically, our main contributions in this work include the following.(i)To the best of our knowledge, our work is the first attempt to design a generic and practical secure data forwarding scheme based on the high dimensional multiattribute and multilevel security requirements for large-scale CPSs.(ii)We propose a bloom filter-based secure forwarding capabilities representation method, which improves the storage efficiency while achieving constant query delay. Furthermore, we derive the optimal secure forwarding information storage size.(iii)To simplify the construction process of bloom filters and minimize the violation of security policies caused by the potential false positive issue, we design a novel link-based bloom filter construction method, with which the offspring entities construct their own bloom filters based on the incoming links from their respective parent entities.(iv)Finally, we evaluate the performance of proposed secure data forwarding scheme with two classical routing protocols, for example, Open Shortest Path First (OSPF) and Greedy Perimeter Stateless Routing (GPSR) routing protocol. The impacts of false positive problem on the average length of routing path are investigated.
2. Preliminaries
2.1. System and Security Models
The CPS is consistent with amount of entities. Within the CPS, there are security attributes such as confidentiality, integrity, availability, and authentication [5, 9]. Each security attribute has security levels, such as high, medium, and low when . The security capability of an entity is described by its security label, which is security attributes and corresponding security levels combination. The security label is denoted as , where specifies the security level of the th security attribute that the entity can offer. If , this means that the entity cannot provide the th security attribute. Similarly, the secure forwarding requirements of a packet are also denoted as a security label. If the packet does not require the th security attribute, then for the security label of packet. For example, in a smart grid system, it may include six main security attributes: integrity, confidentiality, availability, privacy, authentication, and nonrepudiation. Then, for smart meter data reports, they may require integrity, confidentiality, and privacy at high levels. In contrast, the control commands may require high integrity, availability, and authentication [5, 10].
The secure forwarding policy of CPS is expressed in terms of security labels attached to the entities and packets [11]:(i)The entity satisfies the security requirement of the th security attribute of a packet if and only if .(ii)We define that the security label of an entity dominates the security label of a packet if and only if for all security attributes of packet , denoted as The entity has secure capability to forward the packet if and only if the entity dominates the security label of the packet .
Here we use an example to illustrate the secure forwarding policy. Supposing the CPS has two security attributes and there are three security levels on each security attribute, the security labels of entity and entity are and , respectively, and the security label of a packet is . Since dominates while cannot dominate , only entity can securely forward packet .
2.2. Secure Forwarding Capability
To deliver a packet to its destination(s), we need to evaluate the forwarding capability of each potential forwarder for the given security label of the packet. However, the forwarding capability of an entity cannot only be described by its security label, but also be jointly determined based on the security labels of entities along the forwarding path. Next, we use an example to clearly illustrate it. Considering a CPS with four entities, one packet with security label needs to be forwarded to destination , which is shown in Figure 1. In this case, although the security label of entity dominates the security label of the packet, still cannot forward the packet to its destination, because neither of the potential forwarders and has the capability to deliver the packet. This example shows that an entity has forwarding capability for a given packet if and only if there is a path between the entity and the destination along which all the entities have the capabilities to deliver the packet. Therefore, the secure forwarding capability of an entity (E2E deliverable set) is determined by a set of security labels that an entity can receive (receivable set) and a set of security labels that its neighbors can forward to the destination (E2E deliverable sets of neighbors).
Entities and packets with their security labels.
The receivable set of an entity includes all security labels dominated by the entity's security label, which is derived only based on its security label. For example, the receivable set for entity in Figure 1 is . On the other hand, according to the definition of forwarding capability, the E2E deliverable set of an entity is the intersection between its receivable set and the union of E2E deliverable sets of its neighboring entities. For instance, for the destination entity , the E2E deliverable sets for entities and are and , respectively. As the receivable set for entity is , the E2E deliverable set of should be . For a given destination, we adopt the distributed Bellman Ford algorithm to calculate the forwarding capability of each entity [12].
Considering an entity with security label , its E2E deliverable set potentially contains security labels at most, so the size of E2E deliverable set may grow dramatically with the increasing number of security attributes and security levels. However, many entities in CPSs, such as embedded computers and sensors, have limited computational power and storage space [2, 13]. To achieve effective secure forwarding, how to effectively store and query the forwarding capability information with low computation and storage overhead needs to be addressed. In this work, we propose a bloom filter-based secure forwarding scheme to tackle these challenges.
3. Bloom Filter-Based E2E Deliverable Set
In this section, we first introduce the fundamentals of the bloom filter. Next, we analyze the optimal size of bloom filter-based E2E deliverable set. At last, we propose a link-based deliverable set construction approach to reduce the negative impact on security policies caused by the false positive problems.
3.1. Bloom Filter Fundamentals
A bloom filter (BF) is a bit vector with bits, which is used to test whether an element is a member of a set. Initially, the bloom filter is an empty vector; all bits are set to . Considering a set with elements and independent hash functions, to represent the set to a -bit bloom filter, each element is mapped by the independent hash functions to positions in the -bit vector, all set to (each bit might be set to multiple times), where is the th hash function, . After all the elements of set are mapped to the -bit vector, the -bit vector is the bloom filter expression of , denoted as .
To query whether an element is in the set , map to bit positions of via the independent hash functions. If any of these bit positions is , is definitely not in the set . Otherwise, we conjecture that is in the set [8]. The query delay of bloom filter is a constant, described by , which is only determined by the number of hash functions and independent from the number of elements in the set.
However, bloom filter achieves the above advantages with cost of false positive. False positive problem results from the fact that several positions of BF are shared with multiple elements. If the positions of indicated by hash function results of an element , have been set to by several other elements of set , but actually is not in the , then the query result will be a false positive when it queries in the . Therefore, the false positive problem should be paid more attention in the various application with bloom filter. The probability of such false positive for a given BF can be expressed as [8]where is the size of BF, is the number of elements in the BF, and is the number of independent hash functions.
3.2. BF-Based E2E Deliverable Set Size Optimization
Since bloom filter is a space-efficiency data structure with constant query delay, which is suitable to represent the E2E deliverable set at individual entities, in this section, we analyze the minimal size of BF-based E2E deliverable set.
Based on (2), the size of the E2E deliverable set can be calculated aswhere is the number of deliverable security labels inserted into the E2E deliverable set and is the false positive rate of the deliverable set. Considering that many entities have limited storage space and computational power, we aim to minimize the sizes of the E2E deliverable sets with the false positive rate bound. Then, we can formulate our objective as an optimization problem as follows:Constraint (5) is the bound on the false positive rate. Constraint (6) is the maximum number of elements in the E2E deliverable set of an entity.
According to (4), the size of the E2E deliverable set increases linearly with the number of security labels. Since , , and they are independent. To minimize the size of deliverable set, we define as the size factor, which can be optimized independently. The above optimization problem can be expressed asThe optimal number of hash functions for (8) can be obtained with interior point methods [14]. For a given false positive bound with the optimal number of hash functions , the size of the deliverable set is bits.
Figure 2 shows the impacts of number of hash functions on the size factor, that is, (8), with different false positive bounds, where the optimal number of hash functions with different false positive bounds is marked as black square. From the figure we can see that, with the decrease of false positive rate bounds, the size factor and optimal number of hash functions are increased. Since the size of bloom filter-based deliverable set and query delay are proportional to the size factor and optimal number of hash functions, respectively, then the decrease of false positive rate bounds also leads to the increased size of bloom filter-based deliverable set and query delay. For example, the false positive rate bound decreases from to , the optimal size of deliverable set and corresponding number of hash functions increases from bits and 3 to and 10, respectively.
The size factor as a function of number of hash functions with different false positive rate bounds.
3.3. E2E Deliverable Set Construction
Adopting the bloom filter to represent the E2E deliverable set can achieve efficient storage and forwarding capability query delay, but the false positive problem is introduced in forwarding capability query. To reduce the negative impact of security policies caused by the false positive problems; in this section, we design a link-based method to construct the bloom filter-based E2E deliverable set, with which each entity constructs its E2E deliverable set based on the incoming links of its neighboring entities.
3.3.1. Set Operations of Bloom Filter
Before designing the E2E deliverable set construction method, we introduce two common set operations of bloom filter such as union and intersection, because they can simplify the E2E deliverable set construction process in this work.
Considering two sets and , as well as their corresponding bloom filters and , the properties of union and intersection operations can be presented by the following two theorems [15].
The union of and can be represented by a logical or operation between their bloom filters.
Theorem 1. If , , and have the same length and hash functions, then .
The intersection of and can be represented by a logical and operation between their bloom filters.
Theorem 2. If , , and have the same length and hash functions, then with probability , where is the number of hash functions.
According to the above two theorems, we can observe that using the intersection operations of bloom filter cannot always get the accurate bloom filter of two corresponding sets intersection, but using the union operation can get the accurate bloom filter of two corresponding sets union. Therefore, to minimize potential false positive rate, we should only utilize the union operation of bloom filters for E2E deliverable set construction.
3.3.2. Bloom Filter Construction
The bloom filter is used to store all the security labels of E2E deliverable set. As mentioned in Section 2.2, the E2E deliverable set of an entity is the intersection set between its receivable set and the union of E2E deliverable sets of its neighboring entities. Intuitively, each entity do union operation among all the bloom filter-based E2E deliverable sets of its neighbors firstly, then do the intersect operation between its own bloom filter-based receivable set and the union result to obtain its bloom filter-based deliverable set. However, due to the potential false positives for intersection operations in Theorem 2, this intuitive solution cannot work well in practice. For example, assume there are two sets and , with their bloom filter representations as and , respectively. Although , is not an empty bloom filter due to the false positive caused by bloom filter intersection operations.
To reduce the impact of intersection operation on false positive rate, we should only perform the union operation to construct the bloom filter-based E2E deliverable set. Therefore, we introduce a link-based bloom filter construction scheme to construct the bloom filter-based E2E deliverable set. The scheme consists of three phases: link security label calculation, link bloom filter construction, and bloom filter-based E2E deliverable set construction. Next, we elaborate each of the three phases in detail with a walkthrough example in Figure 3. In the example, assuming that entities and have constructed their deliverable sets, we mainly focus on investigating how to construct the bloom filters for intermediate nodes, such as and .
Example network.
Link Security Label Calculation. The link security label is used to describe the maximum forwarding capability between two entities, which is defined as the lower level of each attribute for these two entities; that is, . The link security label is used to filter the deliverable security labels of this link. For example, as shown in Figure 4, and are security labels of entities and . Then the security label of link is .
Calculate the link security label.
Link Bloom Filter Construction. The link bloom filter contains the security labels which can be delivered by either end of entities. To insert a security label into the link bloom filter, an entity which has already constructed its bloom filter extracts one of the security labels within its bloom filter and then compares it with the link security labels of all associated links. If the extracted label is dominated by the link security label, then it will be inserted into to the corresponding link bloom filter.
For example, since has constructed its bloom filter, the security label of is and its bloom filter is [1010110]. Firstly, entity extracts each of its security labels and from its constructed bloom filter, which is shown in Figure 5(a). Then, entity compares each of them with link security labels of and . Security label is dominated by both link security label of and , , and ; then is inserted into the bloom filters of link and . Similarly, is only dominated by ; then is inserted into the bloom filter of link . The above processes are shown in Figure 5(b).
(a) Extraction
(b) Comparison
Link bloom filter construction.
Bloom Filter-Based E2E Deliverable Set Construction. After the link bloom filters are constructed for an entity, the entity simply performs the union operation among all its link bloom filters to obtain its bloom filter-based E2E deliverable set. For example, assuming the bloom filters of link and are [1010110] and [1110111], entity performs the union operation between the two link bloom filters of link AC and BC to obtain its bloom filter-based E2E deliverable set [1110111], which is shown in Figure 6.
Bloom filter-based E2E deliverable set construction.
4. Secure Forwarding
After all the E2E deliverable sets are constructed, the forwarding capability of each entity is expressed as a bloom filter with its security label. In this section, we design the bloom filter-based secure data forwarding scheme. To deliver a packet to its destination(s), we need to evaluate the forwarding capability of each potential forwarder for the given security label of the packet; the forwarding capability evaluation is implemented via bloom filter query. The objective of forwarding capability query is that the source entity or a forwarder judges which neighbors have the capability to forward the packet to destination(s). This is a forwarder candidates selection process, whose outputs are the feasible forwarders satisfied the secure forwarding policy. The final forwarder is decided by routing policy, such as shortest path routing protocols and geographic routing protocols. The bloom filter-based forwarding capability query can be added to any security aware routing protocols as a middleware.
The forwarding capability query process has two steps. Firstly, the forwarder compares the security label of the packet with the security labels of its neighbors; secondly, if the security label of the packet is dominated by the neighbor's security label, then, query whether the security label of packet is in the bloom filter-based deliverable set of this neighbor. If the security label can be extracted from the E2E deliverable set, this entity is selected as a forwarder candidate. In particular, the false positive problem will not lead to the fact that packets are forwarded to the entities which have no capability to receive the packets; this is because the fact that the forwarder compares the security label of the packet with the security labels firstly.
After all the forwarder candidates are selected from the neighbors by relay entities or source entity; the forwarder selects the best candidate as the final forwarder according to the routing policy. In this work, we select two classic routing protocols, such as shortest path routing protocol and geographic routing protocol, which are combined with bloom filter-based forwarding capability query to implement the secure forwarding.
Shortest path routing is the most widely used routing protocol; Open Shortest Path First (OSPF) routing protocol is selected as it is the most typical shortest path routing. OSPF collects link state information from available entity and constructs a topology map of the network. The topology is presented as a routing table, and it computes the shortest path tree for each route using a method based on Dijkstra's algorithm [16]. Bloom filter-based E2E deliverable set introduces the false positives into the forwarding capability query, which may lead to the wrong routing decision; that is, an entity is selected as the forwarder that cannot forward the data to the destination(s). When a false positive occurs, the packet will be forwarded continuously until a forwarder who cannot find the next forwarder to the destination(s) without routing loop. In this case, the false positive can be detected. When a node detects a false positive, the false positive recovery mechanism will be implemented [17]. When a false positive is detected, the forwarder marks the packet as the recovery packet and unicasts the data back to the previous forwarder. Once an entity receives the recovery data, it will select another forwarder to forward this data. If it fails again, the recovery mechanism will be implemented recursively. The worst case is a full exploration of the entities which have the ability to forward this packet. But, in practice, for the given reasonable desired false positive rate, the recovery mechanism is rarely implemented.
We select Greedy Perimeter Stateless Routing (GPSR) as another routing policy which is a typical geographic routing [18]. The packets are forwarded to neighboring entity which is closer to the destination based on a local point of view. The above greedy forwarding mechanism may lead into a dead end, where there is no neighbor closer to the destination, which means there is a void. If a void is detected, GPSR will activate the Planar Perimeters mode and adopt right hand rule to bypass void. The Planar Perimeters mode of GPSR can provide good insight about the effect of false positive on the forwarding routing path of routing protocols.
5. Performance Evaluation
In this section, we evaluate the performance of bloom filter-based secure forwarding scheme through extensive simulations.
5.1. Simulation Setting
We simulate a large-scale CPS with 1000–1500 entities randomly deployed nodes. The average number of neighbors of an entity varies from 20 to 30, and a sink deployed in the center of the field. The default number of attributes of CPS is set to 10. The default number of security levels is set as ; each security attribute is generally classified into four levels, such as high, medium, low, and not applicable [5]. The default false positive rate bound is set as . The presented results are average over 30 runs. We select the bitmap [17] scheme as the baseline, in which the deliverable set is represented to a bit vector. Each bit corresponds to a unique deliverable security label. Therefore, the bitmap can provide accurate forwarding capability query results without false rate.
5.2. Performance Evaluation
In this section, we compare the E2E deliverable set size and query delay between bitmap and bloom filter scheme. As mentioned in Section 2.1, considering the diversity of various entities, each kind of entity only supports a subset of attributes [10, 19], and packets normally also only require a subset of attributes of the system according to their functionalities, so we define the maximum number of attributes that a packet requires as the number of effective security attributes, whose default number is set as 6 in this work.
5.2.1. E2E Deliverable Set Size
In this section, we investigate the optimal sizes of the two different schemes under different false positive rate bounds, different number of security levels, and different number of effective security attributes. Since packets normally also only require a subset of attributes of the system, the total number of effective security labels of the packets that the system supports can be calculated as , where is the number of effective security attributes, which is also the size of bitmap-based E2E deliverable set. Similarly, the maximum number of effective security labels of each entity, , is , where is the maximum number of security attributes that entities can support. The security level on each attribute is randomly assigned. The optimal size of BF-based E2E deliverable set, bits, is derived based on the optimization function (8) in Section 3.2.
Impact of False Positive Rate Bound. The bloom filter achieves the space-efficiency with the cost of false positive rate, so we first study the effect of false positive rate bound on the size of E2E deliverable set. Figure 7 shows the sizes of two schemes when false positive rate bound varies from to . The BF-based scheme requires smaller size when the false positive rate bound becomes larger, which is intuitive. We can see that the size of BF-based deliverable set outperforms the bitmap-based scheme with any given false positive rate bounds. For example, even in the case when false positive rate is , the size of BF-based deliverable set only achieves of the size of bitmap-based deliverable set. This is because the fact that the BF-based deliverable set only needs to store effective security labels of each entity, but all the effective security labels of the packets that the system supports need to be stored in bitmap-based deliverable set.
E2E deliverable set size comparison with varying false positive rate bounds.
Impact of the Number of Security Levels. Since the maximum number of effective security labels in the E2E deliverable set of each entity is determined by the number of security levels, we study the effect of the number of security levels on the size of E2E deliverable set. Figure 8 shows the sizes of two schemes under different number of security levels. When the number of security levels varies from to , the advantage on space-efficiency of BF becomes more obvious. For example, when , comparing with the bitmap, BF-based deliverable set size is a little large compared to that of bitmap scheme; however, when the number of security levels increases to 6, the size improvement of BF achieves about . This is because that the gap between the maximum number of effective security labels of system and that of entities becomes larger with the increase of security levels.
Impact of the number of security levels.
Impact of the Effective Security Attributes. The number of effective security attributes also impacts the maximum number of effective security labels in the E2E deliverable set; then it further affects the storage consumption of entities. Here, the number of effective security attributes varies from 1 to 10; the maximum number of attributes that an entity can support equals the number of effective security attributes. Figure 9 shows the sizes of two schemes under different percentage of effective security attributes. With the percentage of effective security attributes increasing, the sizes of BF-based deliverable set increase as well. When the number of effective security attributes of entities is less than of system attributes, comparing with bitmap, the BF scheme has smaller size. While the number of effective security attributes of entities exceeds of system attributes, the maximum number of security labels of E2E deliverable set is comparable to the number of security labels that the system supports, so the sizes of BF scheme exceed the bitmap. When the percentage of effective security attributes achieves , the sizes of BF and bitmap are 307 Bytes and 2586 Bytes; the size improvement of BF achieves more than .
Impact of the number of effective security attributes.
5.2.2. Query Delay
In this section, we examine the query delay of two different schemes under different false positive rate bounds. The query delay of bitmap is , as it is a one-to-one mapping. For a given false positive rate bound, the query delay of BF scheme can be evaluated by the optimal number of hash operations , which are derived based on the optimization function (8) in Section 3.2.
Figure 10 shows the optimal number of hash operations under different false positive rate bounds of BF scheme. As false positive rate bound decreases, the number of hash operations of BF increases, which means that the query delay is increased. This is because the optimal number of hash functions is increased with smaller false positive rate. For example, when the false positive rate bound decreases from to , the optimal number of hash operations of BF increases from to .
Total number of hash operations with varying false positive rate bound.
5.2.3. Average Length of Routing Path
Utilize the bloom filter to represent the E2E deliverable set of entities; the false positive problem may lead the forwarder to make wrong routing decision; then the length of routing path may be stretched. In this section, we investigate the impact of false positive rate bound of E2E deliverable set on the average length of routing path of OSPF routing with recovery mechanism and GPSR routing. We select the OSPF with bitmap-based E2E deliverable set as the baseline; this is because that this scheme can achieve the shortest routing path. All the results are obtained by averaging 1000 source-to-sink communications.
Impact of the False Positive Rate Bounds. Figure 11 shows the average length of routing path of three different secure forwarding schemes under different false positive rate bounds. When the false positive rate bound is less than , the average length of routing path of OSPF with recovery mechanism and GPSR routing almost keep the same; this is because the incorrect forwarding capability query results rarely occur when the false positive rate bound is less than . With the increase of false positive rate bound, the average length of routing path also increases, which resulted from the increased possibility of the routing protocol triggering a recovery mechanism [17] of OSPF and Planar Perimeters mode [18] of GPSR to reach the destination via longer path. For example, comparing the cases of false positive rate bound of and , the average length of routing path of OSPF and GPSR is stretched about and . The above results demonstrate that the routing path of bloom filter-based secure forwarding scheme is not stretched obviously when the appropriate false positive rate bound is selected. Furthermore, the average length of GPSR routing is still larger than that of OSPF routing, even when the recovery mechanism of OSPF is usually activated; this is because the GPSR routing wastes more routing path on detouring the void.
Impact of false positive rate bounds on average forwarding hops.
Impact of the Average Number of Neighbors. The average length of routing path of different schemes is also impacted by the average number of neighbors of an entity. Figure 12 shows the average length of routing path of different schemes with different number of neighbors, where the false positive rate bound is . When the average number of neighbors increases from 20 to 30, the average length of routing path of the three schemes is also decreased. The decreasing rate of GPSR is faster than OSPF with bloom filter-based E2E deliverable set; this is because the fact that probability of void is decreased quickly with increase of number of neighbors.
Impact of average of number of neighbors on average forwarding hops.
6. Related Work
Two important research topics are involved in this work: secure aware routing and bloom filter application in computer systems. We briefly survey the related works of these two topics in this section.
6.1. Secure Aware Routing
Existing research efforts on security aware routing can be classified into two categories: security reactive routing and security proactive routing [20].
The security reactive routing protocols obtain the necessary security path when required, by using a connection establishment process, which are typical for mobile networks. Many of the existing security reactive routing protocols have been extended from Ad Hoc On-Demand Distance Vector (AODV) routing and Dynamic Source Routing protocol (DSR) routing, such as SAR [9], TQOS [21], Castor [22], Usor [23], THMR [24], and RMR [25]. Security Aware Ad Hoc Routing (SAR) protocol [9] is the most typical one, which adopts trust levels (a security attribute assigned to nodes) to make secure routing decisions. SAR can discover a path consisted of the node that can provide the required security level. TQOS [21] and RMR [25] select the trustworthiness-based quality of service and space reliability as the security metrics to build the security path for defending the attack launched by malicious nodes. THMR [24] focuses on solving the topology-exposure problem to defend against the attacks with a low overhead and short routing convergent time.
The security proactive routing protocols maintain the network topology in the form of routing tables by periodically exchanging security routing information. SEAD [26] and SLSP [27] are two typical security proactive routing protocols. SEAD uses a one-way hash function for authenticating to distinguish update messages that are received from nonmalicious nodes and malicious nodes. SLSP is a secure link state protocol, which adopts one-way hash function and a public key cryptosystem to ensure the security of link state updates.
Our work is the first attempt to efficiently represent amount of secure state information to achieve storage efficiency, quick query, and easy to maintain requirements, which is compatible with existing secure aware routing protocols.
6.2. Bloom Filter Application in Computer Network
Bloom filter is a space-efficient data structure that supports set membership queries with constant delay; therefore, bloom filters and its variants have been widely used in computer network and distribution system [28, 29], such as packet forwarding, information-guided routing, and supporting security operations.
Bloom filters are very useful tools for fast packet forwarding. A bloom filter-based longest-prefix matching algorithm is introduced in [30]. The basic idea is to determine the longest matching prefix membership in sets of prefixes sorted by prefix length via parallel queries of bloom filters and then look up the routing results in a large hash table directly. Yu et al. propose the BUFFALO architecture, which uses a small SRAM to store one bloom filter of the addresses to perform the flat address lookup in the data-center network [31]. Duquennoy et al. adopt the bloom filter to store the knowledge of the subtree of the nodes for routing protocol for low-power and lossy networks with tree topology [17]. Different from these works, we focus on using one bloom filter to store secure forwarding information in CPS.
Bloom filters have also been used for information-guided routing [32–34], which adopt bloom filter-based probabilistic algorithms to locate the objects. Kumar et al. introduce exponentially decaying bloom filter in [35], which is a representation of a set of objects of nodes. The basic idea is that the nodes propagate its object information in bloom filter with exponentially decay within the given range. Meanwhile, each node can obtain the incomplete object information of the other nodes via the union of all received bloom filters. Then, the query results of bloom filter of nodes can be used to guide the random walk to locate the objects. Using the similar design, Acer et al. present the weak state routing for large and dynamic networks [33]. Our "link-based bloom filter construction" scheme is similar to their basic idea of utilizing the union operation of bloom filter to obtain the object information of neighboring nodes. Different from decay model, we utilize the link security label to filter the elements to be inserted into the link bloom filter, which can avoid the entity bloom filter becoming a vector of ones.
Bloom filters have also been used for supporting security operations, such as flow admission [36] and attack detection [36–38]. To achieve immediate broadcast authentication and avoid the security vulnerability, Ren et al. propose an efficient public-key-based schemes integrating bloom filters with partial message recovery signatures and Merkle hash trees [36]. To detect the bogus sensing reports in wireless sensor networks, Ye et al. propose a bloom filter-based statistical en-route filtering approach to detect and drop such false reports [37]. In [38], Shieh et al. adopt bloom filter to detect the replay attacks in the Trickles stateless network stack and transport protocol. Different from these works, we adopt bloom filter to represent the forwarding capability in a space-efficient way, which can assist entities to find an appropriate secure data forwarding path with a constant delay. The bloom filter-based deliverable set representation scheme can be added to the other secure routing protocols of CPS as the access control middleware.
In this paper, we design a practical secure data forwarding scheme for large-scale cyber-physical systems based on the multiattribute and multilevel security requirements, in which the secure forwarding capability information of each entity is represented as a bloom filter. We derived the optimal size of bloom filter and corresponding query delay. Furthermore, we design a novel link-based bloom filter construction method to control the false positive rate of the constructed bloom filter. Finally, the impact of false positive rate bound of forwarding capability query on the average length of secure routing path is investigated. The space-efficiency and comparable query delay of proposed scheme with bloom filter are verified through simulations.
The authors declare that there is no conflict of interests regarding the publication of this paper.
This work was partly supported by the Fundamental Research Funds for the Central Universities (no. 2015RC032), the National Natural Science Foundation of China (no. U1334202, no. U1261109, and no. 61201201), the Key Grant Project of Chinese Ministry of Education (no. 313006), the State Key Laboratory of Rail Traffic Control and Safety (no. RCS2015 K011 and no. RCS2014ZT31), and the Program for New Century Excellent Talents in University (no. NCET-13-0657).
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Copyright © 2015 Siyu Lin and Hao Wu. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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text:
Q: Swift: how to convert argument to argument name string? In order to do logging nicely, I want to know how to convert argument to argument name string In Swift.
I already know Logging Method signature using swift.
I want to know how to log function argument as it is , following its value?

PS: I want to create a Util method helping logging.
func printMore(objName: Any){
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}

the print("objName:..., I want the 'objName' injected automatically.
Suck as conditions:
let foo = "Sark"
print("foo: \(foo)")

PPS: It is about Swift runtime. After I alloc some memory, I create some objects, how to get them through runtime instead of hard coding.

A: Hm, if you called next method inside your function, it shows method declaration with all parameters:
func testFunction(param1: String, param2: String) {
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}

testFunction(param1:param2:)

A: Write C .

U have to release it youself

object.description

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The Grenztruppen der DDR (Border Troops of the GDR) was headquartered out of Pätz, a small village southeast of Berlin near Königswusterhausen. The Grenztruppen forces were divided into four regional commands The first regional command was Grenzkommando Nord or GKN (Border Command North), with its headquarters located at Stendal and was responsible for the northern sector of the East German border. The GKN consisted of six frontier troops regiments, two training regiments, a helicopter flight and some smaller support units. The second command was The Grenzkommando Süd or GKS (Border Command South) with its headquarters located at Erfurt and it was tasked with guarding the southern border sector. The organizational structure of the GKS was similar to that of the GKN, with six regiments of frontier troops, two training regiments, a helicopter flight and some smaller support units. The third command was The Grenzkommando Mitte or GKM (Border Command Center) headquartered in Berlin-Karlshorst. Grenzkommando Mitte was responsible for manning the crossing points into West Berlin and guarded the entire border perimeter surrounding West Berlin. The GKM consisted of six regiments of frontier troops, one border crossing point regiment, two training regiments, an artillery regiment and some smaller support units. The fourth and final command was The Grenzkommando Küste or GKK (Coastal Border Command) headquartered in Rostock, deployed a coastal brigade (Grenzbrigade Küste) consisting of twelve marine battalions and several boat battalions and companies to guard the GDR's relatively small coastline along the Baltic Sea. For command-and-control purposes, the GKK was incorporated into East Germany's Volksmarine.
The fortifications of the inner German border was comprised of a complex system of interlocking fortifications and security zones 1,381 kilometres (858 mi) long and several kilometres deep, running the length of East Germany's territory from the Baltic Sea to Czechoslovakia. The outer fences and walls were the most familiar and visible aspect of the system for Western visitors to the border zone, but they were merely the final obstacle for a would-be escapee from East Germany. The complexity of the border system increased steadily until it reached its full extent in the early 1980s. Travelling nominally from east to west, a potential defector would first reach the edge of the restricted zone (Sperrzone), a closely controlled strip of land 5 kilometres (3.1 mi) wide, running parallel with the border. Evading the patrols and watchful inhabitants of the Sperrzone, the escapee would have reached the first of the border fences. The signal fence (Signalzaun), around 500 to 1,000 metres (1,600 to 3,300 ft) from the actual border, was lined with low-voltage electrified barbed wire which activated alarms when touched or cut.
Beyond the signal fence was the "protective strip" (Schutzstreifen). It was brightly lit by floodlights in many places to reduce an escapee's chances of using the cover of darkness. Guard towers, bunkers and dog runs were positioned at frequent intervals to keep a round-the-clock watch on the strip. Crossing the Schutzstreifen, the escapee would next reach the floodlit control strip, often called the "death strip" in the West. Tripwire-activated flare launchers were situated at various points to help the border guards to pinpoint the location of an escape attempt. The last and most formidable obstacle was the outer fencing. In some places there were multiple parallel rows of fences, each up to several metres high, with dense minefields in between. The fences were not electrified but were booby-trapped with directional anti-personnel mines at intervals of 10 metres (33 ft), each one of which was capable of killing at a range of up to 120 metres (390 ft). Finally, the escapee had to cross whatever natural obstacles were on the western side of the border fence as well as traversing a strip of cleared ground that was up to 500 meters (1640 ft) wide. While crossing this outer strip, the escapee would appear in clear view and shooting range of the border guards before reaching the safety of West German territory.
An East German Mil Mi-24 Hind D gunship helicopter patrolling the border region with West Germany.
In its efforts to effectively patrol and police the sensitive border region with the West, the Grenztruppen der DDR maintained its own fleet of helicopters with multiple Grenzflieger (Border Flying) units operating a number of helicopters to provide aerial surveillance in support of border protection operations. The Grenzflieger service operated three squadrons of helicopters, a squadron of Mil Mi-24 Hind D gunship helicopters out of Steinheid, a squadron of Mil Mi-8T Hip utility helicopters out of Kreuzebra and another squadron of Mil Mi-24 Hind D gunships out of Meiningen.
The uniform displayed here is of a Feldwebel (Sergeant) in the Grenzflieger service of the Grenztruppen der DDR (Border Troops of the German Democratic Republic). Grenzflieger uniforms were made of a different material than standard NVA uniforms being made from wool rather than the standard gabardine material.
The visor cap shown here for a non commissioned officer in the Grenztruppen der DDR's Grenzflieger service. It retains the stone grey color of National Volksarmee uniforms along with its associated dark green piping of the Grenztruppen der DDR but also note the distinctive Air Force propeller in wreath insignia of the flying service. Note the distinctive Air Force style variant of the national insignia with the Hammer and Compass roundel encircled within a wreath with wings extending from it and in being a non commissioned officer's visor there is no silver braiding only a black plastic capband.
Note the interior marking of NVA for the East German National Volksarmee. This visor example shown here carries a letter 'H' designation meaning the visor was manufactured in 1984. The size of this example is 59cm or 7 3/8in by American sizing equivalents.
Shown here is the Kragenspiegeln (Collar Insignia) of a Grenztruppen Grenzflieger non commissioned officer. It is essentially air force style collar tabs with a pair of wings against a green fabric patch of the Grenztruppen service. Also note the silver collar tress of a senior Non Commissioned Officer grade.
Shown here is a close up of the shoulderboard insignia for a Feldwebel in the Grenztruppen Grenzflieger service with the silver tress of a Senior Non Commissioned Officer around the border of the board along with the single silver pip of a Feldwebel. A Feldwebel is essentially the equivalent of a Staff Sergeant in American Army equivalents or a Sergeant in the British Army.
Shown here on the right side of the dress tunic is are the decorations of an enlisted man or a non commissioned officer. Displayed here is the Schutzenschnür (shooting lanyard) of the Grenztruppen. The East German Armed Forces maintained multiple variations of the shooting lanyard for varying specialties of the military including armored forces, infantry, rocket/artillery troops and the Grenztruppen. Also displayed on the uniform is the Grenztruppen Bestenabzeichen (Best Soldier Badge), Grenztruppen Klassifizierungsabzeichen (Classification Badge) similar to the West German system of Tätigkeitsabzeichen and finally an NVA Militärsportabzeichen (NVA Sports Badge).
Here is a close up of the silver Grenztruppen device on the Schutzenschnür. It displays an AK-47 assault rifle against an East German border marker surrounded by a pair of oak leaves. It then is attached to a silver colored cord which is mounted first to the button on the right shoulder underneath the shoulderboard and the end of the lanyard attached to the top button on the uniform tunic.
Here is a picture of the Grenztruppen Bestenabzeichen (Best Soldier Badge) in 4th Class. It is essentially a gold AK-47 barrel with attached bayonet against a green background the color of the Grenztruppen. Across the top is the word 'Bester' (Best) and across the bottom are a pair of oak leaves and the number 4, representing the fourth class of the award.
Displayed here is the Grenztruppen Klassifizierungsabzeichen (Classification Badge) in 3rd Class with an AK-47 assault rifle against an East German border marker in gold against a green center, surrounded by a pair of oak leaves and the East German coat of arms with a hammer and compass at the top and the number 3 for the third class of the badge and essentially wings protruding from the ends of the central round.
Here is the NVA Militärsportabzeichen (NVA Sports Badge) essentially an Oval-shaped gold pin-back badge with a flag design featuring the letters "NVA" for the National Volksarmee (National Peoples Army) rimmed by the state motto 'Für den Schutz der Arbeiter und Bauern Macht' (For the Protection of the Workers' and Farmers' Power) and national coat of arms of East Germany.
Again shown here is a close up of the cuff title of the Grenztruppen der DDR sewn against the left sleeve of the tunic.
The interior of the Grenzflieger service tunic displaying the NVA stamp.
Displayed here is the gray dress shirt issued to regular soldiers in the armed forces for wearing underneath the uniform tunic along with the dark grey NVA tie and the stone grey trousers worn by the Grenztruppen. As these are a different material than the standard gabardine, and the soldier is not an officer there is no colored striping down the length of the pant leg. On certain occasions the jacket could be removed and this variant of the uniform worn. All shirts in the East German government had loops on the shoulder for mounting rank shoulderboards when not wearing the jacket. In summer and warm climates, the tie could be removed and the shirt collar worn open.
The stone grey service trousers worn by NVA and Grenztruppen personnel this example of the matching wool material of Grenzflieger non commissioned officer uniforms.
Here is a close up of the black leather belt worn around the waist of the service tunic. It is similar to the belts worn around the waist of the tunics on Bundeswehr uniforms however this belt features a silver metal buckle with the East German coat of arms in the center. Adjusting the belt to size was made possible by sliding access through the underside of the buckle and secured using two metal prongs which secured through holes in the belt.
Displayed here is a close up of the silver buckle if the belt. This belt was issued to all NVA service members. .
It was not uncommon for Grenzflieger aviation units to encounter western aircraft patrolling along the border and essentially shadowing them mimmicking the altitude and attitudes of Western aircraft. There was atleast one report of a Hind gunship shadowing a U.S. Army AH-1 Huey Cobra along the border region and the Cobra pulled into a hover and turned to face the enemy aircraft however when the Hind tried the same maneuver, the Soviet designed aircraft being heavier and less agile was unable to handle such a maneuver and crashed into the dense forest below. In extensive measures often taken by the East German communist regime, the following day patrolling Western aircraft flew along the area of the crash observing into the East only to find the crash site had been policed with the debris removed and all the scorched landscape painted green as if the incident never happened.


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McLaren P1 hypercar celebrates half a decade in pole position
28 September 2017 | 0 comments
Five years ago, at 1745hrs BST on Thursday September 27, the car built to achieve this ambition was unveiled as a design study at the 2012 'Mondial de l'Automobile' in Paris. Five months later, the production version debuted at the 2013 Geneva International Motor Show.
Leveraging five decades of McLaren motorsport experience and its deep knowledge of road car engineering, the McLaren P1 represented both the birth of the McLaren Ultimate Series and a quantum leap in technology that delivered previously unknown levels of performance in a road car.
"The McLaren P1 is the most exciting, capable and dynamically accomplished supercar ever and a showcase for McLaren's innovation and technology. Absolute top speed was never the priority; we set out to develop a car that could be driven to a racing circuit and at the press of a button be the fastest-ever series production car on the track, which is a much more important technical statement and of far greater relevance to on-road driving."
Mike Flewitt, Chief Executive Officer, McLaren Automotive
Sell-out success
The full production run of 375 cars was sold and allocated before the first was even delivered, such was the insatiable demand for the McLaren P1™. No two examples of the McLaren P1™ were the same; each was custom-built to owner-specification in consultation with McLaren Special Operations (MSO). The cost of MSO features was additional to the £866,000 price of the car.
Outstanding aerodynamics
Aerodynamic performance was prioritised from the outset of the McLaren P1's development. Using CFD (computational fluid dynamics) aerodynamic modelling and wind tunnel testing, McLaren designers engineered a car that produces an astonishing 600kg of downforce at well below its electronically limited maximum speed of 217mph (350km/h).
A Formula 1-style DRS (drag reduction system) helps to achieve the downforce, with the pitch of the rear wing changing to reduce drag and increase straight-line speed. The wing can also operate at an even steeper angle, as an airbrake.
In addition to the active, adjustable rear wing, the aerodynamic performance of the McLaren P1™ is optimised using two flaps mounted under the body, ahead of the front wheels. The flaps change angle automatically to increase downforce and aero efficiency, boosting driver confidence as well as speed.
Dedication to reducing weight
Optimising weight while ensuring maximum strength and rigidity was a development imperative for the McLaren P1™ and is reflected in every aspect of the design. The dry weight of the car is just 1,395kg (3,075lbs).
The McLaren P1™ is based around a McLaren MonoCage, a carbon fibre structure that weighs just 90kg yet provides outstanding rigidity and safety while also guiding air into the car's engine through an integral roof 'snorkel' and air intake ducts.
To keep weight down, all five main body panels that comprise the McLaren P1™ are made from carbon fibre. A further 1.5kg was saved by omitting the top layer of resin from interior carbon fibre components. The fixed-back, carbon fibre-shelled race seats weigh just 10.5kg each.
Super-lightweight glass for both roof and windscreen – respectively just 2.4mm and 3.2mm thick – saves 3.5kg over conventional glass. The lightweight brakes are 4kg lighter than a comparable 'standard' braking system.
The focus on weight was such that the original specification of the McLaren P1™ did not feature sound-deadening material or even carpet in the cabin.
Extreme hybrid performance
The hybrid, petrol-electric IPAS (Instant Power Assist System) powertrain of the McLaren P1 set new standards for innovation and performance when the car was introduced. A modified version of McLaren's 3.8-litre twin-turbo V8 petrol engine, tuned to develop 737PS (727bhp) combined with a lightweight electric motor producing 179PS (176 bhp) – more than double the power of the KERS unit used in Formula 1 at the time – to give the McLaren P1™ astonishing performance.
Together, the petrol engine and electric motor produced 916PS (903bhp), resulting in acceleration of 0-100km/h (62mph) in 2.8 seconds; 0-200km/h (124mph) in 6.8 seconds and 0-300km/h (186mph) in 16.5 seconds – a full five seconds quicker than the legendary McLaren F1.
The instant response of the electric motor provides sharper throttle response more usually associated with a normally aspirated petrol engine. It also helps to deliver quicker upshifts by applying negative torque to allow engine revs to fall more rapidly. When off-throttle and under deceleration, energy that would have otherwise been lost is recovered to the battery by the motor.
The battery for the IPAS weighs just 96kg and is mounted low down, on the underbody of the chassis. The McLaren P1 can drive solely on its electric motor for up to 10km (6 miles) on the NEDC (New European Driving Cycle), allowing the car to be used in low emission zones and for urban driving with near-silent running. McLaren P1™ CO2 emissions overall are just 194g/km.
"The McLaren P1 was designed to be the best driver's car in the world and epitomises the pioneering spirit, innovation and driving excitement that is McLaren. A hybrid powertrain was key to its success and with an increasing number of our customers demanding the ultimate in both performance and technology, the learnings from the McLaren P1™ are helping to develop the next generations of cars that will be introduced under the McLaren Track22 business plan."
Jolyon Nash, McLaren Automotive Executive Director, Global Sales & Marketing
Rigorous test programme
The McLaren P1 underwent the same rigorous development and testing regime as any McLaren car, with a total of 620,000km (385,250 miles) driven on road and track – equivalent to 15.5 times around the world.
Cold weather trials took place on frozen lakes in northern Sweden during an Arctic winter at temperatures as low as minus 30˚C. The Experimental Prototype (XP) cars were then taken to the desert heat of Arizona, California and Nevada, where temperatures soared as high as 52°C as the western coast of The United States experienced some of the hottest temperatures on record.
The focus on durability, refinement and performance during the development programme also saw the McLaren P1 tested extensively on race circuits around the world, including at the famous Nürburgring-Nordschleife, where the car achieved its target lap time of less than seven minutes.
The McLaren P1TM GTR
The McLaren P1 spawned an even more limited volume, track-only version, the McLaren P1 GTR. Resurrecting the model name that adorned the Le Mans-winning F1 GTR in 1995, the McLaren P1™ GTR made its global debut in production form at the 2015 Geneva International Motor Show. The car boasts a power-to-weight ratio of more than 700PS per tonne, an increase of more than 10 per cent over the road-going McLaren P1.
Track-optimisation of the petrol-electric powertrain produced maximum power of 1000PS (986bhp). The McLaren P1 GTR features further weight-saving measures and enhancements to the aerodynamics, driving dynamics and handling balance. The wing mirrors were repositioned to the A pillars to put them closer to the eye line of the driver and reduce aerodynamic drag. The car sits at a fixed ride height, on race-prepared suspension and motorsport alloy wheels. An all-new, titanium alloy, straight-cut, twin-pipe exhaust system was designed exclusively for the McLaren P1 GTR.
Available only to McLaren P1 owners, the track-focused GTR began production upon completion of the 375th and final road car.
Buyers of the McLaren P1 GTR were invited to participate in an exclusive driver training programme that saw them experience some of the world's most iconic racing circuits, behind the wheel of one of the most extreme limited-production track cars ever built.
McLaren P1 facts at a glance
-The McLaren P1 accelerates from standstill to 300km/h (186mph) in 16.5 seconds – a full 5.5 seconds quicker than the legendary McLaren F1
-The adjustable rear wing of the McLaren P1™ extends from the bodywork by up to 120mm on the road and up to 300mm on a track
-Carbon ceramic discs coated in silicon carbide bring the McLaren P1 to standstill from 100km/h (62mph) in just 30.2 metres
-The McLaren P1 zero-emissions range in full electric mode is more than 10km (6.8 miles)
-In Race mode, the McLaren P1 lowers by 50mm and the spring rates stiffen by 300 per cent, allowing the car to corner at more than 2g
-The Formula 1-style Inconel exhaust follows the most direct route from the engine to the back of the McLaren P1™ and weighs just 17kg
-The steering wheel diameter of a McLaren P1 is as technically precise as a wheel used by McLaren racing drivers: the hand grips of McLaren Formula 1 World Champions were modelled on a CAD system during development and scanned to produce an exact replica
-Each McLaren P1 was custom-built by a team of 82 technicians in a four-stage assembly process. From start to finish, the build of each car took 17 days
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