Software audit review
A software audit review, or software audit, is a type of software review in which one or more auditors who are not members of the software development organization conduct "An independent examination of a software product, software process, or set of software processes to assess compliance with specifications, standards, contractual agreements, or other criteria".

"Software product" mostly, but not exclusively, refers to some kind of technical document. IEEE Std. 1028 offers a list of 32 "examples of software products subject to audit", including documentary products such as various sorts of plan, contracts, specifications, designs, procedures, standards, and reports, but also non-documentary products such as data, test data, and deliverable media.

Software audits are distinct from software peer reviews and software management reviews in that they are conducted by personnel external to, and independent of, the software development organization, and are concerned with compliance of products or processes, rather than with their technical content, technical quality, or managerial implications.

The term "software audit review" is adopted here to designate the form of software audit described in IEEE Std. 1028.

Objectives and participants 

"The purpose of a software audit is to provide an independent evaluation of conformance of software products and processes to applicable regulations, standards, guidelines, plans, and procedures".  The following roles are recommended:

The Initiator (who might be a manager in the audited organization, a customer or user representative of the audited organization, or a third party), decides upon the need for an audit, establishes its purpose and scope, specifies the evaluation criteria, identifies the audit personnel, decides what follow-up actions will be required, and distributes the audit report.
The Lead Auditor (who must be someone "free from bias and influence that could reduce his ability to make independent, objective evaluations") is responsible for administrative tasks such as preparing the audit plan and assembling and managing the audit team, and for ensuring that the audit meets its objectives.
The Recorder documents anomalies, action items,  decisions, and recommendations made by the audit team.
The Auditors (who must be, like the Lead Auditor, free from bias) examine products defined in the audit plan, document their observations, and recommend corrective actions.  (There may be only a single auditor.)
The Audited Organization provides a liaison to the auditors, and provides all information requested by the auditors. When the audit is completed, the audited organization should implement corrective actions and recommendations.

Principles of a Software Audit 

The following principles of an audit should find a reflection:

 Timeliness:  Only when the processes and programming is continuous inspected in regard to their potential susceptibility to faults and weaknesses, but as well with regard to the continuation of the analysis of the found strengths, or by comparative functional analysis with similar applications an updated frame can be continued.
 Source openness:  It requires an explicit reference in the audit of encrypted programs, how the handling of open source has to be understood. E.g. programs, offering an open source application, but not considering the IM server as open source, have to be regarded as critical. An auditor should take an own position to the paradigm of the need of the open source nature within cryptologic applications.
 Elaborateness:  Audit processes should be oriented to certain minimum standard. The recent audit processes of encrypting software often vary greatly in quality, in the scope and effectiveness and also experience in the media reception often differing perceptions. Because of the need of special knowledge on the one hand and to be able to read programming code and then on the other hand to also have knowledge of encryption procedures, many users even trust the shortest statements of formal confirmation. Individual commitment as an auditor, e.g. for quality, scale and effectiveness, is thus to be assessed reflexively for yourself and to be documented within the audit.

 The financial context:  Further transparency is needed to clarify whether the software has been developed commercially and whether the audit was funded commercially (paid Audit). It makes a difference whether it is a private hobby / community project or whether a commercial company is behind it.
 Scientific referencing of learning perspectives:  Each audit should describe the findings in detail within the context and also highlight progress and development needs constructively. An auditor is not the parent of the program, but serves in a role of a mentor if the auditor is regarded as part of a PDCA learning circle (PDCA = Plan-Do-Check-Act). There should be next to the description of the detected vulnerabilities also a description of the innovative opportunities and the development of the potentials.
 Literature-inclusion:  A reader should not rely solely on the results of one review, but also judge according to a loop of a management system (e.g. PDCA, see above), to ensure, that the development team or the reviewer was and is prepared to carry out further analysis, and also in the development and review process is open to learnings and to consider notes of others. A list of references should be accompanied in each case of an audit.
 Inclusion of user manuals & documentation:  Further a check should be done, whether there are manuals and technical documentations, and, if these are expanded.
 Identify references to innovations:  Applications that allow both, messaging to offline and online contacts, so considering chat and e-mail in one application - as it is also the case with GoldBug - should be tested with high priority (criterion of presence chats in addition to the e-mail function). The auditor should also highlight the references to innovations and underpin further research and development needs.
This list of audit principles for crypto applications describes - beyond the methods of technical analysis - particularly core values, that should be taken into account

Tools 
Parts of Software audit could be done using static analysis tools that analyze application code  and score its conformance with standards, guidelines, best practices. From the List of tools for static code analysis some are covering a very large spectrum from code to architecture review, and could be use for benchmarking.

References

Software review