3. (13 points) Money placed in the 1st month will be on deposit for 6 months and will bring a nominal income of $8700\left((1+0.06 / 12)^{\wedge}-1\right)=264.28$ rubles.

Funds placed in the 2nd month will be on deposit for 5 months and will bring a nominal income of $8700\left((1+0.06 / 12)^{\wedge} 5-1\right)=219.69$ rubles.

Similarly in the following months:

$8700\left((1+0.06 / 12)^{\wedge} 4-1\right)=175.31$ rubles.

$8700\left((1+0.06 / 12)^{\wedge} 3-1\right)=131.15$ rubles.

$8700\left((1+0.06 / 12)^{\wedge} 2-1\right)=87.22$ rubles.

$8700((1+0.06 / 12)-1)=43.5$ rubles.

Thus, the nominal income for 6 months will be:

$264.28+219.69+175.31+131.15+87.22+43.5=921.15$ rubles.

## Maximum 25 points

## Problem 5

Mobile applications can significantly improve the convenience of paying for services and goods. Imagine that you are developing a mobile internet banking application where users can pay for services of various organizations with their bank card.

List at least 3 security measures that you should implement to protect users of the application from theft of money from their bank card.

#
# Response:

The following security measures can be implemented:

- Use of two-factor authentication when launching the application, i.e., in addition to login|password, require the input of a one-time password from an SMS or token.
- Use of two-factor authentication for payment services, including conducting payments through a specialized payment gateway that supports 3-D Secure technology;
- Ensuring encryption of all data stored by the application (including the user's full name, card number);
- Encrypting data during transmission between the user-side application and the bank's server infrastructure;
- Implementing a fraud protection system (anti-fraud) on the server-side infrastructure of the bank;
- Ensuring obfuscation and other code protection measures to prevent a malicious actor from injecting additional functionality into the application, such as sending a copy of processed data to a remote server controlled by the hacker;
- Prohibiting the installation of the application on user-unlocked devices (so-called root access), as this significantly reduces the security level of all installed applications;
- Including an antivirus agent in the application (as the Sberbank application does by default).

## Maximum 15 points

## Criteria: