Overview

To test for the use of broken encryption algorithms in iOS apps, we need to focus on APIs from cryptographic frameworks and libraries that are used to perform encryption and decryption operations.

Note: the Security framework only supports asymmetric algorithms and is therefore out of scope for this test (see note about symmetric keys).

Steps

  1. Use MASTG-TECH-0058 to extract the relevant binaries from app package.
  2. Use MASTG-TECH-0066 to look for the relevant APIs in the app binaries.

Observation

The output should contain the disassembled code of the functions using the relevant cryptographic functions.

Evaluation

The test case fails if you can find the use of broken encryption algorithms within the source code. For example:

Further Validation Required:

Inspect each reported code location using MASTG-TECH-0076 to determine whether the algorithm is used in a security-relevant context to protect sensitive data.

This applies to Apple-provided APIs (e.g., CommonCrypto), third-party libraries (e.g., OpenSSL, Libsodium) and any custom implementations of cryptographic routines that replicate insecure algorithms (e.g., DES in C code) or use insecure configurations (e.g., ECB mode, short key sizes).

Stay up-to-date: This is a non-exhaustive list of broken algorithms. Make sure to check the latest standards and recommendations from organizations such as the National Institute of Standards and Technology (NIST), the German Federal Office for Information Security (BSI) or any other relevant authority in your region.

Some algorithms may not be considered broken as a whole, but may have risky configurations that should be avoided. For example, using a seed or IV that is not generated by a cryptographically secure pseudorandom number generator (CSPRNG) or that is not considered quantum-safe. For instance, an AES 128-bit key size is insufficient in the face of quantum computing attacks. This is important when building an app that uses data that will be stored for a long time. Make sure you follow the NIST recommendations from NIST IR 8547 "Transition to Post-Quantum Cryptography Standards", 2024.