An issue was discovered in Mbed TLS before 3.6.6 and 4.x before 4.1.0 and TF-PSA-Crypto before 1.1.0. There is a Predictable Seed in a Pseudo-Random Number Generator (PRNG).
Weakness
The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG’s algorithm is not cryptographically strong.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Mbed_tls | Arm | * | 3.6.6 (excluding) |
| Tf-psa-crypto | Trustedfirmware | * | 1.1.0 (excluding) |
| Mbedtls | Ubuntu | esm-apps/xenial | * |
Extended Description
When a non-cryptographic PRNG is used in a cryptographic context, it can expose the cryptography to certain types of attacks. Often a pseudo-random number generator (PRNG) is not designed for cryptography. Sometimes a mediocre source of randomness is sufficient or preferable for algorithms that use random numbers. Weak generators generally take less processing power and/or do not use the precious, finite, entropy sources on a system. While such PRNGs might have very useful features, these same features could be used to break the cryptography.