Why is this an issue?
Strong cipher algorithms are cryptographic systems resistant to cryptanalysis, they
are not vulnerable to well-known attacks like brute force attacks for example.
A general recommendation is to only use cipher algorithms intensively tested and promoted by the cryptographic community.
More specifically for block cipher, it’s not recommended to use algorithm with a block size inferior than 128 bits.
Noncompliant code example
For System.Security.Cryptography library,
these old cryptographic algorithms should no longer be used for any reason:
var tripleDES1 = new TripleDESCryptoServiceProvider(); // Noncompliant: Triple DES is vulnerable to meet-in-the-middle attack
var simpleDES = new DESCryptoServiceProvider(); // Noncompliant: DES works with 56-bit keys allow attacks via exhaustive search
var RC2 = new RC2CryptoServiceProvider(); // Noncompliant: RC2 is vulnerable to a related-key attack
For Bouncycastle library, AESFastEngine has a side channel leak, it
is possible to gain information about the key used to initialize the cipher:
AesFastEngine aesFast = new AesFastEngine(); // Noncompliant
Compliant solution
For System.Security.Cryptography library,
it’s recommended to use AesCryptoServiceProvider:
var AES = new AesCryptoServiceProvider(); // Compliant
For Bouncycastle library, it’s recommended to use AESEngine:
var AES = new AESEngine(); // Compliant
Resources
