Most of cryptographic systems require a sufficient key size to be robust against brute-force attacks.

NIST recommendations will be checked:

Use / Algorithm DSA RSA ECDSA DH MQV ECDH ECMQV Block Cipher
Digital Signature Generation p ≥ 2048 AND q ≥ 224 n ≥ 2048 See table below x x x x x
Digital Signature Verification p ≥ 2048 AND q ≥ 224 n ≥ 2048 See table below x x x x x
Key Agreement x x x p ≥ 2048 AND q ≥ 224 p ≥ 2048 AND q ≥ 224 See table below See table below x
Encryption and Decryption x x x x x x x AES-128, 192, 256

This rule will not raise issues for ciphers that are considered weak (no matter the key size) like DES, Blowfish.

h3. Notation
* DSA ([Digital Signature Algorithm		 https://en.wikipedia.org/wiki/Digital_Signature_Algorithm]): p is key length and q the modulus length
* EC ([Elliptic-curve		 https://en.wikipedia.org/wiki/Elliptic-curve_cryptography])
 EC parameters EB EC ED EE
Length of n 224-255 256-383 384-511 512+
 Maximum bit length of cofactor h 14 16 24

Noncompliant Code Example

KeyPairGenerator keyPairGen1 = KeyPairGenerator.getInstance("RSA");
keyPairGen1.initialize(1024); // Noncompliant

KeyPairGenerator keyPairGen5 = KeyPairGenerator.getInstance("EC");
ECGenParameterSpec ecSpec1 = new ECGenParameterSpec("secp112r1"); // Noncompliant
keyPairGen5.initialize(ecSpec1);

KeyGenerator keyGen1 = KeyGenerator.getInstance("AES");
keyGen1.init(64); // Noncompliant

Compliant Solution

KeyPairGenerator keyPairGen6 = KeyPairGenerator.getInstance("RSA");
keyPairGen6.initialize(2048); // Compliant

KeyPairGenerator keyPairGen5 = KeyPairGenerator.getInstance("EC");
ECGenParameterSpec ecSpec10 = new ECGenParameterSpec("secp224k1"); // compliant
keyPairGen5.initialize(ecSpec10);

KeyGenerator keyGen2 = KeyGenerator.getInstance("AES");
keyGen2.init(128); // Compliant

See