Default key sizes for the AlgorithmParameterGenerator and KeyPairGenerator implementations should be upgraded

The default key size for the RSA and DiffieHellman AlgorithmParameterGenerator and KeyPairGenerator implementations should be increased from 1024 bits to 2048 bits.

The key size for the DSA AlgorithmParameterGenerator and KeyPairGenerator implementations is not yet being increased from 1024 to 2048 bits. This is due to concerns that the larger key sizes may be incompatible with the SHA1withDSA signature algorithm (which could break existing code), and also because some native pkcs11 implementations such as NSS and Solaris do not yet support SHA-2 signature algorithms for DSA.