protected internal static Cipher InitCipherForBlock(Cipher cipher, int block,
IEncryptionInfoBuilder builder, ISecretKey skey, int encryptMode)
{
EncryptionVerifier ver = builder.GetVerifier();
HashAlgorithm hashAlgo = ver.HashAlgorithm;
byte[] blockKey = new byte[4];
LittleEndian.PutUInt(blockKey, 0, block);
MessageDigest hashAlg = CryptoFunctions.GetMessageDigest(hashAlgo);
hashAlg.Update(skey.GetEncoded());
byte[] encKey = hashAlg.Digest(blockKey);
EncryptionHeader header = builder.GetHeader();
int keyBits = header.KeySize;
encKey = CryptoFunctions.GetBlock0(encKey, keyBits / 8);
if (keyBits == 40)
{
encKey = CryptoFunctions.GetBlock0(encKey, 16);
}
ISecretKey key = new SecretKeySpec(encKey, skey.GetAlgorithm());
if (cipher == null)
{
cipher = CryptoFunctions.GetCipher(key, header.CipherAlgorithm, null, null, encryptMode);
}
else
{
cipher.Init(encryptMode, key);
}
return(cipher);
}
protected internal static Cipher InitCipherForBlock(Cipher cipher, int block,
IEncryptionInfoBuilder builder, ISecretKey skey, int encryptMode)
{
EncryptionVerifier ver = builder.GetVerifier();
HashAlgorithm hashAlgo = ver.HashAlgorithm;
byte[] blockKey = new byte[4];
LittleEndian.PutUInt(blockKey, 0, block);
byte[] encKey = CryptoFunctions.GenerateKey(skey.GetEncoded(), hashAlgo, blockKey, 16);
ISecretKey key = new SecretKeySpec(encKey, skey.GetAlgorithm());
if (cipher == null)
{
EncryptionHeader em = builder.GetHeader();
cipher = CryptoFunctions.GetCipher(key, em.CipherAlgorithm, null, null, encryptMode);
}
else
{
cipher.Init(encryptMode, key);
}
return(cipher);
}