| public abstract DecryptKeyExchange ( byte keyEx ) : byte[] | ||
| keyEx | byte | The key exchange data within which the secret information is hidden. |
| return | byte[] | |
public static byte[] SHAHashXorSecret(HashAlgorithm hasher, DiffieHellman dh, byte[] keyEx, byte[] encMacKey) {
byte[] dhShared = dh.DecryptKeyExchange(keyEx);
byte[] shaDhShared = hasher.ComputeHash(ensurePositive(dhShared));
if (shaDhShared.Length != encMacKey.Length) {
throw new ArgumentOutOfRangeException(string.Format(CultureInfo.CurrentCulture,
"encMacKey's length ({0}) does not match the length of the hashing algorithm ({1}).",
encMacKey.Length, shaDhShared.Length));
}
byte[] secret = new byte[encMacKey.Length];
for (int i = 0; i < encMacKey.Length; i++) {
secret[i] = (byte)(encMacKey[i] ^ shaDhShared[i]);
}
return secret;
}
/// <summary>
/// Encrypts/decrypts a shared secret.
/// </summary>
/// <param name="hasher">The hashing algorithm that is agreed by both parties to use as part of the secret exchange.</param>
/// <param name="dh">
/// If the secret is being encrypted, this is the new Diffie Hellman object to use.
/// If the secret is being decrypted, this must be the same Diffie Hellman object used to send the original request message.
/// </param>
/// <param name="remotePublicKey">The public key of the remote party.</param>
/// <param name="plainOrEncryptedSecret">The secret to encode, or the encoded secret. Whichever one is given will generate the opposite in the return value.</param>
/// <returns>
/// The encrypted version of the secret if the secret itself was given in <paramref name="remotePublicKey"/>.
/// The secret itself if the encrypted version of the secret was given in <paramref name="remotePublicKey"/>.
/// </returns>
internal static byte[] SHAHashXorSecret(HashAlgorithm hasher, DiffieHellman dh, byte[] remotePublicKey, byte[] plainOrEncryptedSecret) {
Requires.NotNull(hasher, "hasher");
Requires.NotNull(dh, "dh");
Requires.NotNull(remotePublicKey, "remotePublicKey");
Requires.NotNull(plainOrEncryptedSecret, "plainOrEncryptedSecret");
byte[] sharedBlock = dh.DecryptKeyExchange(remotePublicKey);
byte[] sharedBlockHash = hasher.ComputeHash(EnsurePositive(sharedBlock));
ErrorUtilities.VerifyProtocol(sharedBlockHash.Length == plainOrEncryptedSecret.Length, OpenIdStrings.AssociationSecretHashLengthMismatch, plainOrEncryptedSecret.Length, sharedBlockHash.Length);
byte[] secret = new byte[plainOrEncryptedSecret.Length];
for (int i = 0; i < plainOrEncryptedSecret.Length; i++) {
secret[i] = (byte)(plainOrEncryptedSecret[i] ^ sharedBlockHash[i]);
}
return secret;
}
