/// <summary>
/// Signs the plaintext message and returns the signature as an array of bytes.
/// </summary>
/// <param name="plainTextMessage">
/// Plaintext message to sign.
/// </param>
/// <returns></returns>
public byte[] SignMessage(string plainTextMessage)
{
if (this.PrivateKey == null)
{
throw new NullReferenceException(INVALID_PRIVATE_KEY_ERROR_MESSAGE);
}
RSAPKCS1SignatureFormatter RSAformatter = new RSAPKCS1SignatureFormatter(this.PrivateKey);
RSAformatter.SetHashAlgorithm(this.HashAlgorithm.ToString());
var hash = SimplerHasher.Hash(plainTextMessage, this.HashAlgorithm);
return(RSAformatter.CreateSignature(hash));
}
/// <summary>
/// Verify the plaintext message against the signature block.
/// </summary>
/// <param name="plainTextMessage"></param>
/// <param name="signatureBlock">
/// The signature block as an array of bytes.
/// </param>
/// <returns></returns>
public bool VerifySignature(string plainTextMessage, byte[] signatureBlock)
{
//Throw an exception for invalid keys.
if (this.PublicKey == null)
{
throw new NullReferenceException(INVALID_PUBLIC_KEY_ERROR_MESSAGE);
}
try
{
//Hash the plain text message.
var hash = SimplerHasher.Hash(plainTextMessage, this.HashAlgorithm);
//Compare it to the signature block.
var deformatter = new RSAPKCS1SignatureDeformatter(this.PublicKey);
deformatter.SetHashAlgorithm(HashAlgorithm.ToString());
return(deformatter.VerifySignature(hash, signatureBlock));
}
catch (Exception)
{
return(false);
}
}
