public static AsymmetricAlgorithm GetPublicKeyAlgorithm(this X509Certificate2 certificate)
{
if (certificate == null)
{
throw ExceptionUtility.ArgumentNull("certificate");
}
var cspObject = new Asn1.Common.GostKeyExchangeParameters();
cspObject.DecodeParameters(certificate.PublicKey.EncodedParameters.RawData);
cspObject.DecodePublicKey(certificate.PublicKey.EncodedKeyValue.RawData);
var cspBlobData = CryptoApiHelper.EncodePublicBlob(cspObject);
var publicKey = new Gost3410AsymmetricAlgorithm();
publicKey.ImportCspBlob(cspBlobData);
return(publicKey);
}
private static Asn1.Common.GostKeyExchangeParameters DecodePublicBlob(byte[] encodedPublicBlob)
{
if (encodedPublicBlob == null)
{
throw ExceptionUtility.ArgumentNull("encodedPublicBlob");
}
if (encodedPublicBlob.Length < 80)
{
throw ExceptionUtility.CryptographicException(Constants.NTE_BAD_DATA);
}
var gostKeyMask = BitConverter.ToUInt32(encodedPublicBlob, 8);
if (gostKeyMask != Constants.GR3410_1_MAGIC)
{
throw ExceptionUtility.CryptographicException(Constants.NTE_BAD_DATA);
}
var gostKeySize = BitConverter.ToUInt32(encodedPublicBlob, 12);
if (gostKeySize != 512)
{
throw ExceptionUtility.CryptographicException(Constants.NTE_BAD_DATA);
}
var publicKeyParameters = new Asn1.Common.GostKeyExchangeParameters();
var encodeKeyParameters = new byte[(encodedPublicBlob.Length - 16) - 64];
Array.Copy(encodedPublicBlob, 16, encodeKeyParameters, 0, (encodedPublicBlob.Length - 16) - 64);
publicKeyParameters.DecodeParameters(encodeKeyParameters);
var publicKey = new byte[64];
Array.Copy(encodedPublicBlob, encodedPublicBlob.Length - 64, publicKey, 0, 64);
publicKeyParameters.PublicKey = publicKey;
return(publicKeyParameters);
}
