internal static void ReadPkcs8Blob(this DerSequenceReader reader, ref DSAParameters parameters)
{
// Since the PKCS#8 blob for DSS/DSA does not include the public key (Y) this
// structure is only read after filling the public half.
Debug.Assert(parameters.P != null);
Debug.Assert(parameters.Q != null);
Debug.Assert(parameters.G != null);
Debug.Assert(parameters.Y != null);
// OneAsymmetricKey ::= SEQUENCE {
// version Version,
// privateKeyAlgorithm PrivateKeyAlgorithmIdentifier,
// privateKey PrivateKey,
// attributes [0] Attributes OPTIONAL,
// ...,
// [[2: publicKey [1] PublicKey OPTIONAL ]],
// ...
// }
//
// PrivateKeyInfo ::= OneAsymmetricKey
//
// PrivateKey ::= OCTET STRING
int version = reader.ReadInteger();
// We understand both version 0 and 1 formats,
// which are now known as v1 and v2, respectively.
if (version > 1)
{
throw new CryptographicException();
}
{
// Ensure we're reading DSA, extract the parameters
DerSequenceReader algorithm = reader.ReadSequence();
string algorithmOid = algorithm.ReadOidAsString();
if (algorithmOid != s_idDsa.Value)
{
throw new CryptographicException();
}
// The Dss-Params SEQUENCE is present here, but not needed since
// we got it from the public key already.
}
byte[] privateKeyBlob = reader.ReadOctetString();
DerSequenceReader privateKeyReader = DerSequenceReader.CreateForPayload(privateKeyBlob);
parameters.X = privateKeyReader.ReadIntegerBytes();
}
internal static void ReadSubjectPublicKeyInfo(
this DerSequenceReader algParameters,
byte[] publicKeyBlob,
ref DSAParameters parameters)
{
parameters.P = algParameters.ReadIntegerBytes();
parameters.Q = algParameters.ReadIntegerBytes();
parameters.G = algParameters.ReadIntegerBytes();
DerSequenceReader privateKeyReader = DerSequenceReader.CreateForPayload(publicKeyBlob);
parameters.Y = privateKeyReader.ReadIntegerBytes();
KeyBlobHelpers.TrimPaddingByte(ref parameters.P);
KeyBlobHelpers.TrimPaddingByte(ref parameters.Q);
KeyBlobHelpers.PadOrTrim(ref parameters.G, parameters.P.Length);
KeyBlobHelpers.PadOrTrim(ref parameters.Y, parameters.P.Length);
}
