private CngKeyBuilderImpl GetBuilderFor(Asn1Token.KnownOid oid)
{
switch (oid)
{
case Asn1Token.KnownOid.EcPublicKey:
return(new EllipticCurveCngKeyBuilder());
case Asn1Token.KnownOid.RsaEncryptionPkcs1:
return(new RsaCngKeyBuilder());
}
throw new UnsupportedCurveException("Unsupported key type with oid");
}
private static int GetMagicNumber(Asn1Token.KnownOid curve)
{
switch (curve)
{
case Asn1Token.KnownOid.AnsiX9P256R1:
return(0x31534345);
case Asn1Token.KnownOid.Secp384R1:
return(0x33534345);
case Asn1Token.KnownOid.Secp521R1:
return(0x35534345);
}
throw new UnsupportedCurveException("Unsupported elliptic curve domain");
}
private unsafe CngKey BuildEcKey(byte[] x, byte[] y, Asn1Token.KnownOid curve)
{
int headerSize = Marshal.SizeOf(typeof(BCRYPT_ECCKEY_BLOB));
int blobSize = headerSize + x.Length + y.Length;
byte[] blobBytes = new byte[blobSize];
fixed(byte *pBlobBytes = blobBytes)
{
BCRYPT_ECCKEY_BLOB *pBcryptEccBlob = (BCRYPT_ECCKEY_BLOB *)pBlobBytes;
pBcryptEccBlob->KeyBlobMagicNumber = GetMagicNumber(curve);
pBcryptEccBlob->KeySizeBytes = x.Length;
Buffer.BlockCopy(x, 0, blobBytes, headerSize, x.Length);
Buffer.BlockCopy(y, 0, blobBytes, headerSize + x.Length, y.Length);
}
new KeyContainerPermission(KeyContainerPermissionFlags.Import).Assert();
var key = CngKey.Import(blobBytes, CngKeyBlobFormat.EccPublicBlob);
CodeAccessPermission.RevertAssert();
return(key);
}
private static bool isSupportedCurve(Asn1Token.KnownOid curve)
{
return(curve == Asn1Token.KnownOid.AnsiX9P256R1 ||
curve == Asn1Token.KnownOid.Secp384R1 ||
curve == Asn1Token.KnownOid.Secp521R1);
}
