c# - libreria - Verificar la firma de BouncyCastle ECDsa con las bibliotecas.NET ECDsaCng

signature sha256 c#

Question

Un sistema existente generó firmas usando Bouncy Castle (.NET) y necesito verificar estas firmas existentes usando la clase Microsoft ECDsaCng.

Considere el siguiente código que intenta hacer esto:

 public static void InterchangeTest()
{
//AsymmetricCipherKeyPair bKeyPair_0 = Crypto.GenerateEcdsaKey();
String sPassPhrase = "bob is your uncle";
byte[] bPassPhrase = new UTF8Encoding(false).GetBytes(sPassPhrase);
int SaltBitSize = 128;
int EcdsaBitLength = 521;
byte[] bSalt = new byte[SaltBitSize / 8];
new SecureRandom().NextBytes(bSalt);
if (EcdsaBitLength != 192 && EcdsaBitLength != 256 && EcdsaBitLength != 521)
{
throw new ArgumentException("Invalid EcdsaBitLength length () " + EcdsaBitLength + " ECDSA supports 192, 256, and 521 bit lengths.");
}
string curveName = "P-" + EcdsaBitLength.ToString();
X9ECParameters ecP = NistNamedCurves.GetByName(curveName);
ECDomainParameters ecSpec = new ECDomainParameters(ecP.Curve, ecP.G, ecP.N, ecP.H, ecP.GetSeed());
IAsymmetricCipherKeyPairGenerator g = GeneratorUtilities.GetKeyPairGenerator("ECDH");
g.Init(new ECKeyGenerationParameters(ecSpec, new SecureRandom()));
AsymmetricCipherKeyPair aKeyPair = g.GenerateKeyPair();
ECPrivateKeyParameters mPrivateKey = (ECPrivateKeyParameters)aKeyPair.Private;
ECPublicKeyParameters mPublicKey = (ECPublicKeyParameters)aKeyPair.Public;
byte[] bPrivateKey = ((ECPrivateKeyParameters)aKeyPair.Private).D.ToByteArray();
String SignerName = "SHA-256withECDSA";
ISigner bSigner = SignerUtilities.GetSigner(SignerName);
bSigner.Init(true, aKeyPair.Private);
bSigner.BlockUpdate(bPassPhrase, 0, bPassPhrase.Length);
byte[] bouncySignature = bSigner.GenerateSignature();
ISigner bVerifier = SignerUtilities.GetSigner(SignerName);
bVerifier.Init(false, aKeyPair.Public);
bVerifier.BlockUpdate(bPassPhrase, 0, bPassPhrase.Length);
bool passed = bVerifier.VerifySignature(bouncySignature);
Console.WriteLine("Verified with Bouncy: " + passed);
var xmlImport = "<ECDSAKeyValue xmlns=''http://www.w3.org/2001/04/xmldsig-more#''>/n"
+ " <DomainParameters>/n"
+ " <NamedCurve URN=''urn:oid:1.3.132.0.35'' />/n"
+ " </DomainParameters >/n"
+ " <PublicKey >/n"
+ " <X Value=''" + ((ECPublicKeyParameters)aKeyPair.Public).Q.X.ToBigInteger().ToString() + "'' xsi:type=''PrimeFieldElemType'' xmlns:xsi=''http://www.w3.org/2001/XMLSchema-instance'' />/n"
+ " <Y Value=''" + ((ECPublicKeyParameters)aKeyPair.Public).Q.Y.ToBigInteger().ToString() + "'' xsi:type=''PrimeFieldElemType'' xmlns:xsi=''http://www.w3.org/2001/XMLSchema-instance'' />/n"
+ " </PublicKey >/n"
+ " </ECDSAKeyValue>";
//using (StreamWriter outputFile = new StreamWriter(@"C:/Dev/x2.txt"))
//{
// outputFile.WriteLine(xmlImport);
//}
ECDsaCng eccImporter = new ECDsaCng();
eccImporter.FromXmlString(xmlImport, ECKeyXmlFormat.Rfc4050);
Console.WriteLine("hash algorithm = " + eccImporter.HashAlgorithm + " Probably " + CngAlgorithm.Sha256);
Console.WriteLine("Signature algorithm = " + eccImporter.SignatureAlgorithm + " Probably ECDsa");
Console.WriteLine("After import, key size = " + eccImporter.KeySize + " probably 521");
try
{
if (eccImporter.VerifyData(bPassPhrase, bouncySignature))
{
Console.WriteLine("Verified the signature from bouncy castle using .NET");
}
}
catch (CryptographicException e)
{
// "The parameter is incorrect"
Console.WriteLine("Did not verify bouncy signature with .NET because: " + e.Message);
}
CngKey msKey = CngKey.Create(CngAlgorithm.ECDsaP521, null, new CngKeyCreationParameters { ExportPolicy = CngExportPolicies.AllowPlaintextArchiving });
ECDsaCng ms_ecdsaCNG = new ECDsaCng(msKey);
String xmlExport = ms_ecdsaCNG.ToXmlString(ECKeyXmlFormat.Rfc4050);
eccImporter = new ECDsaCng();
eccImporter.FromXmlString(xmlExport, ECKeyXmlFormat.Rfc4050);
byte[] ms_SignedData = ms_ecdsaCNG.SignData(bPassPhrase);
Console.WriteLine("Verify .NET signature with .NET: " + ms_ecdsaCNG.VerifyData(bPassPhrase, ms_SignedData));
Console.WriteLine("Verify .NET signature with imported .NET: " + eccImporter.VerifyData(bPassPhrase, ms_SignedData));
//Console.WriteLine();
//Console.WriteLine(xmlExport);
//Console.WriteLine();
}

Todo funciona bien hasta que intento verificar la firma con las clases de Microsoft, en cuyo punto genera una excepción que indica que el parámetro es incorrecto.

¿Alguna idea?

Answer 1

Maarten Bodewes tiene razón. Mi problema es que la firma está codificada usando BouncyCastly usando el formato ASN.1 / DER. MS usa un formato más pequeño (creo que es IEEE P-1393). Entonces, escribí esta pequeña rutina en C # para transformar las firmas.

public static byte[] ConvertDerToP1393(byte[] data)
{
byte[] b = new byte[132];
int totalLength = data[1];
int n = 0;
int offset = 4;
int thisLength = data[offset++];
if (data[offset] == 0) {
// Negative number!
++offset;
--thisLength;
}
for (int i= thisLength; i < 66; ++i) {
b[n++] = 0;
}
if (thisLength > 66) {
System.Console.WriteLine("BAD, first number is too big! " + thisLength);
} else {
for (int i = 0; i < thisLength; ++i) {
b[n++] = data[offset++];
}
}
++offset;
thisLength = data[offset++];
for (int i = thisLength; i < 66; ++i){
b[n++] = 0;
}
if (thisLength > 66) {
System.Console.WriteLine("BAD, second number is too big! " + thisLength);
} else {
for (int i = 0; i < thisLength; ++i) {
b[n++] = data[offset++];
}
}
return b;
}

Aunque solo he realizado pruebas limitadas, el código ha funcionado con mis pruebas.