CngKey从ECSsaP192公钥导入

我正在验证公钥作为MEkwEwYHKoZIzj0CAQYIKoZIzj0DAQEDMgAEMyHD625uvsmGq4C43cQ9BnfN2xslVT5V1nOmAMP6qaRRUll3PB1JYmgSm+62sosG

经过大量研究，我认为这是一个ECDsaP192标准密钥(如果我错了，请纠正我(。所以密钥的分解将是

30 13
06 07 2A 86 48 CE 3D 02 01
06 08 2A 86 48 CE 3D 03 01 01
03 32 00
04
33 21 C3 EB 6E 6E BE C9 86 AB 80 B8 DD C4 3D 6 77 CD DB 1B 25 55 3E 55  // Qx, 24 bytes
D6 73 A6 0 C3 FA A9 A4 51 52 59 77 3C 1D 49 62 68 12 9B EE B6 B2 8B 6   // Qy, 24 bytes

我看到了一个secp256r1密钥的例子，它与我的情况非常相似，但我仍然无法让它为我工作。我的代码：

private static readonly byte[] p192r1Prefix =
Convert.FromBase64String("MEkwEwYHKoZIzj0CAQYIKoZIzj0DAQEDMgAE");
private static readonly byte[] s_cngBlobPrefix = { 0x45, 0x43, 0x53, 0x31, 0x18, 0, 0, 0 };
void Main()
{
var pubkey = @"MEkwEwYHKoZIzj0CAQYIKoZIzj0DAQEDMgAEMyHD625uvsmGq4C43cQ9BnfN2xslVT5V1nOmAMP6qaRRUll3PB1JYmgSm+62sosG";
var key = ImportECDsa256PublicKey(pubkey);
}
private static CngKey ImportECDsa256PublicKey(string base64)
{
byte[] subjectPublicKeyInfo = Convert.FromBase64String(base64);
byte[] prefix = p192r1Prefix;
byte[] cngBlob = new byte[s_cngBlobPrefix.Length + 48];
Buffer.BlockCopy(s_cngBlobPrefix, 0, cngBlob, 0, s_cngBlobPrefix.Length);
Buffer.BlockCopy(
subjectPublicKeyInfo,
p192r1Prefix.Length,
cngBlob,
s_cngBlobPrefix.Length,
48);
return CngKey.Import(cngBlob, CngKeyBlobFormat.EccPublicBlob);  // Error: The parameter is incorrect.
}

编辑：使用BouncyCastle

void Main()
{
// Documentation https://developer.apple.com/documentation/storekit/skadnetwork/verifying_an_install_validation_postback
var applePublicKey = @"MEkwEwYHKoZIzj0CAQYIKoZIzj0DAQEDMgAEMyHD625uvsmGq4C43cQ9BnfN2xslVT5V1nOmAMP6qaRRUll3PB1JYmgSm+62sosG";
var keyBytes = Convert.FromBase64String(applePublicKey);
var param = GetPublicKeyParam(keyBytes);

var dataStr = "2.0" + 'u2063' + "com.example" + 'u2063' + "42" + 'u2063' + "525463029" + 'u2063' + "6aafb7a5-0170-41b5-bbe4-fe71dedf1e28" + 'u2063' + "1" + 'u2063' + "1234567891";
var data = Encoding.UTF8.GetBytes(dataStr);
var signature = "MDYCGQCsQ4y8d4BlYU9b8Qb9BPWPi+ixk/OiRysCGQDZZ8fpJnuqs9my8iSQVbJO/oU1AXUROYU=";
var sigBytes = Convert.FromBase64String(signature);

ISigner signer = SignerUtilities.GetSigner("SHA-256withECDSA");
signer.Init(false, param);
signer.BlockUpdate(data, 0, dataStr.Length);
Console.WriteLine(signer.VerifySignature(sigBytes));
}
private ECPublicKeyParameters GetPublicKeyParam(byte[] publicKeyBytes)
{
// parse based on asn1 format the content of the certificate
var asn1 = (Asn1Sequence)Asn1Object.FromByteArray(publicKeyBytes);
var at1 = (DerBitString)asn1[1];
var xyBytes = at1.GetBytes();
//retrieve preddefined parameters for P192(?) curve
X9ECParameters x9 = NistNamedCurves.GetByName("P-192");
//establish domain we will be looking for the x and y
ECDomainParameters domainParams = new ECDomainParameters(x9.Curve, x9.G, x9.N, x9.H, x9.GetSeed());
ECPublicKeyParameters publicKeyParams = new ECPublicKeyParameters(x9.Curve.DecodePoint(xyBytes), domainParams);
return publicKeyParams;
}

公布的公钥是NIST p-192的X.509/SPKI密钥(也称为secp192r1或prime192v1(。签名采用ASN.1格式。这可以通过ASN.1解析器最容易地验证，例如在这里。

代码中有一个错误。在线

signer.BlockUpdate(data, 0, dataStr.Length);

dataStr.Length必须替换为data.Length。除此之外，代码还能正常工作。

然而，您的数据验证失败，即数据和签名由于某种原因不一致(可能公钥和私钥不匹配，或者签名是为其他数据创建的，等等(

代码本身并不是原因。我已经使用以下私钥(PKCS8(和公钥(X.509((适用于NIST P-192(成功测试了(固定(代码：

如果你发布的明文是用上面的私钥签名的，你会得到以下签名(Base64编码(：

MDYCGQDrACykwYbQ6lQppw5PEcu5Bm7BuHjkVHoCGQDZ+RD3KvanoOzYj9bqQP2GHGhyrH6NOwA=

如果使用您的(固定(代码和上面的公钥验证了此签名，则验证成功！

顺便说一句，使用导入公钥更容易

using Org.BouncyCastle.Security;
...
//var param = GetPublicKeyParam(keyBytes);          // remove
var param = PublicKeyFactory.CreateKey(keyBytes);   // add

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