从其他地方导入公钥到CngKey

所以我已经找出了在ECCPublicKeyBlob和ECCPrivateKeyBlob中导出的cnkey的格式。这应该允许其他人在其他密钥格式和CngKey之间进行交互，用于椭圆曲线签名等。

ECCPrivateKeyBlob的格式(对于P256)如下

• [密钥类型(4字节)][密钥长度(4字节)][公钥(64字节)][私钥(32字节)]
• KEY TYPE in HEX = 45-43-53-32
• KEY LENGTH in HEX = 20-00-00-00
• PUBLIC KEY是未压缩的格式减去前导字节(在其他库中总是为04表示未压缩的密钥)

ECCPublicKeyBlob的格式(对于P256)如下

• [密钥类型(4字节)][密钥长度(4字节)][公开密钥(64字节)]
• KEY TYPE in HEX = 45-43-53-31
• KEY LENGTH in HEX = 20-00-00-00
• PUBLIC KEY是未压缩的格式减去前导字节(在其他库中总是为04表示未压缩的密钥)

给定另一种语言的未压缩的十六进制公钥，您可以修剪第一个字节，将这8个字节添加到前面并使用

导入它

CngKey.Import(key,CngKeyBlobFormat.EccPrivateBlob);

注意:键blob格式是由Microsoft文档。

KEY TYPE和KEY LENGTH在BCRYPT_ECCKEY_BLOB struct中定义为:

{ ulong Magic; ulong cbKey; }

ECC公钥内存格式:

BCRYPT_ECCKEY_BLOB
BYTE X[cbKey] // Big-endian.
BYTE Y[cbKey] // Big-endian.

ECC私钥内存格式:

BCRYPT_ECCKEY_BLOB
BYTE X[cbKey] // Big-endian.
BYTE Y[cbKey] // Big-endian.
BYTE d[cbKey] // Big-endian.

. net中可用的MAGIC值在Microsoft官方GitHub dotnet/corefx BCrypt/Interop.Blobs.

internal enum KeyBlobMagicNumber : int
{
    BCRYPT_ECDH_PUBLIC_P256_MAGIC = 0x314B4345,
    BCRYPT_ECDH_PRIVATE_P256_MAGIC = 0x324B4345,
    BCRYPT_ECDH_PUBLIC_P384_MAGIC = 0x334B4345,
    BCRYPT_ECDH_PRIVATE_P384_MAGIC = 0x344B4345,
    BCRYPT_ECDH_PUBLIC_P521_MAGIC = 0x354B4345,
    BCRYPT_ECDH_PRIVATE_P521_MAGIC = 0x364B4345,
    BCRYPT_ECDSA_PUBLIC_P256_MAGIC = 0x31534345,
    BCRYPT_ECDSA_PRIVATE_P256_MAGIC = 0x32534345,
    BCRYPT_ECDSA_PUBLIC_P384_MAGIC = 0x33534345,
    BCRYPT_ECDSA_PRIVATE_P384_MAGIC = 0x34534345
    BCRYPT_ECDSA_PUBLIC_P521_MAGIC = 0x35534345,
    BCRYPT_ECDSA_PRIVATE_P521_MAGIC = 0x36534345,
    ...
    ...
}

多亏了你，我才能够用下面的代码从证书中导入ECDSA_P256公钥:

    private static CngKey ImportCngKeyFromCertificate(X509Certificate2 cert)
    {
        var keyType = new byte[] {0x45, 0x43, 0x53, 0x31};
        var keyLength = new byte[] {0x20, 0x00, 0x00, 0x00};
        var key = cert.PublicKey.EncodedKeyValue.RawData.Skip(1);
        var keyImport = keyType.Concat(keyLength).Concat(key).ToArray();
        var cngKey = CngKey.Import(keyImport, CngKeyBlobFormat.EccPublicBlob);
        return cngKey;
    }

65字节的密钥(仅限公钥)从需要删除的0x04开始。然后添加您描述的标题。

那么我就可以验证这样的签名:

var crypto = ECDsaCng(cngKey);
var verify = crypto.VerifyHash(hash, sig);

我只是想感谢上面两个帖子，因为它极大地帮助了我。我必须使用RSACng对象使用RSA公钥验证签名。我以前使用RSACryptoServiceProvider，但这不是FIPS兼容的，所以我在切换到rsacg时遇到了一些问题。它还需要。net 4.6。下面是我如何使用上面的海报作为例子来工作的:

                    // This structure is as the header for the CngKey
                    // all should be byte arrays in Big-Endian order
                    //typedef struct _BCRYPT_RSAKEY_BLOB {
                    //  ULONG Magic; 
                    //  ULONG BitLength; 
                    //  ULONG cbPublicExp;
                    //  ULONG cbModulus;
                    //  ULONG cbPrime1;  private key only
                    //  ULONG cbPrime2;  private key only
                    //} BCRYPT_RSAKEY_BLOB;
                    // This is the actual Key Data that is attached to the header
                    //BCRYPT_RSAKEY_BLOB
                    //  PublicExponent[cbPublicExp] 
                    //  Modulus[cbModulus]
                    //first get the public key from the cert (modulus and exponent)
                    // not shown
                    byte[] publicExponent = <your public key exponent>; //Typically equal to from what I've found: {0x01, 0x00, 0x01}
                    byte[] btMod = <your public key modulus>;  //for 128 bytes for 1024 bit key, and 256 bytes for 2048 keys
                    //BCRYPT_RSAPUBLIC_MAGIC = 0x31415352,
                    // flip to big-endian
                    byte[] Magic = new byte[] { 0x52, 0x53, 0x41, 0x31}; 
                    // for BitLendth: convert the length of the key's Modulus as a byte array into bits,
                    // so the size of the key, in bits should be btMod.Length * 8. Convert to a DWord, then flip for Big-Endian 
                    // example 128 bytes = 1024 bits = 0x00000400 = {0x00, 0x00, 0x04, 0x00} = flipped {0x00, 0x04, 0x00, 0x00}
                    // example 256 bytes = 2048 bits = 0x00000800 = {0x00, 0x00, 0x08, 0x00} = flipped {0x00, 0x08, 0x00, 0x00}
                    string sHex = (btMod.Length * 8).ToString("X8");
                    byte[] BitLength = Util.ConvertHexStringToByteArray(sHex);
                    Array.Reverse(BitLength); //flip to Big-Endian
                    // same thing for exponent length (in bytes)
                    sHex = (publicExponent.Length).ToString("X8");
                    byte[] cbPublicExp = Util.ConvertHexStringToByteArray(sHex);
                    Array.Reverse(cbPublicExp);
                    // same thing for modulus length (in bytes)
                    sHex = (btMod.Length).ToString("X8");
                    byte[] cbModulus = Util.ConvertHexStringToByteArray(sHex);
                    Array.Reverse(cbModulus);                      
                    // add the 0 bytes for cbPrime1 and cbPrime2 (always zeros for public keys, these are used for private keys, but need to be zero here)
                    // just make one array with both 4 byte primes as zeros
                    byte[] cbPrimes = new byte[] { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
                    //combine all the parts together into the one big byte array in the order the structure
                    var keyImport = Magic.Concat(BitLength).Concat(cbPublicExp).Concat(cbModulus).Concat(cbPrimes).Concat(publicExponent).Concat(btMod).ToArray();
                    var cngKey = CngKey.Import(keyImport, CngKeyBlobFormat.GenericPublicBlob);
                    // pass the key to the class constructor
                    RSACng rsa = new RSACng(cngKey);
                    //verify: our randomly generated M (message) used to create the signature (not shown), the signature, enum for SHA256, padding
                    verified = rsa.VerifyData(M, signature, HashAlgorithmName.SHA256,RSASignaturePadding.Pkcs1);

注意:模数的符号字节(0x00)既可以包含在模数中，也可以不包含在模数中，因此如果包含它，长度将大1。

按如下方式将EC key转换为BCRYPT_ECCKEY_BLOB。我们应该忽略EC key的第一个字节，因为它只表示压缩/未压缩格式。

BCRYPT_ECCKEY_BLOB eccBlobHeader;
PCHAR bycrtptKey;
eccBlobHeader.dwMagic = BCRYPT_ECDH_PUBLIC_P384_MAGIC;  
eccBlobHeader.cbKey = 48;//size of EC key(without 1st byte)
memcpy(bycrtptKey, &eccBlobHeader, 8);//copying 8bytes header blob
memcpy(bycrtptKey+ 8,publicKeyFromOtherParty+1,publicKeyFromOtherPartySize- 1);

现在使用bycrtptKey导入