c# - 从.NET Core中的PEM文件创建X509Certificate2

我想基于pem文件创建一个x509certificate2对象。问题是设置X509Certificate2的PrivateKey属性。我读了X509Certificate2.CreateFromCertFile() on .NET Core然后用

var rsa = new RSACryptoServiceProvider();

rsa.ImportCspBlob(pvk);

其中pvk是私钥的字节数组（从getbytesfrompem读取，如这里所示how to get private key from PEM file?），用于设置私钥，但是我得到一个
内部。加密。CryptoThrowhelper+WindowsCryptographicException，提供程序的消息版本错误。
如何根据PEM文件中的私钥正确设置X509Certificate2的私钥？
如果我看Creating the X509Certificate2，它们使用

 RSACryptoServiceProvider prov = Crypto.DecodeRsaPrivateKey(keyBuffer);
 certificate.PrivateKey = prov;

这看起来是一个很好的方法，但是这在.NET内核中不起作用…

最佳答案

如果您刚刚从私钥文件的base64编码中提取了字节，那么您就有一个pkcs 1、pkcs 8或encrypted pkcs 8私钥blob（取决于它是否显示“begin rsa private key”、“begin private key”或“begin encrypted private key”）。ImportCspBlob想要数据的自定义格式，这就是它抱怨的原因。
Digital signature in c# without using BouncyCastle解释了前进的方向。最简单/最公式化的方法是使用cert和key创建一个pfx，然后让X509Certificate2构造函数完成它的工作。
如果直接加载密钥对象，那么将私钥与证书匹配的方法是使用一个新的CopyWithPrivateKey扩展方法。这将返回一个新的X509Certificate2实例，该实例知道私钥。
setter从.net core中“删除”，因为它对windows有很多副作用，在linux和macos上很难复制，特别是当您从x509store实例中检索证书时。
这段代码是对实际ber规则的过度严格和过度接受的组合，但是除非包含属性，否则应该读取有效编码的pkcs 8文件。

private static readonly byte[] s_derIntegerZero = { 0x02, 0x01, 0x00 };

private static readonly byte[] s_rsaAlgorithmId =
{
    0x30, 0x0D,
    0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01,
    0x05, 0x00,
};

private static int ReadLength(byte[] data, ref int offset)
{
    byte lengthOrLengthLength = data[offset++];

    if (lengthOrLengthLength < 0x80)
    {
        return lengthOrLengthLength;
    }

    int lengthLength = lengthOrLengthLength & 0x7F;
    int length = 0;

    for (int i = 0; i < lengthLength; i++)
    {
        if (length > ushort.MaxValue)
        {
            throw new InvalidOperationException("This seems way too big.");
        }

        length <<= 8;
        length |= data[offset++];
    }

    return length;
}

private static byte[] ReadUnsignedInteger(byte[] data, ref int offset, int targetSize = 0)
{
    if (data[offset++] != 0x02)
    {
        throw new InvalidOperationException("Invalid encoding");
    }

    int length = ReadLength(data, ref offset);

    // Encoding rules say 0 is encoded as the one byte value 0x00.
    // Since we expect unsigned, throw if the high bit is set.
    if (length < 1 || data[offset] >= 0x80)
    {
        throw new InvalidOperationException("Invalid encoding");
    }

    byte[] ret;

    if (length == 1)
    {
        ret = new byte[length];
        ret[0] = data[offset++];
        return ret;
    }

    if (data[offset] == 0)
    {
        offset++;
        length--;
    }

    if (targetSize != 0)
    {
        if (length > targetSize)
        {
            throw new InvalidOperationException("Bad key parameters");
        }

        ret = new byte[targetSize];
    }
    else
    {
        ret = new byte[length];
    }

    Buffer.BlockCopy(data, offset, ret, ret.Length - length, length);
    offset += length;
    return ret;
}

private static void EatFullPayloadTag(byte[] data, ref int offset, byte tagValue)
{
    if (data[offset++] != tagValue)
    {
        throw new InvalidOperationException("Invalid encoding");
    }

    int length = ReadLength(data, ref offset);

    if (data.Length - offset != length)
    {
        throw new InvalidOperationException("Data does not represent precisely one value");
    }
}

private static void EatMatch(byte[] data, ref int offset, byte[] toMatch)
{
    if (data.Length - offset > toMatch.Length)
    {
        if (data.Skip(offset).Take(toMatch.Length).SequenceEqual(toMatch))
        {
            offset += toMatch.Length;
            return;
        }
    }

    throw new InvalidOperationException("Bad data.");
}

private static RSA DecodeRSAPkcs8(byte[] pkcs8Bytes)
{
    int offset = 0;

    // PrivateKeyInfo SEQUENCE
    EatFullPayloadTag(pkcs8Bytes, ref offset, 0x30);
    // PKCS#8 PrivateKeyInfo.version == 0
    EatMatch(pkcs8Bytes, ref offset, s_derIntegerZero);
    // rsaEncryption AlgorithmIdentifier value
    EatMatch(pkcs8Bytes, ref offset, s_rsaAlgorithmId);
    // PrivateKeyInfo.privateKey OCTET STRING
    EatFullPayloadTag(pkcs8Bytes, ref offset, 0x04);
    // RSAPrivateKey SEQUENCE
    EatFullPayloadTag(pkcs8Bytes, ref offset, 0x30);
    // RSAPrivateKey.version == 0
    EatMatch(pkcs8Bytes, ref offset, s_derIntegerZero);

    RSAParameters rsaParameters = new RSAParameters();
    rsaParameters.Modulus = ReadUnsignedInteger(pkcs8Bytes, ref offset);
    rsaParameters.Exponent = ReadUnsignedInteger(pkcs8Bytes, ref offset);
    rsaParameters.D = ReadUnsignedInteger(pkcs8Bytes, ref offset, rsaParameters.Modulus.Length);
    int halfModulus = (rsaParameters.Modulus.Length + 1) / 2;
    rsaParameters.P = ReadUnsignedInteger(pkcs8Bytes, ref offset, halfModulus);
    rsaParameters.Q = ReadUnsignedInteger(pkcs8Bytes, ref offset, halfModulus);
    rsaParameters.DP = ReadUnsignedInteger(pkcs8Bytes, ref offset, halfModulus);
    rsaParameters.DQ = ReadUnsignedInteger(pkcs8Bytes, ref offset, halfModulus);
    rsaParameters.InverseQ = ReadUnsignedInteger(pkcs8Bytes, ref offset, halfModulus);

    if (offset != pkcs8Bytes.Length)
    {
        throw new InvalidOperationException("Something didn't add up");
    }

    RSA rsa = RSA.Create();
    rsa.ImportParameters(rsaParameters);
    return rsa;
}