那些遇到过的问题

C#将RSACryptoServiceProvider中的私有/公共RSA密钥导出为PEM字符串

nid*_*732 37 c# cryptography rsa pem

我有一个System.Security.Cryptography.RSACryptoServiceProvider的实例,我需要将它的密钥导出到PEM字符串 - 如下所示:

-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----
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但根据MSDN文档,没有这样的选项,只有某种XML导出.我不能使用任何第三方库,如BouncyCastle.有没有办法生成这个字符串？

Iri*_*ium 63

请注意:以下代码用于导出私钥.如果你正在寻找出口的公共密钥,请参考给我的答案在这里.

PEM格式只是转换为Base64 的密钥(每个PKCS#1)的ASN.1 DER编码.鉴于表示密钥所需的字段数量有限,创建快速而脏的DER编码器以输出适当的格式然后Base64对其进行编码非常简单.因此,下面的代码不是特别优雅,但是做的工作是:

private static void ExportPrivateKey(RSACryptoServiceProvider csp, TextWriter outputStream)
{
    if (csp.PublicOnly) throw new ArgumentException("CSP does not contain a private key", "csp");
    var parameters = csp.ExportParameters(true);
    using (var stream = new MemoryStream())
    {
        var writer = new BinaryWriter(stream);
        writer.Write((byte)0x30); // SEQUENCE
        using (var innerStream = new MemoryStream())
        {
            var innerWriter = new BinaryWriter(innerStream);
            EncodeIntegerBigEndian(innerWriter, new byte[] { 0x00 }); // Version
            EncodeIntegerBigEndian(innerWriter, parameters.Modulus);
            EncodeIntegerBigEndian(innerWriter, parameters.Exponent);
            EncodeIntegerBigEndian(innerWriter, parameters.D);
            EncodeIntegerBigEndian(innerWriter, parameters.P);
            EncodeIntegerBigEndian(innerWriter, parameters.Q);
            EncodeIntegerBigEndian(innerWriter, parameters.DP);
            EncodeIntegerBigEndian(innerWriter, parameters.DQ);
            EncodeIntegerBigEndian(innerWriter, parameters.InverseQ);
            var length = (int)innerStream.Length;
            EncodeLength(writer, length);
            writer.Write(innerStream.GetBuffer(), 0, length);
        }

        var base64 = Convert.ToBase64String(stream.GetBuffer(), 0, (int)stream.Length).ToCharArray();
        outputStream.WriteLine("-----BEGIN RSA PRIVATE KEY-----");
        // Output as Base64 with lines chopped at 64 characters
        for (var i = 0; i < base64.Length; i += 64)
        {
            outputStream.WriteLine(base64, i, Math.Min(64, base64.Length - i));
        }
        outputStream.WriteLine("-----END RSA PRIVATE KEY-----");
    }
}

private static void EncodeLength(BinaryWriter stream, int length)
{
    if (length < 0) throw new ArgumentOutOfRangeException("length", "Length must be non-negative");
    if (length < 0x80)
    {
        // Short form
        stream.Write((byte)length);
    }
    else
    {
        // Long form
        var temp = length;
        var bytesRequired = 0;
        while (temp > 0)
        {
            temp >>= 8;
            bytesRequired++;
        }
        stream.Write((byte)(bytesRequired | 0x80));
        for (var i = bytesRequired - 1; i >= 0; i--)
        {
            stream.Write((byte)(length >> (8 * i) & 0xff));
        }
    }
}

private static void EncodeIntegerBigEndian(BinaryWriter stream, byte[] value, bool forceUnsigned = true)
{
    stream.Write((byte)0x02); // INTEGER
    var prefixZeros = 0;
    for (var i = 0; i < value.Length; i++)
    {
        if (value[i] != 0) break;
        prefixZeros++;
    }
    if (value.Length - prefixZeros == 0)
    {
        EncodeLength(stream, 1);
        stream.Write((byte)0);
    }
    else
    {
        if (forceUnsigned && value[prefixZeros] > 0x7f)
        {
            // Add a prefix zero to force unsigned if the MSB is 1
            EncodeLength(stream, value.Length - prefixZeros + 1);
            stream.Write((byte)0);
        }
        else
        {
            EncodeLength(stream, value.Length - prefixZeros);
        }
        for (var i = prefixZeros; i < value.Length; i++)
        {
            stream.Write(value[i]);
        }
    }
}
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  • 对于那些感兴趣的人,可以通过我的答案中的代码正确导出公钥:http://stackoverflow.com/questions/28406888/c-sharp-rsa-public-key-output-not-correct/28407693# 28407693,它重复使用了这个答案中的一些方法. (7认同)
  • 我已经编译并稍微修改了 Iridium 的两个出色的导出函数，并将它们与导入函数相结合以获得完整的解决方案（导入和导出公钥和私钥）：[使用 BouncyCastle 在 C# 和 PEM 格式之间导入和导出 RSA 密钥](https: //gist.github.com/therightstuff/aa65356e95f8d0aae888e9f61aa29414) (3认同)

Pra*_*uis 8

如果您使用的是 .NET Core 3.0 并且不需要依赖于 Windows 平台，RSACryptoServiceProvider这已经是开箱即用的

    public string ExportPrivateKey(RSA rsa)
    {
        var privateKeyBytes = rsa.ExportRSAPrivateKey();
        var builder = new StringBuilder("-----BEGIN RSA PRIVATE KEY");
        builder.AppendLine("-----");

        var base64PrivateKeyString = Convert.ToBase64String(privateKeyBytes);
        var offset = 0;
        const int LINE_LENGTH = 64;

        while (offset < base64PrivateKeyString.Length)
        {
            var lineEnd = Math.Min(offset + LINE_LENGTH, base64PrivateKeyString.Length);
            builder.AppendLine(base64PrivateKeyString.Substring(offset, lineEnd - offset));
            offset = lineEnd;
        }

        builder.Append("-----END RSA PRIVATE KEY");
        builder.AppendLine("-----");
        return builder.ToString();
    }
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注意：在 .NET Core 中您不会使用，RSACryptoServiceProvider因为它更特定于 Windows。

小智 6

出口PublicKey使用此代码:

public static String ExportPublicKeyToPEMFormat(RSACryptoServiceProvider csp)
{
    TextWriter outputStream = new StringWriter();

    var parameters = csp.ExportParameters(false);
    using (var stream = new MemoryStream())
    {
        var writer = new BinaryWriter(stream);
        writer.Write((byte)0x30); // SEQUENCE
        using (var innerStream = new MemoryStream())
        {
            var innerWriter = new BinaryWriter(innerStream);
            EncodeIntegerBigEndian(innerWriter, new byte[] { 0x00 }); // Version
            EncodeIntegerBigEndian(innerWriter, parameters.Modulus);
            EncodeIntegerBigEndian(innerWriter, parameters.Exponent);

            //All Parameter Must Have Value so Set Other Parameter Value Whit Invalid Data  (for keeping Key Structure  use "parameters.Exponent" value for invalid data)
            EncodeIntegerBigEndian(innerWriter, parameters.Exponent); // instead of parameters.D
            EncodeIntegerBigEndian(innerWriter, parameters.Exponent); // instead of parameters.P
            EncodeIntegerBigEndian(innerWriter, parameters.Exponent); // instead of parameters.Q
            EncodeIntegerBigEndian(innerWriter, parameters.Exponent); // instead of parameters.DP
            EncodeIntegerBigEndian(innerWriter, parameters.Exponent); // instead of parameters.DQ
            EncodeIntegerBigEndian(innerWriter, parameters.Exponent); // instead of parameters.InverseQ

            var length = (int)innerStream.Length;
            EncodeLength(writer, length);
            writer.Write(innerStream.GetBuffer(), 0, length);
        }

        var base64 = Convert.ToBase64String(stream.GetBuffer(), 0, (int)stream.Length).ToCharArray();
        outputStream.WriteLine("-----BEGIN PUBLIC KEY-----");
        // Output as Base64 with lines chopped at 64 characters
        for (var i = 0; i < base64.Length; i += 64)
        {
            outputStream.WriteLine(base64, i, Math.Min(64, base64.Length - i));
        }
        outputStream.WriteLine("-----END PUBLIC KEY-----");

        return outputStream.ToString();

    }
}

private static void EncodeIntegerBigEndian(BinaryWriter stream, byte[] value, bool forceUnsigned = true)
{
    stream.Write((byte)0x02); // INTEGER
    var prefixZeros = 0;
    for (var i = 0; i < value.Length; i++)
    {
        if (value[i] != 0) break;
        prefixZeros++;
    }
    if (value.Length - prefixZeros == 0)
    {
        EncodeLength(stream, 1);
        stream.Write((byte)0);
    }
    else
    {
        if (forceUnsigned && value[prefixZeros] > 0x7f)
        {
            // Add a prefix zero to force unsigned if the MSB is 1
            EncodeLength(stream, value.Length - prefixZeros + 1);
            stream.Write((byte)0);
        }
        else
        {
            EncodeLength(stream, value.Length - prefixZeros);
        }
        for (var i = prefixZeros; i < value.Length; i++)
        {
            stream.Write(value[i]);
        }
    }
}

private static void EncodeLength(BinaryWriter stream, int length)
{
    if (length < 0) throw new ArgumentOutOfRangeException("length", "Length must be non-negative");
    if (length < 0x80)
    {
        // Short form
        stream.Write((byte)length);
    }
    else
    {
        // Long form
        var temp = length;
        var bytesRequired = 0;
        while (temp > 0)
        {
            temp >>= 8;
            bytesRequired++;
        }
        stream.Write((byte)(bytesRequired | 0x80));
        for (var i = bytesRequired - 1; i >= 0; i--)
        {
            stream.Write((byte)(length >> (8 * i) & 0xff));
        }
    }
}
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  • 这不适合我.相反,我使用了@ Iridium的其他帖子http://stackoverflow.com/questions/28406888/c-sharp-rsa-public-key-output-not-correct/28407693#28407693,根据他在回答下面的评论. (7认同)
  • 六个额外写入到底是什么...... RSA公钥是`{n,e}`对.您应该检查PKCS#1的正确格式,而不是像上面那样共享黑客. (2认同)

gli*_*ihm 6

使用当前版本的 .NET CORE，无需所有其他响应中的所有便利内容即可完成此操作。


  RSA rsa = RSA.Create();
  rsa.KeySize = 4096;

  string hdr = "-----BEGIN RSA PRIVATE KEY-----";
  string ftr = "-----END RSA PRIVATE KEY-----";

  string priv = Convert.ToBase64String(rsa.ExportPkcs8PrivateKey());

  // To export the public key, update hdr and ftr, and use this.
  // string pub = Convert.ToBase64String(rsa.ExportSubjectPublicKeyInfo());

  string PEM = $"{hdr}\n{priv}\n{ftr}";
  // Distribute PEM.
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Ank*_*ain 6

这是一个好消息，在.NET 7中，微软添加了一种新方法来将 RSA 密钥直接导出为 PEM 格式。

请参阅RSA.ExportRSAPrivateKeyPem 方法

以下是如何使用它。

using (var rsa = new RSACryptoServiceProvider(2048)) // Generate a new 2048 bit RSA key
{
    // RSA keys in PKCS#1 format, PEM encoded
    string publicPrivateKeyPEM = rsa.ExportRSAPrivateKeyPem();
    string publicOnlyKeyPEM = rsa.ExportRSAPublicKeyPem();

    // RSA keys in XML format
    string publicPrivateKeyXML = rsa.ToXmlString(true);
    string publicOnlyKeyXML = rsa.ToXmlString(false);

    // RSA keys in byte array
    byte[] publicPrivateKey = rsa.ExportRSAPrivateKey();
    byte[] publicOnlyKey = rsa.ExportRSAPublicKey();
}
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