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.net core 中使用 openssl 公钥私钥进行加解密

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09/11
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这篇博文分享的是 C#中使用OpenSSL的公钥加密/私钥解密 一文中的解决方法在 .net core 中的改进。之前的博文针对的是 .NET Framework ，加解密用的是 RSACryptoServiceProvider 。虽然在 corefx(.NET Core Framework) 中也有 RSACryptoServiceProvider ，但它目前只支持 Windows ，不能跨平台。

之前的 new RSACryptoServiceProvider(); 代码在 mac 上运行，会报下面的错误：

System.PlatformNotSupportedException: Operation is not supported on this platform.
at System.Security.Cryptography.RSACryptoServiceProvider..ctor()

要解决这个问题，需要改用  System.Security.Cryptography.RSA.Create() 工厂方法，使用它之后，在 Windows 上创建的是 System.Security.Cryptography.RSACng 的实例，在 Mac 与 Linux 上创建的是 System.Security.Cryptography.RSAOpenSsl 的实例，它们都继承自 System.Security.Cryptography.RSA 抽象类。

使用了 RSA.Create() 之后，带来了一个问题，RSA 中没有 RSACryptoServiceProvider 中的以下2个签名的加解密方法。

public byte[] Encrypt(byte[] rgb, bool fOAEP);
public byte[] Decrypt(byte[] rgb, bool fOAEP);

只有

public abstract byte[] Encrypt(byte[] data, RSAEncryptionPadding padding);
public abstract byte[] Decrypt(byte[] data, RSAEncryptionPadding padding);

调用时它们时需要传递 RSAEncryptionPadding 类型的参数值：

但对于 openssl 生成的公钥私钥不知道选择哪种 RSAEncryptionPadding ，只能采取笨方法 —— 一个一个试试，试出来的结果是 RSAEncryptionPadding.Pkcs1 。

openssl 的公钥与私钥是在 Mac 上通过下面的2个命令生成的：

openssl genrsa -out rsa_1024_priv.pem 102
openssl rsa -pubout -in rsa_1024_priv.pem -out rsa_1024_pub.pem

（注：一定要用 openssl 命令，用 ssh-keygen -t rsa 命令生成的公钥私钥是不行的）

修改这两个地方（RSA.Create 与 RSAEncryptionPadding.Pkcs1）之后，就可以在 .net core 上使用 openssl 的公钥私钥进行加解密了，以下是测试时所用的完整代码（.net core控制台程序）。经测试，在 Windows，macOS，Linux Ubuntu 上都能成功进行加解密。

Program.cs

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;namespace TryRsa
{
public class Program
{
//openssl genrsa -out rsa_1024_priv.pem 1024
private static readonly string _privateKey = @"MIICXgIBAAKBgQC0xP5HcfThSQr43bAMoopbzcCyZWE0xfUeTA4Nx4PrXEfDvybJ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".Replace("\n", ""); //openssl rsa -pubout -in rsa_1024_priv.pem -out rsa_1024_pub.pem
private static readonly string _publicKey = @"MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC0xP5HcfThSQr43bAMoopbzcCy
ZWE0xfUeTA4Nx4PrXEfDvybJEIjbU/rgANAty1yp7g20J7+wVMPCusxftl/d0rPQ
iCLjeZ3HtlRKld+9htAZtHFZosV29h/hNE9JkxzGXstaSeXIUIWquMZQ8XyscIHh
qoOmjXaCv58CSRAlAQIDAQAB".Replace("\n", ""); public static void Main(string[] args)
{
var plainText = "cnblogs.com"; //Encrypt
RSA rsa = CreateRsaFromPublicKey(_publicKey);
var plainTextBytes = Encoding.UTF8.GetBytes(plainText);
var cipherBytes = rsa.Encrypt(plainTextBytes, RSAEncryptionPadding.Pkcs1);
var cipher = Convert.ToBase64String(cipherBytes);
Console.WriteLine($"{nameof(cipher)}:{cipher}"); //Decrypt
rsa = CreateRsaFromPrivateKey(_privateKey);
cipherBytes = System.Convert.FromBase64String(cipher);
plainTextBytes = rsa.Decrypt(cipherBytes, RSAEncryptionPadding.Pkcs1);
plainText = Encoding.UTF8.GetString(plainTextBytes);
Console.WriteLine($"{nameof(plainText)}:{plainText}");
} private static RSA CreateRsaFromPrivateKey(string privateKey)
{
var privateKeyBits = System.Convert.FromBase64String(privateKey);
var rsa = RSA.Create();
var RSAparams = new RSAParameters(); using (var binr = new BinaryReader(new MemoryStream(privateKeyBits)))
{
byte bt = ;
ushort twobytes = ;
twobytes = binr.ReadUInt16();
if (twobytes == 0x8130)
binr.ReadByte();
else if (twobytes == 0x8230)
binr.ReadInt16();
else
throw new Exception("Unexpected value read binr.ReadUInt16()"); twobytes = binr.ReadUInt16();
if (twobytes != 0x0102)
throw new Exception("Unexpected version"); bt = binr.ReadByte();
if (bt != 0x00)
throw new Exception("Unexpected value read binr.ReadByte()"); RSAparams.Modulus = binr.ReadBytes(GetIntegerSize(binr));
RSAparams.Exponent = binr.ReadBytes(GetIntegerSize(binr));
RSAparams.D = binr.ReadBytes(GetIntegerSize(binr));
RSAparams.P = binr.ReadBytes(GetIntegerSize(binr));
RSAparams.Q = binr.ReadBytes(GetIntegerSize(binr));
RSAparams.DP = binr.ReadBytes(GetIntegerSize(binr));
RSAparams.DQ = binr.ReadBytes(GetIntegerSize(binr));
RSAparams.InverseQ = binr.ReadBytes(GetIntegerSize(binr));
} rsa.ImportParameters(RSAparams);
return rsa;
} private static int GetIntegerSize(BinaryReader binr)
{
byte bt = ;
byte lowbyte = 0x00;
byte highbyte = 0x00;
int count = ;
bt = binr.ReadByte();
if (bt != 0x02)
return ;
bt = binr.ReadByte(); if (bt == 0x81)
count = binr.ReadByte();
else
if (bt == 0x82)
{
highbyte = binr.ReadByte();
lowbyte = binr.ReadByte();
byte[] modint = { lowbyte, highbyte, 0x00, 0x00 };
count = BitConverter.ToInt32(modint, );
}
else
{
count = bt;
} while (binr.ReadByte() == 0x00)
{
count -= ;
}
binr.BaseStream.Seek(-, SeekOrigin.Current);
return count;
} private static RSA CreateRsaFromPublicKey(string publicKeyString)
{
byte[] SeqOID = { 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00 };
byte[] x509key;
byte[] seq = new byte[];
int x509size; x509key = Convert.FromBase64String(publicKeyString);
x509size = x509key.Length; using (var mem = new MemoryStream(x509key))
{
using (var binr = new BinaryReader(mem))
{
byte bt = ;
ushort twobytes = ; twobytes = binr.ReadUInt16();
if (twobytes == 0x8130)
binr.ReadByte();
else if (twobytes == 0x8230)
binr.ReadInt16();
else
return null; seq = binr.ReadBytes();
if (!CompareBytearrays(seq, SeqOID))
return null; twobytes = binr.ReadUInt16();
if (twobytes == 0x8103)
binr.ReadByte();
else if (twobytes == 0x8203)
binr.ReadInt16();
else
return null; bt = binr.ReadByte();
if (bt != 0x00)
return null; twobytes = binr.ReadUInt16();
if (twobytes == 0x8130)
binr.ReadByte();
else if (twobytes == 0x8230)
binr.ReadInt16();
else
return null; twobytes = binr.ReadUInt16();
byte lowbyte = 0x00;
byte highbyte = 0x00; if (twobytes == 0x8102)
lowbyte = binr.ReadByte();
else if (twobytes == 0x8202)
{
highbyte = binr.ReadByte();
lowbyte = binr.ReadByte();
}
else
return null;
byte[] modint = { lowbyte, highbyte, 0x00, 0x00 };
int modsize = BitConverter.ToInt32(modint, ); int firstbyte = binr.PeekChar();
if (firstbyte == 0x00)
{
binr.ReadByte();
modsize -= ;
} byte[] modulus = binr.ReadBytes(modsize); if (binr.ReadByte() != 0x02)
return null;
int expbytes = (int)binr.ReadByte();
byte[] exponent = binr.ReadBytes(expbytes); var rsa = RSA.Create();
var rsaKeyInfo = new RSAParameters
{
Modulus = modulus,
Exponent = exponent
};
rsa.ImportParameters(rsaKeyInfo);
return rsa;
} }
} private static bool CompareBytearrays(byte[] a, byte[] b)
{
if (a.Length != b.Length)
return false;
int i = ;
foreach (byte c in a)
{
if (c != b[i])
return false;
i++;
}
return true;
}
}
}

project.json

{
"version": "1.0.0-*",
"buildOptions": {
"emitEntryPoint": true
}, "dependencies": {
"Microsoft.NETCore.App": {
"type": "platform",
"version": "1.1.0-preview1-001100-00"
},
"System.Security.Cryptography.Algorithms": "4.3.0-preview1-24530-04"
}, "frameworks": {
"netcoreapp1.1": {
"imports": "dnxcore50"
}
}
}

相关链接

  • ASP.NET Core RSA加密或解密

【更新】

如果遇到解密时遇到"Bad Data"的问题：

System.Security.Cryptography.CryptographicException: Bad Data.

可以使用下面的方法（同事实现的代码）：

public string Decrypt(string cipher)
{
return Encoding.UTF8.GetString(_rsa.Decrypt(Convert.FromBase64String(cipher), RSAEncryptionPadding.Pkcs1));
var cipherLength = _rsa.KeySize / ;
var cipherBytes = Convert.FromBase64String(cipher);
if (cipherBytes.Length < cipherLength)
{
var delta = cipherLength - cipherBytes.Length;
var newBytes = new byte[cipherLength];
Array.Copy(cipherBytes, , newBytes, delta, cipherBytes.Length);
cipherBytes = newBytes;
} return Encoding.UTF8.GetString(_rsa.Decrypt(cipherBytes, RSAEncryptionPadding.Pkcs1));
}