使用 RSACryptoServiceProvider 进行公钥加密

问题描述

一段时间以来，我在 CodeProject 上看过一篇文章，其中解释了如何使用 RSA 提供程序进行加密和解密:

I have been over an article at CodeProject a for a while that explains how to encrypt and decrypt using the RSA provider:

RSA 私钥加密

虽然 2009 年的旧版本有问题，但 2012 年的新版本(支持 System.Numerics.BigInteger)似乎更可靠.不过，这个版本缺少的是一种使用 public 密钥加密 并使用 private 密钥解密 的方法.

While the old version from 2009 was buggy, the new 2012 version (with System.Numerics.BigInteger support) seems more reliable. What this version lacks though is a way to encrypt with a public key and decrypt using the private key.

所以，我自己尝试过，但解密时会出现垃圾.我不熟悉 RSA 提供商，所以我在这里一无所知.很难找到更多关于这应该如何工作的信息.

So, I tried it myself but get garbage when I decrypt. I'm not familiar with the RSA provider, so I'm in the dark here. It's hard to find more info on how this is supposed to work.

有人知道这有什么问题吗?以下是使用公钥加密:

// Add 4 byte padding to the data, and convert to BigInteger struct
BigInteger numData = GetBig( AddPadding( data ) );
RSAParameters rsaParams = rsa.ExportParameters( false );
//BigInteger D = GetBig( rsaParams.D ); //only for private key
BigInteger Exponent = GetBig( rsaParams.Exponent );
BigInteger Modulus = GetBig( rsaParams.Modulus );
BigInteger encData = BigInteger.ModPow( numData, Exponent, Modulus );    
return encData.ToByteArray();

执行此操作时是否使用提供商提供的大D"?可能不是，因为它是没有D"的公钥.

Do I use the big "D" from the provider when I do this? Probably not since it's the public key which doesn't have the "D".

然后是对应的(使用 PRIVATE 密钥解密):

BigInteger numEncData = new BigInteger( cipherData );

RSAParameters rsaParams = rsa.ExportParameters( true );
BigInteger D = GetBig( rsaParams.D );
//BigInteger Exponent = GetBig( rsaParams.Exponent );
BigInteger Modulus = GetBig( rsaParams.Modulus );

BigInteger decData = BigInteger.ModPow( numEncData, D, Modulus );

byte[] data = decData.ToByteArray();
byte[] result = new byte[ data.Length - 1 ];
Array.Copy( data, result, result.Length );
result = RemovePadding( result );

Array.Reverse( result );
return result;

这里需要D"还是指数?

Do I need the "D" or the Exponent here?

显然，我需要加密货币在私人-公共-公共-私人两种方式下工作.非常感谢任何帮助！

推荐答案

这里有一个例子:

    public static void rsaPlayground()
    {
        byte[] data = new byte[] { 1, 2, 3, 4, 5 };
        RSACryptoServiceProvider csp = new RSACryptoServiceProvider();//make a new csp with a new keypair
        var pub_key = csp.ExportParameters(false); // export public key
        var priv_key = csp.ExportParameters(true); // export private key

        var encData = csp.Encrypt(data, false); // encrypt with PKCS#1_V1.5 Padding
        var decBytes = MyRSAImpl.plainDecryptPriv(encData, priv_key); //decrypt with own BigInteger based implementation
        var decData = decBytes.SkipWhile(x => x != 0).Skip(1).ToArray();//strip PKCS#1_V1.5 padding

    }

    public class MyRSAImpl 
    {

        private static byte[] rsaOperation(byte[] data, BigInteger exp, BigInteger mod)
        {
            BigInteger bData = new BigInteger(
                data    //our data block
                .Reverse()  //BigInteger has another byte order
                .Concat(new byte[] { 0 }) // append 0 so we are allways handling positive numbers
                .ToArray() // constructor wants an array
            );
            return 
                BigInteger.ModPow(bData, exp, mod) // the RSA operation itself
                .ToByteArray() //make bytes from BigInteger
                .Reverse() // back to "normal" byte order
                .ToArray(); // return as byte array

            /*
             * 
             * A few words on Padding:
             * 
             * you will want to strip padding after decryption or apply before encryption 
             * 
             */
        }

        public static byte[] plainEncryptPriv(byte[] data, RSAParameters key) 
        {
            MyRSAParams myKey = MyRSAParams.fromRSAParameters(key);
            return rsaOperation(data, myKey.privExponent, myKey.Modulus);
        }
        public static byte[] plainEncryptPub(byte[] data, RSAParameters key)
        {
            MyRSAParams myKey = MyRSAParams.fromRSAParameters(key);
            return rsaOperation(data, myKey.pubExponent, myKey.Modulus);
        }
        public static byte[] plainDecryptPriv(byte[] data, RSAParameters key)
        {
            MyRSAParams myKey = MyRSAParams.fromRSAParameters(key);
            return rsaOperation(data, myKey.privExponent, myKey.Modulus);
        }
        public static byte[] plainDecryptPub(byte[] data, RSAParameters key)
        {
            MyRSAParams myKey = MyRSAParams.fromRSAParameters(key);
            return rsaOperation(data, myKey.pubExponent, myKey.Modulus);
        }

    }

    public class MyRSAParams
    {
        public static MyRSAParams fromRSAParameters(RSAParameters key)
        {
            var ret = new MyRSAParams();
            ret.Modulus = new BigInteger(key.Modulus.Reverse().Concat(new byte[] { 0 }).ToArray());
            ret.privExponent = new BigInteger(key.D.Reverse().Concat(new byte[] { 0 }).ToArray());
            ret.pubExponent = new BigInteger(key.Exponent.Reverse().Concat(new byte[] { 0 }).ToArray());

            return ret;
        }
        public BigInteger Modulus;
        public BigInteger privExponent;
        public BigInteger pubExponent;
    }

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