我们来看在C#中如何实现RSA加密解密。直接上代码，如下类是RSA算法实现的加密，加解密，签名以及签名的验证。
我们封装了以下的这个RSA类：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
using System.IO;
namespace WebsiteXXX_Auth
{
/// <summary>
/// 类名：RSACrypt
/// 功能：RSA加密、解密、签名、验签
/// </summary>
public sealed class RSACrypt
{
/// <summary>
/// 签名
/// </summary>
/// <param name="content">待签名字符串</param>
/// <param name="privateKey">私钥</param>
/// <param name="input_charset">编码格式</param>
/// <returns>签名后字符串</returns>
public static string sign(string content, string privateKey, string input_charset)
{
byte[] Data = Encoding.GetEncoding(input_charset).GetBytes(content);
RSACryptoServiceProvider rsa = DecodePemPrivateKey(privateKey);
SHA1 sh = new SHA1CryptoServiceProvider();
byte[] signData = rsa.SignData(Data, sh);
return Convert.ToBase64String(signData);
}
/// <summary>
/// 验签
/// </summary>
/// <param name="content">待验签字符串</param>
/// <param name="signedString">签名</param>
/// <param name="publicKey">公钥</param>
/// <param name="input_charset">编码格式</param>
/// <returns>true(通过)，false(不通过)</returns>
public static bool verify(string content, string signedString, string publicKey, string input_charset)
{
bool result = false;
byte[] Data = Encoding.GetEncoding(input_charset).GetBytes(content);
byte[] data = Convert.FromBase64String(signedString);
RSAParameters paraPub = ConvertFromPublicKey(publicKey);
RSACryptoServiceProvider rsaPub = new RSACryptoServiceProvider();
rsaPub.ImportParameters(paraPub);
SHA1 sh = new SHA1CryptoServiceProvider();
result = rsaPub.VerifyData(Data, sh, data);
return result;
}
/// <summary>
/// 加密
/// </summary>
/// <param name="resData">需要加密的字符串</param>
/// <param name="publicKey">公钥</param>
/// <param name="input_charset">编码格式</param>
/// <returns>明文</returns>
public static string encryptData(string resData, string publicKey, string input_charset)
{
byte[] DataToEncrypt = Encoding.ASCII.GetBytes(resData);
string result = encrypt(DataToEncrypt, publicKey, input_charset);
return result;
}
/// <summary>
/// 解密
/// </summary>
/// <param name="resData">加密字符串</param>
/// <param name="privateKey">私钥</param>
/// <param name="input_charset">编码格式</param>
/// <returns>明文</returns>
public static string decryptData(string resData, string privateKey, string input_charset)
{
byte[] DataToDecrypt = Convert.FromBase64String(resData);
string result = "";
for (int j = 0; j < DataToDecrypt.Length / 128; j++)
{
byte[] buf = new byte[128];
for (int i = 0; i < 128; i++)
{
buf[i] = DataToDecrypt[i + 128 * j];
}
result += decrypt(buf, privateKey, input_charset);
}
return result;
}
private static string encrypt(byte[] data, string publicKey, string input_charset)
{
RSACryptoServiceProvider rsa = DecodePemPublicKey(publicKey);
SHA1 sh = new SHA1CryptoServiceProvider();
byte[] result = rsa.Encrypt(data, false);
return Convert.ToBase64String(result);
}
private static string decrypt(byte[] data, string privateKey, string input_charset)
{
string result = "";
RSACryptoServiceProvider rsa = DecodePemPrivateKey(privateKey);
SHA1 sh = new SHA1CryptoServiceProvider();
byte[] source = rsa.Decrypt(data, false);
char[] asciiChars = new char[Encoding.GetEncoding(input_charset).GetCharCount(source, 0, source.Length)];
Encoding.GetEncoding(input_charset).GetChars(source, 0, source.Length, asciiChars, 0);
result = new string(asciiChars);
return result;
}
private static RSACryptoServiceProvider DecodePemPublicKey(String pemstr)
{
byte[] pkcs8publickkey;
pkcs8publickkey = Convert.FromBase64String(pemstr);
if (pkcs8publickkey != null)
{
RSACryptoServiceProvider rsa = DecodeRSAPublicKey(pkcs8publickkey);
return rsa;
}
else
return null;
}
private static RSACryptoServiceProvider DecodePemPrivateKey(String pemstr)
{
byte[] pkcs8privatekey;
pkcs8privatekey = Convert.FromBase64String(pemstr);
if (pkcs8privatekey != null)
{
RSACryptoServiceProvider rsa = DecodePrivateKeyInfo(pkcs8privatekey);
return rsa;
}
else
return null;
}
private static RSACryptoServiceProvider DecodePrivateKeyInfo(byte[] pkcs8)
{
byte[] SeqOID = { 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00 };
byte[] seq = new byte[15];
MemoryStream mem = new MemoryStream(pkcs8);
int lenstream = (int)mem.Length;
BinaryReader binr = new BinaryReader(mem);
byte bt = 0;
ushort twobytes = 0;
try
{
twobytes = binr.ReadUInt16();
if (twobytes == 0x8130)
binr.ReadByte();
else if (twobytes == 0x8230)
binr.ReadInt16();
else
return null;
bt = binr.ReadByte();
if (bt != 0x02)
return null;
twobytes = binr.ReadUInt16();
if (twobytes != 0x0001)
return null;
seq = binr.ReadBytes(15);
if (!CompareBytearrays(seq, SeqOID))
return null;
bt = binr.ReadByte();
if (bt != 0x04)
return null;
bt = binr.ReadByte();
if (bt == 0x81)
binr.ReadByte();
else
if (bt == 0x82)
binr.ReadUInt16();
byte[] rsaprivkey = binr.ReadBytes((int)(lenstream - mem.Position));
RSACryptoServiceProvider rsacsp = DecodeRSAPrivateKey(rsaprivkey);
return rsacsp;
}
catch (Exception)
{
return null;
}
finally { binr.Close(); }
}
private static bool CompareBytearrays(byte[] a, byte[] b)
{
if (a.Length != b.Length)
return false;
int i = 0;
foreach (byte c in a)
{
if (c != b[i])
return false;
i++;
}
return true;
}
private static RSACryptoServiceProvider DecodeRSAPublicKey(byte[] publickey)
{
byte[] SeqOID = { 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00 };
byte[] seq = new byte[15];
MemoryStream mem = new MemoryStream(publickey);
BinaryReader binr = new BinaryReader(mem);
byte bt = 0;
ushort twobytes = 0;
try
{
twobytes = binr.ReadUInt16();
if (twobytes == 0x8130)
binr.ReadByte();
else if (twobytes == 0x8230)
binr.ReadInt16();
else
return null;
seq = binr.ReadBytes(15);
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, 0);
byte firstbyte = binr.ReadByte();
binr.BaseStream.Seek(-1, SeekOrigin.Current);
if (firstbyte == 0x00)
{
binr.ReadByte();
modsize -= 1;
}
byte[] modulus = binr.ReadBytes(modsize);
if (binr.ReadByte() != 0x02)
return null;
int expbytes = (int)binr.ReadByte();
byte[] exponent = binr.ReadBytes(expbytes);
RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
RSAParameters RSAKeyInfo = new RSAParameters();
RSAKeyInfo.Modulus = modulus;
RSAKeyInfo.Exponent = exponent;
RSA.ImportParameters(RSAKeyInfo);
return RSA;
}
catch (Exception)
{
return null;
}
finally { binr.Close(); }
}
private static RSACryptoServiceProvider DecodeRSAPrivateKey(byte[] privkey)
{
byte[] MODULUS, E, D, P, Q, DP, DQ, IQ;
MemoryStream mem = new MemoryStream(privkey);
BinaryReader binr = new BinaryReader(mem);
byte bt = 0;
ushort twobytes = 0;
int elems = 0;
try
{
twobytes = binr.ReadUInt16();
if (twobytes == 0x8130)
binr.ReadByte();
else if (twobytes == 0x8230)
binr.ReadInt16();
else
return null;
twobytes = binr.ReadUInt16();
if (twobytes != 0x0102)
return null;
bt = binr.ReadByte();
if (bt != 0x00)
return null;
elems = GetIntegerSize(binr);
MODULUS = binr.ReadBytes(elems);
elems = GetIntegerSize(binr);
E = binr.ReadBytes(elems);
elems = GetIntegerSize(binr);
D = binr.ReadBytes(elems);
elems = GetIntegerSize(binr);
P = binr.ReadBytes(elems);
elems = GetIntegerSize(binr);
Q = binr.ReadBytes(elems);
elems = GetIntegerSize(binr);
DP = binr.ReadBytes(elems);
elems = GetIntegerSize(binr);
DQ = binr.ReadBytes(elems);
elems = GetIntegerSize(binr);
IQ = binr.ReadBytes(elems);
RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
RSAParameters RSAparams = new RSAParameters();
RSAparams.Modulus = MODULUS;
RSAparams.Exponent = E;
RSAparams.D = D;
RSAparams.P = P;
RSAparams.Q = Q;
RSAparams.DP = DP;
RSAparams.DQ = DQ;
RSAparams.InverseQ = IQ;
RSA.ImportParameters(RSAparams);
return RSA;
}
catch (Exception)
{
return null;
}
finally { binr.Close(); }
}
private static int GetIntegerSize(BinaryReader binr)
{
byte bt = 0;
byte lowbyte = 0x00;
byte highbyte = 0x00;
int count = 0;
bt = binr.ReadByte();
if (bt != 0x02)
return 0;
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, 0);
}
else
{
count = bt;
}
while (binr.ReadByte() == 0x00)
{
count -= 1;
}
binr.BaseStream.Seek(-1, SeekOrigin.Current);
return count;
}
private static RSAParameters ConvertFromPublicKey(string pemFileConent)
{
byte[] keyData = Convert.FromBase64String(pemFileConent);
if (keyData.Length < 162)
{
throw new ArgumentException("pem file content is incorrect.");
}
byte[] pemModulus = new byte[128];
byte[] pemPublicExponent = new byte[3];
Array.Copy(keyData, 29, pemModulus, 0, 128);
Array.Copy(keyData, 159, pemPublicExponent, 0, 3);
RSAParameters para = new RSAParameters();
para.Modulus = pemModulus;
para.Exponent = pemPublicExponent;
return para;
}
private static RSAParameters ConvertFromPrivateKey(string pemFileConent)
{
byte[] keyData = Convert.FromBase64String(pemFileConent);
if (keyData.Length < 609)
{
throw new ArgumentException("pem file content is incorrect.");
}
int index = 11;
byte[] pemModulus = new byte[128];
Array.Copy(keyData, index, pemModulus, 0, 128);
index += 128;
index += 2;
byte[] pemPublicExponent = new byte[3];
Array.Copy(keyData, index, pemPublicExponent, 0, 3);
index += 3;
index += 4;
byte[] pemPrivateExponent = new byte[128];
Array.Copy(keyData, index, pemPrivateExponent, 0, 128);
index += 128;
index += ((int)keyData[index + 1] == 64 ? 2 : 3);
byte[] pemPrime1 = new byte[64];
Array.Copy(keyData, index, pemPrime1, 0, 64);
index += 64;
index += ((int)keyData[index + 1] == 64 ? 2 : 3);//346
byte[] pemPrime2 = new byte[64];
Array.Copy(keyData, index, pemPrime2, 0, 64);
index += 64;
index += ((int)keyData[index + 1] == 64 ? 2 : 3);
byte[] pemExponent1 = new byte[64];
Array.Copy(keyData, index, pemExponent1, 0, 64);
index += 64;
index += ((int)keyData[index + 1] == 64 ? 2 : 3);
byte[] pemExponent2 = new byte[64];
Array.Copy(keyData, index, pemExponent2, 0, 64);
index += 64;
index += ((int)keyData[index + 1] == 64 ? 2 : 3);
byte[] pemCoefficient = new byte[64];
Array.Copy(keyData, index, pemCoefficient, 0, 64);
RSAParameters para = new RSAParameters();
para.Modulus = pemModulus;
para.Exponent = pemPublicExponent;
para.D = pemPrivateExponent;
para.P = pemPrime1;
para.Q = pemPrime2;
para.DP = pemExponent1;
para.DQ = pemExponent2;
para.InverseQ = pemCoefficient;
return para;
}
}
}下面来看下如何使用：
//rsa_private_pk8.pem内容
string privatekey = "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";
//rsa_public_key.pem内容
string publickey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDLK6Hw+RE///HKM1zukQTao/ybdm7RpbQ2bvDTHtDWysx46vIC4wosNZwP3bmxEpzq8f6B3jZeqtcoxCWfVNi1S1FNjyKpC55xmjzrCTNUe9mSgKwyoGU/kHpR4FyXTgP02XkuDXXJrODlDQQg0UNrgbkA9BboLxdxkZLsp1tshQIDAQAB";
//加密字符串
string data = "piaoyi.org";
richTextBox1.AppendText("加密前字符串内容：" + data + "\r\n\r\n");
//加密和解密
string encrypteddata = RSACrypt.encryptData(data, publickey, "UTF-8");
richTextBox1.AppendText("加密后的字符串为：" + encrypteddata + "\r\n\r\n");
richTextBox1.AppendText("解密后的字符串内容：" + RSACrypt.decryptData(encrypteddata, privatekey, "UTF-8") + "\r\n\r\n");
//签名和验签
string signdata = "piaoyi.org.201901011088";
richTextBox1.AppendText("签名前的字符串内容：" + signdata + "\r\n\r\n");
string sign = RSACrypt.sign(signdata, privatekey, "UTF-8");
richTextBox1.AppendText("签名后的字符串：" + sign + "\r\n\r\n");
bool realSign1 = RSACrypt.verify(signdata, sign, publickey, "UTF-8");
richTextBox1.AppendText(realSign1 + "\r\n\r\n");
bool realSign2 = RSACrypt.verify(signdata + "HAHA", sign, publickey, "UTF-8");
richTextBox1.AppendText(realSign2 + "\r\n\r\n");关于RSA公钥和私钥生成的方法：
RSA中的密钥对通过Apache 的OPENSSL工具生成，生成命令如下： 1 生成RSA私钥： openssl genrsa -out rsa_private_key.pem 1024 2 生成RSA公钥 openssl rsa -in rsa_private_key.pem -pubout -out rsa_public_key.pem 3 将RSA私钥转换成PKCS8格式 openssl pkcs8 -topk8 -inform PEM -in rsa_private_key.pem -outform PEM -nocrypt -out rsa_private_pk8.pem
直接打开rsa_private_pk8.pem和rsa_pub_pk8.pem文件就可以获取密钥对内容，获取密钥对内容组成字符串时，注意将换行符删除。
【参考】：