SM2 是国家密码管理局组织制定并提出的椭圆曲线密码算法标准。
本文使用第三方密码库 BouncyCastle 实现 SM2 加解密，使用 NuGet 安装即可，包名：Portable.BouncyCastle，目前最新版本为：1.9.0。
using Org.BouncyCastle.Asn1.GM;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Digests;
using Org.BouncyCastle.Crypto.Engines;
using Org.BouncyCastle.Crypto.Generators;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Math.EC;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Utilities.Encoders;
using System;
using System.Collections.Generic;
using System.Text;
namespace AI_SXPA.Utility
{
/// <summary>
/// 可用
/// </summary>
public class Sm2Util
{
/// <summary>
/// 加密模式
/// </summary>
public enum Mode
{
C1C2C3,
C1C3C2
}
private readonly Mode _mode;
private readonly string _privkey;
private ICipherParameters _privateKeyParameters;
private string _pubkey;
private ICipherParameters _publicKeyParameters;
public Sm2Util(string pubkey, string privkey, Mode mode = Mode.C1C3C2, bool isPkcs8 = false)
{
if (pubkey != null)
_pubkey = pubkey;
if (privkey != null)
_privkey = privkey;
_mode = mode;
}
public Sm2Util(string pubkey, Mode mode = Mode.C1C3C2, bool isPkcs8 = false)
{
if (pubkey != null)
_pubkey = pubkey;
_mode = mode;
}
private ICipherParameters PrivateKeyParameters
{
get
{
try
{
var r = _privateKeyParameters;
if (r == null)
r = _privateKeyParameters =
new ECPrivateKeyParameters(new BigInteger(_privkey, 16),
new ECDomainParameters(GMNamedCurves.GetByName("SM2P256V1")));
return r;
}
catch (Exception ex)
{
return null;
}
}
}
private ICipherParameters PublicKeyParameters
{
get
{
try
{
var r = _publicKeyParameters;
if (r == null)
{
//截取64字节有效的SM2公钥（如果公钥首个字节为0x04）
if (_pubkey.Length > 128) _pubkey = _pubkey.Substring(_pubkey.Length - 128);
//将公钥拆分为x,y分量（各32字节）
var stringX = _pubkey.Substring(0, 64);
var stringY = _pubkey.Substring(stringX.Length);
//将公钥x、y分量转换为BigInteger类型
var x = new BigInteger(stringX, 16);
var y = new BigInteger(stringY, 16);
//通过公钥x、y分量创建椭圆曲线公钥规范
var x9Ec = GMNamedCurves.GetByName("SM2P256V1");
r = _publicKeyParameters = new ECPublicKeyParameters(x9Ec.Curve.CreatePoint(x, y),
new ECDomainParameters(x9Ec));
}
return r;
}
catch (Exception ex)
{
return null;
}
}
}
/// <summary>
/// 生成秘钥对
/// </summary>
/// <returns></returns>
public static Dictionary<string, string> GenerateKeyPair()
{
string[] param =
{
"FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFF", // p,0
"FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFC", // a,1
"28E9FA9E9D9F5E344D5A9E4BCF6509A7F39789F515AB8F92DDBCBD414D940E93", // b,2
"FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFF7203DF6B21C6052B53BBF40939D54123", // n,3
"32C4AE2C1F1981195F9904466A39C9948FE30BBFF2660BE1715A4589334C74C7", // gx,4
"BC3736A2F4F6779C59BDCEE36B692153D0A9877CC62A474002DF32E52139F0A0" // gy,5
};
var eccParam = param;
var eccP = new BigInteger(eccParam[0], 16);
var eccA = new BigInteger(eccParam[1], 16);
var eccB = new BigInteger(eccParam[2], 16);
var eccN = new BigInteger(eccParam[3], 16);
var eccGx = new BigInteger(eccParam[4], 16);
var eccGy = new BigInteger(eccParam[5], 16);
ECFieldElement element = new FpFieldElement(eccP, eccGx);
ECFieldElement ecFieldElement = new FpFieldElement(eccP, eccGy);
ECCurve eccCurve = new FpCurve(eccP, eccA, eccB);
ECPoint eccPointG = new FpPoint(eccCurve, element, ecFieldElement);
var bcSpec = new ECDomainParameters(eccCurve, eccPointG, eccN);
var ecgenparam = new ECKeyGenerationParameters(bcSpec, new SecureRandom());
var generator = new ECKeyPairGenerator();
generator.Init(ecgenparam);
var key = generator.GenerateKeyPair();
var ecpriv = (ECPrivateKeyParameters)key.Private;
var ecpub = (ECPublicKeyParameters)key.Public;
var privateKey = ecpriv.D;
var publicKey = ecpub.Q;
var dic = new Dictionary<string, string>();
dic.Add("pubkey", Encoding.Default.GetString(Hex.Encode(publicKey.GetEncoded())));
dic.Add("prikey", Encoding.Default.GetString(Hex.Encode(privateKey.ToByteArray())));
//dic.Add("pubkey", Encoding.Default.GetString(Hex.Encode(publicKey.GetEncoded())).ToUpper());
//dic.Add("prikey", Encoding.Default.GetString(Hex.Encode(privateKey.ToByteArray())).ToUpper());
return dic;
}
/// <summary>
/// 解密
/// </summary>
/// <param name="data"></param>
/// <returns></returns>
public byte[] Decrypt(byte[] data)
{
try
{
if (_mode == Mode.C1C3C2)
data = C132ToC123(data);
var sm2 = new SM2Engine(new SM3Digest());
sm2.Init(false, PrivateKeyParameters);
return sm2.ProcessBlock(data, 0, data.Length);
}
catch (Exception ex)
{
return null;
}
}
/// <summary>
/// 加密
/// </summary>
/// <param name="data"></param>
/// <returns></returns>
public byte[] Encrypt(byte[] data)
{
try
{
var sm2 = new SM2Engine(new SM3Digest());
sm2.Init(true, new ParametersWithRandom(PublicKeyParameters));
data = sm2.ProcessBlock(data, 0, data.Length);
if (_mode == Mode.C1C3C2)
data = C123ToC132(data);
return data;
}
catch (Exception ex)
{
return null;
}
}
private static byte[] C123ToC132(byte[] c1c2c3)
{
var gn = GMNamedCurves.GetByName("SM2P256V1");
var c1Len = (gn.Curve.FieldSize + 7) / 8 * 2 + 1;
var c3Len = 32;
var result = new byte[c1c2c3.Length];
Array.Copy(c1c2c3, 0, result, 0, c1Len); //c1
Array.Copy(c1c2c3, c1c2c3.Length - c3Len, result, c1Len, c3Len); //c3
Array.Copy(c1c2c3, c1Len, result, c1Len + c3Len, c1c2c3.Length - c1Len - c3Len); //c2
return result;
}
private static byte[] C132ToC123(byte[] c1c3c2)
{
var gn = GMNamedCurves.GetByName("SM2P256V1");
var c1Len = (gn.Curve.FieldSize + 7) / 8 * 2 + 1;
var c3Len = 32;
var result = new byte[c1c3c2.Length];
Array.Copy(c1c3c2, 0, result, 0, c1Len); //c1: 0->65
Array.Copy(c1c3c2, c1Len + c3Len, result, c1Len, c1c3c2.Length - c1Len - c3Len); //c2
Array.Copy(c1c3c2, c1Len, result, c1c3c2.Length - c3Len, c3Len); //c3
return result;
}
/// <summary>
/// 字节数组转16进制原码字符串
/// </summary>
/// <param name="bytes"></param>
/// <returns></returns>
public static string BytesToHexStr(byte[] bytes)
{
var str = "";
if (bytes != null)
for (var i = 0; i < bytes.Length; i++)
str += bytes[i].ToString("X2");
return str;
}
/// <summary>
/// 16进制原码字符串转字节数组
/// </summary>
/// <param name="hexStr">"AABBCC"或"AA BB CC"格式的字符串</param>
/// <returns></returns>
public static byte[] HexStrToBytes(string hexStr)
{
hexStr = hexStr.Replace(" ", "");
if (hexStr.Length % 2 != 0) throw new ArgumentException("参数长度不正确,必须是偶数位。");
var bytes = new byte[hexStr.Length / 2];
for (var i = 0; i < bytes.Length; i++)
{
var b = Convert.ToByte(hexStr.Substring(i * 2, 2), 16);
bytes[i] = b;
}
return bytes;
}
}
}
SM2 加解密联调时踩坑
1、密文数据，有些加密硬件出来密文结构为 C1|C2|C3 ，有些为 C1|C3|C2 , 需要对应密文结构做解密操作
2、有些加密硬件，公钥前加04 ，私钥前加00，密文前加04 ，在处理时候，可以根据长度处理，尤其 04 的处理。
在线验证：在线SM2加密解密,生成公钥/私钥对 (config.net.cn)
