本文主要讲解“国密加密算法”SM系列之SM4的C#实现方法，加密规则请详阅国密局发布的文档。

首先需第三方Nuget包：Portable.BouncyCastle （源码来自http://www.bouncycastle.org/csharp/）

1.1 SM4主类

 

    /// <summary>/// /// </summary>internal class SM4{/// <summary>/// 加密 非线性τ函数B=τ(A)/// </summary>/// <param name="b"></param>/// <param name="i"></param>/// <returns></returns>private static long GetULongByBe(byte[] b, int i){long n = (long)(b[i] & 0xff) << 24 |(long)((b[i + 1] & 0xff) << 16) |(long)((b[i + 2] & 0xff) << 8) |(long)(b[i + 3] & 0xff) & 0xffffffffL;return n;}/// <summary>/// 解密 非线性τ函数B=τ(A)/// </summary>/// <param name="n"></param>/// <param name="b"></param>/// <param name="i"></param>private static void PutULongToBe(long n, byte[] b, int i){b[i] = (byte)(int)(0xFF & n >> 24);b[i + 1] = (byte)(int)(0xFF & n >> 16);b[i + 2] = (byte)(int)(0xFF & n >> 8);b[i + 3] = (byte)(int)(0xFF & n);}/// <summary>/// 循环移位,为32位的x循环左移n位/// </summary>/// <param name="x"></param>/// <param name="n"></param>/// <returns></returns>private static long Rotl(long x, int n){return ((x & 0xFFFFFFFF) << n) | x >> (32 - n);}/// <summary>/// 将密钥逆序/// </summary>/// <param name="sk"></param>/// <param name="i"></param>private static void Swap(long[] sk, int i){long t = sk[i];sk[i] = sk[(31 - i)];sk[(31 - i)] = t;}/// <summary>/// S盒 /// </summary>public byte[] SboxTable = new byte[] {//   0     1     2     3     4     5     6     7     8     9     a     b     c     d     e     f0xd6, 0x90, 0xe9, 0xfe, 0xcc, 0xe1, 0x3d, 0xb7, 0x16, 0xb6, 0x14, 0xc2, 0x28, 0xfb, 0x2c, 0x05,0x2b, 0x67, 0x9a, 0x76, 0x2a, 0xbe, 0x04, 0xc3, 0xaa, 0x44, 0x13, 0x26, 0x49, 0x86, 0x06, 0x99,0x9c, 0x42, 0x50, 0xf4, 0x91, 0xef, 0x98, 0x7a, 0x33, 0x54, 0x0b, 0x43, 0xed, 0xcf, 0xac, 0x62,0xe4, 0xb3, 0x1c, 0xa9, 0xc9, 0x08, 0xe8, 0x95, 0x80, 0xdf, 0x94, 0xfa, 0x75, 0x8f, 0x3f, 0xa6,0x47, 0x07, 0xa7, 0xfc, 0xf3, 0x73, 0x17, 0xba, 0x83, 0x59, 0x3c, 0x19, 0xe6, 0x85, 0x4f, 0xa8,0x68, 0x6b, 0x81, 0xb2, 0x71, 0x64, 0xda, 0x8b, 0xf8, 0xeb, 0x0f, 0x4b, 0x70, 0x56, 0x9d, 0x35,0x1e, 0x24, 0x0e, 0x5e, 0x63, 0x58, 0xd1, 0xa2, 0x25, 0x22, 0x7c, 0x3b, 0x01, 0x21, 0x78, 0x87,0xd4, 0x00, 0x46, 0x57, 0x9f, 0xd3, 0x27, 0x52, 0x4c, 0x36, 0x02, 0xe7, 0xa0, 0xc4, 0xc8, 0x9e,0xea, 0xbf, 0x8a, 0xd2, 0x40, 0xc7, 0x38, 0xb5, 0xa3, 0xf7, 0xf2, 0xce, 0xf9, 0x61, 0x15, 0xa1,0xe0, 0xae, 0x5d, 0xa4, 0x9b, 0x34, 0x1a, 0x55, 0xad, 0x93, 0x32, 0x30, 0xf5, 0x8c, 0xb1, 0xe3,0x1d, 0xf6, 0xe2, 0x2e, 0x82, 0x66, 0xca, 0x60, 0xc0, 0x29, 0x23, 0xab, 0x0d, 0x53, 0x4e, 0x6f,0xd5, 0xdb, 0x37, 0x45, 0xde, 0xfd, 0x8e, 0x2f, 0x03, 0xff, 0x6a, 0x72, 0x6d, 0x6c, 0x5b, 0x51,0x8d, 0x1b, 0xaf, 0x92, 0xbb, 0xdd, 0xbc, 0x7f, 0x11, 0xd9, 0x5c, 0x41, 0x1f, 0x10, 0x5a, 0xd8,0x0a, 0xc1, 0x31, 0x88, 0xa5, 0xcd, 0x7b, 0xbd, 0x2d, 0x74, 0xd0, 0x12, 0xb8, 0xe5, 0xb4, 0xb0,0x89, 0x69, 0x97, 0x4a, 0x0c, 0x96, 0x77, 0x7e, 0x65, 0xb9, 0xf1, 0x09, 0xc5, 0x6e, 0xc6, 0x84,0x18, 0xf0, 0x7d, 0xec, 0x3a, 0xdc, 0x4d, 0x20, 0x79, 0xee, 0x5f, 0x3e, 0xd7, 0xcb, 0x39, 0x48};/// <summary>/// 系统参数FK/// </summary>public uint[] FK = { 0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc };/// <summary>/// 固定参数CK/// </summary>public uint[] CK = {0x00070e15,0x1c232a31,0x383f464d,0x545b6269,0x70777e85,0x8c939aa1,0xa8afb6bd,0xc4cbd2d9,0xe0e7eef5,0xfc030a11,0x181f262d,0x343b4249,0x50575e65,0x6c737a81,0x888f969d,0xa4abb2b9,0xc0c7ced5,0xdce3eaf1,0xf8ff060d,0x141b2229,0x30373e45,0x4c535a61,0x686f767d,0x848b9299,0xa0a7aeb5,0xbcc3cad1,0xd8dfe6ed,0xf4fb0209,0x10171e25,0x2c333a41,0x484f565d,0x646b7279};/// <summary>/// Sm4的S盒取值/// </summary>/// <param name="inch"></param>/// <returns></returns>private byte Sm4Sbox(byte inch){int i = inch & 0xFF;byte retVal = SboxTable[i];return retVal;}/// <summary>/// 线性变换 L/// </summary>/// <param name="ka"></param>/// <returns></returns>private long Sm4Lt(long ka){byte[] a = new byte[4];byte[] b = new byte[4];PutULongToBe(ka, a, 0);b[0] = Sm4Sbox(a[0]);b[1] = Sm4Sbox(a[1]);b[2] = Sm4Sbox(a[2]);b[3] = Sm4Sbox(a[3]);long bb = GetULongByBe(b, 0);long c = bb ^ Rotl(bb, 2) ^ Rotl(bb, 10) ^ Rotl(bb, 18) ^ Rotl(bb, 24);return c;}/// <summary>/// 轮函数 F/// </summary>/// <param name="x0"></param>/// <param name="x1"></param>/// <param name="x2"></param>/// <param name="x3"></param>/// <param name="rk"></param>/// <returns></returns>private long Sm4F(long x0, long x1, long x2, long x3, long rk){return x0 ^ Sm4Lt(x1 ^ x2 ^ x3 ^ rk);}/// <summary>/// 轮密钥rk/// </summary>/// <param name="ka"></param>/// <returns></returns>private long Sm4CalciRk(long ka){byte[] a = new byte[4];byte[] b = new byte[4];PutULongToBe(ka, a, 0);b[0] = Sm4Sbox(a[0]);b[1] = Sm4Sbox(a[1]);b[2] = Sm4Sbox(a[2]);b[3] = Sm4Sbox(a[3]);long bb = GetULongByBe(b, 0);long rk = bb ^ Rotl(bb, 13) ^ Rotl(bb, 23);return rk;}/// <summary>/// 加密密钥/// </summary>/// <param name="SK"></param>/// <param name="key"></param>private void SetKey(long[] SK, byte[] key){//加密密钥长度为 128 比特long[] MK = new long[4];int i = 0;MK[0] = GetULongByBe(key, 0);MK[1] = GetULongByBe(key, 4);MK[2] = GetULongByBe(key, 8);MK[3] = GetULongByBe(key, 12);long[] k = new long[36];//轮密钥生成方法k[0] = MK[0] ^ (long)FK[0];k[1] = MK[1] ^ (long)FK[1];k[2] = MK[2] ^ (long)FK[2];k[3] = MK[3] ^ (long)FK[3];for (; i < 32; i++){k[(i + 4)] = (k[i] ^ Sm4CalciRk(k[(i + 1)] ^ k[(i + 2)] ^ k[(i + 3)] ^ (long)CK[i]));SK[i] = k[(i + 4)];}}/// <summary>/// 解密函数/// </summary>/// <param name="sk">轮密钥</param>/// <param name="input">输入分组的密文</param>/// <param name="output">输出的对应的分组明文</param>private void Sm4OneRound(long[] sk, byte[] input, byte[] output){int i = 0;long[] ulbuf = new long[36];ulbuf[0] = GetULongByBe(input, 0);ulbuf[1] = GetULongByBe(input, 4);ulbuf[2] = GetULongByBe(input, 8);ulbuf[3] = GetULongByBe(input, 12);while (i < 32) //开始32轮解密 ，一次进行4轮，共计八次{ulbuf[(i + 4)] = Sm4F(ulbuf[i], ulbuf[(i + 1)], ulbuf[(i + 2)], ulbuf[(i + 3)], sk[i]);i++;}PutULongToBe(ulbuf[35], output, 0);PutULongToBe(ulbuf[34], output, 4);PutULongToBe(ulbuf[33], output, 8);PutULongToBe(ulbuf[32], output, 12);}/// <summary>/// 补足 16 进制字符串的 0 字符，返回不带 0x 的16进制字符串/// </summary>/// <param name="input"></param>/// <param name="mode">1表示加密，0表示解密</param>/// <returns></returns>private static byte[] Padding(byte[] input, int mode){if (input == null){return null;}byte[] ret;if (mode == 1){int p = 16 - input.Length % 16;ret = new byte[input.Length + p];Array.Copy(input, 0, ret, 0, input.Length);for (int i = 0; i < p; i++){ret[input.Length + i] = (byte)p;}}else{int p = input[^1];ret = new byte[input.Length - p];Array.Copy(input, 0, ret, 0, input.Length - p);}return ret;}/// <summary>/// 设置加密的key/// </summary>/// <param name="ctx"></param>/// <param name="key"></param>public void SetKeyEnc(Sm4Context ctx, byte[] key){ctx.Mode = 1;SetKey(ctx.Key, key);}/// <summary>/// 设置解密的key/// </summary>/// <param name="ctx"></param>/// <param name="key"></param>public void Sm4SetKeyDec(Sm4Context ctx, byte[] key){ctx.Mode = 0;SetKey(ctx.Key, key);int i;for (i = 0; i < 16; i++){Swap(ctx.Key, i);}}/// <summary>/// ECB/// </summary>/// <param name="ctx"></param>/// <param name="input"></param>/// <returns></returns>public byte[] Sm4CryptEcb(Sm4Context ctx, byte[] input){if (ctx.IsPadding && (ctx.Mode == 1)){input = Padding(input, 1);}int length = input.Length;byte[] bins = new byte[length];Array.Copy(input, 0, bins, 0, length);byte[] bous = new byte[length];for (int i = 0; length > 0; length -= 16, i++){byte[] inBytes = new byte[16];byte[] outBytes = new byte[16];Array.Copy(bins, i * 16, inBytes, 0, length > 16 ? 16 : length);Sm4OneRound(ctx.Key, inBytes, outBytes);Array.Copy(outBytes, 0, bous, i * 16, length > 16 ? 16 : length);}if (ctx.IsPadding && ctx.Mode == 0){bous = Padding(bous, 0);}return bous;}/// <summary>/// CBC/// </summary>/// <param name="ctx"></param>/// <param name="iv"></param>/// <param name="input"></param>/// <returns></returns>public byte[] Sm4CryptCbc(Sm4Context ctx, byte[] iv, byte[] input){if (ctx.IsPadding && ctx.Mode == 1){input = Padding(input, 1);}int length = input.Length;byte[] bins = new byte[length];Array.Copy(input, 0, bins, 0, length);List<byte> bousList = new List<byte>();int i;if (ctx.Mode == 1){for (int j = 0; length > 0; length -= 16, j++){byte[] inBytes = new byte[16];byte[] outBytes = new byte[16];byte[] out1 = new byte[16];Array.Copy(bins, j * 16, inBytes, 0, length > 16 ? 16 : length);for (i = 0; i < 16; i++){outBytes[i] = ((byte)(inBytes[i] ^ iv[i]));}Sm4OneRound(ctx.Key, outBytes, out1);Array.Copy(out1, 0, iv, 0, 16);for (int k = 0; k < 16; k++){bousList.Add(out1[k]);}}}else{byte[] temp = new byte[16];for (int j = 0; length > 0; length -= 16, j++){byte[] inBytes = new byte[16];byte[] outBytes = new byte[16];byte[] out1 = new byte[16];Array.Copy(bins, j * 16, inBytes, 0, length > 16 ? 16 : length);Array.Copy(inBytes, 0, temp, 0, 16);Sm4OneRound(ctx.Key, inBytes, outBytes);for (i = 0; i < 16; i++){out1[i] = ((byte)(outBytes[i] ^ iv[i]));}Array.Copy(temp, 0, iv, 0, 16);for (int k = 0; k < 16; k++){bousList.Add(out1[k]);}}}if (ctx.IsPadding && ctx.Mode == 0){byte[] bous = Padding(bousList.ToArray(), 0);return bous;}else{return bousList.ToArray();}}}

1.2 SM4处理中心

 

    /// <summary>/// /// </summary>internal class Sm4Context{public Sm4Context(){Mode = 1;IsPadding = true;Key = new long[32];}/// <summary>/// 1表示加密，0表示解密/// </summary>public int Mode;/// <summary>/// 密钥/// </summary>public long[] Key;/// <summary>/// 是否补足16进制字符串/// </summary>public bool IsPadding;}

1.3调用

 

    /// <summary>/// Sm4算法  /// 对标国际DES算法/// </summary>public class Sm4Crypto {public Sm4Crypto(){Key = "98145489617106616498";Iv = "0000000000000000";HexString = false;CryptoMode = Sm4CryptoEnum.ECB;}/// <summary>/// 数据/// </summary>public string Data { get; set; }/// <summary>/// 秘钥/// </summary>public string Key { get; set; }/// <summary>/// 向量/// </summary>public string Iv { get; set; }/// <summary>/// 明文是否是十六进制/// </summary>public bool HexString { get; set; }/// <summary>/// 加密模式(默认ECB)/// </summary>public Sm4CryptoEnum CryptoMode { get; set; }#region 加密public string Encrypt(Sm4Crypto entity){return entity.CryptoMode == Sm4CryptoEnum.CBC ? EncryptCBC(entity) : EncryptECB(entity);}/// <summary>/// ECB加密/// </summary>/// <param name="entity"></param>/// <returns></returns>public static string EncryptECB(Sm4Crypto entity){Sm4Context ctx = new Sm4Context{IsPadding = true};byte[] keyBytes = entity.HexString ? Hex.Decode(entity.Key) : Encoding.Default.GetBytes(entity.Key);SM4 sm4 = new SM4();sm4.SetKeyEnc(ctx, keyBytes);byte[] encrypted = sm4.Sm4CryptEcb(ctx, Encoding.Default.GetBytes(entity.Data));return Encoding.Default.GetString(Hex.Encode(encrypted));}/// <summary>/// CBC加密/// </summary>/// <param name="entity"></param>/// <returns></returns>public static string EncryptCBC(Sm4Crypto entity){Sm4Context ctx = new Sm4Context{IsPadding = true};byte[] keyBytes = entity.HexString ? Hex.Decode(entity.Key) : Encoding.Default.GetBytes(entity.Key);byte[] ivBytes = entity.HexString ? Hex.Decode(entity.Iv) : Encoding.Default.GetBytes(entity.Iv);SM4 sm4 = new SM4();sm4.SetKeyEnc(ctx, keyBytes);byte[] encrypted = sm4.Sm4CryptCbc(ctx, ivBytes, Encoding.Default.GetBytes(entity.Data));return encrypted.ToBase64();}#endregion#region 解密public object Decrypt(Sm4Crypto entity){return entity.CryptoMode == Sm4CryptoEnum.CBC ? DecryptCBC(entity) : DecryptECB(entity);}/// <summary>///  ECB解密/// </summary>/// <param name="entity"></param>/// <returns></returns>public static string DecryptECB(Sm4Crypto entity){Sm4Context ctx = new Sm4Context{IsPadding = true,Mode = 0};byte[] keyBytes = entity.HexString ? Hex.Decode(entity.Key) : Encoding.Default.GetBytes(entity.Key);SM4 sm4 = new SM4();sm4.Sm4SetKeyDec(ctx, keyBytes);byte[] decrypted = sm4.Sm4CryptEcb(ctx, Hex.Decode(entity.Data));return Encoding.Default.GetString(decrypted);}/// <summary>/// CBC解密/// </summary>/// <param name="cipherText"></param>/// <returns></returns>public static string DecryptCBC(Sm4Crypto entity){Sm4Context ctx = new Sm4Context{IsPadding = true,Mode = 0};byte[] keyBytes = entity.HexString ? Hex.Decode(entity.Key) : Encoding.Default.GetBytes(entity.Key);byte[] ivBytes = entity.HexString ? Hex.Decode(entity.Iv) : Encoding.Default.GetBytes(entity.Iv);SM4 sm4 = new SM4();sm4.Sm4SetKeyDec(ctx, keyBytes);byte[] decrypted = sm4.Sm4CryptCbc(ctx, ivBytes, Convert.FromBase64String(entity.Data));return Encoding.Default.GetString(decrypted);}#endregion/// <summary>/// 加密类型/// </summary>public enum Sm4CryptoEnum{/// <summary>/// ECB(电码本模式)/// </summary>[Description("ECB模式")]ECB = 0,/// <summary>/// CBC(密码分组链接模式)/// </summary>[Description("CBC模式")]CBC = 1}}

 

1.4 所有类涉及的引用

using Org.BouncyCastle.Utilities.Encoders;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;