C#实现SM4国密加密

眼看着你们堕落 發表於 2020-12-3 09:50:00

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
<div class="cnblogs_code">
<pre> /// <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 & 0xff) << 24 |
 (long)((b & 0xff) << 16) |
 (long)((b & 0xff) << 8) |
 (long)(b & 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 = (byte)(int)(0xFF & n >> 24);
 b = (byte)(int)(0xFF & n >> 16);
 b = (byte)(int)(0xFF & n >> 8);
 b = (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;
 sk = 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 f
 0xd6, 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;
 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 ^ Sm4CalciRk(k[(i + 1)] ^ k[(i + 2)] ^ k[(i + 3)] ^ (long)CK));
 SK = 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, ulbuf[(i + 1)], ulbuf[(i + 2)], ulbuf[(i + 3)], sk);
 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;
 Array.Copy(input, 0, ret, 0, input.Length);
 for (int i = 0; i < p; i++)
 {
 ret = (byte)p;
 }
 }
 else
 {
 int p = input[^1];
 ret = new byte;
 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;
 Array.Copy(input, 0, bins, 0, length);
 byte[] bous = new byte;
 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;
 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 = ((byte)(inBytes ^ iv));
 }
 Sm4OneRound(ctx.Key, outBytes, out1);
 Array.Copy(out1, 0, iv, 0, 16);
 for (int k = 0; k < 16; k++)
 {
 bousList.Add(out1);
 }
 }
 }
 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 = ((byte)(outBytes ^ iv));
 }
 Array.Copy(temp, 0, iv, 0, 16);
 for (int k = 0; k < 16; k++)
 {
 bousList.Add(out1);
 }
 }

 }

 if (ctx.IsPadding && ctx.Mode == 0)
 {
 byte[] bous = Padding(bousList.ToArray(), 0);
 return bous;
 }
 else
 {
 return bousList.ToArray();
 }
 }
}</pre>
</div>
1.2 SM4处理中心
<div class="cnblogs_code">
<pre> /// <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;
}</pre>
</div>
1.3调用
<div class="cnblogs_code">
<pre> /// <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>

 ECB = 0,
 /// <summary>
 /// CBC(密码分组链接模式)
 /// </summary>

 CBC = 1
 }
}</pre>
</div>
1.4 所有类涉及的引用
<div class="cnblogs_code">
<pre>using Org.BouncyCastle.Utilities.Encoders;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;</pre>
</div>
  
来源：https://www.cnblogs.com/raniynight/p/14077878.html

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C#实现SM4国密加密