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 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[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;