針對日常加密演算法，大致分為對稱加密，非對稱加密，雜湊函式(MD5)，其中對稱加密比較常見的，如AES、DES、3DES，對稱加密演算法是指加密和解密採用相同的金鑰口，是可逆的， 實習那會用的就是DES，網上很多現成的輪子。此外非對稱加密演算法， 常用的如 RSA演算法、ECC演算法、DSA等演算法， 非對稱不可逆，安全性更高，相對應加密效率稍微低一些， 國產加密如今崛起，SM系列中很多加密演算法，結合自身業務場景經過比較選取最優解SM4，本文用來記錄具體SM4的使用對接。
（測試版本Net6），直接 安裝BouncyCastle.Cryptography 包即可， 寫個幫助類，直接貼程式碼
#region SM4解密解密 public static void GenerateKeyHex(out string key, out string iv) { //用於生成對稱加密演算法 var keyGenerator = new CipherKeyGenerator(); keyGenerator.Init(new KeyGenerationParameters(new SecureRandom(), 128)); var a = keyGenerator.GenerateKey(); key = Hex.ToHexString(a); SecureRandom random = new SecureRandom(); byte[] b = new byte[16]; // IV長度為16位元組 random.NextBytes(b); iv = Hex.ToHexString(b); } //隨機生成金鑰 public static string GetRandomIV() { SecureRandom random = new(); byte[] b = new byte[16]; // IV長度為16位元組 random.NextBytes(b); return Hex.ToHexString(b); } //CBC模式加密 public static byte[] CBCEncrypt(this string appkey) { byte[] plaintext = Encoding.UTF8.GetBytes(appkey); IBufferedCipher cipher = new PaddedBufferedBlockCipher(new CbcBlockCipher(new SM4Engine()), new Pkcs7Padding()); cipher.Init(true, new ParametersWithIV(new KeyParameter(Decode(AppSetting.Secret.SMKey)), Decode(AppSetting.Secret.SMIV))); byte[] output = new byte[cipher.GetOutputSize(plaintext.Length)]; int bytesProcessed = cipher.ProcessBytes(plaintext, 0, plaintext.Length, output, 0); cipher.DoFinal(output, bytesProcessed); return output; } //CBC模式解密 public static byte[] CBCDecrypt(this string appkey) { try { byte[] ciphertext = Convert.FromBase64String(appkey); IBufferedCipher cipher = new PaddedBufferedBlockCipher(new CbcBlockCipher(new SM4Engine()), new Pkcs7Padding()); cipher.Init(false, new ParametersWithIV(new KeyParameter(Decode(AppSetting.Secret.SMKey)), Decode(AppSetting.Secret.SMIV))); byte[] output = new byte[cipher.GetOutputSize(ciphertext.Length)]; int bytesProcessed = cipher.ProcessBytes(ciphertext, 0, ciphertext.Length, output, 0); cipher.DoFinal(output, bytesProcessed); return RemovePadding(output); } catch { Comm.NLogHelper.WriteError($"登入校驗-解密失敗:{appkey}"); return null; } } static byte[] Decode(string key) { return Regex.IsMatch(key, "^[0-9a-f]+$", RegexOptions.IgnoreCase) ? Hex.Decode(key) : Convert.FromBase64String(key); } // 去除填充字元 public static byte[] RemovePadding(byte[] data) { int lastNonZeroByte = data.Length - 1; while (data[lastNonZeroByte] == 0) { lastNonZeroByte--; } // 擷取非零位元組之前的所有位元組 byte[] result = new byte[lastNonZeroByte + 1]; Array.Copy(data, result, lastNonZeroByte + 1); return result; } #endregion
其中金鑰和偏移量，可以根據上面生成的方法自行生成, 呼叫方法簡單
//加密 var encrypted = "加密欄位XXXXX".CBCEncrypt(); string base64 = Convert.ToBase64String(encrypted); //解密 var original =base64.CBCDecrypt();
但是對於老舊專案的低版本，比如FrameWork4.5 一下, 使用BouncyCastle.Crypto 包，所以需要手動書寫一下SM4 的幫助類, 程式碼如下，需要保證 密碼Key 和 偏移量 IV
public const string CBCKey = "XXXX";
public const string CBCIV = "xxxx";
//CBC模式加密
public static string EncryptCBC(string plainText, bool hexstring = true)
{
var ctx = new SM4Context();
ctx.isPadding = true;
ctx.mode = SM4CryptoServiceProvider.SM4_ENCRYPT;
byte[] keyBytes;
byte[] ivBytes;
if (hexstring)
{
keyBytes = Hex.Decode(CBCKey);
ivBytes = Hex.Decode(CBCIV);
}
else
{
keyBytes = Encoding.UTF8.GetBytes(CBCKey);
ivBytes = Encoding.UTF8.GetBytes(CBCIV);
}
var sm4 = new SM4CryptoServiceProvider();
sm4.sm4_setkey_enc(ctx, keyBytes);
byte[] encrypted = sm4.sm4_crypt_cbc(ctx, ivBytes, Encoding.UTF8.GetBytes(plainText));
string cipherText = Convert.ToBase64String(encrypted);
return cipherText;
}
public string DecryptCBC(string cipherText)
{
var ctx = new SM4Context();
ctx.isPadding = true;
ctx.mode = SM4CryptoServiceProvider.SM4_DECRYPT;
byte[] keyBytes;
byte[] ivBytes;
if (hexstring)
{
keyBytes = Hex.Decode(secretKey);
ivBytes = Hex.Decode(iv);
}
else
{
keyBytes = Encoding.UTF8.GetBytes(secretKey);
ivBytes = Encoding.UTF8.GetBytes(iv);
}
var sm4 = new SM4CryptoServiceProvider();
sm4.sm4_setkey_dec(ctx, keyBytes);
byte[] decrypted = sm4.sm4_crypt_cbc(ctx, ivBytes, Hex.Decode(cipherText));
return Encoding.UTF8.GetString(decrypted);
}
SM4Context 實現如下：
internal class SM4Context { public int mode; public long[] sk; public bool isPadding; public SM4Context() { this.mode = 1; this.isPadding = true; this.sk = new long[32]; } }
SM4CryptoServiceProvider 實現如下：
internal class SM4CryptoServiceProvider { public const int SM4_ENCRYPT = 1; public const int SM4_DECRYPT = 0; private long GET_ULONG_BE(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; } private void PUT_ULONG_BE(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); } private long SHL(long x, int n) { return (x & 0xFFFFFFFF) << n; } private long ROTL(long x, int n) { return SHL(x, n) | x >> (32 - n); } private void SWAP(long[] sk, int i) { long t = sk[i]; sk[i] = sk[(31 - i)]; sk[(31 - i)] = t; } public byte[] SboxTable = new byte[] { (byte) 0xd6, (byte) 0x90, (byte) 0xe9, (byte) 0xfe, (byte) 0xcc, (byte) 0xe1, 0x3d, (byte) 0xb7, 0x16, (byte) 0xb6, 0x14, (byte) 0xc2, 0x28, (byte) 0xfb, 0x2c, 0x05, 0x2b, 0x67, (byte) 0x9a, 0x76, 0x2a, (byte) 0xbe, 0x04, (byte) 0xc3, (byte) 0xaa, 0x44, 0x13, 0x26, 0x49, (byte) 0x86, 0x06, (byte) 0x99, (byte) 0x9c, 0x42, 0x50, (byte) 0xf4, (byte) 0x91, (byte) 0xef, (byte) 0x98, 0x7a, 0x33, 0x54, 0x0b, 0x43, (byte) 0xed, (byte) 0xcf, (byte) 0xac, 0x62, (byte) 0xe4, (byte) 0xb3, 0x1c, (byte) 0xa9, (byte) 0xc9, 0x08, (byte) 0xe8, (byte) 0x95, (byte) 0x80, (byte) 0xdf, (byte) 0x94, (byte) 0xfa, 0x75, (byte) 0x8f, 0x3f, (byte) 0xa6, 0x47, 0x07, (byte) 0xa7, (byte) 0xfc, (byte) 0xf3, 0x73, 0x17, (byte) 0xba, (byte) 0x83, 0x59, 0x3c, 0x19, (byte) 0xe6, (byte) 0x85, 0x4f, (byte) 0xa8, 0x68, 0x6b, (byte) 0x81, (byte) 0xb2, 0x71, 0x64, (byte) 0xda, (byte) 0x8b, (byte) 0xf8, (byte) 0xeb, 0x0f, 0x4b, 0x70, 0x56, (byte) 0x9d, 0x35, 0x1e, 0x24, 0x0e, 0x5e, 0x63, 0x58, (byte) 0xd1, (byte) 0xa2, 0x25, 0x22, 0x7c, 0x3b, 0x01, 0x21, 0x78, (byte) 0x87, (byte) 0xd4, 0x00, 0x46, 0x57, (byte) 0x9f, (byte) 0xd3, 0x27, 0x52, 0x4c, 0x36, 0x02, (byte) 0xe7, (byte) 0xa0, (byte) 0xc4, (byte) 0xc8, (byte) 0x9e, (byte) 0xea, (byte) 0xbf, (byte) 0x8a, (byte) 0xd2, 0x40, (byte) 0xc7, 0x38, (byte) 0xb5, (byte) 0xa3, (byte) 0xf7, (byte) 0xf2, (byte) 0xce, (byte) 0xf9, 0x61, 0x15, (byte) 0xa1, (byte) 0xe0, (byte) 0xae, 0x5d, (byte) 0xa4, (byte) 0x9b, 0x34, 0x1a, 0x55, (byte) 0xad, (byte) 0x93, 0x32, 0x30, (byte) 0xf5, (byte) 0x8c, (byte) 0xb1, (byte) 0xe3, 0x1d, (byte) 0xf6, (byte) 0xe2, 0x2e, (byte) 0x82, 0x66, (byte) 0xca, 0x60, (byte) 0xc0, 0x29, 0x23, (byte) 0xab, 0x0d, 0x53, 0x4e, 0x6f, (byte) 0xd5, (byte) 0xdb, 0x37, 0x45, (byte) 0xde, (byte) 0xfd, (byte) 0x8e, 0x2f, 0x03, (byte) 0xff, 0x6a, 0x72, 0x6d, 0x6c, 0x5b, 0x51, (byte) 0x8d, 0x1b, (byte) 0xaf, (byte) 0x92, (byte) 0xbb, (byte) 0xdd, (byte) 0xbc, 0x7f, 0x11, (byte) 0xd9, 0x5c, 0x41, 0x1f, 0x10, 0x5a, (byte) 0xd8, 0x0a, (byte) 0xc1, 0x31, (byte) 0x88, (byte) 0xa5, (byte) 0xcd, 0x7b, (byte) 0xbd, 0x2d, 0x74, (byte) 0xd0, 0x12, (byte) 0xb8, (byte) 0xe5, (byte) 0xb4, (byte) 0xb0, (byte) 0x89, 0x69, (byte) 0x97, 0x4a, 0x0c, (byte) 0x96, 0x77, 0x7e, 0x65, (byte) 0xb9, (byte) 0xf1, 0x09, (byte) 0xc5, 0x6e, (byte) 0xc6, (byte) 0x84, 0x18, (byte) 0xf0, 0x7d, (byte) 0xec, 0x3a, (byte) 0xdc, 0x4d, 0x20, 0x79, (byte) 0xee, 0x5f, 0x3e, (byte) 0xd7, (byte) 0xcb, 0x39, 0x48 }; public uint[] FK = { 0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc }; 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 }; private byte sm4Sbox(byte inch) { int i = inch & 0xFF; byte retVal = SboxTable[i]; return retVal; } private long sm4Lt(long ka) { long bb = 0L; long c = 0L; byte[] a = new byte[4]; byte[] b = new byte[4]; PUT_ULONG_BE(ka, a, 0); b[0] = sm4Sbox(a[0]); b[1] = sm4Sbox(a[1]); b[2] = sm4Sbox(a[2]); b[3] = sm4Sbox(a[3]); bb = GET_ULONG_BE(b, 0); c = bb ^ ROTL(bb, 2) ^ ROTL(bb, 10) ^ ROTL(bb, 18) ^ ROTL(bb, 24); return c; } private long sm4F(long x0, long x1, long x2, long x3, long rk) { return x0 ^ sm4Lt(x1 ^ x2 ^ x3 ^ rk); } private long sm4CalciRK(long ka) { long bb = 0L; long rk = 0L; byte[] a = new byte[4]; byte[] b = new byte[4]; PUT_ULONG_BE(ka, a, 0); b[0] = sm4Sbox(a[0]); b[1] = sm4Sbox(a[1]); b[2] = sm4Sbox(a[2]); b[3] = sm4Sbox(a[3]); bb = GET_ULONG_BE(b, 0); rk = bb ^ ROTL(bb, 13) ^ ROTL(bb, 23); return rk; } private void sm4_setkey(long[] SK, byte[] key) { long[] MK = new long[4]; long[] k = new long[36]; int i = 0; MK[0] = GET_ULONG_BE(key, 0); MK[1] = GET_ULONG_BE(key, 4); MK[2] = GET_ULONG_BE(key, 8); MK[3] = GET_ULONG_BE(key, 12); 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)]; } } private void sm4_one_round(long[] sk, byte[] input, byte[] output) { int i = 0; long[] ulbuf = new long[36]; ulbuf[0] = GET_ULONG_BE(input, 0); ulbuf[1] = GET_ULONG_BE(input, 4); ulbuf[2] = GET_ULONG_BE(input, 8); ulbuf[3] = GET_ULONG_BE(input, 12); while (i < 32) { ulbuf[(i + 4)] = sm4F(ulbuf[i], ulbuf[(i + 1)], ulbuf[(i + 2)], ulbuf[(i + 3)], sk[i]); i++; } PUT_ULONG_BE(ulbuf[35], output, 0); PUT_ULONG_BE(ulbuf[34], output, 4); PUT_ULONG_BE(ulbuf[33], output, 8); PUT_ULONG_BE(ulbuf[32], output, 12); } private byte[] padding(byte[] input, int mode) { if (input == null) { return null; } byte[] ret = (byte[])null; if (mode == SM4_ENCRYPT) { 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[input.Length - 1]; ret = new byte[input.Length - p]; Array.Copy(input, 0, ret, 0, input.Length - p); } return ret; } public void sm4_setkey_enc(SM4Context ctx, byte[] key) { ctx.mode = SM4_ENCRYPT; sm4_setkey(ctx.sk, key); } public void sm4_setkey_dec(SM4Context ctx, byte[] key) { int i = 0; ctx.mode = SM4_DECRYPT; sm4_setkey(ctx.sk, key); for (i = 0; i < 16; i++) { SWAP(ctx.sk, i); } } public byte[] sm4_crypt_ecb(SM4Context ctx, byte[] input) { if ((ctx.isPadding) && (ctx.mode == SM4_ENCRYPT)) { input = padding(input, SM4_ENCRYPT); } 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); sm4_one_round(ctx.sk, inBytes, outBytes); Array.Copy(outBytes, 0, bous, i * 16, length > 16 ? 16 : length); } if (ctx.isPadding && ctx.mode == SM4_DECRYPT) { bous = padding(bous, SM4_DECRYPT); } return bous; } public byte[] sm4_crypt_cbc(SM4Context ctx, byte[] iv, byte[] input) { if (ctx.isPadding && ctx.mode == SM4_ENCRYPT) { input = padding(input, SM4_ENCRYPT); } int i = 0; int length = input.Length; byte[] bins = new byte[length]; Array.Copy(input, 0, bins, 0, length); byte[] bous = null; List<byte> bousList = new List<byte>(); if (ctx.mode == SM4_ENCRYPT) { 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])); } sm4_one_round(ctx.sk, 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); sm4_one_round(ctx.sk, 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 == SM4_DECRYPT) { bous = padding(bousList.ToArray(), SM4_DECRYPT); return bous; } else { return bousList.ToArray(); } } }
如此大功告成， 兩邊可自行攻守，如果保證Key 和 IV一直，則能夠互通有無