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| 1 | +/** |
| 2 | + * Complete implementation of SM4 cipher encryption/decryption with |
| 3 | + * ECB, CBC, CFB, OFB, CTR block modes. |
| 4 | + * These modes are specified in IETF draft-ribose-cfrg-sm4-09, see: |
| 5 | + * https://tools.ietf.org/id/draft-ribose-cfrg-sm4-09.html |
| 6 | + * for details. |
| 7 | + * |
| 8 | + * Follows spec from Cryptography Standardization Technical Comittee: |
| 9 | + * http://www.gmbz.org.cn/upload/2018-04-04/1522788048733065051.pdf |
| 10 | + * |
| 11 | + * @author swesven |
| 12 | + * @copyright 2021 |
| 13 | + * @license Apache-2.0 |
| 14 | + */ |
| 15 | + |
| 16 | +import OperationError from "../errors/OperationError.mjs"; |
| 17 | + |
| 18 | +/** Number of rounds */ |
| 19 | +const NROUNDS = 32; |
| 20 | + |
| 21 | +/** block size in bytes */ |
| 22 | +const BLOCKSIZE = 16; |
| 23 | + |
| 24 | +/** The S box, 256 8-bit values */ |
| 25 | +const Sbox = [ |
| 26 | + 0xd6, 0x90, 0xe9, 0xfe, 0xcc, 0xe1, 0x3d, 0xb7, 0x16, 0xb6, 0x14, 0xc2, 0x28, 0xfb, 0x2c, 0x05, |
| 27 | + 0x2b, 0x67, 0x9a, 0x76, 0x2a, 0xbe, 0x04, 0xc3, 0xaa, 0x44, 0x13, 0x26, 0x49, 0x86, 0x06, 0x99, |
| 28 | + 0x9c, 0x42, 0x50, 0xf4, 0x91, 0xef, 0x98, 0x7a, 0x33, 0x54, 0x0b, 0x43, 0xed, 0xcf, 0xac, 0x62, |
| 29 | + 0xe4, 0xb3, 0x1c, 0xa9, 0xc9, 0x08, 0xe8, 0x95, 0x80, 0xdf, 0x94, 0xfa, 0x75, 0x8f, 0x3f, 0xa6, |
| 30 | + 0x47, 0x07, 0xa7, 0xfc, 0xf3, 0x73, 0x17, 0xba, 0x83, 0x59, 0x3c, 0x19, 0xe6, 0x85, 0x4f, 0xa8, |
| 31 | + 0x68, 0x6b, 0x81, 0xb2, 0x71, 0x64, 0xda, 0x8b, 0xf8, 0xeb, 0x0f, 0x4b, 0x70, 0x56, 0x9d, 0x35, |
| 32 | + 0x1e, 0x24, 0x0e, 0x5e, 0x63, 0x58, 0xd1, 0xa2, 0x25, 0x22, 0x7c, 0x3b, 0x01, 0x21, 0x78, 0x87, |
| 33 | + 0xd4, 0x00, 0x46, 0x57, 0x9f, 0xd3, 0x27, 0x52, 0x4c, 0x36, 0x02, 0xe7, 0xa0, 0xc4, 0xc8, 0x9e, |
| 34 | + 0xea, 0xbf, 0x8a, 0xd2, 0x40, 0xc7, 0x38, 0xb5, 0xa3, 0xf7, 0xf2, 0xce, 0xf9, 0x61, 0x15, 0xa1, |
| 35 | + 0xe0, 0xae, 0x5d, 0xa4, 0x9b, 0x34, 0x1a, 0x55, 0xad, 0x93, 0x32, 0x30, 0xf5, 0x8c, 0xb1, 0xe3, |
| 36 | + 0x1d, 0xf6, 0xe2, 0x2e, 0x82, 0x66, 0xca, 0x60, 0xc0, 0x29, 0x23, 0xab, 0x0d, 0x53, 0x4e, 0x6f, |
| 37 | + 0xd5, 0xdb, 0x37, 0x45, 0xde, 0xfd, 0x8e, 0x2f, 0x03, 0xff, 0x6a, 0x72, 0x6d, 0x6c, 0x5b, 0x51, |
| 38 | + 0x8d, 0x1b, 0xaf, 0x92, 0xbb, 0xdd, 0xbc, 0x7f, 0x11, 0xd9, 0x5c, 0x41, 0x1f, 0x10, 0x5a, 0xd8, |
| 39 | + 0x0a, 0xc1, 0x31, 0x88, 0xa5, 0xcd, 0x7b, 0xbd, 0x2d, 0x74, 0xd0, 0x12, 0xb8, 0xe5, 0xb4, 0xb0, |
| 40 | + 0x89, 0x69, 0x97, 0x4a, 0x0c, 0x96, 0x77, 0x7e, 0x65, 0xb9, 0xf1, 0x09, 0xc5, 0x6e, 0xc6, 0x84, |
| 41 | + 0x18, 0xf0, 0x7d, 0xec, 0x3a, 0xdc, 0x4d, 0x20, 0x79, 0xee, 0x5f, 0x3e, 0xd7, 0xcb, 0x39, 0x48]; |
| 42 | + |
| 43 | +/** "Fixed parameter CK" used in key expansion */ |
| 44 | +const CK = [ |
| 45 | + 0x00070e15, 0x1c232a31, 0x383f464d, 0x545b6269, |
| 46 | + 0x70777e85, 0x8c939aa1, 0xa8afb6bd, 0xc4cbd2d9, |
| 47 | + 0xe0e7eef5, 0xfc030a11, 0x181f262d, 0x343b4249, |
| 48 | + 0x50575e65, 0x6c737a81, 0x888f969d, 0xa4abb2b9, |
| 49 | + 0xc0c7ced5, 0xdce3eaf1, 0xf8ff060d, 0x141b2229, |
| 50 | + 0x30373e45, 0x4c535a61, 0x686f767d, 0x848b9299, |
| 51 | + 0xa0a7aeb5, 0xbcc3cad1, 0xd8dfe6ed, 0xf4fb0209, |
| 52 | + 0x10171e25, 0x2c333a41, 0x484f565d, 0x646b7279 |
| 53 | +]; |
| 54 | + |
| 55 | +/** "System parameter FK" */ |
| 56 | +const FK = [0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc]; |
| 57 | + |
| 58 | +/** |
| 59 | + * Rotating 32-bit shift left |
| 60 | + * |
| 61 | + * (Note that although JS integers are stored in doubles and thus have 53 bits, |
| 62 | + * the JS bitwise operations are 32-bit) |
| 63 | + */ |
| 64 | +function ROL(i, n) { |
| 65 | + return (i << n) | (i >>> (32 - n)); |
| 66 | +} |
| 67 | + |
| 68 | +/** |
| 69 | + * Linear transformation L |
| 70 | + * |
| 71 | + * @param {integer} b - a 32 bit integer |
| 72 | + */ |
| 73 | +function transformL(b) { |
| 74 | + /* Replace each of the 4 bytes in b with the value at its offset in the Sbox */ |
| 75 | + b = (Sbox[(b >>> 24) & 0xFF] << 24) | (Sbox[(b >>> 16) & 0xFF] << 16) | |
| 76 | + (Sbox[(b >>> 8) & 0xFF] << 8) | Sbox[b & 0xFF]; |
| 77 | + /* circular rotate and xor */ |
| 78 | + return b ^ ROL(b, 2) ^ ROL(b, 10) ^ ROL(b, 18) ^ ROL(b, 24); |
| 79 | +} |
| 80 | + |
| 81 | +/** |
| 82 | + * Linear transformation L' |
| 83 | + * |
| 84 | + * @param {integer} b - a 32 bit integer |
| 85 | + */ |
| 86 | +function transformLprime(b) { |
| 87 | + /* Replace each of the 4 bytes in b with the value at its offset in the Sbox */ |
| 88 | + b = (Sbox[(b >>> 24) & 0xFF] << 24) | (Sbox[(b >>> 16) & 0xFF] << 16) | |
| 89 | + (Sbox[(b >>> 8) & 0xFF] << 8) | Sbox[b & 0xFF]; |
| 90 | + return b ^ ROL(b, 13) ^ ROL(b, 23); /* circular rotate and XOR */ |
| 91 | +} |
| 92 | + |
| 93 | +/** |
| 94 | + * Initialize the round key |
| 95 | + */ |
| 96 | +function initSM4RoundKey(rawkey) { |
| 97 | + const K = rawkey.map((a, i) => a ^ FK[i]); /* K = rawkey ^ FK */ |
| 98 | + const roundKey = []; |
| 99 | + for (let i = 0; i < 32; i++) |
| 100 | + roundKey[i] = K[i + 4] = K[i] ^ transformLprime(K[i + 1] ^ K[i + 2] ^ K[i + 3] ^ CK[i]); |
| 101 | + return roundKey; |
| 102 | +} |
| 103 | + |
| 104 | +/** |
| 105 | + * Encrypts/decrypts a single block X (4 32-bit values) with a prepared round key. |
| 106 | + * |
| 107 | + * @param {intArray} X - A cleartext block. |
| 108 | + * @param {intArray} roundKey - The round key from initSMRoundKey for encrypting (reversed for decrypting). |
| 109 | + * @returns {byteArray} - The cipher text. |
| 110 | + */ |
| 111 | +function encryptBlockSM4(X, roundKey) { |
| 112 | + for (let i = 0; i < NROUNDS; i++) |
| 113 | + X[i + 4] = X[i] ^ transformL(X[i + 1] ^ X[i + 2] ^ X[i + 3] ^ roundKey[i]); |
| 114 | + return [X[35], X[34], X[33], X[32]]; |
| 115 | +} |
| 116 | + |
| 117 | +/** |
| 118 | + * Takes 16 bytes from an offset in an array and returns an array of 4 32-bit Big-Endian values. |
| 119 | + * (DataView won't work portably here as we need Big-Endian) |
| 120 | + * |
| 121 | + * @param {byteArray} bArray - the array of bytes |
| 122 | + * @param {integer} offset - starting offset in the array; 15 bytes must follow it. |
| 123 | + */ |
| 124 | +function bytesToInts(bArray, offs=0) { |
| 125 | + let offset = offs; |
| 126 | + const A = (bArray[offset] << 24) | (bArray[offset + 1] << 16) | (bArray[offset + 2] << 8) | bArray[offset + 3]; |
| 127 | + offset += 4; |
| 128 | + const B = (bArray[offset] << 24) | (bArray[offset + 1] << 16) | (bArray[offset + 2] << 8) | bArray[offset + 3]; |
| 129 | + offset += 4; |
| 130 | + const C = (bArray[offset] << 24) | (bArray[offset + 1] << 16) | (bArray[offset + 2] << 8) | bArray[offset + 3]; |
| 131 | + offset += 4; |
| 132 | + const D = (bArray[offset] << 24) | (bArray[offset + 1] << 16) | (bArray[offset + 2] << 8) | bArray[offset + 3]; |
| 133 | + return [A, B, C, D]; |
| 134 | +} |
| 135 | + |
| 136 | +/** |
| 137 | + * Inverse of bytesToInts above; takes an array of 32-bit integers and turns it into an array of bytes. |
| 138 | + * Again, Big-Endian order. |
| 139 | + */ |
| 140 | +function intsToBytes(ints) { |
| 141 | + const bArr = []; |
| 142 | + for (let i = 0; i < ints.length; i++) { |
| 143 | + bArr.push((ints[i] >> 24) & 0xFF); |
| 144 | + bArr.push((ints[i] >> 16) & 0xFF); |
| 145 | + bArr.push((ints[i] >> 8) & 0xFF); |
| 146 | + bArr.push(ints[i] & 0xFF); |
| 147 | + } |
| 148 | + return bArr; |
| 149 | +} |
| 150 | + |
| 151 | +/** |
| 152 | + * Encrypt using SM4 using a given block cipher mode. |
| 153 | + * |
| 154 | + * @param {byteArray} message - The clear text message; any length under 32 Gb or so. |
| 155 | + * @param {byteArray} key - The cipher key, 16 bytes. |
| 156 | + * @param {byteArray} iv - The IV or nonce, 16 bytes (not used with ECB mode) |
| 157 | + * @param {string} mode - The block cipher mode "CBC", "ECB", "CFB", "OFB", "CTR". |
| 158 | + * @param {boolean} noPadding - Don't add PKCS#7 padding if set. |
| 159 | + * @returns {byteArray} - The cipher text. |
| 160 | + */ |
| 161 | +export function encryptSM4(message, key, iv, mode="ECB", noPadding=false) { |
| 162 | + const messageLength = message.length; |
| 163 | + if (messageLength === 0) |
| 164 | + return []; |
| 165 | + const roundKey = initSM4RoundKey(bytesToInts(key, 0)); |
| 166 | + |
| 167 | + /* Pad with PKCS#7 if requested for ECB/CBC else add zeroes (which are sliced off at the end) */ |
| 168 | + let padByte = 0; |
| 169 | + let nPadding = 16 - (message.length & 0xF); |
| 170 | + if (mode === "ECB" || mode === "CBC") { |
| 171 | + if (noPadding) { |
| 172 | + if (nPadding !== 16) |
| 173 | + throw new OperationError("No padding requested in "+mode+" mode but input is not a 16-byte multiple."); |
| 174 | + nPadding = 0; |
| 175 | + } else |
| 176 | + padByte = nPadding; |
| 177 | + } |
| 178 | + for (let i = 0; i < nPadding; i++) |
| 179 | + message.push(padByte); |
| 180 | + |
| 181 | + const cipherText = []; |
| 182 | + switch (mode) { |
| 183 | + case "ECB": |
| 184 | + for (let i = 0; i < message.length; i += BLOCKSIZE) |
| 185 | + Array.prototype.push.apply(cipherText, intsToBytes(encryptBlockSM4(bytesToInts(message, i), roundKey))); |
| 186 | + break; |
| 187 | + case "CBC": |
| 188 | + iv = bytesToInts(iv, 0); |
| 189 | + for (let i = 0; i < message.length; i += BLOCKSIZE) { |
| 190 | + const block = bytesToInts(message, i); |
| 191 | + block[0] ^= iv[0]; block[1] ^= iv[1]; |
| 192 | + block[2] ^= iv[2]; block[3] ^= iv[3]; |
| 193 | + iv = encryptBlockSM4(block, roundKey); |
| 194 | + Array.prototype.push.apply(cipherText, intsToBytes(iv)); |
| 195 | + } |
| 196 | + break; |
| 197 | + case "CFB": |
| 198 | + iv = bytesToInts(iv, 0); |
| 199 | + for (let i = 0; i < message.length; i += BLOCKSIZE) { |
| 200 | + iv = encryptBlockSM4(iv, roundKey); |
| 201 | + const block = bytesToInts(message, i); |
| 202 | + block[0] ^= iv[0]; block[1] ^= iv[1]; |
| 203 | + block[2] ^= iv[2]; block[3] ^= iv[3]; |
| 204 | + Array.prototype.push.apply(cipherText, intsToBytes(block)); |
| 205 | + iv = block; |
| 206 | + } |
| 207 | + break; |
| 208 | + case "OFB": |
| 209 | + iv = bytesToInts(iv, 0); |
| 210 | + for (let i = 0; i < message.length; i += BLOCKSIZE) { |
| 211 | + iv = encryptBlockSM4(iv, roundKey); |
| 212 | + const block = bytesToInts(message, i); |
| 213 | + block[0] ^= iv[0]; block[1] ^= iv[1]; |
| 214 | + block[2] ^= iv[2]; block[3] ^= iv[3]; |
| 215 | + Array.prototype.push.apply(cipherText, intsToBytes(block)); |
| 216 | + } |
| 217 | + break; |
| 218 | + case "CTR": |
| 219 | + iv = bytesToInts(iv, 0); |
| 220 | + for (let i = 0; i < message.length; i += BLOCKSIZE) { |
| 221 | + let iv2 = [...iv]; /* containing the IV + counter */ |
| 222 | + iv2[3] += (i >> 4);/* Using a 32 bit counter here. 64 Gb encrypts should be enough for everyone. */ |
| 223 | + iv2 = encryptBlockSM4(iv2, roundKey); |
| 224 | + const block = bytesToInts(message, i); |
| 225 | + block[0] ^= iv2[0]; block[1] ^= iv2[1]; |
| 226 | + block[2] ^= iv2[2]; block[3] ^= iv2[3]; |
| 227 | + Array.prototype.push.apply(cipherText, intsToBytes(block)); |
| 228 | + } |
| 229 | + break; |
| 230 | + default: |
| 231 | + throw new OperationError("Invalid block cipher mode: "+mode); |
| 232 | + } |
| 233 | + if (mode !== "ECB" && mode !== "CBC") |
| 234 | + return cipherText.slice(0, messageLength); |
| 235 | + return cipherText; |
| 236 | +} |
| 237 | + |
| 238 | +/** |
| 239 | + * Decrypt using SM4 using a given block cipher mode. |
| 240 | + * |
| 241 | + * @param {byteArray} cipherText - The ciphertext |
| 242 | + * @param {byteArray} key - The cipher key, 16 bytes. |
| 243 | + * @param {byteArray} iv - The IV or nonce, 16 bytes (not used with ECB mode) |
| 244 | + * @param {string} mode - The block cipher mode "CBC", "ECB", "CFB", "OFB", "CTR" |
| 245 | + * @param {boolean] ignorePadding - If true, ignore padding issues in ECB/CBC mode. |
| 246 | + * @returns {byteArray} - The cipher text. |
| 247 | + */ |
| 248 | +export function decryptSM4(cipherText, key, iv, mode="ECB", ignorePadding=false) { |
| 249 | + const originalLength = cipherText.length; |
| 250 | + if (originalLength === 0) |
| 251 | + return []; |
| 252 | + let roundKey = initSM4RoundKey(bytesToInts(key, 0)); |
| 253 | + |
| 254 | + if (mode === "ECB" || mode === "CBC") { |
| 255 | + /* Init decryption key */ |
| 256 | + roundKey = roundKey.reverse(); |
| 257 | + if ((originalLength & 0xF) !== 0 && !ignorePadding) |
| 258 | + throw new OperationError("With ECB or CBC modes, the input must be divisible into 16 byte blocks. ("+(cipherText.length & 0xF)+" bytes extra)"); |
| 259 | + } else /* Pad dummy bytes for other modes, chop them off at the end */ |
| 260 | + while ((cipherText.length & 0xF) !== 0) |
| 261 | + cipherText.push(0); |
| 262 | + |
| 263 | + const clearText = []; |
| 264 | + switch (mode) { |
| 265 | + case "ECB": |
| 266 | + for (let i = 0; i < cipherText.length; i += BLOCKSIZE) |
| 267 | + Array.prototype.push.apply(clearText, intsToBytes(encryptBlockSM4(bytesToInts(cipherText, i), roundKey))); |
| 268 | + break; |
| 269 | + case "CBC": |
| 270 | + iv = bytesToInts(iv, 0); |
| 271 | + for (let i = 0; i < cipherText.length; i += BLOCKSIZE) { |
| 272 | + const block = encryptBlockSM4(bytesToInts(cipherText, i), roundKey); |
| 273 | + block[0] ^= iv[0]; block[1] ^= iv[1]; |
| 274 | + block[2] ^= iv[2]; block[3] ^= iv[3]; |
| 275 | + Array.prototype.push.apply(clearText, intsToBytes(block)); |
| 276 | + iv = bytesToInts(cipherText, i); |
| 277 | + } |
| 278 | + break; |
| 279 | + case "CFB": |
| 280 | + iv = bytesToInts(iv, 0); |
| 281 | + for (let i = 0; i < cipherText.length; i += BLOCKSIZE) { |
| 282 | + iv = encryptBlockSM4(iv, roundKey); |
| 283 | + const block = bytesToInts(cipherText, i); |
| 284 | + block[0] ^= iv[0]; block[1] ^= iv[1]; |
| 285 | + block[2] ^= iv[2]; block[3] ^= iv[3]; |
| 286 | + Array.prototype.push.apply(clearText, intsToBytes(block)); |
| 287 | + iv = bytesToInts(cipherText, i); |
| 288 | + } |
| 289 | + break; |
| 290 | + case "OFB": |
| 291 | + iv = bytesToInts(iv, 0); |
| 292 | + for (let i = 0; i < cipherText.length; i += BLOCKSIZE) { |
| 293 | + iv = encryptBlockSM4(iv, roundKey); |
| 294 | + const block = bytesToInts(cipherText, i); |
| 295 | + block[0] ^= iv[0]; block[1] ^= iv[1]; |
| 296 | + block[2] ^= iv[2]; block[3] ^= iv[3]; |
| 297 | + Array.prototype.push.apply(clearText, intsToBytes(block)); |
| 298 | + } |
| 299 | + break; |
| 300 | + case "CTR": |
| 301 | + iv = bytesToInts(iv, 0); |
| 302 | + for (let i = 0; i < cipherText.length; i += BLOCKSIZE) { |
| 303 | + let iv2 = [...iv]; /* containing the IV + counter */ |
| 304 | + iv2[3] += (i >> 4);/* Using a 32 bit counter here. 64 Gb encrypts should be enough for everyone. */ |
| 305 | + iv2 = encryptBlockSM4(iv2, roundKey); |
| 306 | + const block = bytesToInts(cipherText, i); |
| 307 | + block[0] ^= iv2[0]; block[1] ^= iv2[1]; |
| 308 | + block[2] ^= iv2[2]; block[3] ^= iv2[3]; |
| 309 | + Array.prototype.push.apply(clearText, intsToBytes(block)); |
| 310 | + } |
| 311 | + break; |
| 312 | + default: |
| 313 | + throw new OperationError("Invalid block cipher mode: "+mode); |
| 314 | + } |
| 315 | + /* Check PKCS#7 padding */ |
| 316 | + if (mode === "ECB" || mode === "CBC") { |
| 317 | + if (ignorePadding) |
| 318 | + return clearText; |
| 319 | + const padByte = clearText[clearText.length - 1]; |
| 320 | + if (padByte > 16) |
| 321 | + throw new OperationError("Invalid PKCS#7 padding."); |
| 322 | + for (let i = 0; i < padByte; i++) |
| 323 | + if (clearText[clearText.length -i - 1] !== padByte) |
| 324 | + throw new OperationError("Invalid PKCS#7 padding."); |
| 325 | + return clearText.slice(0, clearText.length - padByte); |
| 326 | + } |
| 327 | + return clearText.slice(0, originalLength); |
| 328 | +} |
| 329 | + |
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