aes.js 7.8 KB

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  1. (function () {
  2. // Shortcuts
  3. var C = CryptoJS;
  4. var C_lib = C.lib;
  5. var BlockCipher = C_lib.BlockCipher;
  6. var C_algo = C.algo;
  7. // Lookup tables
  8. var SBOX = [];
  9. var INV_SBOX = [];
  10. var SUB_MIX_0 = [];
  11. var SUB_MIX_1 = [];
  12. var SUB_MIX_2 = [];
  13. var SUB_MIX_3 = [];
  14. var INV_SUB_MIX_0 = [];
  15. var INV_SUB_MIX_1 = [];
  16. var INV_SUB_MIX_2 = [];
  17. var INV_SUB_MIX_3 = [];
  18. // Compute lookup tables
  19. (function () {
  20. // Compute double table
  21. var d = [];
  22. for (var i = 0; i < 256; i++) {
  23. if (i < 128) {
  24. d[i] = i << 1;
  25. } else {
  26. d[i] = (i << 1) ^ 0x11b;
  27. }
  28. }
  29. // Walk GF(2^8)
  30. var x = 0;
  31. var xi = 0;
  32. for (var i = 0; i < 256; i++) {
  33. // Compute sbox
  34. var sx = xi ^ (xi << 1) ^ (xi << 2) ^ (xi << 3) ^ (xi << 4);
  35. sx = (sx >>> 8) ^ (sx & 0xff) ^ 0x63;
  36. SBOX[x] = sx;
  37. INV_SBOX[sx] = x;
  38. // Compute multiplication
  39. var x2 = d[x];
  40. var x4 = d[x2];
  41. var x8 = d[x4];
  42. // Compute sub bytes, mix columns tables
  43. var t = (d[sx] * 0x101) ^ (sx * 0x1010100);
  44. SUB_MIX_0[x] = (t << 24) | (t >>> 8);
  45. SUB_MIX_1[x] = (t << 16) | (t >>> 16);
  46. SUB_MIX_2[x] = (t << 8) | (t >>> 24);
  47. SUB_MIX_3[x] = t;
  48. // Compute inv sub bytes, inv mix columns tables
  49. var t = (x8 * 0x1010101) ^ (x4 * 0x10001) ^ (x2 * 0x101) ^ (x * 0x1010100);
  50. INV_SUB_MIX_0[sx] = (t << 24) | (t >>> 8);
  51. INV_SUB_MIX_1[sx] = (t << 16) | (t >>> 16);
  52. INV_SUB_MIX_2[sx] = (t << 8) | (t >>> 24);
  53. INV_SUB_MIX_3[sx] = t;
  54. // Compute next counter
  55. if (!x) {
  56. x = xi = 1;
  57. } else {
  58. x = x2 ^ d[d[d[x8 ^ x2]]];
  59. xi ^= d[d[xi]];
  60. }
  61. }
  62. }());
  63. // Precomputed Rcon lookup
  64. var RCON = [0x00, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36];
  65. /**
  66. * AES block cipher algorithm.
  67. */
  68. var AES = C_algo.AES = BlockCipher.extend({
  69. _doReset: function () {
  70. var t;
  71. // Skip reset of nRounds has been set before and key did not change
  72. if (this._nRounds && this._keyPriorReset === this._key) {
  73. return;
  74. }
  75. // Shortcuts
  76. var key = this._keyPriorReset = this._key;
  77. var keyWords = key.words;
  78. var keySize = key.sigBytes / 4;
  79. // Compute number of rounds
  80. var nRounds = this._nRounds = keySize + 6;
  81. // Compute number of key schedule rows
  82. var ksRows = (nRounds + 1) * 4;
  83. // Compute key schedule
  84. var keySchedule = this._keySchedule = [];
  85. for (var ksRow = 0; ksRow < ksRows; ksRow++) {
  86. if (ksRow < keySize) {
  87. keySchedule[ksRow] = keyWords[ksRow];
  88. } else {
  89. t = keySchedule[ksRow - 1];
  90. if (!(ksRow % keySize)) {
  91. // Rot word
  92. t = (t << 8) | (t >>> 24);
  93. // Sub word
  94. t = (SBOX[t >>> 24] << 24) | (SBOX[(t >>> 16) & 0xff] << 16) | (SBOX[(t >>> 8) & 0xff] << 8) | SBOX[t & 0xff];
  95. // Mix Rcon
  96. t ^= RCON[(ksRow / keySize) | 0] << 24;
  97. } else if (keySize > 6 && ksRow % keySize == 4) {
  98. // Sub word
  99. t = (SBOX[t >>> 24] << 24) | (SBOX[(t >>> 16) & 0xff] << 16) | (SBOX[(t >>> 8) & 0xff] << 8) | SBOX[t & 0xff];
  100. }
  101. keySchedule[ksRow] = keySchedule[ksRow - keySize] ^ t;
  102. }
  103. }
  104. // Compute inv key schedule
  105. var invKeySchedule = this._invKeySchedule = [];
  106. for (var invKsRow = 0; invKsRow < ksRows; invKsRow++) {
  107. var ksRow = ksRows - invKsRow;
  108. if (invKsRow % 4) {
  109. var t = keySchedule[ksRow];
  110. } else {
  111. var t = keySchedule[ksRow - 4];
  112. }
  113. if (invKsRow < 4 || ksRow <= 4) {
  114. invKeySchedule[invKsRow] = t;
  115. } else {
  116. invKeySchedule[invKsRow] = INV_SUB_MIX_0[SBOX[t >>> 24]] ^ INV_SUB_MIX_1[SBOX[(t >>> 16) & 0xff]] ^
  117. INV_SUB_MIX_2[SBOX[(t >>> 8) & 0xff]] ^ INV_SUB_MIX_3[SBOX[t & 0xff]];
  118. }
  119. }
  120. },
  121. encryptBlock: function (M, offset) {
  122. this._doCryptBlock(M, offset, this._keySchedule, SUB_MIX_0, SUB_MIX_1, SUB_MIX_2, SUB_MIX_3, SBOX);
  123. },
  124. decryptBlock: function (M, offset) {
  125. // Swap 2nd and 4th rows
  126. var t = M[offset + 1];
  127. M[offset + 1] = M[offset + 3];
  128. M[offset + 3] = t;
  129. this._doCryptBlock(M, offset, this._invKeySchedule, INV_SUB_MIX_0, INV_SUB_MIX_1, INV_SUB_MIX_2, INV_SUB_MIX_3, INV_SBOX);
  130. // Inv swap 2nd and 4th rows
  131. var t = M[offset + 1];
  132. M[offset + 1] = M[offset + 3];
  133. M[offset + 3] = t;
  134. },
  135. _doCryptBlock: function (M, offset, keySchedule, SUB_MIX_0, SUB_MIX_1, SUB_MIX_2, SUB_MIX_3, SBOX) {
  136. // Shortcut
  137. var nRounds = this._nRounds;
  138. // Get input, add round key
  139. var s0 = M[offset] ^ keySchedule[0];
  140. var s1 = M[offset + 1] ^ keySchedule[1];
  141. var s2 = M[offset + 2] ^ keySchedule[2];
  142. var s3 = M[offset + 3] ^ keySchedule[3];
  143. // Key schedule row counter
  144. var ksRow = 4;
  145. // Rounds
  146. for (var round = 1; round < nRounds; round++) {
  147. // Shift rows, sub bytes, mix columns, add round key
  148. var t0 = SUB_MIX_0[s0 >>> 24] ^ SUB_MIX_1[(s1 >>> 16) & 0xff] ^ SUB_MIX_2[(s2 >>> 8) & 0xff] ^ SUB_MIX_3[s3 & 0xff] ^ keySchedule[ksRow++];
  149. var t1 = SUB_MIX_0[s1 >>> 24] ^ SUB_MIX_1[(s2 >>> 16) & 0xff] ^ SUB_MIX_2[(s3 >>> 8) & 0xff] ^ SUB_MIX_3[s0 & 0xff] ^ keySchedule[ksRow++];
  150. var t2 = SUB_MIX_0[s2 >>> 24] ^ SUB_MIX_1[(s3 >>> 16) & 0xff] ^ SUB_MIX_2[(s0 >>> 8) & 0xff] ^ SUB_MIX_3[s1 & 0xff] ^ keySchedule[ksRow++];
  151. var t3 = SUB_MIX_0[s3 >>> 24] ^ SUB_MIX_1[(s0 >>> 16) & 0xff] ^ SUB_MIX_2[(s1 >>> 8) & 0xff] ^ SUB_MIX_3[s2 & 0xff] ^ keySchedule[ksRow++];
  152. // Update state
  153. s0 = t0;
  154. s1 = t1;
  155. s2 = t2;
  156. s3 = t3;
  157. }
  158. // Shift rows, sub bytes, add round key
  159. var t0 = ((SBOX[s0 >>> 24] << 24) | (SBOX[(s1 >>> 16) & 0xff] << 16) | (SBOX[(s2 >>> 8) & 0xff] << 8) | SBOX[s3 & 0xff]) ^ keySchedule[ksRow++];
  160. var t1 = ((SBOX[s1 >>> 24] << 24) | (SBOX[(s2 >>> 16) & 0xff] << 16) | (SBOX[(s3 >>> 8) & 0xff] << 8) | SBOX[s0 & 0xff]) ^ keySchedule[ksRow++];
  161. var t2 = ((SBOX[s2 >>> 24] << 24) | (SBOX[(s3 >>> 16) & 0xff] << 16) | (SBOX[(s0 >>> 8) & 0xff] << 8) | SBOX[s1 & 0xff]) ^ keySchedule[ksRow++];
  162. var t3 = ((SBOX[s3 >>> 24] << 24) | (SBOX[(s0 >>> 16) & 0xff] << 16) | (SBOX[(s1 >>> 8) & 0xff] << 8) | SBOX[s2 & 0xff]) ^ keySchedule[ksRow++];
  163. // Set output
  164. M[offset] = t0;
  165. M[offset + 1] = t1;
  166. M[offset + 2] = t2;
  167. M[offset + 3] = t3;
  168. },
  169. keySize: 256/32
  170. });
  171. /**
  172. * Shortcut functions to the cipher's object interface.
  173. *
  174. * @example
  175. *
  176. * var ciphertext = CryptoJS.AES.encrypt(message, key, cfg);
  177. * var plaintext = CryptoJS.AES.decrypt(ciphertext, key, cfg);
  178. */
  179. C.AES = BlockCipher._createHelper(AES);
  180. }());