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  1. /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
  2. /* AES implementation in JavaScript (c) Chris Veness 2005-2011 */
  3. /* - see http://csrc.nist.gov/publications/PubsFIPS.html#197 */
  4. /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
  5.  
  6. var Aes = {}; // Aes namespace
  7.  
  8. /**
  9. * AES Cipher function: encrypt 'input' state with Rijndael algorithm
  10. * applies Nr rounds (10/12/14) using key schedule w for 'add round key' stage
  11. *
  12. * @param {Number[]} input 16-byte (128-bit) input state array
  13. * @param {Number[][]} w Key schedule as 2D byte-array (Nr+1 x Nb bytes)
  14. * @returns {Number[]} Encrypted output state array
  15. */
  16. Aes.cipher = function(input, w) { // main Cipher function [§5.1]
  17. var Nb = 4; // block size (in words): no of columns in state (fixed at 4 for AES)
  18. var Nr = w.length/Nb - 1; // no of rounds: 10/12/14 for 128/192/256-bit keys
  19.  
  20. var state = [[],[],[],[]]; // initialise 4xNb byte-array 'state' with input [§3.4]
  21. for (var i=0; i<4*Nb; i++) state[i%4][Math.floor(i/4)] = input[i];
  22.  
  23. state = Aes.addRoundKey(state, w, 0, Nb);
  24.  
  25. for (var round=1; round<Nr; round++) {
  26. state = Aes.subBytes(state, Nb);
  27. state = Aes.shiftRows(state, Nb);
  28. state = Aes.mixColumns(state, Nb);
  29. state = Aes.addRoundKey(state, w, round, Nb);
  30. }
  31.  
  32. state = Aes.subBytes(state, Nb);
  33. state = Aes.shiftRows(state, Nb);
  34. state = Aes.addRoundKey(state, w, Nr, Nb);
  35.  
  36. var output = new Array(4*Nb); // convert state to 1-d array before returning [§3.4]
  37. for (var i=0; i<4*Nb; i++) output[i] = state[i%4][Math.floor(i/4)];
  38. return output;
  39. }
  40.  
  41. /**
  42. * Perform Key Expansion to generate a Key Schedule
  43. *
  44. * @param {Number[]} key Key as 16/24/32-byte array
  45. * @returns {Number[][]} Expanded key schedule as 2D byte-array (Nr+1 x Nb bytes)
  46. */
  47. Aes.keyExpansion = function(key) { // generate Key Schedule (byte-array Nr+1 x Nb) from Key [§5.2]
  48. var Nb = 4; // block size (in words): no of columns in state (fixed at 4 for AES)
  49. var Nk = key.length/4 // key length (in words): 4/6/8 for 128/192/256-bit keys
  50. var Nr = Nk + 6; // no of rounds: 10/12/14 for 128/192/256-bit keys
  51.  
  52. var w = new Array(Nb*(Nr+1));
  53. var temp = new Array(4);
  54.  
  55. for (var i=0; i<Nk; i++) {
  56. var r = [key[4*i], key[4*i+1], key[4*i+2], key[4*i+3]];
  57. w[i] = r;
  58. }
  59.  
  60. for (var i=Nk; i<(Nb*(Nr+1)); i++) {
  61. w[i] = new Array(4);
  62. for (var t=0; t<4; t++) temp[t] = w[i-1][t];
  63. if (i % Nk == 0) {
  64. temp = Aes.subWord(Aes.rotWord(temp));
  65. for (var t=0; t<4; t++) temp[t] ^= Aes.rCon[i/Nk][t];
  66. } else if (Nk > 6 && i%Nk == 4) {
  67. temp = Aes.subWord(temp);
  68. }
  69. for (var t=0; t<4; t++) w[i][t] = w[i-Nk][t] ^ temp[t];
  70. }
  71.  
  72. return w;
  73. }
  74.  
  75. /*
  76. * ---- remaining routines are private, not called externally ----
  77. */
  78.  
  79. Aes.subBytes = function(s, Nb) { // apply SBox to state S [§5.1.1]
  80. for (var r=0; r<4; r++) {
  81. for (var c=0; c<Nb; c++) s[r][c] = Aes.sBox[s[r][c]];
  82. }
  83. return s;
  84. }
  85.  
  86. Aes.shiftRows = function(s, Nb) { // shift row r of state S left by r bytes [§5.1.2]
  87. var t = new Array(4);
  88. for (var r=1; r<4; r++) {
  89. for (var c=0; c<4; c++) t[c] = s[r][(c+r)%Nb]; // shift into temp copy
  90. for (var c=0; c<4; c++) s[r][c] = t[c]; // and copy back
  91. } // note that this will work for Nb=4,5,6, but not 7,8 (always 4 for AES):
  92. return s; // see asmaes.sourceforge.net/rijndael/rijndaelImplementation.pdf
  93. }
  94.  
  95. Aes.mixColumns = function(s, Nb) { // combine bytes of each col of state S [§5.1.3]
  96. for (var c=0; c<4; c++) {
  97. var a = new Array(4); // 'a' is a copy of the current column from 's'
  98. var b = new Array(4); // 'b' is a•{02} in GF(2^8)
  99. for (var i=0; i<4; i++) {
  100. a[i] = s[i][c];
  101. b[i] = s[i][c]&0x80 ? s[i][c]<<1 ^ 0x011b : s[i][c]<<1;
  102.  
  103. }
  104. // a[n] ^ b[n] is a•{03} in GF(2^8)
  105. s[0][c] = b[0] ^ a[1] ^ b[1] ^ a[2] ^ a[3]; // 2*a0 + 3*a1 + a2 + a3
  106. s[1][c] = a[0] ^ b[1] ^ a[2] ^ b[2] ^ a[3]; // a0 * 2*a1 + 3*a2 + a3
  107. s[2][c] = a[0] ^ a[1] ^ b[2] ^ a[3] ^ b[3]; // a0 + a1 + 2*a2 + 3*a3
  108. s[3][c] = a[0] ^ b[0] ^ a[1] ^ a[2] ^ b[3]; // 3*a0 + a1 + a2 + 2*a3
  109. }
  110. return s;
  111. }
  112.  
  113. Aes.addRoundKey = function(state, w, rnd, Nb) { // xor Round Key into state S [§5.1.4]
  114. for (var r=0; r<4; r++) {
  115. for (var c=0; c<Nb; c++) state[r][c] ^= w[rnd*4+c][r];
  116. }
  117. return state;
  118. }
  119.  
  120. Aes.subWord = function(w) { // apply SBox to 4-byte word w
  121. for (var i=0; i<4; i++) w[i] = Aes.sBox[w[i]];
  122. return w;
  123. }
  124.  
  125. Aes.rotWord = function(w) { // rotate 4-byte word w left by one byte
  126. var tmp = w[0];
  127. for (var i=0; i<3; i++) w[i] = w[i+1];
  128. w[3] = tmp;
  129. return w;
  130. }
  131.  
  132. // sBox is pre-computed multiplicative inverse in GF(2^8) used in subBytes and keyExpansion [§5.1.1]
  133. Aes.sBox = [0x63,0x7c,0x77,0x7b,0xf2,0x6b,0x6f,0xc5,0x30,0x01,0x67,0x2b,0xfe,0xd7,0xab,0x76,
  134. 0xca,0x82,0xc9,0x7d,0xfa,0x59,0x47,0xf0,0xad,0xd4,0xa2,0xaf,0x9c,0xa4,0x72,0xc0,
  135. 0xb7,0xfd,0x93,0x26,0x36,0x3f,0xf7,0xcc,0x34,0xa5,0xe5,0xf1,0x71,0xd8,0x31,0x15,
  136. 0x04,0xc7,0x23,0xc3,0x18,0x96,0x05,0x9a,0x07,0x12,0x80,0xe2,0xeb,0x27,0xb2,0x75,
  137. 0x09,0x83,0x2c,0x1a,0x1b,0x6e,0x5a,0xa0,0x52,0x3b,0xd6,0xb3,0x29,0xe3,0x2f,0x84,
  138. 0x53,0xd1,0x00,0xed,0x20,0xfc,0xb1,0x5b,0x6a,0xcb,0xbe,0x39,0x4a,0x4c,0x58,0xcf,
  139. 0xd0,0xef,0xaa,0xfb,0x43,0x4d,0x33,0x85,0x45,0xf9,0x02,0x7f,0x50,0x3c,0x9f,0xa8,
  140. 0x51,0xa3,0x40,0x8f,0x92,0x9d,0x38,0xf5,0xbc,0xb6,0xda,0x21,0x10,0xff,0xf3,0xd2,
  141. 0xcd,0x0c,0x13,0xec,0x5f,0x97,0x44,0x17,0xc4,0xa7,0x7e,0x3d,0x64,0x5d,0x19,0x73,
  142. 0x60,0x81,0x4f,0xdc,0x22,0x2a,0x90,0x88,0x46,0xee,0xb8,0x14,0xde,0x5e,0x0b,0xdb,
  143. 0xe0,0x32,0x3a,0x0a,0x49,0x06,0x24,0x5c,0xc2,0xd3,0xac,0x62,0x91,0x95,0xe4,0x79,
  144. 0xe7,0xc8,0x37,0x6d,0x8d,0xd5,0x4e,0xa9,0x6c,0x56,0xf4,0xea,0x65,0x7a,0xae,0x08,
  145. 0xba,0x78,0x25,0x2e,0x1c,0xa6,0xb4,0xc6,0xe8,0xdd,0x74,0x1f,0x4b,0xbd,0x8b,0x8a,
  146. 0x70,0x3e,0xb5,0x66,0x48,0x03,0xf6,0x0e,0x61,0x35,0x57,0xb9,0x86,0xc1,0x1d,0x9e,
  147. 0xe1,0xf8,0x98,0x11,0x69,0xd9,0x8e,0x94,0x9b,0x1e,0x87,0xe9,0xce,0x55,0x28,0xdf,
  148. 0x8c,0xa1,0x89,0x0d,0xbf,0xe6,0x42,0x68,0x41,0x99,0x2d,0x0f,0xb0,0x54,0xbb,0x16];
  149.  
  150. // rCon is Round Constant used for the Key Expansion [1st col is 2^(r-1) in GF(2^8)] [§5.2]
  151. Aes.rCon = [ [0x00, 0x00, 0x00, 0x00],
  152. [0x01, 0x00, 0x00, 0x00],
  153. [0x02, 0x00, 0x00, 0x00],
  154. [0x04, 0x00, 0x00, 0x00],
  155. [0x08, 0x00, 0x00, 0x00],
  156. [0x10, 0x00, 0x00, 0x00],
  157. [0x20, 0x00, 0x00, 0x00],
  158. [0x40, 0x00, 0x00, 0x00],
  159. [0x80, 0x00, 0x00, 0x00],
  160. [0x1b, 0x00, 0x00, 0x00],
  161. [0x36, 0x00, 0x00, 0x00] ];
  162.  
  163.  
  164. /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
  165. /* AES Counter-mode implementation in JavaScript (c) Chris Veness 2005-2011 */
  166. /* - see http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf */
  167. /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
  168.  
  169. Aes.Ctr = {}; // Aes.Ctr namespace: a subclass or extension of Aes
  170.  
  171. /**
  172. * Encrypt a text using AES encryption in Counter mode of operation
  173. *
  174. * Unicode multi-byte character safe
  175. *
  176. * @param {String} plaintext Source text to be encrypted
  177. * @param {String} password The password to use to generate a key
  178. * @param {Number} nBits Number of bits to be used in the key (128, 192, or 256)
  179. * @returns {string} Encrypted text
  180. */
  181. Aes.Ctr.encrypt = function(plaintext, password, nBits) {
  182. var blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
  183. if (!(nBits==128 || nBits==192 || nBits==256)) return ''; // standard allows 128/192/256 bit keys
  184. plaintext = Utf8.encode(plaintext);
  185. password = Utf8.encode(password);
  186. //var t = new Date(); // timer
  187.  
  188. // use AES itself to encrypt password to get cipher key (using plain password as source for key
  189. // expansion) - gives us well encrypted key (though hashed key might be preferred for prod'n use)
  190. var nBytes = nBits/8; // no bytes in key (16/24/32)
  191. var pwBytes = new Array(nBytes);
  192. for (var i=0; i<nBytes; i++) { // use 1st 16/24/32 chars of password for key
  193. pwBytes[i] = isNaN(password.charCodeAt(i)) ? 0 : password.charCodeAt(i);
  194. }
  195. var key = Aes.cipher(pwBytes, Aes.keyExpansion(pwBytes)); // gives us 16-byte key
  196. key = key.concat(key.slice(0, nBytes-16)); // expand key to 16/24/32 bytes long
  197.  
  198. // initialise 1st 8 bytes of counter block with nonce (NIST SP800-38A §B.2): [0-1] = millisec,
  199. // [2-3] = random, [4-7] = seconds, together giving full sub-millisec uniqueness up to Feb 2106
  200. var counterBlock = new Array(blockSize);
  201.  
  202. var nonce = (new Date()).getTime(); // timestamp: milliseconds since 1-Jan-1970
  203. var nonceMs = nonce%1000;
  204. var nonceSec = Math.floor(nonce/1000);
  205. var nonceRnd = Math.floor(Math.random()*0xffff);
  206.  
  207. for (var i=0; i<2; i++) counterBlock[i] = (nonceMs >>> i*8) & 0xff;
  208. for (var i=0; i<2; i++) counterBlock[i+2] = (nonceRnd >>> i*8) & 0xff;
  209. for (var i=0; i<4; i++) counterBlock[i+4] = (nonceSec >>> i*8) & 0xff;
  210.  
  211. // and convert it to a string to go on the front of the ciphertext
  212. var ctrTxt = '';
  213. for (var i=0; i<8; i++) ctrTxt += String.fromCharCode(counterBlock[i]);
  214.  
  215. // generate key schedule - an expansion of the key into distinct Key Rounds for each round
  216. var keySchedule = Aes.keyExpansion(key);
  217.  
  218. var blockCount = Math.ceil(plaintext.length/blockSize);
  219. var ciphertxt = new Array(blockCount); // ciphertext as array of strings
  220.  
  221. for (var b=0; b<blockCount; b++) {
  222. // set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)
  223. // done in two stages for 32-bit ops: using two words allows us to go past 2^32 blocks (68GB)
  224. for (var c=0; c<4; c++) counterBlock[15-c] = (b >>> c*8) & 0xff;
  225. for (var c=0; c<4; c++) counterBlock[15-c-4] = (b/0x100000000 >>> c*8)
  226.  
  227. var cipherCntr = Aes.cipher(counterBlock, keySchedule); // -- encrypt counter block --
  228.  
  229. // block size is reduced on final block
  230. var blockLength = b<blockCount-1 ? blockSize : (plaintext.length-1)%blockSize+1;
  231. var cipherChar = new Array(blockLength);
  232.  
  233. for (var i=0; i<blockLength; i++) { // -- xor plaintext with ciphered counter char-by-char --
  234. cipherChar[i] = cipherCntr[i] ^ plaintext.charCodeAt(b*blockSize+i);
  235. cipherChar[i] = String.fromCharCode(cipherChar[i]);
  236. }
  237. ciphertxt[b] = cipherChar.join('');
  238. }
  239.  
  240. // Array.join is more efficient than repeated string concatenation in IE
  241. var ciphertext = ctrTxt + ciphertxt.join('');
  242. ciphertext = Base64.encode(ciphertext); // encode in base64
  243.  
  244. //alert((new Date()) - t);
  245. return ciphertext;
  246. }
  247.  
  248. /**
  249. * Decrypt a text encrypted by AES in counter mode of operation
  250. *
  251. * @param {String} ciphertext Source text to be encrypted
  252. * @param {String} password The password to use to generate a key
  253. * @param {Number} nBits Number of bits to be used in the key (128, 192, or 256)
  254. * @returns {String} Decrypted text
  255. */
  256. Aes.Ctr.decrypt = function(ciphertext, password, nBits) {
  257. var blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
  258. if (!(nBits==128 || nBits==192 || nBits==256)) return ''; // standard allows 128/192/256 bit keys
  259. ciphertext = Base64.decode(ciphertext);
  260. password = Utf8.encode(password);
  261. //var t = new Date(); // timer
  262.  
  263. // use AES to encrypt password (mirroring encrypt routine)
  264. var nBytes = nBits/8; // no bytes in key
  265. var pwBytes = new Array(nBytes);
  266. for (var i=0; i<nBytes; i++) {
  267. pwBytes[i] = isNaN(password.charCodeAt(i)) ? 0 : password.charCodeAt(i);
  268. }
  269. var key = Aes.cipher(pwBytes, Aes.keyExpansion(pwBytes));
  270. key = key.concat(key.slice(0, nBytes-16)); // expand key to 16/24/32 bytes long
  271.  
  272. // recover nonce from 1st 8 bytes of ciphertext
  273. var counterBlock = new Array(8);
  274. ctrTxt = ciphertext.slice(0, 8);
  275. for (var i=0; i<8; i++) counterBlock[i] = ctrTxt.charCodeAt(i);
  276.  
  277. // generate key schedule
  278. var keySchedule = Aes.keyExpansion(key);
  279.  
  280. // separate ciphertext into blocks (skipping past initial 8 bytes)
  281. var nBlocks = Math.ceil((ciphertext.length-8) / blockSize);
  282. var ct = new Array(nBlocks);
  283. for (var b=0; b<nBlocks; b++) ct[b] = ciphertext.slice(8+b*blockSize, 8+b*blockSize+blockSize);
  284. ciphertext = ct; // ciphertext is now array of block-length strings
  285.  
  286. // plaintext will get generated block-by-block into array of block-length strings
  287. var plaintxt = new Array(ciphertext.length);
  288.  
  289. for (var b=0; b<nBlocks; b++) {
  290. // set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)
  291. for (var c=0; c<4; c++) counterBlock[15-c] = ((b) >>> c*8) & 0xff;
  292. for (var c=0; c<4; c++) counterBlock[15-c-4] = (((b+1)/0x100000000-1) >>> c*8) & 0xff;
  293.  
  294. var cipherCntr = Aes.cipher(counterBlock, keySchedule); // encrypt counter block
  295.  
  296. var plaintxtByte = new Array(ciphertext[b].length);
  297. for (var i=0; i<ciphertext[b].length; i++) {
  298. // -- xor plaintxt with ciphered counter byte-by-byte --
  299. plaintxtByte[i] = cipherCntr[i] ^ ciphertext[b].charCodeAt(i);
  300. plaintxtByte[i] = String.fromCharCode(plaintxtByte[i]);
  301. }
  302. plaintxt[b] = plaintxtByte.join('');
  303. }
  304.  
  305. // join array of blocks into single plaintext string
  306. var plaintext = plaintxt.join('');
  307. plaintext = Utf8.decode(plaintext); // decode from UTF8 back to Unicode multi-byte chars
  308.  
  309. //alert((new Date()) - t);
  310. return plaintext;
  311. }
  312.  
  313.  
  314. /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
  315. /* Base64 class: Base 64 encoding / decoding (c) Chris Veness 2002-2011 */
  316. /* note: depends on Utf8 class */
  317. /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
  318.  
  319. var Base64 = {}; // Base64 namespace
  320.  
  321. Base64.code = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
  322.  
  323. /**
  324. * Encode string into Base64, as defined by RFC 4648 [http://tools.ietf.org/html/rfc4648]
  325. * (instance method extending String object). As per RFC 4648, no newlines are added.
  326. *
  327. * @param {String} str The string to be encoded as base-64
  328. * @param {Boolean} [utf8encode=false] Flag to indicate whether str is Unicode string to be encoded
  329. * to UTF8 before conversion to base64; otherwise string is assumed to be 8-bit characters
  330. * @returns {String} Base64-encoded string
  331. */
  332. Base64.encode = function(str, utf8encode) { // http://tools.ietf.org/html/rfc4648
  333. utf8encode = (typeof utf8encode == 'undefined') ? false : utf8encode;
  334. var o1, o2, o3, bits, h1, h2, h3, h4, e=[], pad = '', c, plain, coded;
  335. var b64 = Base64.code;
  336.  
  337. plain = utf8encode ? str.encodeUTF8() : str;
  338.  
  339. c = plain.length % 3; // pad string to length of multiple of 3
  340. if (c > 0) { while (c++ < 3) { pad += '='; plain += '\0'; } }
  341. // note: doing padding here saves us doing special-case packing for trailing 1 or 2 chars
  342.  
  343. for (c=0; c<plain.length; c+=3) { // pack three octets into four hexets
  344. o1 = plain.charCodeAt(c);
  345. o2 = plain.charCodeAt(c+1);
  346. o3 = plain.charCodeAt(c+2);
  347.  
  348. bits = o1<<16 | o2<<8 | o3;
  349.  
  350. h1 = bits>>18 & 0x3f;
  351. h2 = bits>>12 & 0x3f;
  352. h3 = bits>>6 & 0x3f;
  353. h4 = bits & 0x3f;
  354.  
  355. // use hextets to index into code string
  356. e[c/3] = b64.charAt(h1) + b64.charAt(h2) + b64.charAt(h3) + b64.charAt(h4);
  357. }
  358. coded = e.join(''); // join() is far faster than repeated string concatenation in IE
  359.  
  360. // replace 'A's from padded nulls with '='s
  361. coded = coded.slice(0, coded.length-pad.length) + pad;
  362.  
  363. return coded;
  364. }
  365.  
  366. /**
  367. * Decode string from Base64, as defined by RFC 4648 [http://tools.ietf.org/html/rfc4648]
  368. * (instance method extending String object). As per RFC 4648, newlines are not catered for.
  369. *
  370. * @param {String} str The string to be decoded from base-64
  371. * @param {Boolean} [utf8decode=false] Flag to indicate whether str is Unicode string to be decoded
  372. * from UTF8 after conversion from base64
  373. * @returns {String} decoded string
  374. */
  375. Base64.decode = function(str, utf8decode) {
  376. utf8decode = (typeof utf8decode == 'undefined') ? false : utf8decode;
  377. var o1, o2, o3, h1, h2, h3, h4, bits, d=[], plain, coded;
  378. var b64 = Base64.code;
  379.  
  380. coded = utf8decode ? str.decodeUTF8() : str;
  381.  
  382.  
  383. for (var c=0; c<coded.length; c+=4) { // unpack four hexets into three octets
  384. h1 = b64.indexOf(coded.charAt(c));
  385. h2 = b64.indexOf(coded.charAt(c+1));
  386. h3 = b64.indexOf(coded.charAt(c+2));
  387. h4 = b64.indexOf(coded.charAt(c+3));
  388.  
  389. bits = h1<<18 | h2<<12 | h3<<6 | h4;
  390.  
  391. o1 = bits>>>16 & 0xff;
  392. o2 = bits>>>8 & 0xff;
  393. o3 = bits & 0xff;
  394.  
  395. d[c/4] = String.fromCharCode(o1, o2, o3);
  396. // check for padding
  397. if (h4 == 0x40) d[c/4] = String.fromCharCode(o1, o2);
  398. if (h3 == 0x40) d[c/4] = String.fromCharCode(o1);
  399. }
  400. plain = d.join(''); // join() is far faster than repeated string concatenation in IE
  401.  
  402. return utf8decode ? plain.decodeUTF8() : plain;
  403. }
  404.  
  405.  
  406. /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
  407. /* Utf8 class: encode / decode between multi-byte Unicode characters and UTF-8 multiple */
  408. /* single-byte character encoding (c) Chris Veness 2002-2011 */
  409. /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
  410.  
  411. var Utf8 = {}; // Utf8 namespace
  412.  
  413. /**
  414. * Encode multi-byte Unicode string into utf-8 multiple single-byte characters
  415. * (BMP / basic multilingual plane only)
  416. *
  417. * Chars in range U+0080 - U+07FF are encoded in 2 chars, U+0800 - U+FFFF in 3 chars
  418. *
  419. * @param {String} strUni Unicode string to be encoded as UTF-8
  420. * @returns {String} encoded string
  421. */
  422. Utf8.encode = function(strUni) {
  423. // use regular expressions & String.replace callback function for better efficiency
  424. // than procedural approaches
  425. var strUtf = strUni.replace(
  426. /[\u0080-\u07ff]/g, // U+0080 - U+07FF => 2 bytes 110yyyyy, 10zzzzzz
  427. function(c) {
  428. var cc = c.charCodeAt(0);
  429. return String.fromCharCode(0xc0 | cc>>6, 0x80 | cc&0x3f); }
  430. );
  431. strUtf = strUtf.replace(
  432. /[\u0800-\uffff]/g, // U+0800 - U+FFFF => 3 bytes 1110xxxx, 10yyyyyy, 10zzzzzz
  433. function(c) {
  434. var cc = c.charCodeAt(0);
  435. return String.fromCharCode(0xe0 | cc>>12, 0x80 | cc>>6&0x3F, 0x80 | cc&0x3f); }
  436. );
  437. return strUtf;
  438. }
  439.  
  440. /**
  441. * Decode utf-8 encoded string back into multi-byte Unicode characters
  442. *
  443. * @param {String} strUtf UTF-8 string to be decoded back to Unicode
  444. * @returns {String} decoded string
  445. */
  446. Utf8.decode = function(strUtf) {
  447. // note: decode 3-byte chars first as decoded 2-byte strings could appear to be 3-byte char!
  448. var strUni = strUtf.replace(
  449. /[\u00e0-\u00ef][\u0080-\u00bf][\u0080-\u00bf]/g, // 3-byte chars
  450. function(c) { // (note parentheses for precence)
  451. var cc = ((c.charCodeAt(0)&0x0f)<<12) | ((c.charCodeAt(1)&0x3f)<<6) | ( c.charCodeAt(2)&0x3f);
  452. return String.fromCharCode(cc); }
  453. );
  454. strUni = strUni.replace(
  455. /[\u00c0-\u00df][\u0080-\u00bf]/g, // 2-byte chars
  456. function(c) { // (note parentheses for precence)
  457. var cc = (c.charCodeAt(0)&0x1f)<<6 | c.charCodeAt(1)&0x3f;
  458. return String.fromCharCode(cc); }
  459. );
  460. return strUni;
  461. }
  462.  
  463. /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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