1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
|
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/*
* AES Cipher function: encrypt 'input' with Rijndael algorithm
*
* takes byte-array 'input' (16 bytes)
* 2D byte-array key schedule 'w' (Nr+1 x Nb bytes)
*
* applies Nr rounds (10/12/14) using key schedule w for 'add round key' stage
*
* returns byte-array encrypted value (16 bytes)
*/
function Cipher(input, w) { // main Cipher function [§5.1]
var Nb = 4; // block size (in words): no of columns in state (fixed at 4 for AES)
var Nr = w.length/Nb - 1; // no of rounds: 10/12/14 for 128/192/256-bit keys
var state = [[],[],[],[]]; // initialise 4xNb byte-array 'state' with input [§3.4]
for (var i=0; i<4*Nb; i++) state[i%4][Math.floor(i/4)] = input[i];
state = AddRoundKey(state, w, 0, Nb);
for (var round=1; round<Nr; round++) {
state = SubBytes(state, Nb);
state = ShiftRows(state, Nb);
state = MixColumns(state, Nb);
state = AddRoundKey(state, w, round, Nb);
}
state = SubBytes(state, Nb);
state = ShiftRows(state, Nb);
state = AddRoundKey(state, w, Nr, Nb);
var output = new Array(4*Nb); // convert state to 1-d array before returning [§3.4]
for (var i=0; i<4*Nb; i++) output[i] = state[i%4][Math.floor(i/4)];
return output;
}
function SubBytes(s, Nb) { // apply SBox to state S [§5.1.1]
for (var r=0; r<4; r++) {
for (var c=0; c<Nb; c++) s[r][c] = Sbox[s[r][c]];
}
return s;
}
function ShiftRows(s, Nb) { // shift row r of state S left by r bytes [§5.1.2]
var t = new Array(4);
for (var r=1; r<4; r++) {
for (var c=0; c<4; c++) t[c] = s[r][(c+r)%Nb]; // shift into temp copy
for (var c=0; c<4; c++) s[r][c] = t[c]; // and copy back
} // note that this will work for Nb=4,5,6, but not 7,8 (always 4 for AES):
return s; // see fp.gladman.plus.com/cryptography_technology/rijndael/aes.spec.311.pdf
}
function MixColumns(s, Nb) { // combine bytes of each col of state S [§5.1.3]
for (var c=0; c<4; c++) {
var a = new Array(4); // 'a' is a copy of the current column from 's'
var b = new Array(4); // 'b' is a•{02} in GF(2^8)
for (var i=0; i<4; i++) {
a[i] = s[i][c];
b[i] = s[i][c]&0x80 ? s[i][c]<<1 ^ 0x011b : s[i][c]<<1;
}
// a[n] ^ b[n] is a•{03} in GF(2^8)
s[0][c] = b[0] ^ a[1] ^ b[1] ^ a[2] ^ a[3]; // 2*a0 + 3*a1 + a2 + a3
s[1][c] = a[0] ^ b[1] ^ a[2] ^ b[2] ^ a[3]; // a0 * 2*a1 + 3*a2 + a3
s[2][c] = a[0] ^ a[1] ^ b[2] ^ a[3] ^ b[3]; // a0 + a1 + 2*a2 + 3*a3
s[3][c] = a[0] ^ b[0] ^ a[1] ^ a[2] ^ b[3]; // 3*a0 + a1 + a2 + 2*a3
}
return s;
}
function AddRoundKey(state, w, rnd, Nb) { // xor Round Key into state S [§5.1.4]
for (var r=0; r<4; r++) {
for (var c=0; c<Nb; c++) state[r][c] ^= w[rnd*4+c][r];
}
return state;
}
function KeyExpansion(key) { // generate Key Schedule (byte-array Nr+1 x Nb) from Key [§5.2]
var Nb = 4; // block size (in words): no of columns in state (fixed at 4 for AES)
var Nk = key.length/4 // key length (in words): 4/6/8 for 128/192/256-bit keys
var Nr = Nk + 6; // no of rounds: 10/12/14 for 128/192/256-bit keys
var w = new Array(Nb*(Nr+1));
var temp = new Array(4);
for (var i=0; i<Nk; i++) {
var r = [key[4*i], key[4*i+1], key[4*i+2], key[4*i+3]];
w[i] = r;
}
for (var i=Nk; i<(Nb*(Nr+1)); i++) {
w[i] = new Array(4);
for (var t=0; t<4; t++) temp[t] = w[i-1][t];
if (i % Nk == 0) {
temp = SubWord(RotWord(temp));
for (var t=0; t<4; t++) temp[t] ^= Rcon[i/Nk][t];
} else if (Nk > 6 && i%Nk == 4) {
temp = SubWord(temp);
}
for (var t=0; t<4; t++) w[i][t] = w[i-Nk][t] ^ temp[t];
}
return w;
}
function SubWord(w) { // apply SBox to 4-byte word w
for (var i=0; i<4; i++) w[i] = Sbox[w[i]];
return w;
}
function RotWord(w) { // rotate 4-byte word w left by one byte
w[4] = w[0];
for (var i=0; i<4; i++) w[i] = w[i+1];
return w;
}
// Sbox is pre-computed multiplicative inverse in GF(2^8) used in SubBytes and KeyExpansion [§5.1.1]
var Sbox = [0x63,0x7c,0x77,0x7b,0xf2,0x6b,0x6f,0xc5,0x30,0x01,0x67,0x2b,0xfe,0xd7,0xab,0x76,
0xca,0x82,0xc9,0x7d,0xfa,0x59,0x47,0xf0,0xad,0xd4,0xa2,0xaf,0x9c,0xa4,0x72,0xc0,
0xb7,0xfd,0x93,0x26,0x36,0x3f,0xf7,0xcc,0x34,0xa5,0xe5,0xf1,0x71,0xd8,0x31,0x15,
0x04,0xc7,0x23,0xc3,0x18,0x96,0x05,0x9a,0x07,0x12,0x80,0xe2,0xeb,0x27,0xb2,0x75,
0x09,0x83,0x2c,0x1a,0x1b,0x6e,0x5a,0xa0,0x52,0x3b,0xd6,0xb3,0x29,0xe3,0x2f,0x84,
0x53,0xd1,0x00,0xed,0x20,0xfc,0xb1,0x5b,0x6a,0xcb,0xbe,0x39,0x4a,0x4c,0x58,0xcf,
0xd0,0xef,0xaa,0xfb,0x43,0x4d,0x33,0x85,0x45,0xf9,0x02,0x7f,0x50,0x3c,0x9f,0xa8,
0x51,0xa3,0x40,0x8f,0x92,0x9d,0x38,0xf5,0xbc,0xb6,0xda,0x21,0x10,0xff,0xf3,0xd2,
0xcd,0x0c,0x13,0xec,0x5f,0x97,0x44,0x17,0xc4,0xa7,0x7e,0x3d,0x64,0x5d,0x19,0x73,
0x60,0x81,0x4f,0xdc,0x22,0x2a,0x90,0x88,0x46,0xee,0xb8,0x14,0xde,0x5e,0x0b,0xdb,
0xe0,0x32,0x3a,0x0a,0x49,0x06,0x24,0x5c,0xc2,0xd3,0xac,0x62,0x91,0x95,0xe4,0x79,
0xe7,0xc8,0x37,0x6d,0x8d,0xd5,0x4e,0xa9,0x6c,0x56,0xf4,0xea,0x65,0x7a,0xae,0x08,
0xba,0x78,0x25,0x2e,0x1c,0xa6,0xb4,0xc6,0xe8,0xdd,0x74,0x1f,0x4b,0xbd,0x8b,0x8a,
0x70,0x3e,0xb5,0x66,0x48,0x03,0xf6,0x0e,0x61,0x35,0x57,0xb9,0x86,0xc1,0x1d,0x9e,
0xe1,0xf8,0x98,0x11,0x69,0xd9,0x8e,0x94,0x9b,0x1e,0x87,0xe9,0xce,0x55,0x28,0xdf,
0x8c,0xa1,0x89,0x0d,0xbf,0xe6,0x42,0x68,0x41,0x99,0x2d,0x0f,0xb0,0x54,0xbb,0x16];
// Rcon is Round Constant used for the Key Expansion [1st col is 2^(r-1) in GF(2^8)] [§5.2]
var Rcon = [ [0x00, 0x00, 0x00, 0x00],
[0x01, 0x00, 0x00, 0x00],
[0x02, 0x00, 0x00, 0x00],
[0x04, 0x00, 0x00, 0x00],
[0x08, 0x00, 0x00, 0x00],
[0x10, 0x00, 0x00, 0x00],
[0x20, 0x00, 0x00, 0x00],
[0x40, 0x00, 0x00, 0x00],
[0x80, 0x00, 0x00, 0x00],
[0x1b, 0x00, 0x00, 0x00],
[0x36, 0x00, 0x00, 0x00] ];
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/*
* Use AES to encrypt 'plaintext' with 'password' using 'nBits' key, in 'Counter' mode of operation
* - see http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf
* for each block
* - outputblock = cipher(counter, key)
* - cipherblock = plaintext xor outputblock
*/
function AESEncryptCtr(plaintext, password, nBits) {
if (!(nBits==128 || nBits==192 || nBits==256)) return ''; // standard allows 128/192/256 bit keys
// for this example script, generate the key by applying Cipher to 1st 16/24/32 chars of password;
// for real-world applications, a more secure approach would be to hash the password e.g. with SHA-1
var nBytes = nBits/8; // no bytes in key
var pwBytes = new Array(nBytes);
for (var i=0; i<nBytes; i++) pwBytes[i] = password.charCodeAt(i) & 0xff;
var key = Cipher(pwBytes, KeyExpansion(pwBytes));
key = key.concat(key.slice(0, nBytes-16)); // key is now 16/24/32 bytes long
// initialise counter block (NIST SP800-38A §B.2): millisecond time-stamp for nonce in 1st 8 bytes,
// block counter in 2nd 8 bytes
var blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
var counterBlock = new Array(blockSize); // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
var nonce = (new Date("2000-01-01")).getTime(); // milliseconds since 1-Jan-1970;
// fixed for repeatability
// encode nonce in two stages to cater for JavaScript 32-bit limit on bitwise ops
for (var i=0; i<4; i++) counterBlock[i] = (nonce >>> i*8) & 0xff;
for (var i=0; i<4; i++) counterBlock[i+4] = (nonce/0x100000000 >>> i*8) & 0xff;
// generate key schedule - an expansion of the key into distinct Key Rounds for each round
var keySchedule = KeyExpansion(key);
var blockCount = Math.ceil(plaintext.length/blockSize);
var ciphertext = new Array(blockCount); // ciphertext as array of strings
for (var b=0; b<blockCount; b++) {
// set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)
// again done in two stages for 32-bit ops
for (var c=0; c<4; c++) counterBlock[15-c] = (b >>> c*8) & 0xff;
for (var c=0; c<4; c++) counterBlock[15-c-4] = (b/0x100000000 >>> c*8)
var cipherCntr = Cipher(counterBlock, keySchedule); // -- encrypt counter block --
// calculate length of final block:
var blockLength = b<blockCount-1 ? blockSize : (plaintext.length-1)%blockSize+1;
var ct = '';
for (var i=0; i<blockLength; i++) { // -- xor plaintext with ciphered counter byte-by-byte --
var plaintextByte = plaintext.charCodeAt(b*blockSize+i);
var cipherByte = plaintextByte ^ cipherCntr[i];
ct += String.fromCharCode(cipherByte);
}
// ct is now ciphertext for this block
ciphertext[b] = escCtrlChars(ct); // escape troublesome characters in ciphertext
}
// convert the nonce to a string to go on the front of the ciphertext
var ctrTxt = '';
for (var i=0; i<8; i++) ctrTxt += String.fromCharCode(counterBlock[i]);
ctrTxt = escCtrlChars(ctrTxt);
// use '-' to separate blocks, use Array.join to concatenate arrays of strings for efficiency
return ctrTxt + '-' + ciphertext.join('-');
}
/*
* Use AES to decrypt 'ciphertext' with 'password' using 'nBits' key, in Counter mode of operation
*
* for each block
* - outputblock = cipher(counter, key)
* - cipherblock = plaintext xor outputblock
*/
function AESDecryptCtr(ciphertext, password, nBits) {
if (!(nBits==128 || nBits==192 || nBits==256)) return ''; // standard allows 128/192/256 bit keys
var nBytes = nBits/8; // no bytes in key
var pwBytes = new Array(nBytes);
for (var i=0; i<nBytes; i++) pwBytes[i] = password.charCodeAt(i) & 0xff;
var pwKeySchedule = KeyExpansion(pwBytes);
var key = Cipher(pwBytes, pwKeySchedule);
key = key.concat(key.slice(0, nBytes-16)); // key is now 16/24/32 bytes long
var keySchedule = KeyExpansion(key);
ciphertext = ciphertext.split('-'); // split ciphertext into array of block-length strings
// recover nonce from 1st element of ciphertext
var blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
var counterBlock = new Array(blockSize);
var ctrTxt = unescCtrlChars(ciphertext[0]);
for (var i=0; i<8; i++) counterBlock[i] = ctrTxt.charCodeAt(i);
var plaintext = new Array(ciphertext.length-1);
for (var b=1; b<ciphertext.length; b++) {
// set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)
for (var c=0; c<4; c++) counterBlock[15-c] = ((b-1) >>> c*8) & 0xff;
for (var c=0; c<4; c++) counterBlock[15-c-4] = ((b/0x100000000-1) >>> c*8) & 0xff;
var cipherCntr = Cipher(counterBlock, keySchedule); // encrypt counter block
ciphertext[b] = unescCtrlChars(ciphertext[b]);
var pt = '';
for (var i=0; i<ciphertext[b].length; i++) {
// -- xor plaintext with ciphered counter byte-by-byte --
var ciphertextByte = ciphertext[b].charCodeAt(i);
var plaintextByte = ciphertextByte ^ cipherCntr[i];
pt += String.fromCharCode(plaintextByte);
}
// pt is now plaintext for this block
plaintext[b-1] = pt; // b-1 'cos no initial nonce block in plaintext
}
return plaintext.join('');
}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
function escCtrlChars(str) { // escape control chars which might cause problems handling ciphertext
return str.replace(/[\0\t\n\v\f\r\xa0'"!-]/g, function(c) { return '!' + c.charCodeAt(0) + '!'; });
} // \xa0 to cater for bug in Firefox; include '-' to leave it free for use as a block marker
function unescCtrlChars(str) { // unescape potentially problematic control characters
return str.replace(/!\d\d?\d?!/g, function(c) { return String.fromCharCode(c.slice(1,-1)); });
}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/*
* if escCtrlChars()/unescCtrlChars() still gives problems, use encodeBase64()/decodeBase64() instead
*/
var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
function encodeBase64(str) { // http://tools.ietf.org/html/rfc4648
var o1, o2, o3, h1, h2, h3, h4, bits, i=0, enc='';
str = encodeUTF8(str); // encode multi-byte chars into UTF-8 for byte-array
do { // pack three octets into four hexets
o1 = str.charCodeAt(i++);
o2 = str.charCodeAt(i++);
o3 = str.charCodeAt(i++);
bits = o1<<16 | o2<<8 | o3;
h1 = bits>>18 & 0x3f;
h2 = bits>>12 & 0x3f;
h3 = bits>>6 & 0x3f;
h4 = bits & 0x3f;
// end of string? index to '=' in b64
if (isNaN(o3)) h4 = 64;
if (isNaN(o2)) h3 = 64;
// use hexets to index into b64, and append result to encoded string
enc += b64.charAt(h1) + b64.charAt(h2) + b64.charAt(h3) + b64.charAt(h4);
} while (i < str.length);
return enc;
}
function decodeBase64(str) {
var o1, o2, o3, h1, h2, h3, h4, bits, i=0, enc='';
do { // unpack four hexets into three octets using index points in b64
h1 = b64.indexOf(str.charAt(i++));
h2 = b64.indexOf(str.charAt(i++));
h3 = b64.indexOf(str.charAt(i++));
h4 = b64.indexOf(str.charAt(i++));
bits = h1<<18 | h2<<12 | h3<<6 | h4;
o1 = bits>>16 & 0xff;
o2 = bits>>8 & 0xff;
o3 = bits & 0xff;
if (h3 == 64) enc += String.fromCharCode(o1);
else if (h4 == 64) enc += String.fromCharCode(o1, o2);
else enc += String.fromCharCode(o1, o2, o3);
} while (i < str.length);
return decodeUTF8(enc); // decode UTF-8 byte-array back to Unicode
}
function encodeUTF8(str) { // encode multi-byte string into utf-8 multiple single-byte characters
str = str.replace(
/[\u0080-\u07ff]/g, // U+0080 - U+07FF = 2-byte chars
function(c) {
var cc = c.charCodeAt(0);
return String.fromCharCode(0xc0 | cc>>6, 0x80 | cc&0x3f); }
);
str = str.replace(
/[\u0800-\uffff]/g, // U+0800 - U+FFFF = 3-byte chars
function(c) {
var cc = c.charCodeAt(0);
return String.fromCharCode(0xe0 | cc>>12, 0x80 | cc>>6&0x3F, 0x80 | cc&0x3f); }
);
return str;
}
function decodeUTF8(str) { // decode utf-8 encoded string back into multi-byte characters
str = str.replace(
/[\u00c0-\u00df][\u0080-\u00bf]/g, // 2-byte chars
function(c) {
var cc = (c.charCodeAt(0)&0x1f)<<6 | c.charCodeAt(1)&0x3f;
return String.fromCharCode(cc); }
);
str = str.replace(
/[\u00e0-\u00ef][\u0080-\u00bf][\u0080-\u00bf]/g, // 3-byte chars
function(c) {
var cc = (c.charCodeAt(0)&0x0f)<<12 | (c.charCodeAt(1)&0x3f<<6) | c.charCodeAt(2)&0x3f;
return String.fromCharCode(cc); }
);
return str;
}
function byteArrayToHexStr(b) { // convert byte array to hex string for displaying test vectors
var s = '';
for (var i=0; i<b.length; i++) s += b[i].toString(16) + ' ';
return s;
}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
var plainText = "ROMEO: But, soft! what light through yonder window breaks?\n\
It is the east, and Juliet is the sun.\n\
Arise, fair sun, and kill the envious moon,\n\
Who is already sick and pale with grief,\n\
That thou her maid art far more fair than she:\n\
Be not her maid, since she is envious;\n\
Her vestal livery is but sick and green\n\
And none but fools do wear it; cast it off.\n\
It is my lady, O, it is my love!\n\
O, that she knew she were!\n\
She speaks yet she says nothing: what of that?\n\
Her eye discourses; I will answer it.\n\
I am too bold, 'tis not to me she speaks:\n\
Two of the fairest stars in all the heaven,\n\
Having some business, do entreat her eyes\n\
To twinkle in their spheres till they return.\n\
What if her eyes were there, they in her head?\n\
The brightness of her cheek would shame those stars,\n\
As daylight doth a lamp; her eyes in heaven\n\
Would through the airy region stream so bright\n\
That birds would sing and think it were not night.\n\
See, how she leans her cheek upon her hand!\n\
O, that I were a glove upon that hand,\n\
That I might touch that cheek!\n\
JULIET: Ay me!\n\
ROMEO: She speaks:\n\
O, speak again, bright angel! for thou art\n\
As glorious to this night, being o'er my head\n\
As is a winged messenger of heaven\n\
Unto the white-upturned wondering eyes\n\
Of mortals that fall back to gaze on him\n\
When he bestrides the lazy-pacing clouds\n\
And sails upon the bosom of the air.";
var password = "O Romeo, Romeo! wherefore art thou Romeo?";
var cipherText = AESEncryptCtr(plainText, password, 256);
var decryptedText = AESDecryptCtr(cipherText, password, 256);
assertEq(plainText, decryptedText);
|