1 | 'use strict';
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2 |
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3 | var errors = require('./errors');
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4 | var bitcore = require('bitcore');
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5 | var $ = bitcore.util.preconditions;
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6 |
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7 |
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8 |
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9 | var CBC = function CBC(blockcipher, cipherkeybuf, ivbuf) {
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10 | if (!(this instanceof CBC)) {
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11 | return new CBC(blockcipher, cipherkeybuf, ivbuf);
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12 | }
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13 |
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14 | this.blockcipher = blockcipher;
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15 | this.cipherkeybuf = cipherkeybuf;
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16 | this.ivbuf = ivbuf;
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17 | };
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18 |
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19 | CBC.buf2blockbufs = function(buf, blocksize) {
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20 | var bytesize = blocksize / 8;
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21 | var blockbufs = [];
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22 |
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23 | for (var i = 0; i <= buf.length / bytesize; i++) {
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24 | var blockbuf = buf.slice(i * bytesize, i * bytesize + bytesize);
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25 |
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26 | if (blockbuf.length < blocksize) {
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27 | blockbuf = CBC.pkcs7pad(blockbuf, blocksize);
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28 | }
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29 |
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30 | blockbufs.push(blockbuf);
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31 | }
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32 |
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33 | return blockbufs;
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34 | };
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35 |
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36 | CBC.blockbufs2buf = function(blockbufs) {
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37 | var last = blockbufs[blockbufs.length - 1];
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38 | last = CBC.pkcs7unpad(last);
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39 | blockbufs[blockbufs.length - 1] = last;
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40 |
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41 | var buf = Buffer.concat(blockbufs);
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42 |
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43 | return buf;
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44 | };
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45 |
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46 | CBC.encrypt = function(messagebuf, ivbuf, blockcipher, cipherkeybuf) {
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47 | var blocksize = ivbuf.length * 8;
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48 | var blockbufs = CBC.buf2blockbufs(messagebuf, blocksize);
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49 | var encbufs = CBC.encryptblocks(blockbufs, ivbuf, blockcipher, cipherkeybuf);
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50 | var encbuf = Buffer.concat(encbufs);
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51 | return encbuf;
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52 | };
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53 |
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54 | CBC.decrypt = function(encbuf, ivbuf, blockcipher, cipherkeybuf) {
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55 | var blocksize = ivbuf.length * 8;
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56 | var bytesize = ivbuf.length;
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57 | var encbufs = [];
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58 | for (var i = 0; i < encbuf.length / bytesize; i++) {
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59 | encbufs.push(encbuf.slice(i * bytesize, i * bytesize + bytesize));
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60 | }
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61 | var blockbufs = CBC.decryptblocks(encbufs, ivbuf, blockcipher, cipherkeybuf);
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62 | var buf = CBC.blockbufs2buf(blockbufs, blocksize);
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63 | return buf;
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64 | };
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65 |
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66 | CBC.encryptblock = function(blockbuf, ivbuf, blockcipher, cipherkeybuf) {
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67 | var xorbuf = CBC.xorbufs(blockbuf, ivbuf);
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68 | var encbuf = blockcipher.encrypt(xorbuf, cipherkeybuf);
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69 | return encbuf;
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70 | };
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71 |
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72 | CBC.decryptblock = function(encbuf, ivbuf, blockcipher, cipherkeybuf) {
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73 | var xorbuf = blockcipher.decrypt(encbuf, cipherkeybuf);
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74 | var blockbuf = CBC.xorbufs(xorbuf, ivbuf);
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75 | return blockbuf;
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76 | };
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77 |
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78 | CBC.encryptblocks = function(blockbufs, ivbuf, blockcipher, cipherkeybuf) {
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79 | var encbufs = [];
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80 |
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81 | for (var i = 0; i < blockbufs.length; i++) {
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82 | var blockbuf = blockbufs[i];
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83 | var encbuf = CBC.encryptblock(blockbuf, ivbuf, blockcipher, cipherkeybuf);
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84 |
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85 | encbufs.push(encbuf);
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86 |
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87 | ivbuf = encbuf;
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88 | }
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89 |
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90 | return encbufs;
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91 | };
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92 |
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93 | CBC.decryptblocks = function(encbufs, ivbuf, blockcipher, cipherkeybuf) {
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94 | var blockbufs = [];
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95 |
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96 | for (var i = 0; i < encbufs.length; i++) {
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97 | var encbuf = encbufs[i];
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98 | var blockbuf = CBC.decryptblock(encbuf, ivbuf, blockcipher, cipherkeybuf);
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99 |
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100 | blockbufs.push(blockbuf);
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101 |
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102 | ivbuf = encbuf;
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103 | }
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104 |
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105 | return blockbufs;
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106 | };
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107 |
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108 | CBC.pkcs7pad = function(buf, blocksize) {
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109 | var bytesize = blocksize / 8;
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110 | var padbytesize = bytesize - buf.length;
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111 | var pad = new Buffer(padbytesize);
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112 | pad.fill(padbytesize);
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113 | var paddedbuf = Buffer.concat([buf, pad]);
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114 | return paddedbuf;
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115 | };
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116 |
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117 | CBC.pkcs7unpad = function(paddedbuf) {
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118 | var padlength = paddedbuf[paddedbuf.length - 1];
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119 | var padbuf = paddedbuf.slice(paddedbuf.length - padlength, paddedbuf.length);
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120 | var padbuf2 = new Buffer(padlength);
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121 | padbuf2.fill(padlength);
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122 | if (padbuf.toString('hex') !== padbuf2.toString('hex')) {
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123 | throw new errors.InvalidPadding(padbuf.toString());
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124 | }
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125 | return paddedbuf.slice(0, paddedbuf.length - padlength);
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126 | };
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127 |
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128 | CBC.xorbufs = function(buf1, buf2) {
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129 | $.checkArgument(buf1.length === buf2.length, 'bufs must have the same length');
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130 |
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131 | var buf = new Buffer(buf1.length);
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132 |
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133 | for (var i = 0; i < buf1.length; i++) {
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134 | buf[i] = buf1[i] ^ buf2[i];
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135 | }
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136 |
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137 | return buf;
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138 | };
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139 |
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140 | module.exports = CBC;
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