142 lines
3.2 KiB
JavaScript
142 lines
3.2 KiB
JavaScript
'use strict';
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var assert = require('minimalistic-assert');
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function Cipher(options) {
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this.options = options;
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this.type = this.options.type;
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this.blockSize = 8;
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this._init();
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this.buffer = new Array(this.blockSize);
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this.bufferOff = 0;
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}
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module.exports = Cipher;
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Cipher.prototype._init = function _init() {
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// Might be overrided
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};
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Cipher.prototype.update = function update(data) {
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if (data.length === 0)
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return [];
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if (this.type === 'decrypt')
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return this._updateDecrypt(data);
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else
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return this._updateEncrypt(data);
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};
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Cipher.prototype._buffer = function _buffer(data, off) {
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// Append data to buffer
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var min = Math.min(this.buffer.length - this.bufferOff, data.length - off);
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for (var i = 0; i < min; i++)
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this.buffer[this.bufferOff + i] = data[off + i];
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this.bufferOff += min;
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// Shift next
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return min;
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};
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Cipher.prototype._flushBuffer = function _flushBuffer(out, off) {
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this._update(this.buffer, 0, out, off);
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this.bufferOff = 0;
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return this.blockSize;
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};
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Cipher.prototype._updateEncrypt = function _updateEncrypt(data) {
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var inputOff = 0;
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var outputOff = 0;
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var count = ((this.bufferOff + data.length) / this.blockSize) | 0;
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var out = new Array(count * this.blockSize);
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if (this.bufferOff !== 0) {
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inputOff += this._buffer(data, inputOff);
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if (this.bufferOff === this.buffer.length)
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outputOff += this._flushBuffer(out, outputOff);
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}
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// Write blocks
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var max = data.length - ((data.length - inputOff) % this.blockSize);
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for (; inputOff < max; inputOff += this.blockSize) {
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this._update(data, inputOff, out, outputOff);
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outputOff += this.blockSize;
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}
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// Queue rest
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for (; inputOff < data.length; inputOff++, this.bufferOff++)
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this.buffer[this.bufferOff] = data[inputOff];
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return out;
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};
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Cipher.prototype._updateDecrypt = function _updateDecrypt(data) {
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var inputOff = 0;
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var outputOff = 0;
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var count = Math.ceil((this.bufferOff + data.length) / this.blockSize) - 1;
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var out = new Array(count * this.blockSize);
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// TODO(indutny): optimize it, this is far from optimal
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for (; count > 0; count--) {
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inputOff += this._buffer(data, inputOff);
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outputOff += this._flushBuffer(out, outputOff);
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}
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// Buffer rest of the input
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inputOff += this._buffer(data, inputOff);
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return out;
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};
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Cipher.prototype.final = function final(buffer) {
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var first;
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if (buffer)
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first = this.update(buffer);
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var last;
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if (this.type === 'encrypt')
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last = this._finalEncrypt();
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else
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last = this._finalDecrypt();
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if (first)
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return first.concat(last);
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else
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return last;
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};
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Cipher.prototype._pad = function _pad(buffer, off) {
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if (off === 0)
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return false;
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while (off < buffer.length)
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buffer[off++] = 0;
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return true;
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};
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Cipher.prototype._finalEncrypt = function _finalEncrypt() {
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if (!this._pad(this.buffer, this.bufferOff))
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return [];
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var out = new Array(this.blockSize);
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this._update(this.buffer, 0, out, 0);
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return out;
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};
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Cipher.prototype._unpad = function _unpad(buffer) {
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return buffer;
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};
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Cipher.prototype._finalDecrypt = function _finalDecrypt() {
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assert.equal(this.bufferOff, this.blockSize, 'Not enough data to decrypt');
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var out = new Array(this.blockSize);
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this._flushBuffer(out, 0);
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return this._unpad(out);
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};
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