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