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node_modules/des.js/lib/des/ede.js 1.31 KB
aaac7fed   liuqimichale   add
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  'use strict';
  
  var assert = require('minimalistic-assert');
  var inherits = require('inherits');
  
  var des = require('../des');
  var Cipher = des.Cipher;
  var DES = des.DES;
  
  function EDEState(type, key) {
    assert.equal(key.length, 24, 'Invalid key length');
  
    var k1 = key.slice(0, 8);
    var k2 = key.slice(8, 16);
    var k3 = key.slice(16, 24);
  
    if (type === 'encrypt') {
      this.ciphers = [
        DES.create({ type: 'encrypt', key: k1 }),
        DES.create({ type: 'decrypt', key: k2 }),
        DES.create({ type: 'encrypt', key: k3 })
      ];
    } else {
      this.ciphers = [
        DES.create({ type: 'decrypt', key: k3 }),
        DES.create({ type: 'encrypt', key: k2 }),
        DES.create({ type: 'decrypt', key: k1 })
      ];
    }
  }
  
  function EDE(options) {
    Cipher.call(this, options);
  
    var state = new EDEState(this.type, this.options.key);
    this._edeState = state;
  }
  inherits(EDE, Cipher);
  
  module.exports = EDE;
  
  EDE.create = function create(options) {
    return new EDE(options);
  };
  
  EDE.prototype._update = function _update(inp, inOff, out, outOff) {
    var state = this._edeState;
  
    state.ciphers[0]._update(inp, inOff, out, outOff);
    state.ciphers[1]._update(out, outOff, out, outOff);
    state.ciphers[2]._update(out, outOff, out, outOff);
  };
  
  EDE.prototype._pad = DES.prototype._pad;
  EDE.prototype._unpad = DES.prototype._unpad;