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124 lines
3.1 KiB
124 lines
3.1 KiB
var AuthCipher = require('./authCipher') |
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var Buffer = require('safe-buffer').Buffer |
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var MODES = require('./modes') |
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var StreamCipher = require('./streamCipher') |
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var Transform = require('cipher-base') |
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var aes = require('./aes') |
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var ebtk = require('evp_bytestokey') |
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var inherits = require('inherits') |
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function Decipher (mode, key, iv) { |
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Transform.call(this) |
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this._cache = new Splitter() |
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this._last = void 0 |
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this._cipher = new aes.AES(key) |
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this._prev = Buffer.from(iv) |
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this._mode = mode |
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this._autopadding = true |
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} |
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inherits(Decipher, Transform) |
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Decipher.prototype._update = function (data) { |
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this._cache.add(data) |
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var chunk |
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var thing |
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var out = [] |
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while ((chunk = this._cache.get(this._autopadding))) { |
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thing = this._mode.decrypt(this, chunk) |
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out.push(thing) |
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} |
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return Buffer.concat(out) |
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} |
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Decipher.prototype._final = function () { |
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var chunk = this._cache.flush() |
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if (this._autopadding) { |
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return unpad(this._mode.decrypt(this, chunk)) |
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} else if (chunk) { |
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throw new Error('data not multiple of block length') |
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} |
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} |
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Decipher.prototype.setAutoPadding = function (setTo) { |
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this._autopadding = !!setTo |
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return this |
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} |
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function Splitter () { |
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this.cache = Buffer.allocUnsafe(0) |
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} |
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Splitter.prototype.add = function (data) { |
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this.cache = Buffer.concat([this.cache, data]) |
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} |
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Splitter.prototype.get = function (autoPadding) { |
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var out |
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if (autoPadding) { |
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if (this.cache.length > 16) { |
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out = this.cache.slice(0, 16) |
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this.cache = this.cache.slice(16) |
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return out |
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} |
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} else { |
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if (this.cache.length >= 16) { |
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out = this.cache.slice(0, 16) |
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this.cache = this.cache.slice(16) |
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return out |
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} |
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} |
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return null |
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} |
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Splitter.prototype.flush = function () { |
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if (this.cache.length) return this.cache |
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} |
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function unpad (last) { |
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var padded = last[15] |
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if (padded < 1 || padded > 16) { |
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throw new Error('unable to decrypt data') |
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} |
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var i = -1 |
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while (++i < padded) { |
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if (last[(i + (16 - padded))] !== padded) { |
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throw new Error('unable to decrypt data') |
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} |
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} |
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if (padded === 16) return |
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return last.slice(0, 16 - padded) |
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} |
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function createDecipheriv (suite, password, iv) { |
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var config = MODES[suite.toLowerCase()] |
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if (!config) throw new TypeError('invalid suite type') |
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if (typeof iv === 'string') iv = Buffer.from(iv) |
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if (config.mode !== 'GCM' && iv.length !== config.iv) throw new TypeError('invalid iv length ' + iv.length) |
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if (typeof password === 'string') password = Buffer.from(password) |
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if (password.length !== config.key / 8) throw new TypeError('invalid key length ' + password.length) |
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if (config.type === 'stream') { |
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return new StreamCipher(config.module, password, iv, true) |
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} else if (config.type === 'auth') { |
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return new AuthCipher(config.module, password, iv, true) |
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} |
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return new Decipher(config.module, password, iv) |
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} |
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function createDecipher (suite, password) { |
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var config = MODES[suite.toLowerCase()] |
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if (!config) throw new TypeError('invalid suite type') |
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var keys = ebtk(password, false, config.key, config.iv) |
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return createDecipheriv(suite, keys.key, keys.iv) |
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} |
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exports.createDecipher = createDecipher |
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exports.createDecipheriv = createDecipheriv
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