splitting up decrypter into multiple files

@@ -35,22 +35,6 @@
  * are those of the authors and should not be interpreted as representing
  * are those of the authors and should not be interpreted as representing
  * official policies, either expressed or implied, of the authors.
  * official policies, either expressed or implied, of the authors.
  */
  */
-import Stream from './stream';
-import {unpad} from 'pkcs7';
-
-/**
- * Convert network-order (big-endian) bytes into their little-endian
- * representation.
- */
-const ntoh = function(word) {
-  return (word << 24) |
-    ((word & 0xff00) << 8) |
-    ((word & 0xff0000) >> 8) |
-    (word >>> 24);
-};
-
-
-let aesTables;
 
 
 /**
 /**
  * Schedule out an AES key for both encryption and decryption. This
  * Schedule out an AES key for both encryption and decryption. This
@@ -59,7 +43,7 @@ let aesTables;
  * @constructor
  * @constructor
  * @param key {Array} The key as an array of 4, 6 or 8 words.
  * @param key {Array} The key as an array of 4, 6 or 8 words.
  */
  */
-class AES {
+export default class AES {
   constructor(key) {
   constructor(key) {
    /**
    /**
     * The expanded S-box and inverse S-box tables. These will be computed
     * The expanded S-box and inverse S-box tables. These will be computed
@@ -255,161 +239,4 @@ class AES {
       a2 = a; a = b; b = c; c = d; d = a2;
       a2 = a; a = b; b = c; c = d; d = a2;
     }
     }
   }
   }
-
-}
-
-/* eslint-disable max-len */
-/**
- * Decrypt bytes using AES-128 with CBC and PKCS#7 padding.
- * @param encrypted {Uint8Array} the encrypted bytes
- * @param key {Uint32Array} the bytes of the decryption key
- * @param initVector {Uint32Array} the initialization vector (IV) to
- * use for the first round of CBC.
- * @return {Uint8Array} the decrypted bytes
- *
- * @see http://en.wikipedia.org/wiki/Advanced_Encryption_Standard
- * @see http://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_Block_Chaining_.28CBC.29
- * @see https://tools.ietf.org/html/rfc2315
- */
-/* eslint-enable max-len */
-export const decrypt = function(encrypted, key, initVector) {
-  // word-level access to the encrypted bytes
-  let encrypted32 = new Int32Array(encrypted.buffer,
-                                   encrypted.byteOffset,
-                                   encrypted.byteLength >> 2);
-
-  let decipher = new AES(Array.prototype.slice.call(key));
-
-  // byte and word-level access for the decrypted output
-  let decrypted = new Uint8Array(encrypted.byteLength);
-  let decrypted32 = new Int32Array(decrypted.buffer);
-
-  // temporary variables for working with the IV, encrypted, and
-  // decrypted data
-  let init0;
-  let init1;
-  let init2;
-  let init3;
-  let encrypted0;
-  let encrypted1;
-  let encrypted2;
-  let encrypted3;
-
-  // iteration variable
-  let wordIx;
-
-  // pull out the words of the IV to ensure we don't modify the
-  // passed-in reference and easier access
-  init0 = initVector[0];
-  init1 = initVector[1];
-  init2 = initVector[2];
-  init3 = initVector[3];
-
-  // decrypt four word sequences, applying cipher-block chaining (CBC)
-  // to each decrypted block
-  for (wordIx = 0; wordIx < encrypted32.length; wordIx += 4) {
-    // convert big-endian (network order) words into little-endian
-    // (javascript order)
-    encrypted0 = ntoh(encrypted32[wordIx]);
-    encrypted1 = ntoh(encrypted32[wordIx + 1]);
-    encrypted2 = ntoh(encrypted32[wordIx + 2]);
-    encrypted3 = ntoh(encrypted32[wordIx + 3]);
-
-    // decrypt the block
-    decipher.decrypt(encrypted0,
-                     encrypted1,
-                     encrypted2,
-                     encrypted3,
-                     decrypted32,
-                     wordIx);
-
-    // XOR with the IV, and restore network byte-order to obtain the
-    // plaintext
-    decrypted32[wordIx] = ntoh(decrypted32[wordIx] ^ init0);
-    decrypted32[wordIx + 1] = ntoh(decrypted32[wordIx + 1] ^ init1);
-    decrypted32[wordIx + 2] = ntoh(decrypted32[wordIx + 2] ^ init2);
-    decrypted32[wordIx + 3] = ntoh(decrypted32[wordIx + 3] ^ init3);
-
-    // setup the IV for the next round
-    init0 = encrypted0;
-    init1 = encrypted1;
-    init2 = encrypted2;
-    init3 = encrypted3;
-  }
-
-  return decrypted;
-};
-
-export class AsyncStream extends Stream {
-  constructor() {
-    super(Stream);
-    this.jobs = [];
-    this.delay = 1;
-    this.timeout_ = null;
-  }
-  processJob_() {
-    this.jobs.shift()();
-    if (this.jobs.length) {
-      this.timeout_ = setTimeout(this.processJob_.bind(this),
-                                 this.delay);
-    } else {
-      this.timeout_ = null;
-    }
-  }
-  push(job) {
-    this.jobs.push(job);
-    if (!this.timeout_) {
-      this.timeout_ = setTimeout(this.processJob_.bind(this),
-                                 this.delay);
-    }
-  }
 }
 }
-
-export class Decrypter {
-  constructor(encrypted, key, initVector, done) {
-    let step = Decrypter.STEP;
-    let encrypted32 = new Int32Array(encrypted.buffer);
-    let decrypted = new Uint8Array(encrypted.byteLength);
-    let i = 0;
-
-    this.asyncStream_ = new AsyncStream();
-
-    // split up the encryption job and do the individual chunks asynchronously
-    this.asyncStream_.push(this.decryptChunk_(encrypted32.subarray(i, i + step),
-                                              key,
-                                              initVector,
-                                              decrypted));
-    for (i = step; i < encrypted32.length; i += step) {
-      initVector = new Uint32Array([ntoh(encrypted32[i - 4]),
-                                    ntoh(encrypted32[i - 3]),
-                                    ntoh(encrypted32[i - 2]),
-                                    ntoh(encrypted32[i - 1])]);
-      this.asyncStream_.push(this.decryptChunk_(encrypted32.subarray(i, i + step),
-                                                key,
-                                                initVector,
-                                                decrypted));
-    }
-    // invoke the done() callback when everything is finished
-    this.asyncStream_.push(function() {
-      // remove pkcs#7 padding from the decrypted bytes
-      done(null, unpad(decrypted));
-    });
-  }
-  decryptChunk_(encrypted, key, initVector, decrypted) {
-    return function() {
-      let bytes = decrypt(encrypted, key, initVector);
-
-      decrypted.set(bytes, encrypted.byteOffset);
-    };
-  }
-}
-
-// the maximum number of bytes to process at one time
-// 4 * 8000;
-Decrypter.STEP = 32000;
-
-export default {
-  decrypt,
-  Decrypter,
-  AsyncStream
-};

+import Stream from '../stream';
+
+export default class AsyncStream extends Stream {
+  constructor() {
+    super(Stream);
+    this.jobs = [];
+    this.delay = 1;
+    this.timeout_ = null;
+  }
+  processJob_() {
+    this.jobs.shift()();
+    if (this.jobs.length) {
+      this.timeout_ = setTimeout(this.processJob_.bind(this),
+                                 this.delay);
+    } else {
+      this.timeout_ = null;
+    }
+  }
+  push(job) {
+    this.jobs.push(job);
+    if (!this.timeout_) {
+      this.timeout_ = setTimeout(this.processJob_.bind(this),
+                                 this.delay);
+    }
+  }
+}
+

+import ntoh from './ntoh';
+import AES from './aes';
+
+/* eslint-disable max-len */
+/**
+ * Decrypt bytes using AES-128 with CBC and PKCS#7 padding.
+ * @param encrypted {Uint8Array} the encrypted bytes
+ * @param key {Uint32Array} the bytes of the decryption key
+ * @param initVector {Uint32Array} the initialization vector (IV) to
+ * use for the first round of CBC.
+ * @return {Uint8Array} the decrypted bytes
+ *
+ * @see http://en.wikipedia.org/wiki/Advanced_Encryption_Standard
+ * @see http://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_Block_Chaining_.28CBC.29
+ * @see https://tools.ietf.org/html/rfc2315
+ */
+/* eslint-enable max-len */
+const decrypt = function(encrypted, key, initVector) {
+  // word-level access to the encrypted bytes
+  let encrypted32 = new Int32Array(encrypted.buffer,
+                                   encrypted.byteOffset,
+                                   encrypted.byteLength >> 2);
+
+  let decipher = new AES(Array.prototype.slice.call(key));
+
+  // byte and word-level access for the decrypted output
+  let decrypted = new Uint8Array(encrypted.byteLength);
+  let decrypted32 = new Int32Array(decrypted.buffer);
+
+  // temporary variables for working with the IV, encrypted, and
+  // decrypted data
+  let init0;
+  let init1;
+  let init2;
+  let init3;
+  let encrypted0;
+  let encrypted1;
+  let encrypted2;
+  let encrypted3;
+
+  // iteration variable
+  let wordIx;
+
+  // pull out the words of the IV to ensure we don't modify the
+  // passed-in reference and easier access
+  init0 = initVector[0];
+  init1 = initVector[1];
+  init2 = initVector[2];
+  init3 = initVector[3];
+
+  // decrypt four word sequences, applying cipher-block chaining (CBC)
+  // to each decrypted block
+  for (wordIx = 0; wordIx < encrypted32.length; wordIx += 4) {
+    // convert big-endian (network order) words into little-endian
+    // (javascript order)
+    encrypted0 = ntoh(encrypted32[wordIx]);
+    encrypted1 = ntoh(encrypted32[wordIx + 1]);
+    encrypted2 = ntoh(encrypted32[wordIx + 2]);
+    encrypted3 = ntoh(encrypted32[wordIx + 3]);
+
+    // decrypt the block
+    decipher.decrypt(encrypted0,
+                     encrypted1,
+                     encrypted2,
+                     encrypted3,
+                     decrypted32,
+                     wordIx);
+
+    // XOR with the IV, and restore network byte-order to obtain the
+    // plaintext
+    decrypted32[wordIx] = ntoh(decrypted32[wordIx] ^ init0);
+    decrypted32[wordIx + 1] = ntoh(decrypted32[wordIx + 1] ^ init1);
+    decrypted32[wordIx + 2] = ntoh(decrypted32[wordIx + 2] ^ init2);
+    decrypted32[wordIx + 3] = ntoh(decrypted32[wordIx + 3] ^ init3);
+
+    // setup the IV for the next round
+    init0 = encrypted0;
+    init1 = encrypted1;
+    init2 = encrypted2;
+    init3 = encrypted3;
+  }
+
+  return decrypted;
+};
+
+export default decrypt;

+import AsyncStream from './async-stream';
+import ntoh from './ntoh';
+import {unpad} from 'pkcs7';
+import decrypt from './decrypt';
+
+export default class Decrypter {
+  constructor(encrypted, key, initVector, done) {
+    let step = Decrypter.STEP;
+    let encrypted32 = new Int32Array(encrypted.buffer);
+    let decrypted = new Uint8Array(encrypted.byteLength);
+    let i = 0;
+
+    this.asyncStream_ = new AsyncStream();
+
+    // split up the encryption job and do the individual chunks asynchronously
+    this.asyncStream_.push(this.decryptChunk_(encrypted32.subarray(i, i + step),
+                                              key,
+                                              initVector,
+                                              decrypted));
+    for (i = step; i < encrypted32.length; i += step) {
+      initVector = new Uint32Array([ntoh(encrypted32[i - 4]),
+                                    ntoh(encrypted32[i - 3]),
+                                    ntoh(encrypted32[i - 2]),
+                                    ntoh(encrypted32[i - 1])]);
+      this.asyncStream_.push(this.decryptChunk_(encrypted32.subarray(i, i + step),
+                                                key,
+                                                initVector,
+                                                decrypted));
+    }
+    // invoke the done() callback when everything is finished
+    this.asyncStream_.push(function() {
+      // remove pkcs#7 padding from the decrypted bytes
+      done(null, unpad(decrypted));
+    });
+  }
+  decryptChunk_(encrypted, key, initVector, decrypted) {
+    return function() {
+      let bytes = decrypt(encrypted, key, initVector);
+
+      decrypted.set(bytes, encrypted.byteOffset);
+    };
+  }
+}
+
+// the maximum number of bytes to process at one time
+// 4 * 8000;
+Decrypter.STEP = 32000;
+

+import decrypt from './decrypt';
+import AsyncStream from './async-stream';
+import Decrypter from './decrypter';
+
+export default {
+  decrypt,
+  Decrypter,
+  AsyncStream
+};

+/**
+ * Convert network-order (big-endian) bytes into their little-endian
+ * representation.
+ */
+const ntoh = function(word) {
+  return (word << 24) |
+    ((word & 0xff00) << 8) |
+    ((word & 0xff0000) >> 8) |
+    (word >>> 24);
+};
+
+export default ntoh;