Skip to content

Commit

Permalink
Updated readme for 3.x update.
Browse files Browse the repository at this point in the history
  • Loading branch information
@ricmoo
ricmoo committed Feb 8, 2017
1 parent e27b99d commit 8ac229a
Showing 1 changed file with 141 additions and 41 deletions.
182 changes: 141 additions & 41 deletions README.md
View file
Expand Up @@ -13,6 +13,51 @@ Features
- Supports all common modes of operation (CBC, CFB, CTR, ECB and OFB)
- Works in either node.js or web browsers

Migrating from 2.x to 3.x
-------------------------

The utility functions have been renamed in the 3.x branch, since they were causing a great deal of confusion converting between bytes and string.

The examples have also been updated to encode binary data as printable hex strings.

**Strings and Bytes**

Strings should **NOT** be used as keys. UTF-8 allows variable length, multi-byte characters, so a string that is 16 *characters* long may not be 16 *bytes* long.

Also, UTF8 should **NOT** be used to store arbitrary binary data as it is a *string* encoding format, not a *binary* encoding format.

```javascript
// aesjs.util.convertStringToBytes(aString)
// Becomes:
aesjs.utils.utf8.toBytes(aString)


// aesjs.util.convertBytesToString(aString)
// Becomes:
aesjs.utils.utf8.fromBytes(aString)
```

**Bytes and Hex strings**

Binary data, such as encrypted bytes, can safely be stored and printed as hexidecimal strings.

```javascript
// aesjs.util.convertStringToBytes(aString, 'hex')
// Becomes:
aesjs.utils.hex.toBytes(aString)


// aesjs.util.convertBytesToString(aString, 'hex')
// Becomes:
aesjs.utils.hex.fromBytes(aString)
```

**Typed Arrays**

The 3.x and above versions of aes-js use [Uint8Array](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array) instead of Array, which reduces code size when used with Browserify (it no longer pulls in Buffer) and is also about **twice** the speed.

However, if you need to support browsers older than IE 10, you should continue using version 2.x.


API
===
Expand All @@ -36,13 +81,15 @@ var aesjs = require('aes-js');
To use `aes-js` in a web page, add the following:

```html
<script type="text/javascript" src="https://rawgit.com/ricmoo/aes-js/master/index.js"></script>
<script type="text/javascript" src="https://cdn.rawgit.com/ricmoo/aes-js/e27b99df/index.js"></script>
```

Keys
----

All keys must be 128 bits (16 bytes), 192 bits (24 bytes) or 256 bits (32 bytes) long. The API's work on either arrays or `Buffer` objects.
All keys must be 128 bits (16 bytes), 192 bits (24 bytes) or 256 bits (32 bytes) long.

The library work with `Array`, `Uint8Array` and `Buffer` objects as well as any *array-like* object (i.e. must have a `length` property, and have a valid byte value for each entry).

```javascript
// 128-bit, 192-bit and 256-bit keys
Expand All @@ -53,18 +100,19 @@ var key_256 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,
29, 30, 31];

// or, similarly, with buffers (node.js only):
var key_128 = new Buffer([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]);
var key_192 = new Buffer([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
16, 17, 18, 19, 20, 21, 22, 23]);
var key_256 = new Buffer([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,
29, 30, 31]);
// or, you may use Uint8Array:
var key_128_array = new Uint8Array(key_128);
var key_192_array = new Uint8Array(key_192);
var key_258_array = new Uint8Array(key_256);

// or, you may use Buffer in node.js:
var key_128_buffer = new Buffer(key_128);
var key_192_buffer = new Buffer(key_192);
var key_258_buffer = new Buffer(key_256);
```


To generate keys from simple-to-remember passwords, consider using a password-based key-derivation function such as [scrypt](https://www.npmjs.com/search?q=scrypt) or [bcrypt](https://www.npmjs.com/search?q=bcrypt).
To generate keys from simple-to-remember passwords, consider using a password-based key-derivation function such as [scrypt](https://www.npmjs.com/package/scrypt-js) or [bcrypt](https://www.npmjs.com/search?q=bcrypt).


Common Modes of Operation
Expand All @@ -75,23 +123,33 @@ There are several modes of operations, each with various pros and cons. In gener
### CTR - Counter (recommended)

```javascript
var key = aesjs.util.convertStringToBytes("Example128BitKey");
// An example 128-bit key (16 bytes * 8 bits/byte = 128 bits)
var key = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 ];

// Convert text to bytes
var text = 'Text may be any length you wish, no padding is required.';
var textBytes = aesjs.util.convertStringToBytes(text);
var textBytes = aesjs.utils.utf8.toBytes(text);

// The counter is optional, and if omitted will begin at 0
// The counter is optional, and if omitted will begin at 1
var aesCtr = new aesjs.ModeOfOperation.ctr(key, new aesjs.Counter(5));
var encryptedBytes = aesCtr.encrypt(textBytes);

// To print or store the binary data, you may convert it to hex
var encryptedHex = aesjs.utils.hex.fromBytes(encryptedBytes);
console.log(encryptedHex);
// "a338eda3874ed884b6199150d36f49988c90f5c47fe7792b0cf8c7f77eeffd87
// ea145b73e82aefcf2076f881c88879e4e25b1d7b24ba2788"

// When ready to decrypt the hex string, convert it back to bytes
var encryptedBytes = aesjs.utils.hex.toBytes(encryptedHex);

// The counter mode of operation maintains internal state, so to
// decrypt a new instance must be instantiated.
var aesCtr = new aesjs.ModeOfOperation.ctr(key, new aesjs.Counter(5));
var decryptedBytes = aesCtr.decrypt(encryptedBytes);

// Convert our bytes back into text
var decryptedText = aesjs.util.convertBytesToString(decryptedBytes);
var decryptedText = aesjs.utils.utf8.fromBytes(decryptedBytes);
console.log(decryptedText);
// "Text may be any length you wish, no padding is required."
```
Expand All @@ -100,25 +158,34 @@ console.log(decryptedText);
### CBC - Cipher-Block Chaining (recommended)

```javascript
var key = aesjs.util.convertStringToBytes("Example128BitKey");
// An example 128-bit key
var key = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 ];

// The initialization vector, which must be 16 bytes
var iv = aesjs.util.convertStringToBytes("IVMustBe16Bytes.");
// The initialization vector (must be 16 bytes)
var iv = [ 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34,35, 36 ];

// Convert text to bytes
// Convert text to bytes (text must be a multiple of 16 bytes)
var text = 'TextMustBe16Byte';
var textBytes = aesjs.util.convertStringToBytes(text);
var textBytes = aesjs.utils.utf8.toBytes(text);

var aesCbc = new aesjs.ModeOfOperation.cbc(key, iv);
var encryptedBytes = aesCbc.encrypt(textBytes);

// To print or store the binary data, you may convert it to hex
var encryptedHex = aesjs.utils.hex.fromBytes(encryptedBytes);
console.log(encryptedHex);
// "104fb073f9a131f2cab49184bb864ca2"

// When ready to decrypt the hex string, convert it back to bytes
var encryptedBytes = aesjs.utils.hex.toBytes(encryptedHex);

// The cipher-block chaining mode of operation maintains internal
// state, so to decrypt a new instance must be instantiated.
var aesCbc = new aesjs.ModeOfOperation.cbc(key, iv);
var decryptedBytes = aesCbc.decrypt(encryptedBytes);

// Convert our bytes back into text
var decryptedText = aesjs.util.convertBytesToString(decryptedBytes);
var decryptedText = aesjs.utils.utf8.fromBytes(decryptedBytes);
console.log(decryptedText);
// "TextMustBe16Byte"
```
Expand All @@ -127,26 +194,36 @@ console.log(decryptedText);
### CFB - Cipher Feedback

```javascript
var key = aesjs.util.convertStringToBytes("Example128BitKey");
// An example 128-bit key
var key = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 ];

// The initialization vector, which must be 16 bytes
var iv = aesjs.util.convertStringToBytes("IVMustBe16Bytes.");
// The initialization vector (must be 16 bytes)
var iv = [ 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34,35, 36 ];

// Convert text to bytes
// Convert text to bytes (must be a multiple of the segment size you choose below)
var text = 'TextMustBeAMultipleOfSegmentSize';
var textBytes = aesjs.util.convertStringToBytes(text);
var textBytes = aesjs.utils.utf8.toBytes(text);

// The segment size is optional, and defaults to 1
var aesCfb = new aesjs.ModeOfOperation.cfb(key, iv, 8);
var segmentSize = 8;
var aesCfb = new aesjs.ModeOfOperation.cfb(key, iv, segmentSize);
var encryptedBytes = aesCfb.encrypt(textBytes);

// To print or store the binary data, you may convert it to hex
var encryptedHex = aesjs.utils.hex.fromBytes(encryptedBytes);
console.log(encryptedHex);
// "55e3af2638c560b4fdb9d26a630733ea60197ec23deb85b1f60f71f10409ce27"

// When ready to decrypt the hex string, convert it back to bytes
var encryptedBytes = aesjs.utils.hex.toBytes(encryptedHex);

// The cipher feedback mode of operation maintains internal state,
// so to decrypt a new instance must be instantiated.
var aesCfb = new aesjs.ModeOfOperation.cfb(key, iv, 8);
var decryptedBytes = aesCfb.decrypt(encryptedBytes);

// Convert our bytes back into text
var decryptedText = aesjs.util.convertBytesToString(decryptedBytes);
var decryptedText = aesjs.utils.utf8.fromBytes(decryptedBytes);
console.log(decryptedText);
// "TextMustBeAMultipleOfSegmentSize"
```
Expand All @@ -155,25 +232,35 @@ console.log(decryptedText);
### OFB - Output Feedback

```javascript
var key = aesjs.util.convertStringToBytes("Example128BitKey");
// An example 128-bit key
var key = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 ];

// The initialization vector, which must be 16 bytes
var iv = aesjs.util.convertStringToBytes("IVMustBe16Bytes.");
// The initialization vector (must be 16 bytes)
var iv = [ 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34,35, 36 ];

// Convert text to bytes
var text = 'Text may be any length you wish, no padding is required.';
var textBytes = aesjs.util.convertStringToBytes(text);
var textBytes = aesjs.utils.utf8.toBytes(text);

var aesOfb = new aesjs.ModeOfOperation.ofb(key, iv);
var encryptedBytes = aesOfb.encrypt(textBytes);

// To print or store the binary data, you may convert it to hex
var encryptedHex = aesjs.utils.hex.fromBytes(encryptedBytes);
console.log(encryptedHex);
// "55e3af2655dd72b9f32456042f39bae9accff6259159e608be55a1aa313c598d
// b4b18406d89c83841c9d1af13b56de8eda8fcfe9ec8e75e8"

// When ready to decrypt the hex string, convert it back to bytes
var encryptedBytes = aesjs.utils.hex.toBytes(encryptedHex);

// The output feedback mode of operation maintains internal state,
// so to decrypt a new instance must be instantiated.
var aesOfb = new aesjs.ModeOfOperation.ofb(key, iv);
var decryptedBytes = aesOfb.decrypt(encryptedBytes);

// Convert our bytes back into text
var decryptedText = aesjs.util.convertBytesToString(decryptedBytes);
var decryptedText = aesjs.utils.utf8.fromBytes(decryptedBytes);
console.log(decryptedText);
// "Text may be any length you wish, no padding is required."
```
Expand All @@ -184,22 +271,31 @@ console.log(decryptedText);
This mode is **not** recommended. Since, for a given key, the same plaintext block in produces the same ciphertext block out, this mode of operation can leak data, such as patterns. For more details and examples, see the Wikipedia article, [Electronic Codebook](http://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Electronic_Codebook_.28ECB.29).

```javascript
var key = aesjs.util.convertStringToBytes("Example128BitKey");
// An example 128-bit key
var key = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 ];

// Convert text to bytes
var text = 'TextMustBe16Byte';
var textBytes = aesjs.util.convertStringToBytes(text);
var textBytes = aesjs.utils.utf8.toBytes(text);

var aesEcb = new aesjs.ModeOfOperation.ecb(key);
var encryptedBytes = aesEcb.encrypt(textBytes);

// To print or store the binary data, you may convert it to hex
var encryptedHex = aesjs.utils.hex.fromBytes(encryptedBytes);
console.log(encryptedHex);
// "a7d93b35368519fac347498dec18b458"

// When ready to decrypt the hex string, convert it back to bytes
var encryptedBytes = aesjs.utils.hex.toBytes(encryptedHex);

// Since electronic codebook does not store state, we can
// reuse the same instance.
//var aesEcb = new aesjs.ModeOfOperation.ecb(key);
var decryptedBytes = aesEcb.decrypt(encryptedBytes);

// Convert our bytes back into text
var decryptedText = aesjs.util.convertBytesToString(decryptedBytes);
var decryptedText = aesjs.utils.utf8.fromBytes(decryptedBytes);
console.log(decryptedText);
// "TextMustBe16Byte"
```
Expand All @@ -217,21 +313,26 @@ But this might be useful to experiment with custom modes of operation or play wi

// the AES block cipher algorithm works on 16 byte bloca ks, no more, no less
var text = "ABlockIs16Bytes!";
var textAsBytes = aesjs.util.convertStringToBytes(text)
var textAsBytes = aesjs.utils.utf8.toBytes(text)
console.log(textAsBytes);
// [65, 66, 108, 111, 99, 107, 73, 115, 49, 54, 66, 121, 116, 101, 115, 33]


// create an instance of the block cipher algorithm
var key = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5, 8, 9, 7, 9, 3];
var aes = new aesjs.AES(key);


// encrypt...
var encryptedBytes = aes.encrypt(textAsBytes);
console.log(encryptedBytes);
// [136, 15, 199, 174, 118, 133, 233, 177, 143, 47, 42, 211, 96, 55, 107, 109]

// To print or store the binary data, you may convert it to hex
var encryptedHex = aesjs.utils.hex.fromBytes(encryptedBytes);
console.log(encryptedHex);
// "880fc7ae7685e9b18f2f2ad360376b6d"

// When ready to decrypt the hex string, convert it back to bytes
var encryptedBytes = aesjs.utils.hex.toBytes(encryptedHex);

// decrypt...
var decryptedBytes = aes.decrypt(encryptedBytes);
Expand All @@ -240,7 +341,7 @@ console.log(decryptedBytes);


// decode the bytes back into our original text
var decryptedText = aesjs.util.convertBytesToString(decryptedBytes);
var decryptedText = aesjs.utils.utf8.fromBytes(decryptedBytes);
console.log(decryptedText);
// "ABlockIs16Bytes!"
```
Expand Down Expand Up @@ -302,5 +403,4 @@ Donations
Obviously, it's all licensed under the MIT license, so use it as you wish; but if you'd like to buy me a coffee, I won't complain. =)

- Bitcoin - `1K1Ax9t6uJmjE4X5xcoVuyVTsiLrYRqe2P`
- Dogecoin - `DFhgqVuaboxFnGQssyX84ZuV5r6aBRz8QJ`
- Testnet3 - `n1F2Eb6cknqqknUPp7m9oBNMgXFuaDowvF`
- Ethereum - `0x70bDC274028F3f391E398dF8e3977De64FEcBf04`

0 comments on commit 8ac229a

Please sign in to comment.