Update README.md

README.md

@@ -1,17 +1,53 @@
-cipher-base
-===
+# cipher-base
 
-[![Build Status](https://travis-ci.org/crypto-browserify/cipher-base.svg)](https://travis-ci.org/crypto-browserify/cipher-base)
+[![NPM Package](https://img.shields.io/npm/v/cipher-base.svg?style=flat-square)](https://www.npmjs.org/package/cipher-base)
+[![Build Status](https://img.shields.io/travis/crypto-browserify/cipher-base.svg?branch=master&style=flat-square)](https://travis-ci.org/crypto-browserify/cipher-base)
 
-Abstract base class to inherit from if you want to create streams implementing
-the same api as node crypto streams.
+[![js-standard-style](https://cdn.rawgit.com/feross/standard/master/badge.svg)](https://github.com/feross/standard)
 
-Requires you to implement 2 methods `_final` and `_update`. `_update` takes a
-buffer and should return a buffer, `_final` takes no arguments and should return
-a buffer.
+Abstract base class to inherit from if you want to create streams implementing the same API as node crypto [Cipher][1] or [Decipher][2] (for [Hash][3] check [crypto-browserify/hash-base][4]).
 
+## Example
 
-The constructor takes one argument and that is a string which if present switches
-it into hash mode, i.e. the object you get from crypto.createHash or
-crypto.createSign, this switches the name of the final method to be the string
-you passed instead of `final` and returns `this` from update.
+```js
+const CipherBase = require('cipher-base')
+const inherits = require('inherits')
+
+// our cipher will apply XOR 0x42 to every byte
+function MyCipher () {
+  CipherBase.call(this, true) // for Deciper you need pass `false`
+}
+
+inherits(MyCipher, CipherBase)
+
+MyCipher.prototype._isAuthenticatedMode = function () {
+  return false
+}
+
+MyCipher.prototype._setAutoPadding = function (ap) {}
+MyCipher.prototype._setAAD = function (aadbuf) {}
+
+MyCipher.prototype._update = function (data) {
+  const result = Buffer.allocUnsafe(data.length)
+  for (let i = 0; i < data.length; ++i) result[i] = data[i] ^ 0x42
+  return result
+}
+
+MyCipher.prototype._final = function () {
+  return Buffer.allocUnsafe(0)
+}
+
+const data = Buffer.from([ 0x00, 0x42 ])
+const cipher = new MyCipher()
+console.log(Buffer.concat([cipher.update(data), cipher.final()]))
+// => <Buffer 42 00>
+```
+
+## LICENSE
+
+MIT
+
+[1]: https://nodejs.org/api/crypto.html#crypto_class_cipher
+[2]: https://nodejs.org/api/crypto.html#crypto_class_decipher
+[3]: https://nodejs.org/api/crypto.html#crypto_class_hash
+[4]: https://github.com/crypto-browserify/hash-base