update readme

README.md

@@ -64,3 +64,23 @@ feed.ready(() => {
   })
 })
 ```
+
+```js
+const { publicKey, secretKey } = boxKeypair(seed)
+```
+
+```js
+const boxed = box(publicKey, message, [contextMessage])
+```
+Encrypts a message to a given public key and returns it as a buffer
+- `publicKey` buffer or hex encoded string
+- `message` buffer or hex encoded string of any length
+- `contextMessage`, if passed, will be hashed in to the shared secret. Should be a buffer or hex encoded string.
+
+```js
+const unboxed = unbox(cipherText, keypair, [contextMessage])
+```
+Decrypts a message using the given keypair.
+- `cipherText` the encrypted message given as a buffer.
+- `keypair` an object of the form `{ publicKey, secretKey }` both of which should be buffers or hex encoded strings.
+- `contextMessage`, if given, will be hashed into the shared secret. Should be a buffer or hex encoded string.