# simple AES
[](https://github.com/substrate-system/simple-aes/actions/workflows/nodejs.yml)
[](README.md)
[](README.md)
[](https://semver.org/)
[](https://packagephobia.com/result?p=@substrate-system/simple-aes)
[](https://bundlephobia.com/package/@substrate-system/simple-aes)
[](LICENSE)
Cryptography used by [vanishing.page](https://vanishing.page/). Works in
browsers and node.
This is generally useful as a dead simple way of working with symmetric keys
in a browser or node.
Thanks to [Fission](https://github.com/fission-codes/), the original author
for much of this code.
- [Install](#install)
- [Use](#use)
* [Bundler](#bundler)
* [pre-bundled](#pre-bundled)
- [API](#api)
* [`@substrate-system/simple-aes`](#substrate-systemsimple-aes)
* [`@substrate-system/simple-aes/compat`](#substrate-systemsimple-aescompat)
* [`encryptMessage`](#encryptmessage)
* [`decryptMessage`](#decryptmessage)
## Install
```sh
npm i -S @substrate-system/simple-aes
```
## Use
### Bundler
Just import
```js
import {
decryptMessage,
encryptMessage,
type Message
} from '@substrate-system/simple-aes'
// } from '@substtrate-system/simple-aes/compat' // for older browsers
```
### pre-bundled
This exposes pre-bundled & minified JS files.
#### copy
```sh
cp ./node_modules/@substrate-system/simple-aes/dist/compat.min.js ./public
cp ./node_modules/@substrate-system/simple-aes/dist/index.min.js ./public/simple-aes.min.js
```
#### link
```html
```
## API
### `@substrate-system/simple-aes`
Use the `webcrypto` API.
```js
import {
decryptMessage,
encryptMessage,
type Message
} from '@substrate-system/simple-aes'
```
### `@substrate-system/simple-aes/compat`
Use a user-land module,
[@noble/ciphers](https://github.com/paulmillr/noble-ciphers). This will work
in browsers of all ages.
```js
import {
encryptMessage,
decryptMessage
} from '@substrate-system/simple-aes/compat'
```
### `encryptMessage`
Generate a new AES key and encrypt the given message object.
Return an array of `[ encryptedMessage, { key }]`,
where `key` is a new AES key, encoded as `base64url`.
Can pass in a size for the key. By default it uses 256 bits.
```ts
async function encryptMessage (
msg:{ content:string },
opts:{ length:SymmKeyLength } = { length: DEFAULT_SYMM_LEN }
):Promise<[{ content:string }, { key:string }]>
```
#### encrypt example
```ts
import { SymmKeyLength, encryptMessage } from '@substrate-system/simple-aes'
const [encryptedMsg, { key }] = await encryptMessage({
content: 'hello world'
})
// or pass in a key size
await encryptMessage({
content: 'hello'
}, {
length: SymmKeyLength.B128
})
console.log(encryptedMessage)
// => { content: '5eAcA6+jnBfbuCx8L...' }
```
### `decryptMessage`
Decrypt the given message with the given key. Suitable for decrypting a message that was encrypted by this library. Key is an AES key, `base64url` encoded.
```ts
async function decryptMessage (
msg:{ content:string },
keyString:string // <-- base64url
):Promise<{ content:string }>
```
#### decrypt example
```js
import { test } from '@substrate-system/tapzero'
import { decryptMessage } from '@substrate-system/simple-aes'
test('decrypt the message', async t => {
const decrypted = await decryptMessage(message, key)
t.equal(decrypted.content, 'hello world',
'should decrypt to the right text')
})
```