wormhole-crypto 
Streaming encryption for Wormhole.app, based on Encrypted Content-Encoding for HTTP (RFC 8188)
This package is used by Wormhole.app.
Install
npm install wormhole-cryptoUsage
Here's a quick example of how to use this package to turn a plaintext WHATWG readable stream into an encrypted stream.
import { Keychain } from 'wormhole-crypto'
// Create a new keychain. Since no arguments are specified, the key and salt
// are generated.
const keychain = new Keychain()
// Get a WHATWG stream somehow, from fetch(), from a Blob(), etc.
const stream = getStream()
// Create an encrypted version of that stream
const encryptedStream = await keychain.encryptStream(stream)
// Normally you'd now use `encryptedStream`, e.g. in fetch(), etc.
// However, for this example, we'll just decrypt the stream immediately
const plaintextStream = await keychain.decryptStream(encryptedStream)
// Now, you can use `plaintextStream` and it will be identical to if you had
// used `stream`.API
new Keychain([key, [salt]])
Type: Class
Returns: Keychain
Create a new keychain object. The keychain can be used to create encryption streams, decryption streams, and to encrypt or decrypt a "metadata" buffer.
key
Type: Uint8Array | string | null
Default: null
The main key. This should be 16 bytes in length. If a string is given,
then it should be a base64-encoded string. If the argument is null, then a
key will be automatically generated.
salt
Type: Uint8Array | string | null
Default: null
The salt. This should be 16 bytes in length. If a string is given,
then it should be a base64-encoded string. If this argument is null, then a
salt will be automatically generated.
keychain.key
Type: Uint8Array
The main key.
keychain.keyB64
Type: string
The main key as a base64-encoded string.
keychain.salt
Type: Uint8Array
The salt.
Implementation note: The salt is used to derive the (internal) metadata key and authentication token.
keychain.saltB64
Type: string
The salt as a base64-encoded string.
keychain.authToken()
Type: Function
Returns: Promise[Uint8Array]
Returns a Promise which resolves to the authentication token. By default, the
authentication token is automatically derived from the main key using
HKDF SHA-256.
In Wormhole, the authentication token is used to communicate with the server and prove that the client has permission to fetch data for a room. Without a valid authentication token, the server will not return the encrypted room metadata or allow downloading the encrypted file data.
Since the authentication token is derived from the main key, the client presents it to the Wormhole server as a "reader token" to prove that it is in possession of the main key without revealing the main key to the server.
For destructive operations, like modifying the room, the client instead presents
a "writer token", which is not derived from the main key but is provided by the
server to the room creator who overrides the keychain authentication token by
calling keychain.setAuthToken(authToken) with the "writer token".
keychain.authTokenB64()
Type: Function
Returns: Promise[string]
Returns a Promise that resolves to the authentication token as a
base64-encoded string.
keychain.authHeader()
Type: Function
Returns: Promise[string]
Returns a Promise that resolves to the HTTP header value to be provided to the
Wormhole server. It contains the authentication token.
keychain.setAuthToken(authToken)
Type: Function
Returns: undefined
Update the keychain authentication token to authToken.
authToken
Type: Uint8Array | string | null
Default: null
The authentication token. This should be 16 bytes in length. If a string is
given, then it should be a base64-encoded string. If this argument is null,
then an authentication token will be automatically generated.
keychain.encryptStream(stream)
Type: Function
Returns: Promise[ReadableStream]
Returns a Promise that resolves to a ReadableStream encryption stream that
consumes the data in stream and returns an encrypted version. Data is
encrypted with Encrypted Content-Encoding for HTTP (RFC 8188).
stream
Type: ReadableStream
A WHATWG readable stream used as a data source for the encrypted stream.
keychain.decryptStream(encryptedStream)
Type: Function
Returns: Promise[ReadableStream]
Returns a Promise that resolves to a ReadableStream decryption stream that
consumes the data in encryptedStream and returns a plaintext version.
keychain.decryptStreamRange(offset, length, totalEncryptedLength)
Type: Function
Returns: Promise[{ ranges, decrypt }]
Returns a Promise that resolves to a object containing ranges, which is an array of
objects containing offset and length integers specifying the encrypted byte ranges
that are needed to decrypt the client's specified range, and a decrypt function.
Once the client has gathered a stream for each byte range in ranges, the client
should call decrypt(streams), where streams is an array of ReadableStream objects,
one for each of the requested ranges. decrypt will then return a ReadableStream
containing the plaintext data for the client's desired byte range.
encryptedStream
Type: ReadableStream
A WHATWG readable stream used as a data source for the plaintext stream.
keychain.encryptMeta(meta)
Type: Function
Returns: Promise[Uint8Array]
Returns a Promise that resolves to an encrypted version of meta. The
metadata is encrypted with AES-GCM.
Implementation note: The metadata key is automatically derived from the main key using HKDF SHA-256. The value is not user-controlled.
Implementation note: The initialization vector (IV) is automatically generated and included in the encrypted output. No need to generate it or to manage it separately from the encrypted output.
meta
Type: Uint8Array
The metadata buffer to encrypt.
keychain.decryptMeta(encryptedMeta)
Type: Function
Returns: Promise[Uint8Array]
Returns a Promise that resolves to a decrypted version of encryptedMeta.
encryptedMeta
Type: Uint8Array
The encrypted metadata buffer to decrypt.
plaintextSize(encryptedSize)
Type: Function
Returns: Number
Given an encrypted size, return the corresponding plaintext size.
encryptedSize(plaintextSize)
Type: Function
Returns: Number
Given a plaintext size, return the corresponding encrypted size.
License
MIT. Copyright (c) Socket Inc