miscreant.js [![Latest Version][npm-shield]][npm-link] [![Build Status][build-image]][build-link] [![MIT licensed][license-image]][license-link] [![Gitter Chat][gitter-image]][gitter-link]

The best crypto you've never heard of, brought to you by [Phil Rogaway]

JavaScript-compatible TypeScript implementation of Miscreant: Advanced symmetric encryption library which provides the [AES-SIV] ([RFC 5297]), [AES-PMAC-SIV], and [STREAM] constructions. These algorithms are easy-to-use (or rather, hard-to-misuse) and support encryption of individual messages or message streams.

AES-SIV provides [nonce-reuse misuse-resistance] (NRMR): accidentally reusing a nonce with this construction is not a security catastrophe, unlike it is with more popular AES encryption modes like [AES-GCM]. With AES-SIV, the worst outcome of reusing a nonce is an attacker can see you've sent the same plaintext twice, as opposed to almost all other AES modes where it can facilitate [chosen ciphertext attacks] and/or full plaintext recovery.

Help and Discussion

Have questions? Want to suggest a feature or change?

• [Gitter]: web-based chat about miscreant projects including miscreant.js
• [Google Group]: join via web or email ([miscreant-crypto+subscribe@googlegroups.com])

Security Notice

Though this library is written by cryptographic professionals, it has not undergone a thorough security audit, and cryptographic professionals are still humans that make mistakes.

USE AT YOUR OWN RISK

Installation

Via npm:

npm install miscreant

Via Yarn:

yarn install miscreant

Import Miscreant into your project with:

import * as miscreant from "miscreant";

Import

Import Miscreant into your project with the following:

import * as miscreant from "miscreant";

API: Symmetric Encryption (AEAD)

The Authenticated Encryption with Associated Data API, or AEAD API, is the recommended API for encrypting and decrypting data with Miscreant. It accepts a nonce, optional associated data (i.e. data you'd like to authenticate along with the encrypted message), and a message to encrypt.

When decrypting, the same nonce and associated data must be supplied as were passed at the time of encryption. If anything is amiss, e.g. if the ciphertext has been tampered with, the cipher will detect it and throw an error.

miscreant.AEAD.importKey()

The miscreant.AEAD.importKey() method creates a new instance of an AES-SIV AEAD encryptor/decryptor.

Syntax

miscreant.AEAD.importKey(keyData, algorithm[, provider = new miscreant.WebCryptoProvider()])

Parameters

• keyData: a [Uint8Array] containing the encryption key to use. Key must be 32-bytes (for AES-128) or 64-bytes (for AES-256), as SIV uses two distinct AES keys to perform its operations.
• algorithm: a string describing the algorithm to use. The following algorithms are supported:
  • "AES-SIV": CMAC-based construction described in [RFC 5297]. Slower but standardized and more common.
  • "AES-PMAC-SIV": PMAC-based construction. Supports potentially faster implementations, but is non-standard and only available in Miscreant libraries.
• provider: a cryptography provider that implements Miscreant's [ICryptoProvider] interface.

Return Value

The miscreant.AEAD.importKey() method returns a [Promise] that, when fulfilled, returns an AEAD encryptor/decryptor.

Example

import * as miscreant from "miscreant";

let keyData = new Uint32Array(32);

// Assuming window.crypto.getRandomValues is available
window.crypto.getRandomValues(keyData);

let key = await miscreant.AEAD.importKey(keyData, "AES-PMAC-SIV");

seal()

The seal() method encrypts a message along with an optional associated data value which will be authenticated along with the message.

Syntax

key.seal(plaintext, nonce[, associatedData = ""])

Parameters

• plaintext: [Uint8Array] data to be encrypted.
• nonce: a single-use value which MUST be unique per encrypted message. Can be any length, and use any uniqueness strategy you like, e.g. a counter or a cryptographically secure random number generator.
• associatedData: (optional) [Uint8Array] that will be authenticated along with the message (but not encrypted).

Return Value

The seal() method returns a [Promise] that, when fulfilled, returns a [Uint8Array] containing the resulting ciphertext.

Example

import * as miscreant from "miscreant";

let keyData = new Uint8Array(32);

// Assuming window.crypto.getRandomValues is available
window.crypto.getRandomValues(keyData);

let key = await miscreant.SIV.importKey(keyData, "AES-PMAC-SIV");

// Encrypt plaintext

let plaintext = new Uint8Array([2,3,5,7,11,13,17,19,23,29]);
let nonce = new Uint8Array(16);
window.crypto.getRandomValues(nonce);

let ciphertext = await key.seal(plaintext, nonce);

open()

The open() method decrypts a message which has been encrypted using AES-SIV or AES-PMAC-SIV.

Syntax

key.open(ciphertext, nonce[, associatedData = ""])

Parameters

• ciphertext: [Uint8Array] containing an encrypted message.
• nonce: [Uint8Array] supplied when the message was originally encrypted.
• associatedData: (optional) [Uint8Array] supplied when the message was originally encrypted.

Return Value

The open() method returns a [Promise] that, when fulfilled, returns a [Uint8Array] containing the decrypted plaintext.

Exceptions

If the message has been tampered with or is otherwise corrupted, the promise will be rejected with an IntegrityError.

Example

import * as miscreant from "miscreant";

let keyData = new Uint8Array(32);

// Assuming window.crypto.getRandomValues is available
window.crypto.getRandomValues(keyData);

let key = await miscreant.SIV.importKey(keyData, "AES-PMAC-SIV");

// Encrypt plaintext

let plaintext = new Uint8Array([2,3,5,7,11,13,17,19,23,29]);
let nonce = new Uint8Array(16);
window.crypto.getRandomValues(nonce);

let ciphertext = await key.seal(plaintext, nonce);

// Decrypt ciphertext
var decrypted = await key.open(ciphertext, nonce);

STREAM API

Miscreant implements an interface that permits incremental processing of encrypted data based on the [STREAM] construction, which is provably secure against a wide range of attacks including truncation and reordering attacks.

The API is provided in the form of miscreant.StreamEncryptor and miscreant.StreamDecryptor classes, which each take a per-STREAM key and nonce, and from there operate a message-at-a-time on input plaintext/ciphertext along with optional per-message associated data (i.e. data you'd like to authenticate along with the encrypted message).

miscreant.StreamEncryptor.importKey()

The miscreant.StreamEncryptor.importKey() method creates a new instance of a STREAM encryptor, capable of encrypting a stream of authenticated messages and ensuring their integrity, ordering, and termination.

Syntax

miscreant.StreamEncryptor.importKey(keyData, nonceData, algorithm[, provider = new miscreant.WebCryptoProvider()])

Parameters

• keyData: a [Uint8Array] containing the encryption key to use. Key must be 32-bytes (for AES-128) or 64-bytes (for AES-256), as SIV uses two distinct AES keys to perform its operations.
• nonceData: a 64-bit (8-byte) [Uint8Array] which MUST be unique to this message stream (for a given key).
• algorithm: a string describing the algorithm to use. The following algorithms are supported:
  • "AES-SIV": CMAC-based construction described in [RFC 5297]. Slower but standardized and more common.
  • "AES-PMAC-SIV": PMAC-based construction. Supports potentially faster implementations, but is non-standard and only available in Miscreant libraries.
• provider: a cryptography provider that implements Miscreant's [ICryptoProvider] interface.

Return Value

The miscreant.StreamEncryptor.importKey() method returns a [Promise] that, when fulfilled, returns a StreamEncryptor object.

Example

import * as miscreant from "miscreant";

let keyData = new Uint32Array(32);
let nonceData = new Uint8Array(8);

// Assuming window.crypto.getRandomValues is available
window.crypto.getRandomValues(keyData);
window.crypto.getRandomValues(nonceData);

let encryptor = await miscreant.StreamEncryptor.importKey(keyData, nonceData, "AES-PMAC-SIV");

seal()

The seal() method of miscreant.StreamEncryptor encrypts a message, and also takes an optional associated data value which will be authenticated along with the message (but not encrypted).

Note that unlike the AEAD API, STREAM encodes the position of the message into the message stream, so the order in which seal() is called is significant.

Syntax

encryptor.seal(plaintext, [lastBlock = false[, associatedData = ""]])

Parameters

• plaintext: [Uint8Array] data to be encrypted.
• lastBlock: (optional; default: false) is this the last block in the stream?
• associatedData: (optional) [Uint8Array] that will be authenticated along with the message (but not encrypted).

Return Value

The seal() method returns a [Promise] that, when fulfilled, returns a [Uint8Array] containing the resulting ciphertext.

Example

import * as miscreant from "miscreant";

let keyData = new Uint32Array(32);
let nonceData = new Uint8Array(8);

// Assuming window.crypto.getRandomValues is available
window.crypto.getRandomValues(keyData);
window.crypto.getRandomValues(nonceData);

let encryptor = await miscreant.StreamEncryptor.importKey(keyData, nonceData, "AES-PMAC-SIV");

// Encrypt plaintext

let msg1 = new Uint8Array([1,2]);
let msg2 = new Uint8Array([3,4,5]);
let msg3 = new Uint8Array([6,7,8,9]);