s library wraps tweetnacl, doing a few things.

• Performs type conversion on the UTF8 and Base64 encodings used in tweetnacl. All methods take and return strings.
• Wraps synchronous methods into a callback API using process.nextTick. This is to make it easier to switch to different algorithms in the future, or offload processing to workers.
• Simplifies key management. Tweetnacl provides box (public key encryption), secretbox (symmetric encryption), and sign (cryptographic signatures). Each of these takes a different kind of key, but they can all be generated from a box secret key. Microstar-crypto does this generation automatically so that you only need to handle and store one private key. Additionally, box and sign use separate public keys. Microstar-crypto concatenates these into one string, and then extracts the correct public key depending on method.

Using tweetnacl by itself:

var keys = {
  box: {
    secretKey: Uint8Array, // 32 bytes
    publicKey: Uint8Array // 32 bytes
  },
  sign: {
    secretKey: Uint8Array, // 32 bytes
    publicKey: Uint8Array // 64 bytes
  },
  secretbox: {
    secretKey: Uint8Array // 32 bytes
  }
}

Using microstar-crypto;

var keys = {
  publicKey: String, // 88 characters
  secretKey: String // 44 characters
}

.keys([secretKey, ]callback)

Generates a keypair. Called with a secretKey it will generate the corresponding public key. Without, it will generate both keys from scratch.

mCrypto.keys(function (err, keys) {
//  keys = {
//    publicKey: String, // 88 characters
//    secretKey: String // 44 characters
//  }
})

.box(string, nonce, theirPublicKey, mySecretKey, callback)

Encrypts a string using a public key. Returns a string.

mCrypto.box(string, nonce, alicePublicKey, bobSecretKey, function (err, box) {
//  box = String // encrypted
})

mCrypto.box.open(box, nonce, bobPublicKey, aliceSecretKey, function (err, string) {
//  string = String // plaintext
})

.secretbox(string, nonce, secretKey, callback)

Encrypts a string symmetrically with one secret key. Returns a string.

mCrypto.secretbox(string, nonce, secretKey, function (err, box) {
//  box = String // encrypted
})

mCrypto.secretbox.open(box, nonce, secretKey, function (err, string) {
//  string = String // plaintext
})

.sign(string, secretKey, callback)

Signs a string, returning a signature as a string. This uses tweetnacl.sign.detached under the hood.

mCrypto.sign(string, secretKey, function (err, signature) {
//  signature = String
})

mCrypto.sign.verify(string, signature, publicKey, function (err, valid) {
//  valid = Boolean
})