Monocypher for Nim

Allows the Monocypher cryptography library to be used in Nim. Please refer to its manual for detailed usage and security considerations.

Examples

Create a secret key using the sysrandom library, and ensure that it is erased from memory once it's no longer used:

import monocypher
import sysrandom

let secretKey = getRandomBytes(sizeof(Key))
defer: crypto_wipe(secretKey)

Exchange a shared symmetric key using public keys:

let yourPublicKey = crypto_key_exchange_public_key(secretKey)
let theirPublicKey = # obtain public key from other party
let sharedKey = crypto_key_exchange(secretKey, theirPublicKey)
defer: crypto_wipe(sharedKey)

Encrypt a message using a symmetric key:

let nonce = getRandomBytes(sizeof(Nonce))
let plaintext = cast[seq[byte]]("hello")
let (mac, ciphertext) = crypto_lock(sharedKey, nonce, plaintext)

Decrypt a message using a symmetric key:

let decrypted = crypto_unlock(sharedKey, nonce, mac, ciphertext)
defer: crypto_wipe(decrypted)

Sign a message:

let publicKey = crypto_sign_public_key(secretKey)
let message = cast[seq[byte]]("hello")
let signature = crypto_sign(secretKey, publicKey, message)

Hash a byte array or a string:

let hashOfBytes = crypto_blake2b([1u8, 2u8, 3u8])
let hashOfString = crypto_blake2b("hello")

Timing-safe comparisons for byte arrays of length 16, 32 or 64:

let hash1 = crypto_blake2b("one")
let hash2 = crypto_blake2b("two")
let hashesAreEqual = crypto_verify(hash1, hash2) # false