authenticated-public-key-encryption.md

Authenticated public-key encryption

See also: Libsodium's documentation on its public-key authenticated encryption features.

crypto_box

Public-key authenticated encryption.

Parameters and their respective types:

1. {string|Buffer} plaintext
2. {Buffer} nonce (must be 24 bytes)
3. {X25519SecretKey} secret key
4. {X25519PublicKey} public key

Returns a Promise that resolves to a Buffer.

crypto_box_open

Public-key authenticated encryption.

Parameters and their respective types:

1. {Buffer} ciphertext
2. {Buffer} nonce (must be 24 bytes)
3. {X25519SecretKey} secret key
4. {X25519PublicKey} public key

Returns a Promise that resolves to a Buffer. Throws a SodiumError on decryption failure.

crypto_box_keypair

Returns a Promise that resolves to a CryptographyKey containing a 64-byte Buffer. The first 32 bytes are your X25519 secret key, the latter 32 are your X25519 public key.

crypto_box_keypair_from_secretkey_and_publickey

Combine two X25519 keys (secret, public) into a keypair object.

Parameters and their respective types:

1. {X25519SecretKey} secret key
2. {X25519PublicKey} public key

Returns a Promise that resolves to a CryptographyKey.

crypto_box_publickey

Parameters and their respective types:

1. {CryptographyKey} (buffer must be 64 bytes long)

Returns a Promise that resolves to a X25519PublicKey.

crypto_box_secretkey

Parameters and their respective types:

1. {CryptographyKey} (buffer must be 64 bytes long)

Returns a Promise that resolves to a X25519SecretKey.

crypto_box_publickey_from_secretkey

Derive the public key from a given X25519 secret key.

Parameters and their respective types:

1. {X25519SecretKey}

Returns a Promise that resolves to a X25519PublicKey.

Example for crypto_box

const { SodiumPlus } = require('sodium-plus');
let sodium;

(async function () {
    if (!sodium) sodium = await SodiumPlus.auto();
    let aliceKeypair = await sodium.crypto_box_keypair();
        let aliceSecret = await sodium.crypto_box_secretkey(aliceKeypair);
        let alicePublic = await sodium.crypto_box_publickey(aliceKeypair);
    let bobKeypair = await sodium.crypto_box_keypair();
        let bobSecret = await sodium.crypto_box_secretkey(bobKeypair);
        let bobPublic = await sodium.crypto_box_publickey(bobKeypair);
    
    let plaintext = 'Your message goes here';
    let nonce = await sodium.randombytes_buf(24);

    let ciphertext = await sodium.crypto_box(plaintext, nonce, aliceSecret, bobPublic);    
    console.log(ciphertext);

    let decrypted = await sodium.crypto_box_open(ciphertext, nonce, bobSecret, alicePublic);
    console.log(decrypted.toString());
})();