core/library/sodium-plus/docs/SodiumPlus/stream-ciphers.md

Stream Ciphers

See also: Libsodium's documentation on its stream cipher features.

crypto_stream

Obtain an arbitrary-length stream of pseudorandom bytes from a given nonce and key.

Parameters and their respective types:

1. {number} length
2. {Buffer} nonce (must be 24 bytes)
3. {CryptographyKey} key

Returns a Promise that resolves to a Buffer containing the pseudorandom bytes.

crypto_stream_xor

Encrypt a message with a given nonce and key.

Danger: Unauthenticated encryption! Without a subsequent message authentication strategy, this is vulnerable to chosen-ciphertext attacks. Proceed with caution!

Parameters and their respective types:

1. {string|Buffer} plaintext
2. {Buffer} nonce (must be 24 bytes)
3. {CryptographyKey} key

Returns a Promise that resolves to a Buffer containing the encrypted bytes.

Example for crypto_stream

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

let sodium;
(async function () {
    if (!sodium) sodium = await SodiumPlus.auto();
    let key = await sodium.crypto_stream_keygen();
    let iv = await sodium.randombytes_buf(24);
    let output = await sodium.crypto_stream(64, iv, key);
    console.log(output);

    iv = await sodium.randombytes_buf(24);
    let plaintext = 'This is a secret message';
    let ciphertext = await sodium.crypto_stream_xor(plaintext, iv, key);
    let decrypted =  await sodium.crypto_stream_xor(ciphertext, iv, key);
    console.log(decrypted.toString());
})();