core/library/sodium-plus/docs/SodiumPlus/general-purpose-cryptographic-hash.md

General-purpose cryptographic hash

See also: Libsodium's documentation on its generic hashing features.

crypto_generichash

General-purpose cryptographic hash (powered by BLAKE2).

Parameters and their respective types:

1. {Buffer} message
2. {CryptographyKey|null} key (optional)
3. {number} output length (optional, defaults to 32)

Returns a Promise that resolves to a Buffer.

crypto_generichash_keygen

Returns a CryptographyKey object containing a key appropriate for the crypto_generichash API.

crypto_generichash_init

Initialize a BLAKE2 hash context for stream hashing.

Parameters and their respective types:

1. {CryptographyKey|null} key (optional)
2. {number} output length (optional, defaults to 32)

Returns a Promise that resolves to... well, that depends on your backend.

• sodium-native returns a CryptoGenericHashWrap object.
• libsodium-wrappers returns a number (a buffer's memory address)

crypto_generichash_update

Update the BLAKE2 hash state with a block of data.

Parameters and their respective types:

1. {*} hash state (see crypto_generichash_init())
2. {string|Buffer} message chunk

Returns a Promise that resolves to void. Instead, state is updated in-place.

crypto_generichash_final

Obtain the final BLAKE2 hash output.

Parameters and their respective types:

1. {*} hash state (see crypto_generichash_init())
2. {number} output length (optional, defaults to 32)

Returns a Promise that resolves to a Buffer.

Example for crypto_generichash

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

(async function () {
    if (!sodium) sodium = await SodiumPlus.auto();
    let message = 'Any message can go here';
    let hashed = await sodium.crypto_generichash(message);
    console.log(hashed.toString('hex'));

    let key = await sodium.crypto_generichash_keygen();
    let hash2 = await sodium.crypto_generichash(message, key, 64);
    let state = await sodium.crypto_generichash_init(key, 64);

    await sodium.crypto_generichash_update(state, 'Any message ');
    await sodium.crypto_generichash_update(state, 'can go here');
    let hash3 = await sodium.crypto_generichash_final(state, 64);
    if (!await sodium.sodium_memcmp(hash2, hash3)) {
        throw new Error('Implementation is broken. You should never see this.');
    }
    console.log(hash2.toString('hex'));
})();