The php Function sodium_bin2hex

The php function sodium_bin2hex converts binary data into hexadecimal. It can also be used to generate a sequence of random numbers for use as a seed for an RNG. This is useful for encrypting and decrypting messages.

Libsodium is a cryptography library for PHP that provides a range of functionality, from symmetric encryption to key management and authentication. It is similar in functionality to the mcrypt and OpenSSL extensions but offers more advanced features, particularly around the authentication of asymmetric encryption/decryption messages.

The functions in libsodium include a password hashing algorithm that is resistant to side-channel attacks, which are often used to steal sensitive information. This is a major improvement over the older scrypt algorithm which was susceptible to these attacks.

Other key functions in libsodium include sodium_base642bin, which decodes a base64-encoded string into raw binary, and sodium_bin2hex, which converts a binary string to hexadecimal data. Libsodium provides a number of functions for generating random numbers, including sodium_pwhash(password) which derives a strong secret key from a user's password, and sodium_crypto_kx_seed_keypair() which derives a deterministic public/private key pair from a known secret salt.

Lastly, the libsodium library includes sodium_crypto_aead_chacha20poly1305_ietf_keygen() which generates a random ChaCha20-Poly1305 (IETF) key. For those looking for a more generic random number generator, the library has the sodium_rand() function. There is also a timing-safe variant of the native strcmp() function, the sodium_increment(), which can be useful for comparing nonces to prevent replay attacks.