module Crypto

Cryptography: require "crypto". RSA keys (PEM and DER, PKCS#8, PKCS#1 and SPKI) and signatures (PKCS#1 v1.5 and PSS), as HTTP Signatures, JWT RS256 and webhook signatures need; AES-GCM, to encrypt a secret at rest or seal a cookie; argon2id (Crypto::Argon2), to store passwords; and Crypto.random_bytes, for keys and nonces.

require "crypto"
key = Crypto::RSA::PrivateKey.from_pem(File.read("std/test/fixtures/crypto/rsa2048_pkcs8.pem"))
sig = key.sign("hello", :sha256)
key.public_key.verify("hello", sig, :sha256)   # => true
key.public_key.verify("hullo", sig, :sha256)   # => false

Keys are data values holding their DER, so they are immutable and Shareable, and two readings of one key are ==; their inspect and to_s never show the key. The runtime keeps the keys it parsed (by contents), so signing again with one key does not parse it again. Keys of 1024 to 8192 bits are read (generate makes 2048 to 4096). There is no RSA encryption, no encrypted PEM, no EC or Ed25519 key, no other cipher mode (CBC, CTR), and no key derivation but Digest::PBKDF2 (argon2id makes password hashes, not keys) yet.

<std:crypto>:23

Classes and modules

• Crypto::AES AES, in its authenticated mode GCM.
• Crypto::Argon2 argon2id password hashes (RFC 9106), through the RustCrypto argon2 crate: what a server stores for a password, as a PHC string such as $argon2id$v=19$m=19456,t=2,p=1$<salt>$<hash> (the salt and the 32-byte hash in unpadded Base64), which names its parameters, so that stored hashes stay readable when the parameters change.
• Crypto::AuthenticationError Data that did not authenticate: the key, the nonce or the associated data is not the one it was sealed with, or the data was changed. The message never includes the data.
• Crypto::Error A key that does not parse, is of another kind, or is too small; a PEM text that is not one key.
• Crypto::RSA RSA keys and signatures, through the RustCrypto rsa crate. A hash is named by a symbol: :sha256, :sha384 or :sha512 (ArgumentError otherwise).

Class methods

Crypto.random_bytes(16).size                               # => 16
Crypto.random_bytes(16) == Crypto.random_bytes(16)         # => false