Crate double_ratchet_2[−][src]
Expand description
Implementation of the double ratchet system/encryption as specified by Signal.
The implementation follows the cryptographic recommendations provided by Signal. The AEAD Algorithm uses a constant Nonce. This might be changed in the future.
Example Usage:
Standard:
use double_ratchet_2::ratchet::Ratchet; let sk = [1; 32]; // Initial Key created by a symmetric key agreement protocol let (mut bob_ratchet, public_key) = Ratchet::init_bob(sk); // Creating Bobs Ratchet (returns Bobs PublicKey) let mut alice_ratchet = Ratchet::init_alice(sk, public_key); // Creating Alice Ratchet with Bobs PublicKey let data = b"Hello World".to_vec(); // Data to be encrypted let ad = b"Associated Data"; // Associated Data let (header, encrypted, nonce) = alice_ratchet.ratchet_encrypt(&data, ad); // Encrypting message with Alice Ratchet (Alice always needs to send the first message) let decrypted = bob_ratchet.ratchet_decrypt(&header, &encrypted, &nonce, ad); // Decrypt message with Bobs Ratchet assert_eq!(data, decrypted)
With lost message:
let sk = [1; 32]; // Initial Key created by a symmetric key agreement protocol let (mut bob_ratchet, public_key) = Ratchet::init_bob(sk); // Creating Bobs Ratchet (returns Bobs PublicKey) let mut alice_ratchet = Ratchet::init_alice(sk, public_key); // Creating Alice Ratchet with Bobs PublicKey let data = b"Hello World".to_vec(); // Data to be encrypted let ad = b"Associated Data"; // Associated Data let (header1, encrypted1, nonce1) = alice_ratchet.ratchet_encrypt(&data, ad); // Lost message let (header2, encrypted2, nonce2) = alice_ratchet.ratchet_encrypt(&data, ad); // Successful message let decrypted2 = bob_ratchet.ratchet_decrypt(&header2, &encrypted2, &nonce2, ad); // Decrypting second message first let decrypted1 = bob_ratchet.ratchet_decrypt(&header1, &encrypted1, &nonce1, ad); // Decrypting latter message let comp = decrypted1 == data && decrypted2 == data; assert!(comp);
Encryption before recieving inital message
ⓘ
use double_ratchet_2::ratchet::Ratchet; let sk = [1; 32]; let ad = b"Associated Data"; let (mut bob_ratchet, _) = Ratchet::init_bob(sk); let data = b"Hello World".to_vec(); let (_, _, _) = bob_ratchet.ratchet_encrypt(&data, ad);
Encryption after recieving initial message
However bob can (of course) also encrypt messages. This is possible, after decrypting the first message from alice.
use double_ratchet_2::ratchet::Ratchet; let sk = [1; 32]; let (mut bob_ratchet, public_key) = Ratchet::init_bob(sk); let mut alice_ratchet = Ratchet::init_alice(sk, public_key); let data = b"Hello World".to_vec(); let ad = b"Associated Data"; let (header1, encrypted1, nonce1) = alice_ratchet.ratchet_encrypt(&data, ad); let _decrypted1 = bob_ratchet.ratchet_decrypt(&header1, &encrypted1, &nonce1, ad); let (header2, encrypted2, nonce2) = bob_ratchet.ratchet_encrypt(&data, ad); let decrypted2 = alice_ratchet.ratchet_decrypt(&header2, &encrypted2, &nonce2, ad); assert_eq!(data, decrypted2);
Constructing and Deconstructing Headers
let header_bytes: Vec<u8> = header.clone().into(); let header_const = Header::from(header_bytes); assert_eq!(header, header_const);
Example Ratchet with encrypted headers
use double_ratchet_2::ratchet::RatchetEncHeader; let sk = [0; 32]; let shared_hka = [1; 32]; let shared_nhkb = [2; 32]; let (mut bob_ratchet, public_key) = RatchetEncHeader::init_bob(sk, shared_hka, shared_nhkb); let mut alice_ratchet = RatchetEncHeader::init_alice(sk, public_key, shared_hka, shared_nhkb); let data = b"Hello World".to_vec(); let ad = b"Associated Data"; let (header, encrypted, nonce) = alice_ratchet.ratchet_encrypt(&data, ad); let decrypted = bob_ratchet.ratchet_decrypt(&header, &encrypted, &nonce, ad); assert_eq!(data, decrypted)
Features
Currently the crate only supports one feature: ring. If feature is enabled the crate switches to ring-compat and uses ring as backend for Sha512 Hashing. May result in slightly better performance.
TODO:
- Standard Double Ratchet
- Double Ratchet with encrypted headers
Modules
header | Message Header |
ratchet | Encryption with encrypted Headers |
Structs
PublicKey | A Diffie-Hellman public key, corresponding to an |