254 lines
9.8 KiB
Rust
254 lines
9.8 KiB
Rust
use std::{convert::TryInto, fmt::Display};
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use hkdf::Hkdf;
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use sha2::Sha384;
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use hmac::{Hmac, Mac};
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use scrypt::{scrypt, Params};
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use rand::{RngCore, rngs::OsRng};
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use aes_gcm::{aead::Aead, NewAead, Nonce};
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use aes_gcm_siv::Aes256GcmSiv;
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use zeroize::Zeroize;
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pub const HASH_OUTPUT_LEN: usize = 48; //SHA384
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const KEY_LEN: usize = 16;
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pub const IV_LEN: usize = 12;
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pub const AES_TAG_LEN: usize = 16;
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pub const SALT_LEN: usize = 32;
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const PASSWORD_HASH_LEN: usize = 32;
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pub const MASTER_KEY_LEN: usize = 32;
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fn hkdf_expand_label(key: &[u8], label: &str, context: Option<&[u8]>, okm: &mut [u8]) {
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let hkdf = Hkdf::<Sha384>::from_prk(key).unwrap();
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//can't set info conditionnally because of different array size
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match context {
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Some(context) => {
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let info = [&(label.len() as u32).to_be_bytes(), label.as_bytes(), &(context.len() as u32).to_be_bytes(), context];
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hkdf.expand_multi_info(&info, okm).unwrap();
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}
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None => {
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let info = [&(label.len() as u32).to_be_bytes(), label.as_bytes()];
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hkdf.expand_multi_info(&info, okm).unwrap();
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}
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};
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}
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fn get_labels(handshake: bool, i_am_bob: bool) -> (String, String) {
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let mut label = if handshake {
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"handshake"
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} else {
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"application"
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}.to_owned();
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label += "_i_am_";
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let local_label = label.clone() + if i_am_bob {
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"bob"
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} else {
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"alice"
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};
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let peer_label = label + if i_am_bob {
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"alice"
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} else {
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"bob"
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};
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(local_label, peer_label)
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}
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pub struct HandshakeKeys {
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pub local_key: [u8; KEY_LEN],
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pub local_iv: [u8; IV_LEN],
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pub local_handshake_traffic_secret: [u8; HASH_OUTPUT_LEN],
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pub peer_key: [u8; KEY_LEN],
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pub peer_iv: [u8; IV_LEN],
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pub peer_handshake_traffic_secret: [u8; HASH_OUTPUT_LEN],
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pub handshake_secret: [u8; HASH_OUTPUT_LEN],
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}
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impl HandshakeKeys {
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pub fn derive_keys(shared_secret: [u8; 32], handshake_hash: [u8; HASH_OUTPUT_LEN], i_am_bob: bool) -> HandshakeKeys {
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let (handshake_secret, _) = Hkdf::<Sha384>::extract(None, &shared_secret);
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let (local_label, peer_label) = get_labels(true, i_am_bob);
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let mut local_handshake_traffic_secret = [0; HASH_OUTPUT_LEN];
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hkdf_expand_label(handshake_secret.as_slice(), &local_label, Some(&handshake_hash), &mut local_handshake_traffic_secret);
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let mut peer_handshake_traffic_secret = [0; HASH_OUTPUT_LEN];
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hkdf_expand_label(handshake_secret.as_slice(), &peer_label, Some(&handshake_hash), &mut peer_handshake_traffic_secret);
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let mut local_handshake_key = [0; KEY_LEN];
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hkdf_expand_label(&local_handshake_traffic_secret, "key", None, &mut local_handshake_key);
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let mut local_handshake_iv = [0; IV_LEN];
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hkdf_expand_label(&local_handshake_traffic_secret, "iv", None, &mut local_handshake_iv);
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let mut peer_handshake_key = [0; KEY_LEN];
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hkdf_expand_label(&peer_handshake_traffic_secret, "key", None, &mut peer_handshake_key);
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let mut peer_handshake_iv = [0; IV_LEN];
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hkdf_expand_label(&peer_handshake_traffic_secret,"iv", None, &mut peer_handshake_iv);
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HandshakeKeys {
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local_key: local_handshake_key,
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local_iv: local_handshake_iv,
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local_handshake_traffic_secret,
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peer_key: peer_handshake_key,
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peer_iv: peer_handshake_iv,
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peer_handshake_traffic_secret,
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handshake_secret: handshake_secret.as_slice().try_into().unwrap(),
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}
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}
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}
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pub struct ApplicationKeys {
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pub local_key: [u8; KEY_LEN],
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pub local_iv: [u8; IV_LEN],
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pub peer_key: [u8; KEY_LEN],
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pub peer_iv: [u8; IV_LEN],
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}
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impl ApplicationKeys {
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pub fn derive_keys(handshake_secret: [u8; HASH_OUTPUT_LEN], handshake_hash: [u8; HASH_OUTPUT_LEN], i_am_bob: bool) -> ApplicationKeys {
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let mut derived_secret = [0; HASH_OUTPUT_LEN];
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hkdf_expand_label(&handshake_secret, "derived", None, &mut derived_secret);
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let (master_secret, _) = Hkdf::<Sha384>::extract(Some(&derived_secret), b"");
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let (local_label, peer_label) = get_labels(false, i_am_bob);
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let mut local_application_traffic_secret = [0; HASH_OUTPUT_LEN];
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hkdf_expand_label(&master_secret, &local_label, Some(&handshake_hash), &mut local_application_traffic_secret);
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let mut peer_application_traffic_secret = [0; HASH_OUTPUT_LEN];
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hkdf_expand_label(&master_secret, &peer_label, Some(&handshake_hash), &mut peer_application_traffic_secret);
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let mut local_application_key = [0; KEY_LEN];
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hkdf_expand_label(&local_application_traffic_secret, "key", None, &mut local_application_key);
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let mut local_application_iv = [0; IV_LEN];
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hkdf_expand_label(&local_application_traffic_secret, "iv", None, &mut local_application_iv);
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let mut peer_application_key = [0; KEY_LEN];
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hkdf_expand_label(&peer_application_traffic_secret, "key", None, &mut peer_application_key);
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let mut peer_application_iv = [0; IV_LEN];
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hkdf_expand_label(&peer_application_traffic_secret,"iv", None, &mut peer_application_iv);
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ApplicationKeys {
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local_key: local_application_key,
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local_iv: local_application_iv,
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peer_key: peer_application_key,
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peer_iv: peer_application_iv,
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}
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}
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}
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pub fn compute_handshake_finished(local_handshake_traffic_secret: [u8; HASH_OUTPUT_LEN], handshake_hash: [u8; HASH_OUTPUT_LEN]) -> [u8; HASH_OUTPUT_LEN] {
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let mut finished_key = [0; HASH_OUTPUT_LEN];
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hkdf_expand_label(&local_handshake_traffic_secret, "finished", None, &mut finished_key);
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let mut hmac = Hmac::<Sha384>::new_from_slice(&finished_key).unwrap();
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hmac.update(&handshake_hash);
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hmac.finalize().into_bytes().as_slice().try_into().unwrap()
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}
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pub fn verify_handshake_finished(peer_handshake_finished: [u8; HASH_OUTPUT_LEN], peer_handshake_traffic_secret: [u8; HASH_OUTPUT_LEN], handshake_hash: [u8; HASH_OUTPUT_LEN]) -> bool {
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let mut peer_finished_key = [0; HASH_OUTPUT_LEN];
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hkdf_expand_label(&peer_handshake_traffic_secret, "finished", None, &mut peer_finished_key);
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let mut hmac = Hmac::<Sha384>::new_from_slice(&peer_finished_key).unwrap();
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hmac.update(&handshake_hash);
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hmac.verify_slice(&peer_handshake_finished).is_ok()
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}
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pub fn generate_fingerprint(public_key: &[u8]) -> String {
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let mut raw_fingerprint = [0; 16];
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Hkdf::<Sha384>::new(None, public_key).expand(&[], &mut raw_fingerprint).unwrap();
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hex::encode(raw_fingerprint).to_uppercase()
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}
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pub fn generate_master_key() -> [u8; MASTER_KEY_LEN] {
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let mut master_key = [0; MASTER_KEY_LEN];
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OsRng.fill_bytes(&mut master_key);
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master_key
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}
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pub fn encrypt_data(data: &[u8], master_key: &[u8]) -> Result<Vec<u8>, CryptoError> {
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if master_key.len() != MASTER_KEY_LEN {
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return Err(CryptoError::InvalidLength);
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}
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let cipher = Aes256GcmSiv::new_from_slice(master_key).unwrap();
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let mut iv = [0; IV_LEN];
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OsRng.fill_bytes(&mut iv); //use it for IV for now
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let mut cipher_text = iv.to_vec();
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cipher_text.extend(cipher.encrypt(Nonce::from_slice(&iv), data).unwrap());
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Ok(cipher_text)
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}
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#[derive(Debug, PartialEq, Eq)]
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pub enum CryptoError {
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DecryptionFailed,
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InvalidLength
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}
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impl Display for CryptoError {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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f.write_str(match self {
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CryptoError::DecryptionFailed => "Decryption failed",
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CryptoError::InvalidLength => "Invalid length",
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})
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}
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}
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pub fn decrypt_data(data: &[u8], master_key: &[u8]) -> Result<Vec<u8>, CryptoError> {
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if data.len() <= IV_LEN || master_key.len() != MASTER_KEY_LEN {
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return Err(CryptoError::InvalidLength);
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}
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let cipher = Aes256GcmSiv::new_from_slice(master_key).unwrap();
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match cipher.decrypt(Nonce::from_slice(&data[..IV_LEN]), &data[IV_LEN..]) {
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Ok(data) => {
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Ok(data)
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},
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Err(_) => Err(CryptoError::DecryptionFailed)
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}
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}
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fn scrypt_params() -> Params {
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Params::new(16, 8, 1).unwrap()
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}
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pub fn encrypt_master_key(mut master_key: [u8; MASTER_KEY_LEN], password: &[u8]) -> (
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[u8; SALT_LEN], //salt
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[u8; IV_LEN+MASTER_KEY_LEN+AES_TAG_LEN] //encrypted masterkey with IV
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) {
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let mut salt = [0; SALT_LEN];
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OsRng.fill_bytes(&mut salt);
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let mut password_hash = [0; PASSWORD_HASH_LEN];
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scrypt(password, &salt, &scrypt_params(), &mut password_hash).unwrap();
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let mut output = [0; IV_LEN+MASTER_KEY_LEN+AES_TAG_LEN];
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OsRng.fill_bytes(&mut output); //use it for IV for now
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let cipher = Aes256GcmSiv::new_from_slice(&password_hash).unwrap();
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let encrypted_master_key = cipher.encrypt(Nonce::from_slice(&output[..IV_LEN]), master_key.as_ref()).unwrap();
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master_key.zeroize();
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password_hash.zeroize();
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encrypted_master_key.into_iter().enumerate().for_each(|i|{
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output[IV_LEN+i.0] = i.1; //append encrypted master key to IV
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});
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(salt, output)
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}
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pub fn decrypt_master_key(encrypted_master_key: &[u8], password: &[u8], salt: &[u8]) -> Result<[u8; MASTER_KEY_LEN], CryptoError> {
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if encrypted_master_key.len() != IV_LEN+MASTER_KEY_LEN+AES_TAG_LEN || salt.len() != SALT_LEN {
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return Err(CryptoError::InvalidLength);
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}
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let mut password_hash = [0; PASSWORD_HASH_LEN];
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scrypt(password, salt, &scrypt_params(), &mut password_hash).unwrap();
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let cipher = Aes256GcmSiv::new_from_slice(&password_hash).unwrap();
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let result = match cipher.decrypt(Nonce::from_slice(&encrypted_master_key[..IV_LEN]), &encrypted_master_key[IV_LEN..]) {
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Ok(master_key) => {
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if master_key.len() == MASTER_KEY_LEN {
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Ok(master_key.try_into().unwrap())
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} else {
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return Err(CryptoError::InvalidLength)
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}
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},
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Err(_) => Err(CryptoError::DecryptionFailed)
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};
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password_hash.zeroize();
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result
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}
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