653c6c050b
Protocol: - history.rs: derive_history_key (HKDF from seed, info="warzone-history") - encrypt_history / decrypt_history (ChaCha20-Poly1305, WZH1 magic) - 2 new tests (roundtrip + wrong seed), total 19/19 CLI: - `warzone backup [output.wzb]` — exports all sessions + pre-keys as encrypted blob (only your seed can decrypt) - `warzone restore <input.wzb>` — imports backup, merges (no overwrite) - Backup format: WZH1 magic + nonce + encrypted JSON Storage: - export_all() — dumps sessions + pre-keys as base64 JSON - import_all() — merges backup data (skip existing entries) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
59 lines
1.8 KiB
Rust
59 lines
1.8 KiB
Rust
//! Encrypted message history: backup and restore.
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//!
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//! History key derived from seed via HKDF (info="warzone-history").
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//! Format: MAGIC(4) + nonce(12) + ciphertext (ChaCha20-Poly1305).
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use crate::crypto::{aead_decrypt, aead_encrypt, hkdf_derive};
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use crate::errors::ProtocolError;
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const HISTORY_MAGIC: &[u8; 4] = b"WZH1";
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/// Derive history encryption key from seed.
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pub fn derive_history_key(seed: &[u8; 32]) -> [u8; 32] {
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let derived = hkdf_derive(seed, b"", b"warzone-history", 32);
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let mut key = [0u8; 32];
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key.copy_from_slice(&derived);
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key
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}
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/// Encrypt a history blob (JSON messages serialized to bytes).
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pub fn encrypt_history(seed: &[u8; 32], plaintext: &[u8]) -> Vec<u8> {
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let key = derive_history_key(seed);
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let encrypted = aead_encrypt(&key, plaintext, HISTORY_MAGIC);
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let mut result = Vec::with_capacity(4 + encrypted.len());
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result.extend_from_slice(HISTORY_MAGIC);
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result.extend_from_slice(&encrypted);
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result
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}
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/// Decrypt a history blob.
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pub fn decrypt_history(seed: &[u8; 32], data: &[u8]) -> Result<Vec<u8>, ProtocolError> {
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if data.len() < 4 || &data[..4] != HISTORY_MAGIC {
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return Err(ProtocolError::DecryptionFailed);
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}
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let key = derive_history_key(seed);
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aead_decrypt(&key, &data[4..], HISTORY_MAGIC)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn roundtrip() {
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let seed = [42u8; 32];
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let messages = b"[{\"from\":\"alice\",\"text\":\"hello\"}]";
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let encrypted = encrypt_history(&seed, messages);
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let decrypted = decrypt_history(&seed, &encrypted).unwrap();
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assert_eq!(decrypted, messages);
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}
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#[test]
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fn wrong_seed_fails() {
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let seed = [42u8; 32];
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let wrong = [99u8; 32];
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let encrypted = encrypt_history(&seed, b"secret");
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assert!(decrypt_history(&wrong, &encrypted).is_err());
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}
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}
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