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|
// The general idea is that we NEVER send cleartext history to the server
// This way the odds of anything private ending up where it should not are
// very low
// The server authenticates via the usual username and password. This has
// nothing to do with the encryption, and is purely authentication! The client
// generates its own secret key, and encrypts all shell history with libsodium's
// secretbox. The data is then sent to the server, where it is stored. All
// clients must share the secret in order to be able to sync, as it is needed
// to decrypt
use std::{io::prelude::*, path::PathBuf};
use base64::prelude::{Engine, BASE64_STANDARD};
pub use crypto_secretbox::Key;
use crypto_secretbox::{
aead::{Nonce, OsRng},
AeadCore, AeadInPlace, KeyInit, XSalsa20Poly1305,
};
use eyre::{bail, ensure, eyre, Context, Result};
use fs_err as fs;
use rmp::{decode::Bytes, Marker};
use serde::{Deserialize, Serialize};
use time::{format_description::well_known::Rfc3339, macros::format_description, OffsetDateTime};
use crate::{history::History, settings::Settings};
#[derive(Debug, Serialize, Deserialize)]
pub struct EncryptedHistory {
pub ciphertext: Vec<u8>,
pub nonce: Nonce<XSalsa20Poly1305>,
}
pub fn generate_encoded_key() -> Result<(Key, String)> {
let key = XSalsa20Poly1305::generate_key(&mut OsRng);
let encoded = encode_key(&key)?;
Ok((key, encoded))
}
pub fn new_key(settings: &Settings) -> Result<Key> {
let path = settings.key_path.as_str();
let path = PathBuf::from(path);
if path.exists() {
bail!("key already exists! cannot overwrite");
}
let (key, encoded) = generate_encoded_key()?;
let mut file = fs::File::create(path)?;
file.write_all(encoded.as_bytes())?;
Ok(key)
}
// Loads the secret key, will create + save if it doesn't exist
pub fn load_key(settings: &Settings) -> Result<Key> {
let path = settings.key_path.as_str();
let key = if PathBuf::from(path).exists() {
let key = fs_err::read_to_string(path)?;
decode_key(key)?
} else {
new_key(settings)?
};
Ok(key)
}
pub fn encode_key(key: &Key) -> Result<String> {
let mut buf = vec![];
rmp::encode::write_array_len(&mut buf, key.len() as u32)
.wrap_err("could not encode key to message pack")?;
for b in key {
rmp::encode::write_uint(&mut buf, *b as u64)
.wrap_err("could not encode key to message pack")?;
}
let buf = BASE64_STANDARD.encode(buf);
Ok(buf)
}
pub fn decode_key(key: String) -> Result<Key> {
use rmp::decode;
let buf = BASE64_STANDARD
.decode(key.trim_end())
.wrap_err("encryption key is not a valid base64 encoding")?;
// old code wrote the key as a fixed length array of 32 bytes
// new code writes the key with a length prefix
match <[u8; 32]>::try_from(&*buf) {
Ok(key) => Ok(key.into()),
Err(_) => {
let mut bytes = rmp::decode::Bytes::new(&buf);
match Marker::from_u8(buf[0]) {
Marker::Bin8 => {
let len = decode::read_bin_len(&mut bytes).map_err(|err| eyre!("{err:?}"))?;
ensure!(len == 32, "encryption key is not the correct size");
let key = <[u8; 32]>::try_from(bytes.remaining_slice())
.context("could not decode encryption key")?;
Ok(key.into())
}
Marker::Array16 => {
let len = decode::read_array_len(&mut bytes).map_err(|err| eyre!("{err:?}"))?;
ensure!(len == 32, "encryption key is not the correct size");
let mut key = Key::default();
for i in &mut key {
*i = rmp::decode::read_int(&mut bytes).map_err(|err| eyre!("{err:?}"))?;
}
Ok(key)
}
_ => bail!("could not decode encryption key"),
}
}
}
}
pub fn encrypt(history: &History, key: &Key) -> Result<EncryptedHistory> {
// serialize with msgpack
let mut buf = encode(history)?;
let nonce = XSalsa20Poly1305::generate_nonce(&mut OsRng);
XSalsa20Poly1305::new(key)
.encrypt_in_place(&nonce, &[], &mut buf)
.map_err(|_| eyre!("could not encrypt"))?;
Ok(EncryptedHistory {
ciphertext: buf,
nonce,
})
}
pub fn decrypt(mut encrypted_history: EncryptedHistory, key: &Key) -> Result<History> {
XSalsa20Poly1305::new(key)
.decrypt_in_place(
&encrypted_history.nonce,
&[],
&mut encrypted_history.ciphertext,
)
.map_err(|_| eyre!("could not encrypt"))?;
let plaintext = encrypted_history.ciphertext;
let history = decode(&plaintext)?;
Ok(history)
}
fn format_rfc3339(ts: OffsetDateTime) -> Result<String> {
// horrible hack. chrono AutoSI limits to 0, 3, 6, or 9 decimal places for nanoseconds.
// time does not have this functionality.
static PARTIAL_RFC3339_0: &[time::format_description::FormatItem<'static>] =
format_description!("[year]-[month]-[day]T[hour]:[minute]:[second]Z");
static PARTIAL_RFC3339_3: &[time::format_description::FormatItem<'static>] =
format_description!("[year]-[month]-[day]T[hour]:[minute]:[second].[subsecond digits:3]Z");
static PARTIAL_RFC3339_6: &[time::format_description::FormatItem<'static>] =
format_description!("[year]-[month]-[day]T[hour]:[minute]:[second].[subsecond digits:6]Z");
static PARTIAL_RFC3339_9: &[time::format_description::FormatItem<'static>] =
format_description!("[year]-[month]-[day]T[hour]:[minute]:[second].[subsecond digits:9]Z");
let fmt = match ts.nanosecond() {
0 => PARTIAL_RFC3339_0,
ns if ns % 1_000_000 == 0 => PARTIAL_RFC3339_3,
ns if ns % 1_000 == 0 => PARTIAL_RFC3339_6,
_ => PARTIAL_RFC3339_9,
};
Ok(ts.format(fmt)?)
}
fn encode(h: &History) -> Result<Vec<u8>> {
use rmp::encode;
let mut output = vec![];
// INFO: ensure this is updated when adding new fields
encode::write_array_len(&mut output, 9)?;
encode::write_str(&mut output, &h.id.0)?;
encode::write_str(&mut output
|