1 files changed, 142 insertions, 0 deletions
diff --git a/crates/daemon/src/aclient/encryption.rs b/crates/daemon/src/aclient/encryption.rs
new file mode 100644
index 00000000..220ac74e
--- /dev/null
+++ b/crates/daemon/src/aclient/encryption.rs
@@ -0,0 +1,142 @@
+// 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::Write;
+
+use base64::prelude::{BASE64_STANDARD, Engine};
+pub(crate) use crypto_secretbox::Key;
+use crypto_secretbox::{KeyInit, XSalsa20Poly1305, aead::OsRng};
+use eyre::{Context, Result, bail, ensure, eyre};
+use fs_err as fs;
+use rmp::Marker;
+
+use crate::aclient::settings::Settings;
+
+pub(crate) fn generate_encoded_key() -> Result<(Key, String)> {
+    let key = XSalsa20Poly1305::generate_key(&mut OsRng);
+    let encoded = encode_key(&key)?;
+
+    Ok((key, encoded))
+}
+
+pub(crate) fn new_key(settings: &Settings) -> Result<Key> {
+    if settings.sync.encryption_key()?.is_some() {
+        bail!("key already exists! cannot overwrite");
+    } else if let Some(path) = settings.sync.encryption_key_path.as_ref() {
+        let (key, encoded) = generate_encoded_key()?;
+
+        let mut file = fs::File::create(path)?;
+        file.write_all(encoded.as_bytes())?;
+
+        Ok(key)
+    } else {
+        bail!("No key-path set, cannot generate key")
+    }
+}
+
+// Loads the secret key, will create + save if it doesn't exist
+pub(crate) fn load_key(settings: &Settings) -> Result<Key> {
+    if let Some(key) = settings.sync.encryption_key()? {
+        Ok(key)
+    } else {
+        Ok(new_key(settings)?)
+    }
+}
+
+pub(crate) 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, u64::from(*b))
+            .wrap_err("could not encode key to message pack")?;
+    }
+    let buf = BASE64_STANDARD.encode(buf);
+
+    Ok(buf)
+}
+
+pub(crate) fn decode_key(key: &str) -> 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
+    if let Ok(key) = <[u8; 32]>::try_from(&*buf) {
+        Ok(key.into())
+    } else {
+        let mut bytes = 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 = decode::read_int(&mut bytes).map_err(|err| eyre!("{err:?}"))?;
+                }
+                Ok(key)
+            }
+            _ => bail!("could not decode encryption key"),
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    #[test]
+    fn key_encodings() {
+        use super::{Key, decode_key, encode_key};
+
+        // a history of our key encodings.
+        // v11.0.0 xCAbWypb0msJ2Kq+8j4GVEWUlDX7deKnrTRSIopuqXxc5Q==
+        // v12.0.0 xCAbWypb0msJ2Kq+8j4GVEWUlDX7deKnrTRSIopuqXxc5Q==
+        // v13.0.0 xCAbWypb0msJ2Kq+8j4GVEWUlDX7deKnrTRSIopuqXxc5Q==
+        // v13.0.1 xCAbWypb0msJ2Kq+8j4GVEWUlDX7deKnrTRSIopuqXxc5Q==
+        // v14.0.0 xCAbWypb0msJ2Kq+8j4GVEWUlDX7deKnrTRSIopuqXxc5Q==
+        // v14.0.1 xCAbWypb0msJ2Kq+8j4GVEWUlDX7deKnrTRSIopuqXxc5Q==
+        // c7d89c1 3AAgG1sqW8zSawnM2MyqzL7M8j4GVEXMlMyUNcz7dczizKfMrTRSIsyKbsypfFzM5Q== (https://github.com/ellie/atuin/pull/805)
+        // b53ca35 3AAgG1sqW8zSawnM2MyqzL7M8j4GVEXMlMyUNcz7dczizKfMrTRSIsyKbsypfFzM5Q== (https://github.com/ellie/atuin/pull/974)
+        // v15.0.0 3AAgG1sqW8zSawnM2MyqzL7M8j4GVEXMlMyUNcz7dczizKfMrTRSIsyKbsypfFzM5Q==
+        // b8b57c8 xCAbWypb0msJ2Kq+8j4GVEWUlDX7deKnrTRSIopuqXxc5Q==                     (https://github.com/ellie/atuin/pull/1057)
+        // 8c94d79 3AAgG1sqW8zSawnM2MyqzL7M8j4GVEXMlMyUNcz7dczizKfMrTRSIsyKbsypfFzM5Q== (https://github.com/ellie/atuin/pull/1089)
+
+        let key = Key::from([
+            27, 91, 42, 91, 210, 107, 9, 216, 170, 190, 242, 62, 6, 84, 69, 148, 148, 53, 251, 117,
+            226, 167, 173, 52, 82, 34, 138, 110, 169, 124, 92, 229,
+        ]);
+
+        assert_eq!(
+            encode_key(&key).unwrap(),
+            "3AAgG1sqW8zSawnM2MyqzL7M8j4GVEXMlMyUNcz7dczizKfMrTRSIsyKbsypfFzM5Q=="
+        );
+
+        // key encodings we have to support
+        let valid_encodings = [
+            "xCAbWypb0msJ2Kq+8j4GVEWUlDX7deKnrTRSIopuqXxc5Q==",
+            "3AAgG1sqW8zSawnM2MyqzL7M8j4GVEXMlMyUNcz7dczizKfMrTRSIsyKbsypfFzM5Q==",
+        ];
+
+        for k in valid_encodings {
+            assert_eq!(decode_key(k).expect(k), key);
+        }
+    }
+}