2 files changed, 67 insertions, 6 deletions

diff --git a/src/command/client/sync.rs b/src/command/client/sync.rs
index b97a2240..f71bcc99 100644
--- a/src/command/client/sync.rs
+++ b/src/command/client/sync.rs
@@ -27,7 +27,11 @@ pub enum Cmd {
     Register(register::Cmd),
 
     /// Print the encryption key for transfer to another machine
-    Key,
+    Key {
+        /// Switch to base64 output of the key
+        #[arg(long)]
+        base64: bool,
+    },
 }
 
 impl Cmd {
@@ -37,11 +41,18 @@ impl Cmd {
             Self::Login(l) => l.run(&settings).await,
             Self::Logout => logout::run(),
             Self::Register(r) => r.run(&settings).await,
-            Self::Key => {
+            Self::Key { base64 } => {
                 use atuin_client::encryption::{encode_key, load_key};
                 let key = load_key(&settings).wrap_err("could not load encryption key")?;
-                let encode = encode_key(key).wrap_err("could not encode encryption key")?;
-                println!("{encode}");
+
+                if base64 {
+                    let encode = encode_key(key).wrap_err("could not encode encryption key")?;
+                    println!("{encode}");
+                } else {
+                    let mnemonic = bip39::Mnemonic::from_entropy(&key.0, bip39::Language::English)
+                        .map_err(|_| eyre::eyre!("invalid key"))?;
+                    println!("{mnemonic}");
+                }
                 Ok(())
             }
         }
diff --git a/src/command/client/sync/login.rs b/src/command/client/sync/login.rs
index 038e822b..bd3a8029 100644
--- a/src/command/client/sync/login.rs
+++ b/src/command/client/sync/login.rs
@@ -1,10 +1,14 @@
 use std::io;
 
 use clap::Parser;
-use eyre::Result;
+use eyre::{bail, ContextCompat, Result};
 use tokio::{fs::File, io::AsyncWriteExt};
 
-use atuin_client::{api_client, settings::Settings};
+use atuin_client::{
+    api_client,
+    encryption::{encode_key, Key},
+    settings::Settings,
+};
 use atuin_common::api::LoginRequest;
 use rpassword::prompt_password;
 
@@ -54,6 +58,31 @@ impl Cmd {
 
         let key_path = settings.key_path.as_str();
         let mut file = File::create(key_path).await?;
+
+        // try parse the key as a mnemonic...
+        let key = match bip39::Mnemonic::from_phrase(&key, bip39::Language::English) {
+            Ok(mnemonic) => encode_key(
+                Key::from_slice(mnemonic.entropy()).context("key was not the correct length")?,
+            )?,
+            Err(err) => {
+                if let Some(err) = err.downcast_ref::<bip39::ErrorKind>() {
+                    match err {
+                        // assume they copied in the base64 key
+                        bip39::ErrorKind::InvalidWord => key,
+                        bip39::ErrorKind::InvalidChecksum => bail!("key mnemonic was not valid"),
+                        bip39::ErrorKind::InvalidKeysize(_)
+                        | bip39::ErrorKind::InvalidWordLength(_)
+                        | bip39::ErrorKind::InvalidEntropyLength(_, _) => {
+                            bail!("key was not the correct length")
+                        }
+                    }
+                } else {
+                    // unknown error. assume they copied the base64 key
+                    key
+                }
+            }
+        };
+
         file.write_all(key.as_bytes()).await?;
 
         println!("Logged in!");
@@ -75,3 +104,24 @@ fn read_user_input(name: &'static str) -> String {
     eprint!("Please enter {name}: ");
     get_input().expect("Failed to read from input")
 }
+
+#[cfg(test)]
+mod tests {
+    use atuin_client::encryption::Key;
+
+    #[test]
+    fn mnemonic_round_trip() {
+        let key = Key {
+            0: [
+                3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5, 8, 9, 7, 9, 3, 2, 3, 8, 4, 6, 2, 6, 4, 3, 3, 8, 3,
+                2, 7, 9, 5,
+            ],
+        };
+        let phrase = bip39::Mnemonic::from_entropy(&key.0, bip39::Language::English)
+            .unwrap()
+            .into_phrase();
+        let mnemonic = bip39::Mnemonic::from_phrase(&phrase, bip39::Language::English).unwrap();
+        assert_eq!(mnemonic.entropy(), &key.0);
+        assert_eq!(phrase, "adapt amused able anxiety mother adapt beef gaze amount else seat alcohol cage lottery avoid scare alcohol cactus school avoid coral adjust catch pink");
+    }
+}