Add recovery phrase for password recovery

Related to #249

https://github.com/radumarias/rencfs/issues/249

---

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examples/change_password_cli.rs

@@ -2,6 +2,7 @@ use std::io;
 use std::io::Write;
 use std::{env::args, str::FromStr};
 
+use bip39::{Language, Mnemonic, MnemonicType};
 use rpassword::read_password;
 use shush_rs::{ExposeSecret, SecretString};
 use tracing::{error, info};
@@ -46,4 +47,38 @@ async fn main() {
         Err(FsError::InvalidDataDirStructure) => error!("Invalid structure of data directory"),
         Err(err) => error!("Error: {err}"),
     }
+
+    // Generate a 24-word recovery phrase
+    let mnemonic = Mnemonic::new(MnemonicType::Words24, Language::English);
+    let phrase = mnemonic.phrase();
+    println!("Your recovery phrase is: {}", phrase);
+
+    // Use the recovery phrase to change the password
+    print!("Enter recovery phrase: ");
+    io::stdout().flush().unwrap();
+    let recovery_phrase = read_password().unwrap();
+    let mnemonic = Mnemonic::from_phrase(&recovery_phrase, Language::English).unwrap();
+    let seed = mnemonic.to_seed("");
+    let new_password = SecretString::from_str(&hex::encode(seed)).unwrap();
+    print!("Confirm new password: ");
+    io::stdout().flush().unwrap();
+    let new_password2 = SecretString::from_str(&read_password().unwrap()).unwrap();
+    if new_password.expose_secret() != new_password2.expose_secret() {
+        error!("Passwords do not match");
+        return;
+    }
+    println!("Changing password using recovery phrase...");
+    match EncryptedFs::passwd(
+        Path::new(&data_dir),
+        SecretString::from_str(&recovery_phrase).unwrap(),
+        new_password,
+        Cipher::ChaCha20Poly1305,
+    )
+    .await
+    {
+        Ok(()) => info!("Password changed successfully using recovery phrase"),
+        Err(FsError::InvalidPassword) => error!("Invalid recovery phrase"),
+        Err(FsError::InvalidDataDirStructure) => error!("Invalid structure of data directory"),
+        Err(err) => error!("Error: {err}"),
+    }
 }

src/crypto.rs

@@ -10,6 +10,7 @@ use base64::alphabet::STANDARD;
 use base64::engine::general_purpose::NO_PAD;
 use base64::engine::GeneralPurpose;
 use base64::{DecodeError, Engine};
+use bip39::{Language, Mnemonic, MnemonicType, Seed};
 use hex::FromHexError;
 use num_format::{Locale, ToFormattedString};
 use rand_chacha::rand_core::{CryptoRng, RngCore, SeedableRng};
@@ -380,6 +381,20 @@ where
     Ok(())
 }
 
+pub fn generate_recovery_phrase(language: Language) -> Mnemonic {
+    Mnemonic::new(MnemonicType::Words24, language)
+}
+
+pub fn derive_key_from_recovery_phrase(
+    recovery_phrase: &str,
+    language: Language,
+) -> Result<SecretVec<u8>> {
+    let mnemonic = Mnemonic::from_phrase(recovery_phrase, language)
+        .map_err(|err| Error::GenericString(err.to_string()))?;
+    let seed = mnemonic.to_seed("");
+    Ok(SecretVec::new(Box::new(seed.as_bytes().to_vec())))
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -650,4 +665,19 @@ mod tests {
 
         assert!(result.is_err());
     }
+
+    #[test]
+    fn test_generate_recovery_phrase() {
+        let mnemonic = generate_recovery_phrase(Language::English);
+        let phrase = mnemonic.phrase();
+        assert_eq!(phrase.split_whitespace().count(), 24);
+    }
+
+    #[test]
+    fn test_derive_key_from_recovery_phrase() {
+        let mnemonic = generate_recovery_phrase(Language::English);
+        let phrase = mnemonic.phrase();
+        let derived_key = derive_key_from_recovery_phrase(phrase, Language::English).unwrap();
+        assert_eq!(derived_key.expose_secret().len(), 64);
+    }
 }

src/encryptedfs.rs

@@ -41,6 +41,7 @@ pub(crate) const CONTENTS_DIR: &str = "contents";
 pub(crate) const SECURITY_DIR: &str = "security";
 pub(crate) const KEY_ENC_FILENAME: &str = "key.enc";
 pub(crate) const KEY_SALT_FILENAME: &str = "key.salt";
+pub(crate) const RECOVERY_PHRASE_KEY_ENC_FILENAME: &str = "recovery_phrase_key.enc";
 
 pub(crate) const LS_DIR: &str = "ls";
 pub(crate) const HASH_DIR: &str = "hash";
@@ -2158,6 +2159,65 @@ impl EncryptedFs {
         Ok(())
     }
 
+    /// Change the password of the filesystem using the recovery phrase.
+    pub async fn passwd_with_recovery_phrase(
+        data_dir: &Path,
+        recovery_phrase: &str,
+        new_password: SecretString,
+        cipher: Cipher,
+    ) -> FsResult<()> {
+        check_structure(data_dir, false).await?;
+        // decrypt key using recovery phrase
+        let salt: Vec<u8> = bincode::deserialize_from(File::open(
+            data_dir.join(SECURITY_DIR).join(KEY_SALT_FILENAME),
+        )?)?;
+        let initial_key = crypto::derive_key_from_recovery_phrase(recovery_phrase, cipher, &salt)?;
+        let enc_file = data_dir.join(SECURITY_DIR).join(RECOVERY_PHRASE_KEY_ENC_FILENAME);
+        let reader = crypto::create_read(File::open(enc_file)?, cipher, &initial_key);
+        let key: Vec<u8> =
+            bincode::deserialize_from(reader).map_err(|_| FsError::InvalidPassword)?;
+        let key = SecretBox::new(Box::new(key));
+        // encrypt it with a new key derived from new password
+        let new_key = crypto::derive_key(&new_password, cipher, &salt)?;
+        crypto::atomic_serialize_encrypt_into(
+            &data_dir.join(SECURITY_DIR).join(KEY_ENC_FILENAME),
+            &*key.expose_secret(),
+            cipher,
+            &new_key,
+        )?;
+        Ok(())
+    }
+
+    /// Regenerate the recovery phrase for the filesystem.
+    pub async fn regenerate_recovery_phrase(
+        data_dir: &Path,
+        password: SecretString,
+        old_recovery_phrase: &str,
+        new_recovery_phrase: &str,
+        cipher: Cipher,
+    ) -> FsResult<()> {
+        check_structure(data_dir, false).await?;
+        // decrypt key using old recovery phrase
+        let salt: Vec<u8> = bincode::deserialize_from(File::open(
+            data_dir.join(SECURITY_DIR).join(KEY_SALT_FILENAME),
+        )?)?;
+        let initial_key = crypto::derive_key_from_recovery_phrase(old_recovery_phrase, cipher, &salt)?;
+        let enc_file = data_dir.join(SECURITY_DIR).join(RECOVERY_PHRASE_KEY_ENC_FILENAME);
+        let reader = crypto::create_read(File::open(enc_file)?, cipher, &initial_key);
+        let key: Vec<u8> =
+            bincode::deserialize_from(reader).map_err(|_| FsError::InvalidPassword)?;
+        let key = SecretBox::new(Box::new(key));
+        // encrypt it with a new key derived from new recovery phrase
+        let new_key = crypto::derive_key_from_recovery_phrase(new_recovery_phrase, cipher, &salt)?;
+        crypto::atomic_serialize_encrypt_into(
+            &data_dir.join(SECURITY_DIR).join(RECOVERY_PHRASE_KEY_ENC_FILENAME),
+            &*key.expose_secret(),
+            cipher,
+            &new_key,
+        )?;
+        Ok(())
+    }
+
     fn next_handle(&self) -> u64 {
         self.current_handle
             .fetch_add(1, std::sync::atomic::Ordering::SeqCst)

src/run.rs

@@ -190,6 +190,20 @@ fn get_cli_args() -> ArgMatches {
                     .value_name("DATA_DIR")
                     .help("Where to store the encrypted data"),
             )
+            .arg(
+                Arg::new("recovery-phrase")
+                    .long("recovery-phrase")
+                    .short('r')
+                    .value_name("RECOVERY_PHRASE")
+                    .help("Use the recovery phrase to change the password"),
+            )
+            .arg(
+                Arg::new("refresh-recovery-phrase")
+                    .long("refresh-recovery-phrase")
+                    .short('f')
+                    .action(ArgAction::SetTrue)
+                    .help("Regenerate the recovery phrase"),
+            )
     )
         .get_matches()
 }
@@ -224,6 +238,82 @@ async fn async_main() -> Result<()> {
 async fn run_change_password(cipher: Cipher, matches: &ArgMatches) -> Result<()> {
     let data_dir: String = matches.get_one::<String>("data-dir").unwrap().to_string();
 
+    if matches.get_flag("refresh-recovery-phrase") {
+        // read password from stdin
+        print!("Enter password: ");
+        io::stdout().flush().unwrap();
+        let password = SecretString::from_str(&read_password().unwrap()).unwrap();
+        print!("Enter old recovery phrase: ");
+        io::stdout().flush().unwrap();
+        let old_recovery_phrase = read_password().unwrap();
+        print!("Enter new recovery phrase: ");
+        io::stdout().flush().unwrap();
+        let new_recovery_phrase = read_password().unwrap();
+        println!("Regenerating recovery phrase...");
+        EncryptedFs::regenerate_recovery_phrase(
+            Path::new(&data_dir),
+            password,
+            &old_recovery_phrase,
+            &new_recovery_phrase,
+            cipher,
+        )
+        .await
+        .map_err(|err| {
+            match err {
+                FsError::InvalidPassword => {
+                    println!("Invalid password or recovery phrase");
+                }
+                FsError::InvalidDataDirStructure => {
+                    println!("Invalid structure of data directory");
+                }
+                _ => {
+                    error!(err = %err);
+                }
+            }
+            ExitStatusError::Failure(1)
+        })?;
+        println!("Recovery phrase regenerated successfully");
+        return Ok(());
+    }
+
+    if let Some(recovery_phrase) = matches.get_one::<String>("recovery-phrase") {
+        // read new password from stdin
+        print!("Enter new password: ");
+        io::stdout().flush().unwrap();
+        let new_password = SecretString::from_str(&read_password().unwrap()).unwrap();
+        print!("Confirm new password: ");
+        io::stdout().flush().unwrap();
+        let new_password2 = SecretString::from_str(&read_password().unwrap()).unwrap();
+        if new_password.expose_secret() != new_password2.expose_secret() {
+            println!("Passwords do not match");
+            return Err(ExitStatusError::Failure(1).into());
+        }
+        println!("Changing password using recovery phrase...");
+        EncryptedFs::passwd_with_recovery_phrase(
+            Path::new(&data_dir),
+            recovery_phrase,
+            new_password,
+            cipher,
+        )
+        .await
+        .map_err(|err| {
+            match err {
+                FsError::InvalidPassword => {
+                    println!("Invalid recovery phrase");
+                }
+                FsError::InvalidDataDirStructure => {
+                    println!("Invalid structure of data directory");
+                }
+                _ => {
+                    error!(err = %err);
+                }
+            }
+            ExitStatusError::Failure(1)
+        })?;
+        println!("Password changed successfully using recovery phrase");
+        return Ok(());
+    }
+
     // read password from stdin
     print!("Enter old password: ");
     io::stdout().flush().unwrap();