Basic API

Signed-off-by: Lee Smet <lee.smet@hotmail.com>

vault/src/key/symmetric.rs

@@ -83,4 +83,22 @@ impl SymmetricKey {
             .decrypt(nonce, ciphertext)
             .map_err(|_| CryptoError::DecryptionFailed)
     }
+
+    /// Derives a new symmetric key from a password.
+    ///
+    /// Derivation is done using pbkdf2 with Sha256 hashing.
+    pub fn derive_from_password(password: &str) -> Self {
+        /// Salt to use for PBKDF2. This needs to be consistent accross runs to generate the same
+        /// key. Additionally, it does not really matter what this is, as long as its unique.
+        const SALT: &[u8; 10] = b"vault_salt";
+        /// Amount of rounds to use for key generation. More rounds => more cpu time. Changing this
+        /// also chagnes the generated keys.
+        const ROUNDS: u32 = 100_000;
+
+        let mut key = [0; 32];
+
+        pbkdf2::pbkdf2_hmac::<sha2::Sha256>(password.as_bytes(), SALT, ROUNDS, &mut key);
+
+        Self(key)
+    }
 }