Add BIP85 derivation helpers and tests

src/password_manager/password_generation.py

@@ -19,6 +19,7 @@ import hashlib
 import string
 import random
 import traceback
+import base64
 from typing import Optional
 from termcolor import colored
 from pathlib import Path
@@ -332,3 +333,19 @@ class PasswordGenerator:
             logger.error(f"Error ensuring password complexity: {e}", exc_info=True)
             print(colored(f"Error: Failed to ensure password complexity: {e}", "red"))
             raise
+
+
+def derive_totp_secret(bip85: BIP85, idx: int) -> str:
+    """Derive a TOTP secret for the given index using BIP85."""
+    entropy = bip85.derive_entropy(index=idx, bytes_len=10, app_no=2)
+    return base64.b32encode(entropy).decode("utf-8")
+
+
+def derive_ssh_key(bip85: BIP85, idx: int) -> bytes:
+    """Derive 32 bytes of entropy suitable for an SSH key."""
+    return bip85.derive_entropy(index=idx, bytes_len=32, app_no=32)
+
+
+def derive_seed_phrase(bip85: BIP85, idx: int, words: int = 24) -> str:
+    """Derive a new BIP39 seed phrase using BIP85."""
+    return bip85.derive_mnemonic(index=idx, words_num=words)