Session resume for interrupted runs

[StrongWind1]

What problem does this solve?

Large credential sprays over slow or unstable links can take hours. If the process is interrupted (network drop, Ctrl-C, system reboot), all progress is lost and the operator must re-run from the beginning. This wastes time and causes duplicate bad-password counter increments for credentials that were already tested.

Proposed solution

Add --resume <state-file> support. CredWolf would save progress to a state file after each credential attempt, recording which user/secret pairs have been tested. On resume, it skips already-tested pairs and continues from where it left off.

State file should track:

• The original command-line options (to detect mismatched resumes)
• Set of completed (user, secret_hash) pairs (hash the secret to avoid storing plaintext credentials in the state file)
• Per-user salt cache (to avoid redundant salt retrieval requests)
• Per-user status (principal_unknown, revoked, wrong_realm) to preserve skip logic
• Timestamp of last attempt

File format options:

• SQLite — robust, handles concurrent writes, easy to query
• JSON lines — simple, append-only, human-readable

The --resume flag should error if the state file's original options don't match the current invocation (different domain, target, protocol, etc.).

Alternatives considered

• Piping output through tee and using --exclude-file on re-run — doesn't preserve internal state (salt cache, revoked users, lockout counter)
• Checkpointing at the user level instead of per-attempt — simpler but loses progress within a user's password list