HARBORMINT / BY WD DIGI
Custody, explained.
The files belong to you. Here is how the released design keeps them, and what that protection can and cannot do.
Encrypted at rest
A passphrase of at least 12 characters derives a 256-bit key with PBKDF2-SHA256, a random 32-byte salt and 600,000 iterations. Metadata and supporting files use AES-256-GCM with fresh nonces and authentication tags. Attachment identifiers bind file authentication to their record. No key is stored in plaintext by the app.
Only an unlocked session holds the working key. Manual lock or five minutes without activity clears it and removes record data from the interface. Metadata is an encrypted versioned JSON vault, not a SQLCipher database.
Original bytes and hashes
Import checks PDF, JPEG or PNG file signatures, applies the plan’s per-file limit and records a SHA-256 hash of the original bytes. Opening and exporting decrypts and verifies each file. Export stops if a file fails verification. Hashes check integrity relative to the recorded file; they do not prove authorship, truth, eligibility or acceptance by a plan.
Backups and exports serve different jobs
A .hmb backup contains encrypted metadata and files. Restore requires an empty installation, the original passphrase and a backup up to 1 GB. It authenticates the data and verifies every referenced attachment before accepting the restored vault.
An evidence ZIP is designed for portability. It contains readable CSV and JSON plus original files. Treat it as sensitive, unencrypted material. Select a private destination and remove copies you no longer need.
Local protection needs a healthy device
Use a strong Windows sign-in, device encryption, updates and a separate backup drive. Malware in an unlocked session, screenshots, OS dumps, clipboard contents and people with your passphrase fall outside vault protection. Managed .NET strings and WebView2 memory are not guaranteed to be forensically zeroed immediately. WD DIGI does not promise secure deletion, HIPAA certification, tamper-proof evidence or reimbursement approval.
Report an issue
Email support@wddigi.com with HarborMint security report in the subject. Include the app version, affected behavior and reproducible steps using fictional data. Do not include real receipts, keys, credentials or a working exploit against another person’s device.