Choose the Right Archive Encryption Method

Recommendation

For sensitive files, prefer a modern AES-based format with confirmed recipient support, a long unique passphrase, and file-name encryption when metadata is sensitive. If compatibility forces ZipCrypto, change the delivery method rather than weakening valuable data.

Pre-send checklist

Recipient software supports the selected encrypted format The passphrase is long, unique, and shared separately File names are hidden when their disclosure matters A harmless extraction test passed An authorized recovery copy exists

When an archive is not the right container

Folder Lock

Folder Lock provides dedicated encrypted lockers and file-protection workflows on supported platforms. It does not make a ZipCrypto archive strong or guarantee that recipients can open proprietary archive formats. Consider it when the need is ongoing local protection rather than a one-off interoperable attachment.

Review Folder Lock

Technical references

NIST: Advanced Encryption Standard
7-Zip: 7z format and AES-256
WinRAR: RAR5 encryption changes
PKWARE: ZIP APPNOTE specification
Library of Congress: ZIP format description