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Versioning

Lasco uses separate version indicators for different layers of the format.

Library format version​

The library format version is stored as an empty sentinel file in the library/ directory on the remote:

library/
  version_1

Encrypted blob format​

Every encrypted blob (media files .data, thumbnails .thumb, and operation group files .op) begins with a single-byte version header:

[ format_version: u8 (1 byte) | nonce: 24 bytes | ciphertext ]

Master key protocol version​

Each per-user master key file (mk_{username}_{uuid}.enc) stores a version field before ciphertext:

[ protocol_version: u32 | nonce: 12 bytes | ciphertext ]

App config version​

The global config.json file carries a version:

{
  "version": 1,
  ...
}

Remote secret key version​

There is no separate per-remote credential file. S3 credentials live in library.json, and the secret key's version is a plain string tag checked by equality:

{
  "secret_key_encryption_description": "AES-256-GCM v1",
  ...
}