Module crypt 

The standard security handler, read side (ISO 32000-2 §7.6).

Reads revisions 2 to 6: RC4 with 40- to 128-bit keys, AES-128 and AES-256, including the deprecated revision 5. Writes revision 6 (AES-256) only, never RC4 or AES-128 (docs/PLAN.md §2).

Structs

Permissions

What an encrypted document allows a user-password reader to do (ISO 32000-2 Table 22). The owner password allows everything.

SecurityHandler

A security handler, authenticated and ready to decrypt.

Enums

Authentication

Which password opened the file.

CryptMethod

How one class of data (strings, streams, embedded files) is encrypted.

Traits

Entropy

Randomness, injected by the host (docs/PLAN.md §2: no ambient I/O). Encryption takes keys, salts and IVs from it; a deterministic source gives byte-identical output.