Module security 

PDF security and encryption support

Implements PDF encryption per PDF specification:

• RC4-128 (PDF 1.4, /V 2 /R 3)
• AES-256 (PDF 2.0, /V 5 /R 6)

Supports owner/user passwords and permission flags (PDF spec Table 3.20).

Pure Rust implementation using aes, cbc, sha2, and md5 crates — no C FFI.

Structs

EncryptionDict

Computed encryption dictionary and keys

PdfPermissions

PDF permission flags per PDF spec Table 3.20

PdfSecurity

PDF encryption settings

Enums

EncryptionAlgorithm

PDF encryption algorithm

Functions

generate_file_id

Generate a PDF file ID (two identical 16-byte MD5 hashes)