Struct Aes 

pub struct Aes { /* private fields */ }

AES cipher implementation using RustCrypto (production-grade)

This implementation uses the audited aes and cbc crates from the RustCrypto project for secure AES-128 and AES-256 encryption.

Implementations

impl Aes

pub fn new(key: AesKey) -> Self

Create new AES cipher

pub fn encrypt_cbc(&self, data: &[u8], iv: &[u8]) -> Result<Vec<u8>, AesError>

Encrypt data using AES-CBC mode with PKCS#7 padding

Uses RustCrypto’s cbc crate for production-grade encryption.

pub fn decrypt_cbc(&self, data: &[u8], iv: &[u8]) -> Result<Vec<u8>, AesError>

Decrypt data using AES-CBC mode with PKCS#7 padding removal

Uses RustCrypto’s cbc crate for production-grade decryption.

pub fn encrypt_ecb(&self, data: &[u8]) -> Result<Vec<u8>, AesError>

Encrypt data using AES-ECB mode (for Perms entry in R6)

Note: ECB mode is generally insecure but required by PDF spec for Perms entry.

pub fn decrypt_ecb(&self, data: &[u8]) -> Result<Vec<u8>, AesError>

Decrypt data using AES-ECB mode (for Perms entry verification in R6)

pub fn encrypt_cbc_raw( &self, data: &[u8], iv: &[u8], ) -> Result<Vec<u8>, AesError>

Encrypt data using AES-CBC mode WITHOUT padding

Used for R5/R6 UE entry encryption where data is already block-aligned (32 bytes). Unlike encrypt_cbc, this does not add PKCS#7 padding.

Requirements

• Data length must be a multiple of 16 bytes
• IV must be exactly 16 bytes

Security Note

The XOR operations in CBC chaining use simple loops. While Rust/LLVM typically produces constant-time code for fixed-size array XOR operations, this is not formally guaranteed. PDF encryption is designed for offline brute-force attacks where timing side-channels are not in the threat model.

pub fn decrypt_cbc_raw( &self, data: &[u8], iv: &[u8], ) -> Result<Vec<u8>, AesError>

Decrypt data using AES-CBC mode WITHOUT padding

Used for R5/R6 UE entry decryption where data is already block-aligned (32 bytes). Unlike decrypt_cbc, this does not expect or remove PKCS#7 padding.

Requirements

• Data length must be a multiple of 16 bytes
• IV must be exactly 16 bytes

Security Note

The XOR operations in CBC chaining use simple loops. While Rust/LLVM typically produces constant-time code for fixed-size array XOR operations, this is not formally guaranteed. PDF encryption is designed for offline brute-force attacks where timing side-channels are not in the threat model.