fn decrypt()

in aws-lc-rs/src/cipher.rs [783:824]

• 40 lines of code
• 2 McCabe index (conditional complexity)

fn decrypt<'in_out>(
    algorithm: &'static Algorithm,
    key: &SymmetricCipherKey,
    mode: OperatingMode,
    in_out: &'in_out mut [u8],
    context: DecryptionContext,
) -> Result<&'in_out mut [u8], Unspecified> {
    let block_len = algorithm.block_len();

    match mode {
        OperatingMode::CBC | OperatingMode::ECB => {
            if in_out.len() % block_len != 0 {
                return Err(Unspecified);
            }
        }
        _ => {}
    }

    match mode {
        OperatingMode::CBC => match algorithm.id() {
            AlgorithmId::Aes128 | AlgorithmId::Aes192 | AlgorithmId::Aes256 => {
                aes::decrypt_cbc_mode(key, context, in_out)
            }
        },
        OperatingMode::CTR => match algorithm.id() {
            AlgorithmId::Aes128 | AlgorithmId::Aes192 | AlgorithmId::Aes256 => {
                aes::decrypt_ctr_mode(key, context, in_out)
            }
        },
        // TODO: Hopefully support CFB1, and CFB8
        OperatingMode::CFB128 => match algorithm.id() {
            AlgorithmId::Aes128 | AlgorithmId::Aes192 | AlgorithmId::Aes256 => {
                aes::decrypt_cfb_mode(key, mode, context, in_out)
            }
        },
        OperatingMode::ECB => match algorithm.id() {
            AlgorithmId::Aes128 | AlgorithmId::Aes192 | AlgorithmId::Aes256 => {
                aes::decrypt_ecb_mode(key, context, in_out)
            }
        },
    }
}