//! Low level AES IGE and key wrapping functionality

//!

//! AES ECB, CBC, XTS, CTR, CFB, GCM and other conventional symmetric encryption

//! modes are found in [`symm`].  This is the implementation of AES IGE and key wrapping

//!

//! Advanced Encryption Standard (AES) provides symmetric key cipher that

//! the same key is used to encrypt and decrypt data.  This implementation

//! uses 128, 192, or 256 bit keys.  This module provides functions to

//! create a new key with [`new_encrypt`] and perform an encryption/decryption

//! using that key with [`aes_ige`].

//!

//! [`new_encrypt`]: struct.AesKey.html#method.new_encrypt

//! [`aes_ige`]: fn.aes_ige.html

//!

//! The [`symm`] module should be used in preference to this module in most cases.

//! The IGE block cipher is a non-traditional cipher mode.  More traditional AES

//! encryption methods are found in the [`Crypter`] and [`Cipher`] structs.

//!

//! [`symm`]: ../symm/index.html

//! [`Crypter`]: ../symm/struct.Crypter.html

//! [`Cipher`]: ../symm/struct.Cipher.html

//!

//! # Examples

#![cfg_attr(

    all(not(boringssl), not(osslconf = "OPENSSL_NO_DEPRECATED_3_0")),

    doc = r#"\

## AES IGE

```rust

use openssl::aes::{AesKey, aes_ige};

use openssl::symm::Mode;

let key = b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F";

let plaintext = b"\x12\x34\x56\x78\x90\x12\x34\x56\x12\x34\x56\x78\x90\x12\x34\x56";

let mut iv = *b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F\

                \x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1A\x1B\x1C\x1D\x1E\x1F";

 let key = AesKey::new_encrypt(key).unwrap();

 let mut output = [0u8; 16];

 aes_ige(plaintext, &mut output, &key, &mut iv, Mode::Encrypt);

 assert_eq!(output, *b"\xa6\xad\x97\x4d\x5c\xea\x1d\x36\xd2\xf3\x67\x98\x09\x07\xed\x32");

```"#

)]

//!

//! ## Key wrapping

//! ```rust

//! use openssl::aes::{AesKey, unwrap_key, wrap_key};

//!

//! let kek = b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F";

//! let key_to_wrap = b"\x00\x11\x22\x33\x44\x55\x66\x77\x88\x99\xAA\xBB\xCC\xDD\xEE\xFF";

//!

//! let enc_key = AesKey::new_encrypt(kek).unwrap();

//! let mut ciphertext = [0u8; 24];

//! wrap_key(&enc_key, None, &mut ciphertext, &key_to_wrap[..]).unwrap();

//! let dec_key = AesKey::new_decrypt(kek).unwrap();

//! let mut orig_key = [0u8; 16];

//! unwrap_key(&dec_key, None, &mut orig_key, &ciphertext[..]).unwrap();

//!

//! assert_eq!(&orig_key[..], &key_to_wrap[..]);

//! ```

//!

use cfg_if::cfg_if;

use libc::{c_int, c_uint};

use std::mem::MaybeUninit;

use std::ptr;

#[cfg(not(boringssl))]

use crate::symm::Mode;

use openssl_macros::corresponds;

/// Provides Error handling for parsing keys.

#[derive(Debug)]

pub struct KeyError(());

/// The key used to encrypt or decrypt cipher blocks.

pub struct AesKey(ffi::AES_KEY);

cfg_if! {

    if #[cfg(boringssl)] {

        type AesBitType = c_uint;

        type AesSizeType = usize;

    } else {

        type AesBitType = c_int;

        type AesSizeType = c_uint;

    }

}

impl AesKey {

    /// Prepares a key for encryption.

    ///

    /// # Failure

    ///

    /// Returns an error if the key is not 128, 192, or 256 bits.

    #[corresponds(AES_set_encrypt_key)]

    pub fn new_encrypt(key: &[u8]) -> Result<AesKey, KeyError> {

        unsafe {

            assert!(key.len() <= c_int::max_value() as usize / 8);

            let mut aes_key = MaybeUninit::uninit();

            let r = ffi::AES_set_encrypt_key(

                key.as_ptr() as *const _,

                key.len() as AesBitType * 8,

                aes_key.as_mut_ptr(),

            );

            if r == 0 {

                Ok(AesKey(aes_key.assume_init()))

            } else {

                Err(KeyError(()))

            }

        }

    }

    /// Prepares a key for decryption.

    ///

    /// # Failure

    ///

    /// Returns an error if the key is not 128, 192, or 256 bits.

    #[corresponds(AES_set_decrypt_key)]

    pub fn new_decrypt(key: &[u8]) -> Result<AesKey, KeyError> {

        unsafe {

            assert!(key.len() <= c_int::max_value() as usize / 8);

            let mut aes_key = MaybeUninit::uninit();

            let r = ffi::AES_set_decrypt_key(

                key.as_ptr() as *const _,

                key.len() as AesBitType * 8,

                aes_key.as_mut_ptr(),

            );

            if r == 0 {

                Ok(AesKey(aes_key.assume_init()))

            } else {

                Err(KeyError(()))

            }

        }

    }

}

/// Performs AES IGE encryption or decryption

///

/// AES IGE (Infinite Garble Extension) is a form of AES block cipher utilized in

/// OpenSSL.  Infinite Garble refers to propagating forward errors.  IGE, like other

/// block ciphers implemented for AES requires an initialization vector.  The IGE mode

/// allows a stream of blocks to be encrypted or decrypted without having the entire

/// plaintext available.  For more information, visit [AES IGE Encryption].

///

/// This block cipher uses 16 byte blocks.  The rust implementation will panic

/// if the input or output does not meet this 16-byte boundary.  Attention must

/// be made in this low level implementation to pad the value to the 128-bit boundary.

///

/// [AES IGE Encryption]: http://www.links.org/files/openssl-ige.pdf

///

/// # Panics

///

/// Panics if `in_` is not the same length as `out`, if that length is not a multiple of 16, or if

/// `iv` is not at least 32 bytes.

#[cfg(not(boringssl))]

#[cfg(not(osslconf = "OPENSSL_NO_DEPRECATED_3_0"))]

#[corresponds(AES_ige_encrypt)]

pub fn aes_ige(in_: &[u8], out: &mut [u8], key: &AesKey, iv: &mut [u8], mode: Mode) {

    unsafe {

        assert!(in_.len() == out.len());

        assert!(in_.len() % ffi::AES_BLOCK_SIZE as usize == 0);

        assert!(iv.len() >= ffi::AES_BLOCK_SIZE as usize * 2);

        let mode = match mode {

            Mode::Encrypt => ffi::AES_ENCRYPT,

            Mode::Decrypt => ffi::AES_DECRYPT,

        };

        ffi::AES_ige_encrypt(

            in_.as_ptr() as *const _,

            out.as_mut_ptr() as *mut _,

            in_.len(),

            &key.0,

            iv.as_mut_ptr() as *mut _,

            mode,

        );

    }

}

/// Wrap a key, according to [RFC 3394](https://tools.ietf.org/html/rfc3394)

///

/// * `key`: The key-encrypting-key to use. Must be a encrypting key

/// * `iv`: The IV to use. You must use the same IV for both wrapping and unwrapping

/// * `out`: The output buffer to store the ciphertext

/// * `in_`: The input buffer, storing the key to be wrapped

///

/// Returns the number of bytes written into `out`

///

/// # Panics

///

/// Panics if either `out` or `in_` do not have sizes that are a multiple of 8, or if

/// `out` is not 8 bytes longer than `in_`

#[corresponds(AES_wrap_key)]

pub fn wrap_key(

    key: &AesKey,

    iv: Option<[u8; 8]>,

    out: &mut [u8],

    in_: &[u8],

) -> Result<usize, KeyError> {

    unsafe {

        assert!(out.len() >= in_.len() + 8); // Ciphertext is 64 bits longer (see 2.2.1)

        let written = ffi::AES_wrap_key(

            &key.0 as *const _ as *mut _, // this is safe, the implementation only uses the key as a const pointer.

            iv.as_ref()

                .map_or(ptr::null(), |iv| iv.as_ptr() as *const _),

            out.as_ptr() as *mut _,

            in_.as_ptr() as *const _,

            in_.len() as AesSizeType,

        );

        if written <= 0 {

            Err(KeyError(()))

        } else {

            Ok(written as usize)

        }

    }

}

/// Unwrap a key, according to [RFC 3394](https://tools.ietf.org/html/rfc3394)

///

/// * `key`: The key-encrypting-key to decrypt the wrapped key. Must be a decrypting key

/// * `iv`: The same IV used for wrapping the key

/// * `out`: The buffer to write the unwrapped key to

/// * `in_`: The input ciphertext

///

/// Returns the number of bytes written into `out`

///

/// # Panics

///

/// Panics if either `out` or `in_` do not have sizes that are a multiple of 8, or

/// if `in_` is not 8 bytes longer than `out`

#[corresponds(AES_unwrap_key)]

pub fn unwrap_key(

    key: &AesKey,

    iv: Option<[u8; 8]>,

    out: &mut [u8],

    in_: &[u8],

) -> Result<usize, KeyError> {

    unsafe {

        assert!(out.len() + 8 <= in_.len());

        let written = ffi::AES_unwrap_key(

            &key.0 as *const _ as *mut _, // this is safe, the implementation only uses the key as a const pointer.

            iv.as_ref()

                .map_or(ptr::null(), |iv| iv.as_ptr() as *const _),

            out.as_ptr() as *mut _,

            in_.as_ptr() as *const _,

            in_.len() as AesSizeType,

        );

        if written <= 0 {

            Err(KeyError(()))

        } else {

            Ok(written as usize)

        }

    }

}

#[cfg(test)]

mod test {

    use hex::FromHex;

    use super::*;

    #[cfg(not(boringssl))]

    use crate::symm::Mode;

    // From https://www.mgp25.com/AESIGE/

    #[test]

    #[cfg(not(boringssl))]

    #[cfg(not(osslconf = "OPENSSL_NO_DEPRECATED_3_0"))]

    fn ige_vector_1() {

        let raw_key = "000102030405060708090A0B0C0D0E0F";

        let raw_iv = "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F";

        let raw_pt = "0000000000000000000000000000000000000000000000000000000000000000";

        let raw_ct = "1A8519A6557BE652E9DA8E43DA4EF4453CF456B4CA488AA383C79C98B34797CB";

        let key = AesKey::new_encrypt(&Vec::from_hex(raw_key).unwrap()).unwrap();

        let mut iv = Vec::from_hex(raw_iv).unwrap();

        let pt = Vec::from_hex(raw_pt).unwrap();

        let ct = Vec::from_hex(raw_ct).unwrap();

        let mut ct_actual = vec![0; ct.len()];

        aes_ige(&pt, &mut ct_actual, &key, &mut iv, Mode::Encrypt);

        assert_eq!(ct_actual, ct);

        let key = AesKey::new_decrypt(&Vec::from_hex(raw_key).unwrap()).unwrap();

        let mut iv = Vec::from_hex(raw_iv).unwrap();

        let mut pt_actual = vec![0; pt.len()];

        aes_ige(&ct, &mut pt_actual, &key, &mut iv, Mode::Decrypt);

        assert_eq!(pt_actual, pt);

    }

    // from the RFC https://tools.ietf.org/html/rfc3394#section-2.2.3

    #[test]

    fn test_wrap_unwrap() {

        let raw_key = Vec::from_hex("000102030405060708090A0B0C0D0E0F").unwrap();

        let key_data = Vec::from_hex("00112233445566778899AABBCCDDEEFF").unwrap();

        let expected_ciphertext =

            Vec::from_hex("1FA68B0A8112B447AEF34BD8FB5A7B829D3E862371D2CFE5").unwrap();

        let enc_key = AesKey::new_encrypt(&raw_key).unwrap();

        let mut wrapped = [0; 24];

        assert_eq!(

            wrap_key(&enc_key, None, &mut wrapped, &key_data).unwrap(),

            24

        );

        assert_eq!(&wrapped[..], &expected_ciphertext[..]);

        let dec_key = AesKey::new_decrypt(&raw_key).unwrap();

        let mut unwrapped = [0; 16];

        assert_eq!(

            unwrap_key(&dec_key, None, &mut unwrapped, &wrapped).unwrap(),

            16

        );

        assert_eq!(&unwrapped[..], &key_data[..]);

    }

}