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//! # padding_128bit
//! `padding_128bit` is a padding mod for encryption and decryption which use 128 bits blocks, 
//! especially the `aes_core` mod.
/// PKCS #7 padding
/// # Examples
/// ```
/// use aes_frast::padding_128bit::pa_pkcs7;
/// 
/// let mut origin = vec![0xFFu8; 7];
/// 
/// pa_pkcs7(&mut origin);
/// 
/// assert_eq!(origin, vec![0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0x09u8,
///                         0x09u8, 0x09u8, 0x09u8, 0x09u8, 0x09u8, 0x09u8, 0x09u8, 0x09u8]);
/// ```
pub fn pa_pkcs7(input_vec: &mut Vec<u8>) {
    let r = 16 - (input_vec.len() & 0b1111);
    input_vec.append(&mut vec![r as u8; r]);
}
/// ANSIX923 padding
/// # Examples
/// ```
/// use aes_frast::padding_128bit::pa_ansix923;
/// 
/// let mut origin = vec![0xFFu8; 7];
/// 
/// pa_ansix923(&mut origin);
/// 
/// assert_eq!(origin, vec![0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0x00u8,
///                         0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x09u8]);
/// ```
pub fn pa_ansix923(input_vec: &mut Vec<u8>) {
    let r = 16 - (input_vec.len() & 0b1111);
    let mut tail = vec![0u8; r];
    tail[r - 1] = r as u8;
    input_vec.append(&mut tail);
}
/// ANSIX923 or PKCS #7 depadding  
/// 
/// **[Attention!]** Please be sure the parameter ends with exactly the ANSIX923 or PKCS #7 padding string.
/// # Examples
/// ```
/// use aes_frast::padding_128bit::de_ansix923_pkcs7;
/// 
/// let mut ansix923 = vec![0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0x00u8,
///                         0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x09u8];
/// 
/// de_ansix923_pkcs7(&mut ansix923);
/// 
/// let mut pkcs7 = vec![0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0x09u8,
///                      0x09u8, 0x09u8, 0x09u8, 0x09u8, 0x09u8, 0x09u8, 0x09u8, 0x09u8];
///
/// de_ansix923_pkcs7(&mut pkcs7);
/// 
/// let expected = vec![0xFFu8; 7];
/// assert_eq!(ansix923, expected);
/// assert_eq!(pkcs7, expected);
/// ```
pub fn de_ansix923_pkcs7(input_vec: &mut Vec<u8>) {
    let r = input_vec.pop().unwrap();
    for _ in 1..r {
        input_vec.pop();
    }
}
/// Zeros padding
/// 
/// This padding has never been standardized in cryptography specifications. So, **NOT** recommended.  
/// This padding here maybe differ from it in other implements, because this function still adds a 
/// complete block after the complete end-block, while maybe some other implements don't and only add 
/// to the incomplete end-block. If you are looking for function like that, see [`pa_zeros_ifnotcomplete`].
/// 
/// **[Attention!]** If the origin data ends with zero(s) (one or more 0xFF), depadding will remove all these zeros.
/// # Examples
/// ```
/// use aes_frast::padding_128bit::pa_zeros;
/// 
/// let mut origin = vec![0xFFu8; 7];
/// pa_zeros(&mut origin);
/// 
/// assert_eq!(origin, vec![0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0x00u8,
///                         0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8]);
/// 
/// origin = vec![0xFFu8; 16];
/// pa_zeros(&mut origin);
/// 
/// assert_eq!(origin, vec![0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8,
///                         0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8,
///                         0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8,
///                         0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8]);
/// ```
/// 
/// [`pa_zeros_ifnotcomplete`]: ../padding_128bit/fn.pa_zeros_ifnotcomplete.html
pub fn pa_zeros(input_vec: &mut Vec<u8>) {
    let r = 16 - (input_vec.len() & 0b1111);
    input_vec.append(&mut vec![0u8; r]);
}
/// Zeros padding only if not complete
/// 
/// This padding has never been standardized in cryptography specifications. So, **NOT** recommended.  
/// Different from the [`pa_zeros`] function, this function only adds zeros to the incomplete end-block.
/// When the end-block is complete, it keeps it unchanged.
/// 
/// **[Attention!]** If the origin data ends with zero(s) (one or more 0xFF), depadding will remove all these zeros.
/// # Examples
/// ```
/// use aes_frast::padding_128bit::pa_zeros_ifnotcomplete;
/// 
/// let mut origin = vec![0xFFu8; 7];
/// pa_zeros_ifnotcomplete(&mut origin);
/// 
/// assert_eq!(origin, vec![0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0x00u8,
///                         0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8]);
/// 
/// origin = vec![0xFFu8; 16];
/// pa_zeros_ifnotcomplete(&mut origin);
/// 
/// assert_eq!(origin, vec![0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8,
///                         0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8]);
/// ```
/// 
/// [`pa_zeros`]: ../padding_128bit/fn.pa_zeros.html
pub fn pa_zeros_ifnotcomplete(input_vec: &mut Vec<u8>) {
    let r = 16 - (input_vec.len() & 0b1111);
    if r != 16 {
        input_vec.append(&mut vec![0u8; r]);
    }
}
/// Zeros depadding  
/// 
/// **[Attention!]** If the origin data ends with zero(s) (one or more 0xFF), depadding will remove all these zeros.
/// # Examples
/// ```
/// use aes_frast::padding_128bit::de_zeros;
/// 
/// let mut zeros = vec![0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0xFFu8, 0x00u8,
///                      0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8, 0x00u8];
/// 
/// de_zeros(&mut zeros);
/// 
/// assert_eq!(zeros, vec![0xFFu8; 7]);
/// ```
pub fn de_zeros(input_vec: &mut Vec<u8>) {
    let mut tmp: u8;
    loop {
        tmp = input_vec.pop().unwrap();
        if tmp != 0 {
            input_vec.push(tmp);
            break;
        }
    }
}
/// Drop the last incomplete or complete block.
/// # Examples
/// ```
/// use aes_frast::padding_128bit::drop_last_block;
/// 
/// // Drop the last incomplete block.
/// let mut origin = vec![0xFFu8; 21];
/// drop_last_block(&mut origin);
/// 
/// assert_eq!(origin, vec![0xFFu8; 16]);
/// 
/// // Drop the last incomplete block.
/// origin = vec![0xFFu8; 32];
/// drop_last_block(&mut origin);
/// 
/// assert_eq!(origin, vec![0xFFu8; 16]);
/// ```
pub fn drop_last_block(input_vec: &mut Vec<u8>) {
    let r = match input_vec.len() & 0b1111 {
        0 => 16,
        r @ _ => r,
    };
    for _ in 0..r {
        input_vec.pop();
    }
}