libs.nfc_rs/src/crypto/util.rs

use crate::error::{Result, Error};
use simple_error::simple_error;
use block_modes::block_padding::{ZeroPadding, Padding};

pub fn extract_last_block(data: &[u8], blocksize: usize) -> Result<&[u8]> {
    if data.len() % blocksize != 0 {
        return Err(simple_error!("Data is not compatible with blocksize: data(length): {}, blocksize: {}.", data.len(), blocksize).into())
    }

    Ok(&data[(data.len() - blocksize)..])
}

pub fn expand_to_blocksize(data: &mut [u8], blocksize: usize) -> Result<&mut [u8]> {
    // let diff = data.len() % blocksize;

    match ZeroPadding::pad(data, data.len(), blocksize) {
        Ok(x) => {Ok(x)}
        Err(e) => {Err(Error::PadError(e))}
    }
}