BytePadding - A collection of different byte padding methods

BytePadding is a small and simple repository that offers a collection of various byte padding methods.

Byte padding is a technique used to add additional bytes to a data stream, typically at the end, to ensure the data meets specific alignment requirements or fits a particular format.

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Requirements

• Requires C++17 so you need to compile it with the compilation flag -std=c++17.

Currently Available Padding Headers

#include "padding/ANSI_X9_23.hpp"
#include "padding/PKCS_5_7.hpp"
#include "padding/ISO_IEC_7816_4.hpp"

Sample program:

/*    sample.cpp    */
#include <iostream>
#include "padding/PKCS_5_7.hpp"

using namespace Padding;

int main()
{
    size_t padding_block = 8;

    unsigned char data1[] = { 0xfd, 0xfd, 0xfd, };

    unsigned char data2[] = {
      0xfd, 0xfd, 0xfd, 0xfd, 0xfd, 0xfd, 0xfd,
    };

    unsigned char data3[] = {
      0xfd, 0xfd, 0xfd, 0xfd, 0xfd, 0xfd, 0xfd, 0xfd,
    };

    ByteArray pad1 = PKCS_5_7::Add(subject1, sizeof(subject1), padding_block);
    ByteArray old1 = PKCS_5_7::Remove(pad1.data(), pad1.size());

    ByteArray pad2 = PKCS_5_7::Add(subject2, sizeof(subject2), padding_block);
    ByteArray old2 = PKCS_5_7::Remove(pad2.data(), pad2.size());

    ByteArray pad3 = PKCS_5_7::Add(subject3, sizeof(subject3), padding_block);
    ByteArray old3 = PKCS_5_7::Remove(pad3.data(), pad3.size());
}

Encrypted Value:

// data 1 padded result
0xfd, 0xfd, 0xfd, 0x05, 0x05, 0x05, 0x05, 0x05,

// data 2 padded result
0xfd, 0xfd, 0xfd, 0xfd, 0xfd, 0xfd, 0xfd, 0x01,

// data 3 padded result
0xfd, 0xfd, 0xfd, 0xfd, 0xfd, 0xfd, 0xfd, 0xfd,
0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08,

Byte Array Holder Class

The Padding::ByteArray class is used to hold the result of the padding function and it offeres a small amount of method to handle different operations, and a destructor to automatically free the array after going out of scope.

If you want to read the array of a Padding::ByteArray object instance you can call the ByteArray.data() method, this method will return a const unsigned char * containing the array values.

If you want to manage the Raw C style array yourself, you can use the ByteArray.size() method to get the size of the array, then ByteArray.detach() method to get the unsigned char * pointer of the array, this will detach the pointer inside the ByteArray so you will need to dellocate the detached pointer yourself! free()/delete [].