block.md

Block ciphers

#include <maid/block.h>

Internal Interface

struct maid_block_def

Type that defines a block cipher algorithm

External Interface

maid_block

Opaque type that contains the state of a block cipher

maid_block *maid_block_new(struct maid_block_def def, const u8 *restrict key, const u8 *restrict iv)

Creates a block cipher instance

Parameters

name	description
def	Algorithm definition
key	Algorithm-dependent
iv	Algorithm-dependent

Return value

case	description
Success	maid_block instance
Failure	NULL

maid_block *maid_block_del(maid_block *bl)

Deletes a block cipher instance

Parameters

name	description
bl	maid_block instance

Return value

case	description
Always	NULL

void maid_block_renew(maid_block *bl,const u8 *restrict key, const u8 *restrict iv)

Recreates a block cipher instance

Parameters

name	description
bl	maid_block instance
key	Algorithm-dependent
iv	Algorithm-dependent

void maid_block_ecb(maid_block *bl, u8 *buffer, bool decrypt)

Applies ECB mode (doesn't change the iv)

Parameters

name	description
bl	maid_block instance
buffer	Block to be ciphered
decrypt	Encrypt/Decrypt operation

void maid_block_ctr(maid_block *bl, u8 *buffer, size_t size)

Applies CTR mode (increases iv accordingly)

Parameters

name	description
bl	maid_block instance
buffer	Memory to be ciphered
size	Size of the operation

External Algorithms

const struct maid_block_def maid_aes_128

AES-128 block cipher (NIST)

Parameters

name	description
key	128-bit key
iv	128-bit iv

const struct maid_block_def maid_aes_192

AES-192 block cipher (NIST)

Parameters

name	description
key	192-bit key
iv	128-bit iv

const struct maid_block_def maid_aes_256

AES-256 block cipher (NIST)

Parameters

name	description
key	256-bit key
iv	128-bit iv

Example Code

#include <stdio.h>
#include <stdlib.h>

#include <maid/block.h>

int main(void)
{
    u8 key[32] = {0};
    u8 iv [16] = {0};

    maid_block *bl = maid_block_new(maid_aes_256, key, iv);

    u8 data[64] = {0};
    if (bl)
        maid_block_ctr(bl, data, sizeof(data));

    maid_block_del(bl);

    for (size_t i = 0; i < sizeof(data); i++)
        printf("%02x", data[i]);
    printf("\n");

    return EXIT_SUCCESS;
}

Without installation:

cc -static -Iinclude example.c -Lbuild -lmaid

With installation:

cc example.c -lmaid