MatasanoCrypto/set1/ecb.c

#include <openssl/evp.h>
#include <stdint.h>
#include <string.h>

uint32_t ecb_decrypt(   const unsigned char* i_stream,
                        const uint32_t i_stream_size,
                        const unsigned char* i_pass,
                        const uint32_t i_pass_size,
                        unsigned char* o_buff)
{
    int ret, ret_fin;
    ret=ret_fin=0;
    EVP_CIPHER_CTX ctx;

    EVP_DecryptInit(&ctx, EVP_aes_128_ecb(), NULL, NULL);
    EVP_CIPHER_CTX_set_key_length(&ctx, i_pass_size);
    EVP_DecryptInit  (&ctx, NULL, i_pass, NULL);
    EVP_DecryptUpdate(&ctx, o_buff, &ret, i_stream, i_stream_size);
    EVP_DecryptFinal (&ctx, o_buff+ret, &ret_fin);
    return ret+ret_fin;
}


uint32_t ecb_encrypt(   const unsigned char* i_stream,
                        const uint32_t i_stream_size,
                        const unsigned char* i_pass,
                        const uint32_t i_pass_size,
                        unsigned char* o_buff)
{
    int ret, ret_fin;
    ret=ret_fin=0;
    EVP_CIPHER_CTX ctx;

    EVP_DecryptInit(&ctx, EVP_aes_128_ecb(), NULL, NULL);
    EVP_CIPHER_CTX_set_key_length(&ctx, i_pass_size);
    EVP_EncryptInit  (&ctx, NULL, i_pass, NULL);
    EVP_EncryptUpdate(&ctx, o_buff, &ret, i_stream, i_stream_size);
    EVP_EncryptFinal (&ctx, o_buff+ret, &ret_fin);
    return ret+ret_fin;
}

// checks if there are identical blocks in the i_textline
int same_blocks(const char* i_textline, const int i_bs, int* first_block, int* second_block)
{
    int chunk_nb = strlen(i_textline)/i_bs;
    for(int i=0; i<chunk_nb-1; i++)
    {
        for(int j=i+1; j<chunk_nb; j++)
        {
            if(memcmp(&i_textline[i*i_bs], &i_textline[j*i_bs],i_bs)==0)
            {
                *first_block = i+1;
                *second_block = j+1;
                return 1;
            }
        }
    }
    return 0;
}