HP mask using CTR vs ECB using stock openssl (Ubuntu 16)

gistfile1.txt

/* Test whether CTR and ECB produce the same HP mask */

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

#include <openssl/evp.h>
#include <openssl/ssl.h>

/* Set everything to zero for our test: */
static unsigned char KEY[16];
static unsigned char IV[16];
static unsigned char IN[5];


static int
generate_mask (const EVP_CIPHER *cipher, unsigned char mask[16])
{
    EVP_CIPHER_CTX *hp_ctx;
    int out_len, retval;

    hp_ctx = EVP_CIPHER_CTX_new();
    if (EVP_EncryptInit_ex(hp_ctx, cipher, NULL, KEY, IV)
        && EVP_EncryptUpdate(hp_ctx, mask, &out_len, IN, sizeof(IN))
        && EVP_EncryptFinal_ex(hp_ctx, mask + out_len, &out_len))
    {
        retval = 0;
    }
    else
    {
        retval = -1;
    }

    EVP_CIPHER_CTX_free(hp_ctx);
    return retval;
}

static void
hexstr (const unsigned char *buf, size_t bufsz, char *out, size_t outsz)
{
    static const char b2c[16] = "0123456789ABCDEF";
    const unsigned char *const end_input = buf + bufsz;
    char *const end_output = out + outsz;

    while (buf < end_input && out + 2 < end_output)
    {
        *out++ = b2c[ *buf >> 4 ];
        *out++ = b2c[ *buf & 0xF ];
        ++buf;
    }

    if (buf < end_input)
        out[-1] = '!';

    *out = '\0';
}

int
main (void)
{
    unsigned char mask[16];
    char str[sizeof(mask)* 2 + 1];

    memset(mask, 0xCE, sizeof(mask));
    if (0 != generate_mask(EVP_aes_128_ctr(), mask))
    {
        fprintf(stderr, "failed to generate CTR mask\n");
        return 1;
    }
    hexstr(mask, sizeof(mask), str, sizeof(str));
    printf("CTR mask: %s\n", str);

    memset(mask, 0xCE, sizeof(mask));
    if (0 != generate_mask(EVP_aes_128_ecb(), mask))
    {
        fprintf(stderr, "failed to generate ECB mask\n");
        return 1;
    }
    hexstr(mask, sizeof(mask), str, sizeof(str));
    printf("ECB mask: %s\n", str);

    return 0;
}

__END__

Results when run:

CTR mask: 66E94BD4EF0000006D0B400000000000
ECB mask: EA301DE00E1D5CB994996F635C3B1DD8

Proposed changes:

static int
generate_mask_ctr (unsigned char mask[16])
{
    onst EVP_CIPHER *cipher;
    EVP_CIPHER_CTX *hp_ctx;
    int out_len, retval;

    cipher = EVP_aes_128_ctr();
    hp_ctx = EVP_CIPHER_CTX_new();
    if (EVP_EncryptInit_ex(hp_ctx, cipher, NULL, KEY, IV)
        && EVP_EncryptUpdate(hp_ctx, mask, &out_len, IN, sizeof(IN))
        && EVP_EncryptFinal_ex(hp_ctx, mask + out_len, &out_len))
    {
        retval = 0;
    }
    else
    {
        retval = -1;
    }

    EVP_CIPHER_CTX_free(hp_ctx);
    return retval;
}

static int
generate_mask_ecb (unsigned char mask[16])
{
    onst EVP_CIPHER *cipher;
    EVP_CIPHER_CTX *hp_ctx;
    int out_len, retval;

    cipher = EVP_aes_128_ecb();
    hp_ctx = EVP_CIPHER_CTX_new();
    if (EVP_EncryptInit_ex(hp_ctx, cipher, NULL, KEY, 0)
        && EVP_EncryptUpdate(hp_ctx, mask, &out_len, IV, sizeof(IV))
        && EVP_EncryptFinal_ex(hp_ctx, mask + out_len, &out_len))
    {
        retval = 0;
    }
    else
    {
        retval = -1;
    }

    EVP_CIPHER_CTX_free(hp_ctx);
    return retval;
}