crypto_secretbox_example.c

crypto_secretbox_example.c

#include <stdio.h>
#include <string.h>
#include <sodium.h>

#define PLAINTEXT "123456789"
#define PLAINTEXT_LEN (sizeof PLAINTEXT)

int main(void)
{
    sodium_init();

    size_t mlen = PLAINTEXT_LEN + crypto_secretbox_ZEROBYTES;
    unsigned char mpad[mlen];
    unsigned char cwithnonce[crypto_secretbox_NONCEBYTES + mlen];
    unsigned char *cpad = cwithnonce + crypto_secretbox_NONCEBYTES;
    unsigned char key[crypto_secretbox_KEYBYTES];

    randombytes_buf(key, sizeof key);
    randombytes_buf(cwithnonce, crypto_secretbox_NONCEBYTES);
    memset(mpad, 0, crypto_secretbox_ZEROBYTES);
    memcpy(mpad + crypto_secretbox_ZEROBYTES, "123456789", PLAINTEXT_LEN);
    crypto_secretbox(cpad, mpad, mlen, cwithnonce, key);

    size_t clen = mlen;
    unsigned char mpad2[clen];
    cpad = cwithnonce + crypto_secretbox_NONCEBYTES;
    memset(cpad, 0, crypto_secretbox_BOXZEROBYTES);
    int res = crypto_secretbox_open(mpad2, cpad, clen,
                                    cwithnonce, key);
    printf("%d %s\n", res, mpad2 + crypto_secretbox_ZEROBYTES);

    return 0;
}