void AES_CBC_IV0_ENCRYPT()

in src/ecdh_support.c [245:290]

• 38 lines of code
• 11 McCabe index (conditional complexity)

void AES_CBC_IV0_ENCRYPT(octet *k,const octet *m,octet *c)
{
    /* AES CBC encryption, with Null IV and key k */
    /* Input is from an octet string m, output is to an octet string c */
    /* Input is padded as necessary to make up a full final block */
    amcl_aes a;
    int fin;
    int i;
    int ipt;
    int opt;
    char buff[16];
    int padlen;

    OCT_clear(c);
    if (m->len==0) return;
    AES_init(&a,CBC,k->len,k->val,NULL);

    ipt=opt=0;
    fin=0;
    for(;;)
    {
        for (i=0; i<16; i++)
        {
            if (ipt<m->len) buff[i]=m->val[ipt++];
            else
            {
                fin=1;
                break;
            }
        }
        if (fin) break;
        AES_encrypt(&a,buff);
        for (i=0; i<16; i++)
            if (opt<c->max) c->val[opt++]=buff[i];
    }

    /* last block, filled up to i-th index */

    padlen=16-i;
    for (int j=i; j<16; j++) buff[j]=(char)padlen;
    AES_encrypt(&a,buff);
    for (i=0; i<16; i++)
        if (opt<c->max) c->val[opt++]=buff[i];
    AES_end(&a);
    c->len=opt;
}