Subversion Repositories planix.SVN

#include "os.h"
#include <libsec.h>

/* rfc5869 */
void
hkdf_x(salt, nsalt, info, ninfo, key, nkey, d, dlen, x, xlen)
        uchar *salt, *info, *key, *d;
        ulong nsalt, ninfo, nkey, dlen;
        DigestState* (*x)(uchar*, ulong, uchar*, ulong, uchar*, DigestState*);
        int xlen;
{
        uchar prk[256], tmp[256], cnt;
        DigestState *ds;

        assert(xlen <= sizeof(tmp));

        memset(tmp, 0, xlen);
        if(nsalt == 0){
                salt = tmp;
                nsalt = xlen;
        }
        /* note that salt and key are swapped in this case */
        (*x)(key, nkey, salt, nsalt, prk, nil);
        ds = nil;
        for(cnt=1;; cnt++) {
                if(ninfo > 0)
                        ds = (*x)(info, ninfo, prk, xlen, nil, ds);
                (*x)(&cnt, 1, prk, xlen, tmp, ds);
                if(dlen <= xlen){
                        memmove(d, tmp, dlen);
                        break;
                }
                memmove(d, tmp, xlen);
                dlen -= xlen;
                d += xlen;
                ds = (*x)(tmp, xlen, prk, xlen, nil, nil);
        }
}