ref: c1d40df49550393f3afe53fb6e6d500dfa8eb7a8
dir: /sys/src/cmd/auth/factotum/wpapsk.c/
/* * WPA-PSK * * Client protocol: * write challenge: smac[6] + amac[6] + snonce[32] + anonce[32] * read response: ptk[64] * * Server protocol: * unimplemented */ #include "dat.h" enum { PMKlen = 256/8, PTKlen = 512/8, Eaddrlen = 6, Noncelen = 32, }; enum { CNeedChal, CHaveResp, Maxphase, }; static char *phasenames[Maxphase] = { [CNeedChal] "CNeedChal", [CHaveResp] "CHaveResp", }; struct State { uchar resp[PTKlen]; }; static void pass2pmk(char *pass, char *ssid, uchar pmk[PMKlen]) { int npass = strlen(pass); if(npass == 2*PMKlen && dec16(pmk, PMKlen, pass, npass) == PMKlen) return; pbkdf2_x((uchar*)pass, npass, (uchar*)ssid, strlen(ssid), 4096, pmk, PMKlen, hmac_sha1, SHA1dlen); } static void prfn(uchar *k, int klen, char *a, uchar *b, int blen, uchar *d, int dlen) { uchar r[SHA1dlen], i; DigestState *ds; int n; i = 0; while(dlen > 0){ ds = hmac_sha1((uchar*)a, strlen(a)+1, k, klen, nil, nil); hmac_sha1(b, blen, k, klen, nil, ds); hmac_sha1(&i, 1, k, klen, r, ds); i++; n = dlen; if(n > sizeof(r)) n = sizeof(r); memmove(d, r, n); d += n; dlen -= n; } } static void calcptk(uchar pmk[PMKlen], uchar smac[Eaddrlen], uchar amac[Eaddrlen], uchar snonce[Noncelen], uchar anonce[Noncelen], uchar ptk[PTKlen]) { uchar b[2*Eaddrlen + 2*Noncelen]; if(memcmp(smac, amac, Eaddrlen) > 0){ memmove(b + Eaddrlen*0, amac, Eaddrlen); memmove(b + Eaddrlen*1, smac, Eaddrlen); } else { memmove(b + Eaddrlen*0, smac, Eaddrlen); memmove(b + Eaddrlen*1, amac, Eaddrlen); } if(memcmp(snonce, anonce, Eaddrlen) > 0){ memmove(b + Eaddrlen*2 + Noncelen*0, anonce, Noncelen); memmove(b + Eaddrlen*2 + Noncelen*1, snonce, Noncelen); } else { memmove(b + Eaddrlen*2 + Noncelen*0, snonce, Noncelen); memmove(b + Eaddrlen*2 + Noncelen*1, anonce, Noncelen); } prfn(pmk, PMKlen, "Pairwise key expansion", b, sizeof(b), ptk, PTKlen); } static int wpapskinit(Proto *p, Fsstate *fss) { int iscli; State *s; if((iscli = isclient(_strfindattr(fss->attr, "role"))) < 0) return failure(fss, nil); if(!iscli) return failure(fss, "%s server not supported", p->name); s = emalloc(sizeof *s); fss->phasename = phasenames; fss->maxphase = Maxphase; fss->phase = CNeedChal; fss->ps = s; return RpcOk; } static int wpapskwrite(Fsstate *fss, void *va, uint n) { uchar pmk[PMKlen], *smac, *amac, *snonce, *anonce; char *pass, *essid; State *s; int ret; Key *k; Keyinfo ki; Attr *attr; s = fss->ps; if(fss->phase != CNeedChal) return phaseerror(fss, "write"); if(n != (2*Eaddrlen + 2*Noncelen)) return phaseerror(fss, "bad write size"); attr = _delattr(_copyattr(fss->attr), "role"); mkkeyinfo(&ki, fss, attr); ret = findkey(&k, &ki, "%s", fss->proto->keyprompt); _freeattr(attr); if(ret != RpcOk) return ret; pass = _strfindattr(k->privattr, "!password"); if(pass == nil) return failure(fss, "key has no password"); essid = _strfindattr(k->attr, "essid"); if(essid == nil) return failure(fss, "key has no essid"); setattrs(fss->attr, k->attr); closekey(k); pass2pmk(pass, essid, pmk); smac = va; amac = smac + Eaddrlen; snonce = amac + Eaddrlen; anonce = snonce + Noncelen; calcptk(pmk, smac, amac, snonce, anonce, s->resp); fss->phase = CHaveResp; return RpcOk; } static int wpapskread(Fsstate *fss, void *va, uint *n) { State *s; s = fss->ps; if(fss->phase != CHaveResp) return phaseerror(fss, "read"); if(*n > sizeof(s->resp)) *n = sizeof(s->resp); memmove(va, s->resp, *n); fss->phase = Established; fss->haveai = 0; return RpcOk; } static void wpapskclose(Fsstate *fss) { State *s; s = fss->ps; free(s); } Proto wpapsk = { .name= "wpapsk", .init= wpapskinit, .write= wpapskwrite, .read= wpapskread, .close= wpapskclose, .addkey= replacekey, .keyprompt= "!password? essid?" };