X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/tripe/blobdiff_plain/5fb10b44d547dfcb3612b85e7115355301535ca0..11ad66c29764521f87f0dd399a1e592147c7af36:/server/keyexch.c diff --git a/server/keyexch.c b/server/keyexch.c index c2f035d4..9d08bec6 100644 --- a/server/keyexch.c +++ b/server/keyexch.c @@ -9,19 +9,18 @@ * * This file is part of Trivial IP Encryption (TrIPE). * - * TrIPE is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. + * TrIPE is free software: you can redistribute it and/or modify it under + * the terms of the GNU General Public License as published by the Free + * Software Foundation; either version 3 of the License, or (at your + * option) any later version. * - * TrIPE is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. + * TrIPE is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * for more details. * * You should have received a copy of the GNU General Public License - * along with TrIPE; if not, write to the Free Software Foundation, - * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * along with TrIPE. If not, see . */ /*----- Header files ------------------------------------------------------*/ @@ -75,13 +74,6 @@ * Switch received. Committed; send data; move to @KXS_SWITCH@. */ -/*----- Tunable parameters ------------------------------------------------*/ - -#define T_VALID MIN(2) /* Challenge validity period */ -#define T_RETRY SEC(10) /* Challenge retransmit interval */ - -#define VALIDP(kx, now) ((now) < (kx)->t_valid) - /*----- Static tables -----------------------------------------------------*/ static const char *const pkname[] = { @@ -90,10 +82,22 @@ static const char *const pkname[] = { /*----- Various utilities -------------------------------------------------*/ +/* --- @VALIDP@ --- * + * + * Arguments: @const keyexch *kx@ = key exchange state + * @time_t now@ = current time in seconds + * + * Returns: Whether the challenge in the key-exchange state is still + * valid or should be regenerated. + */ + +#define VALIDP(kx, now) ((now) < (kx)->t_valid) + /* --- @hashge@ --- * * * Arguments: @ghash *h@ = pointer to hash context - * @ge *x@ = pointer to group element + * @const dhgrp *g@ = pointer to group + * @const dhge *Y@ = pointer to group element * * Returns: --- * @@ -101,11 +105,12 @@ static const char *const pkname[] = { * @buf_t@. */ -static void hashge(ghash *h, ge *x) +static void hashge(ghash *h, const dhgrp *g, const dhge *Y) { buf b; + buf_init(&b, buf_t, sizeof(buf_t)); - G_TOBUF(gg, &b, x); + g->ops->stge(g, &b, Y, DHFMT_HASH); assert(BOK(&b)); GH_HASH(h, BBASE(&b), BLEN(&b)); } @@ -113,78 +118,84 @@ static void hashge(ghash *h, ge *x) /* --- @mpmask@ --- * * * Arguments: @buf *b@ = output buffer - * @mp *x@ = the plaintext integer + * @const dhgrp *g@ = the group + * @const dhsc *x@ = the plaintext scalar * @size_t n@ = the expected size of the plaintext + * @gcipher *mgfc@ = mask-generating function to use * @const octet *k@ = pointer to key material * @size_t ksz@ = size of the key * - * Returns: Pointer to the output. + * Returns: --- * - * Use: Masks a multiprecision integer: returns %$x \xor H(k)$%, so - * it's a random oracle thing rather than an encryption thing. + * Use: Masks a scalar: returns %$x \xor H(k)$%, so it's a random + * oracle thing rather than an encryption thing. Breaks the + * output buffer on error. */ -static octet *mpmask(buf *b, mp *x, size_t n, const octet *k, size_t ksz) +static void mpmask(buf *b, const dhgrp *g, const dhsc *x, size_t n, + const gccipher *mgfc, const octet *k, size_t ksz) { gcipher *mgf; octet *p; - if ((p = buf_get(b, n)) == 0) - return (0); - mgf = GC_INIT(algs.mgf, k, ksz); + if ((p = buf_get(b, n)) == 0) return; + mgf = GC_INIT(mgfc, k, ksz); IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { - trace(T_CRYPTO, "masking index = %s", mpstr(x)); - trace_block(T_CRYPTO, "masking key", k, ksz); + trace(T_CRYPTO, "crypto: masking scalar = %s", g->ops->scstr(g, x)); + trace_block(T_CRYPTO, "crypto: masking key", k, ksz); })) - mp_storeb(x, buf_t, n); + if (g->ops->stsc(g, buf_t, n, x)) { buf_break(b); return; } GC_ENCRYPT(mgf, buf_t, p, n); IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { - trace_block(T_CRYPTO, "index plaintext", buf_t, n); - trace_block(T_CRYPTO, "masked ciphertext", p, n); + trace_block(T_CRYPTO, "crypto: scalar plaintext", buf_t, n); + trace_block(T_CRYPTO, "crypto: masked ciphertext", p, n); })) GC_DESTROY(mgf); - return (p); } /* --- @mpunmask@ --- * * - * Arguments: @mp *d@ = the output integer + * Arguments: @const dhgrp *g@ = the group * @const octet *p@ = pointer to the ciphertext * @size_t n@ = the size of the ciphertext + * @gcipher *mgfc@ = mask-generating function to use * @const octet *k@ = pointer to key material * @size_t ksz@ = size of the key * - * Returns: The decrypted integer, or null. + * Returns: The decrypted scalar, or null. * - * Use: Unmasks a multiprecision integer. + * Use: Unmasks a scalar. */ -static mp *mpunmask(mp *d, const octet *p, size_t n, - const octet *k, size_t ksz) +static dhsc *mpunmask(const dhgrp *g, const octet *p, size_t n, + const gccipher *mgfc, const octet *k, size_t ksz) { gcipher *mgf; + dhsc *x; - mgf = GC_INIT(algs.mgf, k, ksz); + mgf = GC_INIT(mgfc, k, ksz); IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { - trace_block(T_CRYPTO, "unmasking key", k, ksz); - trace_block(T_CRYPTO, "masked ciphertext", p, n); + trace_block(T_CRYPTO, "crypto: unmasking key", k, ksz); + trace_block(T_CRYPTO, "crypto: masked ciphertext", p, n); })) GC_DECRYPT(mgf, p, buf_t, n); - d = mp_loadb(d, buf_t, n); + x = g->ops->ldsc(g, buf_t, n); IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { - trace_block(T_CRYPTO, "index plaintext", buf_t, n); - trace(T_CRYPTO, "unmasked index = %s", mpstr(d)); + trace_block(T_CRYPTO, "crypto: scalar plaintext", buf_t, n); + trace(T_CRYPTO, "crypto: unmasked scalar = %s", + x ? g->ops->scstr(g, x) : ""); })) GC_DESTROY(mgf); - return (d); + return (x); } /* --- @hashcheck@ --- * * - * Arguments: @ge *kpub@ = sender's public key - * @ge *cc@ = receiver's challenge - * @ge *c@ = sender's challenge - * @ge *y@ = reply to sender's challenge + * Arguments: @keyexch *kx@ = pointer to key-exchange block + * @const dhge *K@ = sender's public key + * @const dhge *CC@ = receiver's challenge + * @const dhge *C@ = sender's challenge + * @const dhge *Y@ = reply to sender's challenge * * Returns: Pointer to the hash value (in @buf_t@) * @@ -192,29 +203,31 @@ static mp *mpunmask(mp *d, const octet *p, size_t n, * indices to prove the validity of challenges. This computes * the masking key used in challenge check values. This is * really the heart of the whole thing, since it ensures that - * the index can be recovered from the history of hashing + * the scalar can be recovered from the history of hashing * queries, which gives us (a) a proof that the authentication * process is zero-knowledge, and (b) a proof that the whole * key-exchange is deniable. */ -static const octet *hashcheck(ge *kpub, ge *cc, ge *c, ge *y) +static const octet *hashcheck(keyexch *kx, const dhge *K, + const dhge *CC, const dhge *C, const dhge *Y) { - ghash *h = GH_INIT(algs.h); + ghash *h = GH_INIT(kx->kpriv->algs.h); + const dhgrp *g = kx->kpriv->grp; HASH_STRING(h, "tripe-expected-reply"); - hashge(h, kpub); - hashge(h, cc); - hashge(h, c); - hashge(h, y); + hashge(h, g, K); + hashge(h, g, CC); + hashge(h, g, C); + hashge(h, g, Y); GH_DONE(h, buf_t); IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { - trace(T_CRYPTO, "computing challenge check hash"); - trace(T_CRYPTO, "public key = %s", gestr(gg, kpub)); - trace(T_CRYPTO, "receiver challenge = %s", gestr(gg, cc)); - trace(T_CRYPTO, "sender challenge = %s", gestr(gg, c)); - trace(T_CRYPTO, "sender reply = %s", gestr(gg, y)); - trace_block(T_CRYPTO, "hash output", buf_t, algs.hashsz); + trace(T_CRYPTO, "crypto: computing challenge check hash"); + trace(T_CRYPTO, "crypto: public key = %s", g->ops->gestr(g, K)); + trace(T_CRYPTO, "crypto: receiver challenge = %s", g->ops->gestr(g, CC)); + trace(T_CRYPTO, "crypto: sender challenge = %s", g->ops->gestr(g, C)); + trace(T_CRYPTO, "crypto: sender reply = %s", g->ops->gestr(g, Y)); + trace_block(T_CRYPTO, "crypto: hash output", buf_t, kx->kpriv->algs.hashsz); })) GH_DESTROY(h); return (buf_t); @@ -224,7 +237,7 @@ static const octet *hashcheck(ge *kpub, ge *cc, ge *c, ge *y) * * Arguments: @keyexch *kx@ = pointer to key exchange block * @buf *b@ = output buffer for challenge - * @ge *c@ = peer's actual challenge + * @const dhge *C@ = peer's actual challenge * @const octet *hc@ = peer's challenge cookie * * Returns: --- @@ -232,12 +245,15 @@ static const octet *hashcheck(ge *kpub, ge *cc, ge *c, ge *y) * Use: Writes a full challenge to the message buffer. */ -static void sendchallenge(keyexch *kx, buf *b, ge *c, const octet *hc) +static void sendchallenge(keyexch *kx, buf *b, + const dhge *C, const octet *hc) { - G_TOBUF(gg, b, kx->c); - buf_put(b, hc, algs.hashsz); - mpmask(b, kx->alpha, indexsz, - hashcheck(kpub, c, kx->c, kx->rx), algs.hashsz); + const dhgrp *g = kx->kpriv->grp; + g->ops->stge(g, b, kx->C, DHFMT_VAR); + buf_put(b, hc, kx->kpriv->algs.hashsz); + mpmask(b, g, kx->a, g->scsz, kx->kpriv->algs.mgf, + hashcheck(kx, kx->kpriv->K, C, kx->C, kx->RX), + kx->kpriv->algs.hashsz); } /* --- @timer@ --- * @@ -261,24 +277,102 @@ static void timer(struct timeval *tv, void *v) /* --- @settimer@ --- * * * Arguments: @keyexch *kx@ = pointer to key exchange context - * @time_t t@ = when to set the timer for + * @struct timeval *tv@ = when to set the timer for * * Returns: --- * * Use: Sets the timer for the next key exchange attempt. */ -static void settimer(keyexch *kx, time_t t) +static void settimer(keyexch *kx, struct timeval *tv) { - struct timeval tv; - if (kx->f & KXF_TIMER) - sel_rmtimer(&kx->t); - tv.tv_sec = t; - tv.tv_usec = 0; - sel_addtimer(&sel, &kx->t, &tv, timer, kx); + if (kx->f & KXF_TIMER) sel_rmtimer(&kx->t); + sel_addtimer(&sel, &kx->t, tv, timer, kx); kx->f |= KXF_TIMER; } +/* --- @f2tv@ --- * + * + * Arguments: @struct timeval *tv@ = where to write the timeval + * @double t@ = a time as a floating point number + * + * Returns: --- + * + * Use: Converts a floating-point time into a timeval. + */ + +static void f2tv(struct timeval *tv, double t) +{ + tv->tv_sec = t; + tv->tv_usec = (t - tv->tv_sec)*MILLION; +} + +/* --- @wobble@ --- * + * + * Arguments: @double t@ = a time interval + * + * Returns: The same time interval, with a random error applied. + */ + +static double wobble(double t) +{ + uint32 r = rand_global.ops->word(&rand_global); + double w = (r/F_2P32) - 0.5; + return (t + t*w*T_WOBBLE); +} + +/* --- @rs_time@ --- * + * + * Arguments: @retry *rs@ = current retry state + * @struct timeval *tv@ = where to write the result + * @const struct timeval *now@ = current time, or null + * + * Returns: --- + * + * Use: Computes a time at which to retry sending a key-exchange + * packet. This algorithm is subject to change, but it's + * currently a capped exponential backoff, slightly randomized + * to try to keep clients from hammering a server that's only + * just woken up. + * + * If @now@ is null then the function works out the time for + * itself. + */ + +static void rs_time(retry *rs, struct timeval *tv, const struct timeval *now) +{ + double t; + struct timeval rtv; + + if (!rs->t) + t = SEC(2); + else { + t = (rs->t * 5)/4; + if (t > MIN(5)) t = MIN(5); + } + rs->t = t; + + if (!now) { + now = tv; + gettimeofday(tv, 0); + } + f2tv(&rtv, wobble(t)); + TV_ADD(tv, now, &rtv); +} + +/* --- @retry_reset@ --- * + * + * Arguments: @retry *rs@ = retry state + * + * Returns: -- + * + * Use: Resets a retry state to indicate that progress has been + * made. Also useful for initializing the state in the first + * place. + */ + +static void rs_reset(retry *rs) { rs->t = 0; } + /*----- Challenge management ----------------------------------------------*/ /* --- Notes on challenge management --- * @@ -305,10 +399,11 @@ static void settimer(keyexch *kx, time_t t) static void kxc_destroy(kxchal *kxc) { + const dhgrp *g = kxc->kx->kpriv->grp; if (kxc->f & KXF_TIMER) sel_rmtimer(&kxc->t); - G_DESTROY(gg, kxc->c); - G_DESTROY(gg, kxc->r); + g->ops->freege(g, kxc->C); + g->ops->freege(g, kxc->R); ks_drop(kxc->ks); DESTROY(kxc); } @@ -338,6 +433,8 @@ static void kxc_stoptimer(kxchal *kxc) * Returns: A pointer to the challenge block. * * Use: Returns a pointer to a new challenge block to fill in. + * In particular, the @c@ and @r@ members are left + * uninitialized. */ static kxchal *kxc_new(keyexch *kx) @@ -357,31 +454,31 @@ static kxchal *kxc_new(keyexch *kx) /* --- Fill in the new structure --- */ kxc = CREATE(kxchal); - kxc->c = G_CREATE(gg); - kxc->r = G_CREATE(gg); kxc->ks = 0; kxc->kx = kx; kxc->f = 0; kx->r[i] = kxc; + rs_reset(&kxc->rs); return (kxc); } /* --- @kxc_bychal@ --- * * * Arguments: @keyexch *kx@ = pointer to key exchange block - * @ge *c@ = challenge from remote host + * @const dhge *C@ = challenge from remote host * * Returns: Pointer to the challenge block, or null. * * Use: Finds a challenge block, given its challenge. */ -static kxchal *kxc_bychal(keyexch *kx, ge *c) +static kxchal *kxc_bychal(keyexch *kx, const dhge *C) { + const dhgrp *g = kx->kpriv->grp; unsigned i; for (i = 0; i < kx->nr; i++) { - if (G_EQ(gg, c, kx->r[i]->c)) + if (g->ops->eq(g, C, kx->r[i]->C)) return (kx->r[i]); } return (0); @@ -402,7 +499,7 @@ static kxchal *kxc_byhc(keyexch *kx, const octet *hc) unsigned i; for (i = 0; i < kx->nr; i++) { - if (memcmp(hc, kx->r[i]->hc, algs.hashsz) == 0) + if (memcmp(hc, kx->r[i]->hc, kx->kpriv->algs.hashsz) == 0) return (kx->r[i]); } return (0); @@ -432,15 +529,16 @@ static void kxc_answer(keyexch *kx, kxchal *kxc) { stats *st = p_stats(kx->p); buf *b = p_txstart(kx->p, MSG_KEYEXCH | KX_REPLY); + const dhgrp *g = kx->kpriv->grp; struct timeval tv; buf bb; /* --- Build the reply packet --- */ T( trace(T_KEYEXCH, "keyexch: sending reply to `%s'", p_name(kx->p)); ) - sendchallenge(kx, b, kxc->c, kxc->hc); + sendchallenge(kx, b, kxc->C, kxc->hc); buf_init(&bb, buf_i, sizeof(buf_i)); - G_TORAW(gg, &bb, kxc->r); + g->ops->stge(g, &bb, kxc->R, DHFMT_STD); buf_flip(&bb); ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_REPLY, &bb, b); @@ -457,7 +555,7 @@ static void kxc_answer(keyexch *kx, kxchal *kxc) if (kxc->f & KXF_TIMER) sel_rmtimer(&kxc->t); gettimeofday(&tv, 0); - tv.tv_sec += T_RETRY; + rs_time(&kxc->rs, &tv, &tv); sel_addtimer(&sel, &kxc->t, &tv, kxc_timer, kxc); kxc->f |= KXF_TIMER; } @@ -477,7 +575,8 @@ static void kxc_answer(keyexch *kx, kxchal *kxc) static int doprechallenge(keyexch *kx, buf *b) { stats *st = p_stats(kx->p); - ge *c = G_CREATE(gg); + const dhgrp *g = kx->kpriv->grp; + dhge *C = 0; ghash *h; /* --- Ensure that we're in a sensible state --- */ @@ -489,20 +588,20 @@ static int doprechallenge(keyexch *kx, buf *b) /* --- Unpack the packet --- */ - if (G_FROMBUF(gg, b, c) || BLEFT(b)) + if ((C = g->ops->ldge(g, b, DHFMT_VAR)) == 0 || BLEFT(b)) goto bad; IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { - trace(T_CRYPTO, "crypto: challenge = %s", gestr(gg, c)); + trace(T_CRYPTO, "crypto: challenge = %s", g->ops->gestr(g, C)); })) /* --- Send out a full challenge by return --- */ b = p_txstart(kx->p, MSG_KEYEXCH | KX_CHAL); - h = GH_INIT(algs.h); + h = GH_INIT(kx->kpriv->algs.h); HASH_STRING(h, "tripe-cookie"); - hashge(h, c); - sendchallenge(kx, b, c, GH_DONE(h, 0)); + hashge(h, g, C); + sendchallenge(kx, b, C, GH_DONE(h, 0)); GH_DESTROY(h); st->n_kxout++; st->sz_kxout += BLEN(b); @@ -510,11 +609,11 @@ static int doprechallenge(keyexch *kx, buf *b) /* --- Done --- */ - G_DESTROY(gg, c); + g->ops->freege(g, C); return (0); bad: - if (c) G_DESTROY(gg, c); + if (C) g->ops->freege(g, C); return (-1); } @@ -532,12 +631,15 @@ bad: static kxchal *respond(keyexch *kx, unsigned msg, buf *b) { - ge *c = G_CREATE(gg); - ge *r = G_CREATE(gg); - ge *cc = G_CREATE(gg); + const dhgrp *g = kx->kpriv->grp; + const algswitch *algs = &kx->kpriv->algs; + size_t ixsz = g->scsz; + dhge *C = 0; + dhge *R = 0; + dhge *CC = 0; const octet *hc, *ck; size_t x, y, z; - mp *cv = 0; + dhsc *c = 0; kxchal *kxc; ghash *h = 0; buf bb; @@ -545,21 +647,21 @@ static kxchal *respond(keyexch *kx, unsigned msg, buf *b) /* --- Unpack the packet --- */ - if (G_FROMBUF(gg, b, c) || - (hc = buf_get(b, algs.hashsz)) == 0 || - (ck = buf_get(b, indexsz)) == 0) { + if ((C = g->ops->ldge(g, b, DHFMT_VAR)) == 0 || + (hc = buf_get(b, algs->hashsz)) == 0 || + (ck = buf_get(b, ixsz)) == 0) { a_warn("KX", "?PEER", kx->p, "invalid", "%s", pkname[msg], A_END); goto bad; } IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { - trace(T_CRYPTO, "crypto: challenge = %s", gestr(gg, c)); - trace_block(T_CRYPTO, "crypto: cookie", hc, algs.hashsz); - trace_block(T_CRYPTO, "crypto: check-value", ck, indexsz); + trace(T_CRYPTO, "crypto: challenge = %s", g->ops->gestr(g, C)); + trace_block(T_CRYPTO, "crypto: cookie", hc, algs->hashsz); + trace_block(T_CRYPTO, "crypto: check-value", ck, ixsz); })) /* --- Discard a packet with an invalid cookie --- */ - if (hc && memcmp(hc, kx->hc, algs.hashsz) != 0) { + if (hc && memcmp(hc, kx->hc, algs->hashsz) != 0) { a_warn("KX", "?PEER", kx->p, "incorrect", "cookie", A_END); goto bad; } @@ -572,109 +674,107 @@ static kxchal *respond(keyexch *kx, unsigned msg, buf *b) * This will also find a challenge block and, if necessary, populate it. */ - if ((kxc = kxc_bychal(kx, c)) != 0) { - h = GH_INIT(algs.h); + if ((kxc = kxc_bychal(kx, C)) != 0) { + h = GH_INIT(algs->h); HASH_STRING(h, "tripe-check-hash"); - GH_HASH(h, ck, indexsz); - ok = !memcmp(kxc->ck, GH_DONE(h, 0), algs.hashsz); + GH_HASH(h, ck, ixsz); + ok = !memcmp(kxc->ck, GH_DONE(h, 0), algs->hashsz); GH_DESTROY(h); if (!ok) goto badcheck; } else { /* --- Compute the reply, and check the magic --- */ - G_EXP(gg, r, c, kpriv); - cv = mpunmask(MP_NEW, ck, indexsz, - hashcheck(kx->kpub, kx->c, c, r), algs.hashsz); + R = g->ops->mul(g, kx->kpriv->k, C); + if ((c = mpunmask(g, ck, ixsz, algs->mgf, + hashcheck(kx, kx->kpub->K, kx->C, C, R), + algs->hashsz)) == 0) + goto badcheck; IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { - trace(T_CRYPTO, "crypto: computed reply = %s", gestr(gg, r)); - trace(T_CRYPTO, "crypto: recovered log = %s", mpstr(cv)); + trace(T_CRYPTO, "crypto: computed reply = %s", g->ops->gestr(g, R)); + trace(T_CRYPTO, "crypto: recovered log = %s", g->ops->scstr(g, c)); })) - if (MP_CMP(cv, >, gg->r) || - (G_EXP(gg, cc, gg->g, cv), !G_EQ(gg, c, cc))) - goto badcheck; + CC = g->ops->mul(g, c, 0); + if (!g->ops->eq(g, CC, C)) goto badcheck; /* --- Fill in a new challenge block --- */ kxc = kxc_new(kx); - G_COPY(gg, kxc->c, c); - G_COPY(gg, kxc->r, r); + kxc->C = C; C = 0; + kxc->R = R; R = 0; - h = GH_INIT(algs.h); - HASH_STRING(h, "tripe-check-hash"); - GH_HASH(h, ck, indexsz); - GH_DONE(h, kxc->ck); - GH_DESTROY(h); + h = GH_INIT(algs->h); HASH_STRING(h, "tripe-check-hash"); + GH_HASH(h, ck, ixsz); + GH_DONE(h, kxc->ck); GH_DESTROY(h); - h = GH_INIT(algs.h); - HASH_STRING(h, "tripe-cookie"); - hashge(h, kxc->c); - GH_DONE(h, kxc->hc); - GH_DESTROY(h); + h = GH_INIT(algs->h); HASH_STRING(h, "tripe-cookie"); + hashge(h, g, kxc->C); + GH_DONE(h, kxc->hc); GH_DESTROY(h); IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { - trace_block(T_CRYPTO, "crypto: computed cookie", kxc->hc, algs.hashsz); + trace_block(T_CRYPTO, "crypto: computed cookie", + kxc->hc, algs->hashsz); })) /* --- Work out the shared key --- */ - G_EXP(gg, r, c, kx->alpha); + R = g->ops->mul(g, kx->a, kxc->C); IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { - trace(T_CRYPTO, "crypto: shared secret = %s", gestr(gg, r)); + trace(T_CRYPTO, "crypto: shared secret = %s", g->ops->gestr(g, R)); })) /* --- Compute the switch messages --- */ - h = GH_INIT(algs.h); HASH_STRING(h, "tripe-switch-request"); - hashge(h, kx->c); hashge(h, kxc->c); + h = GH_INIT(algs->h); HASH_STRING(h, "tripe-switch-request"); + hashge(h, g, kx->C); hashge(h, g, kxc->C); GH_DONE(h, kxc->hswrq_out); GH_DESTROY(h); - h = GH_INIT(algs.h); HASH_STRING(h, "tripe-switch-confirm"); - hashge(h, kx->c); hashge(h, kxc->c); + h = GH_INIT(algs->h); HASH_STRING(h, "tripe-switch-confirm"); + hashge(h, g, kx->C); hashge(h, g, kxc->C); GH_DONE(h, kxc->hswok_out); GH_DESTROY(h); - h = GH_INIT(algs.h); HASH_STRING(h, "tripe-switch-request"); - hashge(h, kxc->c); hashge(h, kx->c); + h = GH_INIT(algs->h); HASH_STRING(h, "tripe-switch-request"); + hashge(h, g, kxc->C); hashge(h, g, kx->C); GH_DONE(h, kxc->hswrq_in); GH_DESTROY(h); - h = GH_INIT(algs.h); HASH_STRING(h, "tripe-switch-confirm"); - hashge(h, kxc->c); hashge(h, kx->c); + h = GH_INIT(algs->h); HASH_STRING(h, "tripe-switch-confirm"); + hashge(h, g, kxc->C); hashge(h, g, kx->C); GH_DONE(h, kxc->hswok_in); GH_DESTROY(h); IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { trace_block(T_CRYPTO, "crypto: outbound switch request", - kxc->hswrq_out, algs.hashsz); + kxc->hswrq_out, algs->hashsz); trace_block(T_CRYPTO, "crypto: outbound switch confirm", - kxc->hswok_out, algs.hashsz); + kxc->hswok_out, algs->hashsz); trace_block(T_CRYPTO, "crypto: inbound switch request", - kxc->hswrq_in, algs.hashsz); + kxc->hswrq_in, algs->hashsz); trace_block(T_CRYPTO, "crypto: inbound switch confirm", - kxc->hswok_in, algs.hashsz); + kxc->hswok_in, algs->hashsz); })) /* --- Create a new symmetric keyset --- */ buf_init(&bb, buf_o, sizeof(buf_o)); - G_TOBUF(gg, &bb, kx->c); x = BLEN(&bb); - G_TOBUF(gg, &bb, kxc->c); y = BLEN(&bb); - G_TOBUF(gg, &bb, r); z = BLEN(&bb); + g->ops->stge(g, &bb, kx->C, DHFMT_HASH); x = BLEN(&bb); + g->ops->stge(g, &bb, kxc->C, DHFMT_HASH); y = BLEN(&bb); + g->ops->stge(g, &bb, R, DHFMT_HASH); z = BLEN(&bb); assert(BOK(&bb)); kxc->ks = ks_gen(BBASE(&bb), x, y, z, kx->p); } - G_DESTROY(gg, c); - G_DESTROY(gg, cc); - G_DESTROY(gg, r); - mp_drop(cv); + if (C) g->ops->freege(g, C); + if (CC) g->ops->freege(g, CC); + if (R) g->ops->freege(g, R); + if (c) g->ops->freesc(g, c); return (kxc); badcheck: a_warn("KX", "?PEER", kx->p, "bad-expected-reply-log", A_END); goto bad; bad: - G_DESTROY(gg, c); - G_DESTROY(gg, cc); - G_DESTROY(gg, r); - mp_drop(cv); + if (C) g->ops->freege(g, C); + if (CC) g->ops->freege(g, CC); + if (R) g->ops->freege(g, R); + if (c) g->ops->freesc(g, c); return (0); } @@ -724,6 +824,8 @@ static void resend(keyexch *kx) kxchal *kxc; buf bb; stats *st = p_stats(kx->p); + struct timeval tv; + const dhgrp *g = kx->kpriv->grp; buf *b; switch (kx->s) { @@ -731,18 +833,18 @@ static void resend(keyexch *kx) T( trace(T_KEYEXCH, "keyexch: sending prechallenge to `%s'", p_name(kx->p)); ) b = p_txstart(kx->p, MSG_KEYEXCH | KX_PRECHAL); - G_TOBUF(gg, b, kx->c); + g->ops->stge(g, b, kx->C, DHFMT_VAR); break; case KXS_COMMIT: T( trace(T_KEYEXCH, "keyexch: sending switch request to `%s'", p_name(kx->p)); ) kxc = kx->r[0]; b = p_txstart(kx->p, MSG_KEYEXCH | KX_SWITCH); - buf_put(b, kx->hc, algs.hashsz); - buf_put(b, kxc->hc, algs.hashsz); + buf_put(b, kx->hc, kx->kpriv->algs.hashsz); + buf_put(b, kxc->hc, kx->kpriv->algs.hashsz); buf_init(&bb, buf_i, sizeof(buf_i)); - G_TORAW(gg, &bb, kxc->r); - buf_put(&bb, kxc->hswrq_out, algs.hashsz); + g->ops->stge(g, &bb, kxc->R, DHFMT_STD); + buf_put(&bb, kxc->hswrq_out, kx->kpriv->algs.hashsz); buf_flip(&bb); ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCH, &bb, b); break; @@ -752,7 +854,7 @@ static void resend(keyexch *kx) kxc = kx->r[0]; b = p_txstart(kx->p, MSG_KEYEXCH | KX_SWITCHOK); buf_init(&bb, buf_i, sizeof(buf_i)); - buf_put(&bb, kxc->hswok_out, algs.hashsz); + buf_put(&bb, kxc->hswok_out, kx->kpriv->algs.hashsz); buf_flip(&bb); ks_encrypt(kxc->ks, MSG_KEYEXCH | KX_SWITCHOK, &bb, b); break; @@ -766,8 +868,10 @@ static void resend(keyexch *kx) p_txend(kx->p); } - if (kx->s < KXS_SWITCH) - settimer(kx, time(0) + T_RETRY); + if (kx->s < KXS_SWITCH) { + rs_time(&kx->rs, &tv, 0); + settimer(kx, &tv); + } } /* --- @decryptrest@ --- * @@ -792,6 +896,7 @@ static int decryptrest(keyexch *kx, kxchal *kxc, unsigned msg, buf *b) a_warn("KX", "?PEER", kx->p, "decrypt-failed", "%s", pkname[msg], A_END); return (-1); } + if (!BOK(&bb)) return (-1); buf_init(b, BBASE(&bb), BLEN(&bb)); return (0); } @@ -810,25 +915,26 @@ static int decryptrest(keyexch *kx, kxchal *kxc, unsigned msg, buf *b) static int checkresponse(keyexch *kx, unsigned msg, buf *b) { - ge *r = G_CREATE(gg); + const dhgrp *g = kx->kpriv->grp; + dhge *R; - if (G_FROMRAW(gg, b, r)) { + if ((R = g->ops->ldge(g, b, DHFMT_STD)) == 0) { a_warn("KX", "?PEER", kx->p, "invalid", "%s", pkname[msg], A_END); goto bad; } IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { - trace(T_CRYPTO, "crypto: reply = %s", gestr(gg, r)); + trace(T_CRYPTO, "crypto: reply = %s", g->ops->gestr(g, R)); })) - if (!G_EQ(gg, r, kx->rx)) { + if (!g->ops->eq(g, R, kx->RX)) { a_warn("KX", "?PEER", kx->p, "incorrect", "response", A_END); goto bad; } - G_DESTROY(gg, r); + g->ops->freege(g, R); return (0); bad: - G_DESTROY(gg, r); + if (R) g->ops->freege(g, R); return (-1); } @@ -907,8 +1013,13 @@ bad: static void kxfinish(keyexch *kx) { kxchal *kxc = kx->r[0]; + struct timeval now, tv; + ks_activate(kxc->ks); - settimer(kx, ks_tregen(kxc->ks)); + gettimeofday(&now, 0); + f2tv(&tv, wobble(T_REGEN)); + TV_ADD(&tv, &now, &tv); + settimer(kx, &tv); kx->s = KXS_SWITCH; a_notify("KXDONE", "?PEER", kx->p, A_END); p_stats(kx->p)->t_kx = time(0); @@ -926,34 +1037,35 @@ static void kxfinish(keyexch *kx) static int doswitch(keyexch *kx, buf *b) { + size_t hsz = kx->kpriv->algs.hashsz; const octet *hc_in, *hc_out, *hswrq; kxchal *kxc; - if ((hc_in = buf_get(b, algs.hashsz)) == 0 || - (hc_out = buf_get(b, algs.hashsz)) == 0) { + if ((hc_in = buf_get(b, hsz)) == 0 || + (hc_out = buf_get(b, hsz)) == 0) { a_warn("KX", "?PEER", kx->p, "invalid", "switch-rq", A_END); goto bad; } IF_TRACING(T_KEYEXCH, IF_TRACING(T_CRYPTO, { - trace_block(T_CRYPTO, "crypto: challenge", hc_in, algs.hashsz); - trace_block(T_CRYPTO, "crypto: cookie", hc_out, algs.hashsz); + trace_block(T_CRYPTO, "crypto: challenge", hc_in, hsz); + trace_block(T_CRYPTO, "crypto: cookie", hc_out, hsz); })) if ((kxc = kxc_byhc(kx, hc_in)) == 0 || - memcmp(hc_out, kx->hc, algs.hashsz) != 0) { + memcmp(hc_out, kx->hc, hsz) != 0) { a_warn("KX", "?PEER", kx->p, "incorrect", "switch-rq", A_END); goto bad; } if (decryptrest(kx, kxc, KX_SWITCH, b) || checkresponse(kx, KX_SWITCH, b)) goto bad; - if ((hswrq = buf_get(b, algs.hashsz)) == 0 || BLEFT(b)) { + if ((hswrq = buf_get(b, hsz)) == 0 || BLEFT(b)) { a_warn("KX", "?PEER", kx->p, "invalid", "switch-rq", A_END); goto bad; } IF_TRACING(T_KEYEXCH, { - trace_block(T_CRYPTO, "crypto: switch request hash", hswrq, algs.hashsz); + trace_block(T_CRYPTO, "crypto: switch request hash", hswrq, hsz); }) - if (memcmp(hswrq, kxc->hswrq_in, algs.hashsz) != 0) { + if (memcmp(hswrq, kxc->hswrq_in, hsz) != 0) { a_warn("KX", "?PEER", kx->p, "incorrect", "switch-rq", A_END); goto bad; } @@ -980,6 +1092,7 @@ bad: static int doswitchok(keyexch *kx, buf *b) { + size_t hsz = kx->kpriv->algs.hashsz; const octet *hswok; kxchal *kxc; buf bb; @@ -992,15 +1105,15 @@ static int doswitchok(keyexch *kx, buf *b) buf_init(&bb, buf_o, sizeof(buf_o)); if (decryptrest(kx, kxc, KX_SWITCHOK, b)) goto bad; - if ((hswok = buf_get(b, algs.hashsz)) == 0 || BLEFT(b)) { + if ((hswok = buf_get(b, hsz)) == 0 || BLEFT(b)) { a_warn("KX", "?PEER", kx->p, "invalid", "switch-ok", A_END); goto bad; } IF_TRACING(T_KEYEXCH, { trace_block(T_CRYPTO, "crypto: switch confirmation hash", - hswok, algs.hashsz); + hswok, hsz); }) - if (memcmp(hswok, kxc->hswok_in, algs.hashsz) != 0) { + if (memcmp(hswok, kxc->hswok_in, hsz) != 0) { a_warn("KX", "?PEER", kx->p, "incorrect", "switch-ok", A_END); goto bad; } @@ -1030,6 +1143,7 @@ bad: static void stop(keyexch *kx) { + const dhgrp *g = kx->kpriv->grp; unsigned i; if (kx->f & KXF_DEAD) @@ -1039,9 +1153,9 @@ static void stop(keyexch *kx) sel_rmtimer(&kx->t); for (i = 0; i < kx->nr; i++) kxc_destroy(kx->r[i]); - mp_drop(kx->alpha); - G_DESTROY(gg, kx->c); - G_DESTROY(gg, kx->rx); + g->ops->freesc(g, kx->a); + g->ops->freege(g, kx->C); + g->ops->freege(g, kx->RX); kx->t_valid = 0; kx->f |= KXF_DEAD; kx->f &= ~KXF_TIMER; @@ -1060,31 +1174,35 @@ static void stop(keyexch *kx) static void start(keyexch *kx, time_t now) { + algswitch *algs = &kx->kpriv->algs; + const dhgrp *g = kx->kpriv->grp; ghash *h; assert(kx->f & KXF_DEAD); kx->f &= ~(KXF_DEAD | KXF_CORK); kx->nr = 0; - kx->alpha = mprand_range(MP_NEW, gg->r, &rand_global, 0); - kx->c = G_CREATE(gg); G_EXP(gg, kx->c, gg->g, kx->alpha); - kx->rx = G_CREATE(gg); G_EXP(gg, kx->rx, kx->kpub, kx->alpha); + kx->a = g->ops->randsc(g); + kx->C = g->ops->mul(g, kx->a, 0); + kx->RX = g->ops->mul(g, kx->a, kx->kpub->K); kx->s = KXS_CHAL; kx->t_valid = now + T_VALID; - h = GH_INIT(algs.h); + h = GH_INIT(algs->h); HASH_STRING(h, "tripe-cookie"); - hashge(h, kx->c); + hashge(h, g, kx->C); GH_DONE(h, kx->hc); GH_DESTROY(h); IF_TRACING(T_KEYEXCH, { trace(T_KEYEXCH, "keyexch: creating new challenge"); IF_TRACING(T_CRYPTO, { - trace(T_CRYPTO, "crypto: secret = %s", mpstr(kx->alpha)); - trace(T_CRYPTO, "crypto: challenge = %s", gestr(gg, kx->c)); - trace(T_CRYPTO, "crypto: expected response = %s", gestr(gg, kx->rx)); - trace_block(T_CRYPTO, "crypto: challenge cookie", kx->hc, algs.hashsz); + trace(T_CRYPTO, "crypto: secret = %s", g->ops->scstr(g, kx->a)); + trace(T_CRYPTO, "crypto: challenge = %s", g->ops->gestr(g, kx->C)); + trace(T_CRYPTO, "crypto: expected response = %s", + g->ops->gestr(g, kx->RX)); + trace_block(T_CRYPTO, "crypto: challenge cookie", + kx->hc, algs->hashsz); }) }) } @@ -1102,13 +1220,17 @@ static void start(keyexch *kx, time_t now) static int checkpub(keyexch *kx) { time_t now; + unsigned f = 0; + if (kx->f & KXF_DEAD) return (-1); now = time(0); - if (KEY_EXPIRED(now, kx->texp_kpub)) { + if (KEY_EXPIRED(now, kx->kpriv->t_exp)) f |= 1; + if (KEY_EXPIRED(now, kx->kpub->t_exp)) f |= 2; + if (f) { stop(kx); - a_warn("KX", "?PEER", kx->p, "public-key-expired", A_END); - G_COPY(gg, kx->kpub, gg->i); + if (f & 1) a_warn("KX", "?PEER", kx->p, "private-key-expired", A_END); + if (f & 2) a_warn("KX", "?PEER", kx->p, "public-key-expired", A_END); kx->f &= ~KXF_PUBKEY; return (-1); } @@ -1155,23 +1277,26 @@ void kx_start(keyexch *kx, int forcep) void kx_message(keyexch *kx, unsigned msg, buf *b) { - time_t now = time(0); + struct timeval now, tv; stats *st = p_stats(kx->p); size_t sz = BSZ(b); int rc; + gettimeofday(&now, 0); + rs_reset(&kx->rs); if (kx->f & KXF_CORK) { - start(kx, now); - settimer(kx, now + T_RETRY); - a_notify("KXSTART", A_END); + start(kx, now.tv_sec); + rs_time(&kx->rs, &tv, &now); + settimer(kx, &tv); + a_notify("KXSTART", "?PEER", kx->p, A_END); } if (checkpub(kx)) return; - if (!VALIDP(kx, now)) { + if (!VALIDP(kx, now.tv_sec)) { stop(kx); - start(kx, now); + start(kx, now.tv_sec); } T( trace(T_KEYEXCH, "keyexch: processing %s packet from `%s'", msg < KX_NMSG ? pkname[msg] : "unknown", p_name(kx->p)); ) @@ -1218,7 +1343,8 @@ void kx_message(keyexch *kx, unsigned msg, buf *b) void kx_free(keyexch *kx) { stop(kx); - G_DESTROY(gg, kx->kpub); + km_unref(kx->kpub); + km_unref(kx->kpriv); } /* --- @kx_newkeys@ --- * @@ -1235,13 +1361,112 @@ void kx_free(keyexch *kx) void kx_newkeys(keyexch *kx) { - if (km_getpubkey(p_name(kx->p), kx->kpub, &kx->texp_kpub)) - return; + kdata *kpriv, *kpub; + unsigned i; + int switchp; + time_t now = time(0); + + T( trace(T_KEYEXCH, "keyexch: checking new keys for `%s'", + p_name(kx->p)); ) + + /* --- Find out whether we can use new keys --- * + * + * Try each available combination of new and old, public and private, + * except both old (which is status quo anyway). The selection is encoded + * in @i@, with bit 0 for the private key and bit 1 for public key; a set + * bit means to use the old value, and a clear bit means to use the new + * one. + * + * This means that we currently prefer `old private and new public' over + * `new private and old public'. I'm not sure which way round this should + * actually be. + */ + + for (i = 0; i < 3; i++) { + + /* --- Select the keys we're going to examine --- * + * + * If we're meant to have a new key and don't, then skip this + * combination. + */ + + T( trace(T_KEYEXCH, "keyexch: checking %s private, %s public", + i & 1 ? "old" : "new", i & 2 ? "old" : "new"); ) + + if (i & 1) kpriv = kx->kpriv; + else if (kx->kpriv->kn->kd != kx->kpriv) kpriv = kx->kpriv->kn->kd; + else { + T( trace(T_KEYEXCH, "keyexch: private key unchanged, skipping"); ) + continue; + } + + if (i & 2) kpub = kx->kpub; + else if (kx->kpub->kn->kd != kx->kpub) kpub = kx->kpub->kn->kd; + else { + T( trace(T_KEYEXCH, "keyexch: public key unchanged, skipping"); ) + continue; + } + + /* --- Skip if either key is expired --- * + * + * We're not going to get far with expired keys, and this simplifies the + * logic below. + */ + + if (KEY_EXPIRED(now, kx->kpriv->t_exp) || + KEY_EXPIRED(now, kx->kpub->t_exp)) { + T( trace(T_KEYEXCH, "keyexch: %s expired, skipping", + !KEY_EXPIRED(now, kx->kpriv->t_exp) ? "public key" : + !KEY_EXPIRED(now, kx->kpub->t_exp) ? "private key" : + "both keys"); ) + continue; + } + + /* --- If the groups don't match then we can't use this pair --- */ + + if (!km_samealgsp(kpriv, kpub)) { + T( trace(T_KEYEXCH, "keyexch: peer `%s' group mismatch; " + "%s priv `%s' and %s pub `%s'", p_name(kx->p), + i & 1 ? "old" : "new", km_tag(kx->kpriv), + i & 2 ? "old" : "new", km_tag(kx->kpub)); ) + continue; + } + goto newkeys; + } + T( trace(T_KEYEXCH, "keyexch: peer `%s' continuing with old keys", + p_name(kx->p)); ) + return; + + /* --- We've chosen new keys --- * + * + * Switch the new ones into place. Neither of the keys we're switching to + * is expired (we checked that above), so we should just crank everything + * up. + * + * A complication arises: we don't really want to force a new key exchange + * unless we have to. If the group is unchanged, and we're currently + * running OK, then we should just let things lie. + */ + +newkeys: + switchp = ((kx->f & KXF_DEAD) || + kx->s != KXS_SWITCH || + kpriv->grp->ops != kx->kpriv->grp->ops || + !kpriv->grp->ops->samegrpp(kpriv->grp, kx->kpriv->grp)); + + T( trace(T_KEYEXCH, "keyexch: peer `%s' adopting " + "%s priv `%s' and %s pub `%s'; %sforcing exchange", p_name(kx->p), + i & 1 ? "old" : "new", km_tag(kx->kpriv), + i & 2 ? "old" : "new", km_tag(kx->kpub), + switchp ? "" : "not "); ) + + if (switchp) stop(kx); + km_ref(kpriv); km_unref(kx->kpriv); kx->kpriv = kpriv; + km_ref(kpub); km_unref(kx->kpub); kx->kpub = kpub; kx->f |= KXF_PUBKEY; - if ((kx->f & KXF_DEAD) || kx->s != KXS_SWITCH) { + if (switchp) { T( trace(T_KEYEXCH, "keyexch: restarting key negotiation with `%s'", p_name(kx->p)); ) - stop(kx); start(kx, time(0)); resend(kx); } @@ -1263,20 +1488,33 @@ void kx_newkeys(keyexch *kx) int kx_init(keyexch *kx, peer *p, keyset **ks, unsigned f) { + if ((kx->kpriv = km_findpriv(p_privtag(p))) == 0) goto fail_0; + if ((kx->kpub = km_findpub(p_tag(p))) == 0) goto fail_1; + if (!km_samealgsp(kx->kpriv, kx->kpub)) { + a_warn("KX", "?PEER", p, "group-mismatch", + "local-private-key", "%s", p_privtag(p), + "peer-public-key", "%s", p_tag(p), + A_END); + goto fail_2; + } + kx->ks = ks; kx->p = p; - kx->kpub = G_CREATE(gg); - if (km_getpubkey(p_name(p), kx->kpub, &kx->texp_kpub)) { - G_DESTROY(gg, kx->kpub); - return (-1); - } kx->f = KXF_DEAD | KXF_PUBKEY | f; + rs_reset(&kx->rs); if (!(kx->f & KXF_CORK)) { start(kx, time(0)); resend(kx); /* Don't notify here: the ADD message hasn't gone out yet. */ } return (0); + +fail_2: + km_unref(kx->kpub); +fail_1: + km_unref(kx->kpriv); +fail_0: + return (-1); } /*----- That's all, folks -------------------------------------------------*/