X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/tripe/blobdiff_plain/a50f9a0eaed03dfe85ff3d7a4c24da20ac705dae..HEAD:/server/keyset.c diff --git a/server/keyset.c b/server/keyset.c index 9dd17fac..a0c4577d 100644 --- a/server/keyset.c +++ b/server/keyset.c @@ -9,46 +9,28 @@ * * 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 ------------------------------------------------------*/ #include "tripe.h" -/*----- Tunable parameters ------------------------------------------------*/ - -/* --- Note on size limits --- * - * - * For a 64-bit block cipher (e.g., Blowfish), the probability of a collision - * occurring after 32 MB is less than %$2^{-21}$%, and the probability of a - * collision occurring after 64 MB is less than %$2^{-19}$%. These could be - * adjusted dependent on the encryption scheme, but it's too much pain. - */ - -#define T_EXP MIN(60) /* Expiry time for a key */ -#define T_REGEN MIN(45) /* Regeneration time for a key */ -#define SZ_EXP MEG(64) /* Expiry data size for a key */ -#define SZ_REGEN MEG(32) /* Data size threshold for regen */ - /*----- Handy macros ------------------------------------------------------*/ #define KEYOK(ks, now) ((ks)->sz_exp > 0 && (ks)->t_exp > now) -#define SEQSZ 4 /* Size of sequence number packet */ - /*----- Low-level packet encryption and decryption ------------------------*/ /* --- Encrypted data format --- * @@ -92,73 +74,38 @@ static int doencrypt(keyset *ks, unsigned ty, buf *b, buf *bb) { - ghash *h; - gcipher *c = ks->cout; - const octet *p = BCUR(b); + int rc; size_t sz = BLEFT(b); - octet *qmac, *qseq, *qiv, *qpk; - uint32 oseq; - size_t ivsz = GC_CLASS(c)->blksz; - size_t tagsz = ks->tagsz; size_t osz, nsz; - octet t[4]; - int rc = 0; - - /* --- Allocate the required buffer space --- */ - if (buf_ensure(bb, tagsz + SEQSZ + ivsz + sz)) - return (0); /* Caution! */ - qmac = BCUR(bb); qseq = qmac + tagsz; qiv = qseq + SEQSZ; qpk = qiv + ivsz; - BSTEP(bb, tagsz + SEQSZ + ivsz + sz); - STORE32(t, ty); + /* --- Initial tracing --- */ - oseq = ks->oseq++; STORE32(qseq, oseq); IF_TRACING(T_KEYSET, { - trace(T_KEYSET, "keyset: encrypting packet %lu using keyset %u", - (unsigned long)oseq, ks->seq); - trace_block(T_CRYPTO, "crypto: plaintext packet", p, sz); + trace(T_KEYSET, + "keyset: encrypting packet %lu (type 0x%02x) using keyset %u", + (unsigned long)ks->oseq, ty, ks->seq); + trace_block(T_CRYPTO, "crypto: plaintext packet", BCUR(b), sz); }) - /* --- Encrypt the packet --- */ + /* --- Apply the bulk-crypto transformation --- */ - if (ivsz) { - rand_get(RAND_GLOBAL, qiv, ivsz); - GC_SETIV(c, qiv); - IF_TRACING(T_KEYSET, { - trace_block(T_CRYPTO, "crypto: initialization vector", qiv, ivsz); - }) - } - GC_ENCRYPT(c, p, qpk, sz); - IF_TRACING(T_KEYSET, { - trace_block(T_CRYPTO, "crypto: encrypted packet", qpk, sz); - }) + rc = ks->bulk->ops->encrypt(ks->bulk, ty, b, bb, ks->oseq); + if (rc || !BOK(bb)) return (rc); + ks->oseq++; - /* --- Now compute the MAC --- */ - - if (tagsz) { - h = GM_INIT(ks->mout); - GH_HASH(h, t, sizeof(t)); - GH_HASH(h, qseq, SEQSZ + ivsz + sz); - memcpy(qmac, GH_DONE(h, 0), tagsz); - GH_DESTROY(h); - IF_TRACING(T_KEYSET, { - trace_block(T_CRYPTO, "crypto: computed MAC", qmac, tagsz); - }) - } - - /* --- Deduct the packet size from the key's data life --- */ + /* --- Do the necessary accounting for data volume --- */ osz = ks->sz_exp; - if (osz > sz) - nsz = osz - sz; - else - nsz = 0; - if (osz >= SZ_REGEN && nsz < SZ_REGEN) { + nsz = osz > sz ? osz - sz : 0; + if (osz >= ks->sz_regen && ks->sz_regen > nsz) { T( trace(T_KEYSET, "keyset: keyset %u data regen limit exceeded -- " "forcing exchange", ks->seq); ) rc = KSERR_REGEN; } ks->sz_exp = nsz; + + /* --- We're done --- */ + return (rc); } @@ -182,71 +129,24 @@ static int doencrypt(keyset *ks, unsigned ty, buf *b, buf *bb) static int dodecrypt(keyset *ks, unsigned ty, buf *b, buf *bb, uint32 *seq) { - const octet *pmac, *piv, *pseq, *ppk; - size_t psz = BLEFT(b); - size_t sz; - octet *q = BCUR(bb); - ghash *h; - gcipher *c = ks->cin; - size_t ivsz = GC_CLASS(c)->blksz; - size_t tagsz = ks->tagsz; - octet *mac; - int eq; - octet t[4]; - - /* --- Break up the packet into its components --- */ - - if (psz < ivsz + SEQSZ + tagsz) { - T( trace(T_KEYSET, "keyset: block too small for keyset %u", ks->seq); ) - return (KSERR_DECRYPT); - } - sz = psz - ivsz - SEQSZ - tagsz; - pmac = BCUR(b); pseq = pmac + tagsz; piv = pseq + SEQSZ; ppk = piv + ivsz; - STORE32(t, ty); + const octet *q = BCUR(bb); + int rc; IF_TRACING(T_KEYSET, { - trace(T_KEYSET, "keyset: decrypting using keyset %u", ks->seq); - trace_block(T_CRYPTO, "crypto: ciphertext packet", ppk, sz); + trace(T_KEYSET, + "keyset: try decrypting packet (type 0x%02x) using keyset %u", + ty, ks->seq); + trace_block(T_CRYPTO, "crypto: ciphertext packet", BCUR(b), BLEFT(b)); }) - /* --- Verify the MAC on the packet --- */ - - if (tagsz) { - h = GM_INIT(ks->min); - GH_HASH(h, t, sizeof(t)); - GH_HASH(h, pseq, SEQSZ + ivsz + sz); - mac = GH_DONE(h, 0); - eq = !memcmp(mac, pmac, tagsz); - IF_TRACING(T_KEYSET, { - trace_block(T_CRYPTO, "crypto: computed MAC", mac, tagsz); - }) - GH_DESTROY(h); - if (!eq) { - IF_TRACING(T_KEYSET, { - trace(T_KEYSET, "keyset: incorrect MAC: decryption failed"); - trace_block(T_CRYPTO, "crypto: expected MAC", pmac, tagsz); - }) - return (KSERR_DECRYPT); - } - } - - /* --- Decrypt the packet --- */ + rc = ks->bulk->ops->decrypt(ks->bulk, ty, b, bb, seq); + if (rc) return (rc); - if (ivsz) { - GC_SETIV(c, piv); - IF_TRACING(T_KEYSET, { - trace_block(T_CRYPTO, "crypto: initialization vector", piv, ivsz); - }) - } - GC_DECRYPT(c, ppk, q, sz); - if (seq) - *seq = LOAD32(pseq); IF_TRACING(T_KEYSET, { trace(T_KEYSET, "keyset: decrypted OK (sequence = %lu)", - (unsigned long)LOAD32(pseq)); - trace_block(T_CRYPTO, "crypto: decrypted packet", q, sz); + (unsigned long)*seq); + trace_block(T_CRYPTO, "crypto: decrypted packet", q, BCUR(bb) - q); }) - BSTEP(bb, sz); return (0); } @@ -264,118 +164,53 @@ static int dodecrypt(keyset *ks, unsigned ty, buf *b, buf *bb, uint32 *seq) void ks_drop(keyset *ks) { - if (--ks->ref) - return; - GC_DESTROY(ks->cin); - GC_DESTROY(ks->cout); - GM_DESTROY(ks->min); - GM_DESTROY(ks->mout); + if (--ks->ref) return; + ks->bulk->ops->freectx(ks->bulk); DESTROY(ks); } /* --- @ks_gen@ --- * * - * Arguments: @const void *k@ = pointer to key material - * @size_t x, y, z@ = offsets into key material (see below) + * Arguments: @deriveargs *a@ = key derivation parameters (modified) * @peer *p@ = pointer to peer information * * Returns: A pointer to the new keyset. * - * Use: Derives a new keyset from the given key material. The - * offsets @x@, @y@ and @z@ separate the key material into three - * parts. Between the @k@ and @k + x@ is `my' contribution to - * the key material; between @k + x@ and @k + y@ is `your' - * contribution; and between @k + y@ and @k + z@ is a shared - * value we made together. These are used to construct two - * pairs of symmetric keys. Each pair consists of an encryption - * key and a message authentication key. One pair is used for - * outgoing messages, the other for incoming messages. + * Use: Derives a new keyset from the given key material. This will + * set the @what@, @f@, and @hc@ members in @*a@; other members + * must be filled in by the caller. * * The new key is marked so that it won't be selected for output * by @ksl_encrypt@. You can still encrypt data with it by * calling @ks_encrypt@ directly. */ -keyset *ks_gen(const void *k, size_t x, size_t y, size_t z, peer *p) +keyset *ks_gen(deriveargs *a, peer *p) { - ghash *h; - const octet *hh; keyset *ks = CREATE(keyset); time_t now = time(0); - const octet *pp = k; + const algswitch *algs = &p->kx.kpriv->algs; T( static unsigned seq = 0; ) T( trace(T_KEYSET, "keyset: adding new keyset %u", seq); ) - /* --- Construct the various keys --- * - * - * This is done with macros, because it's quite tedious. - */ - -#define MINE GH_HASH(h, pp, x) -#define YOURS GH_HASH(h, pp + x, y - x) -#define OURS GH_HASH(h, pp + y, z - y) - -#define HASH_in MINE; YOURS; OURS -#define HASH_out YOURS; MINE; OURS -#define INIT_c(k) GC_INIT(algs.c, (k), algs.cksz) -#define INIT_m(k) GM_KEY(algs.m, (k), algs.mksz) -#define STR_c "encryption" -#define STR_m "integrity" -#define STR_in "incoming" -#define STR_out "outgoing" - -#define SETKEY(a, dir) do { \ - h = GH_INIT(algs.h); \ - HASH_STRING(h, "tripe-" STR_##a); \ - HASH_##dir; \ - hh = GH_DONE(h, 0); \ - IF_TRACING(T_KEYSET, { \ - trace_block(T_CRYPTO, "crypto: " STR_##dir " key " STR_##a, \ - hh, algs.a##ksz); \ - }) \ - ks->a##dir = INIT_##a(hh); \ - GH_DESTROY(h); \ -} while (0) - - SETKEY(c, in); SETKEY(c, out); - SETKEY(m, in); SETKEY(m, out); - -#undef MINE -#undef YOURS -#undef OURS -#undef STR_c -#undef STR_m -#undef STR_in -#undef STR_out -#undef INIT_c -#undef INIT_m -#undef HASH_in -#undef HASH_out -#undef SETKEY + a->what = "tripe-"; a->f = DF_IN | DF_OUT; a->hc = algs->h; + ks->bulk = algs->bulk->ops->genkeys(algs->bulk, a); + ks->bulk->ops = algs->bulk->ops; T( ks->seq = seq++; ) ks->ref = 1; ks->t_exp = now + T_EXP; - ks->sz_exp = SZ_EXP; + ks->sz_exp = algs->bulk->ops->expsz(algs->bulk); + ks->sz_regen = ks->sz_exp/2; ks->oseq = 0; seq_reset(&ks->iseq); ks->next = 0; ks->p = p; ks->f = KSF_LISTEN; - ks->tagsz = algs.tagsz; return (ks); } -/* --- @ks_tregen@ --- * - * - * Arguments: @keyset *ks@ = pointer to a keyset - * - * Returns: The time at which moves ought to be made to replace this key. - */ - -time_t ks_tregen(keyset *ks) { return (ks->t_exp - T_EXP + T_REGEN); } - /* --- @ks_activate@ --- * * * Arguments: @keyset *ks@ = pointer to a keyset @@ -410,6 +245,11 @@ void ks_activate(keyset *ks) * ought to be replaced' notification is only ever given once * for each key. Also note that this call forces a keyset to be * used even if it's marked as not for data output. + * + * The encryption transform is permitted to corrupt @buf_u@ for + * its own purposes. Neither the source nor destination should + * be within @buf_u@; and callers mustn't expect anything stored + * in @buf_u@ to still */ int ks_encrypt(keyset *ks, unsigned ty, buf *b, buf *bb) @@ -430,25 +270,30 @@ int ks_encrypt(keyset *ks, unsigned ty, buf *b, buf *bb) * @buf *b@ = pointer to an input buffer * @buf *bb@ = pointer to an output buffer * - * Returns: Zero on success; @KSERR_DECRYPT@ on failure. Also returns + * Returns: Zero on success; @KSERR_...@ on failure. Also returns * zero if there was insufficient buffer (but the output buffer * is broken in this case). * * Use: Attempts to decrypt a message using a given key. Note that * requesting decryption with a key directly won't clear a * marking that it's not for encryption. + * + * The decryption transform is permitted to corrupt @buf_u@ for + * its own purposes. Neither the source nor destination should + * be within @buf_u@; and callers mustn't expect anything stored + * in @buf_u@ to still */ int ks_decrypt(keyset *ks, unsigned ty, buf *b, buf *bb) { time_t now = time(0); uint32 seq; + int err; - if (!KEYOK(ks, now) || - buf_ensure(bb, BLEN(b)) || - dodecrypt(ks, ty, b, bb, &seq) || - seq_check(&ks->iseq, seq, "SYMM")) - return (KSERR_DECRYPT); + if (!KEYOK(ks, now)) return (KSERR_DECRYPT); + if (buf_ensure(bb, BLEN(b))) return (0); + if ((err = dodecrypt(ks, ty, b, bb, &seq)) != 0) return (err); + if (seq_check(&ks->iseq, seq, "SYMM")) return (KSERR_SEQ); return (0); } @@ -583,24 +428,26 @@ int ksl_decrypt(keyset **ksroot, unsigned ty, buf *b, buf *bb) time_t now = time(0); keyset *ks; uint32 seq; + int err; if (buf_ensure(bb, BLEN(b))) - return (KSERR_DECRYPT); + return (0); for (ks = *ksroot; ks; ks = ks->next) { if (!KEYOK(ks, now)) continue; - if (!dodecrypt(ks, ty, b, bb, &seq)) { + if ((err = dodecrypt(ks, ty, b, bb, &seq)) == 0) { if (ks->f & KSF_LISTEN) { T( trace(T_KEYSET, "keyset: implicitly activating keyset %u", ks->seq); ) ks->f &= ~KSF_LISTEN; } if (seq_check(&ks->iseq, seq, "SYMM")) - return (KSERR_DECRYPT); + return (KSERR_SEQ); else return (0); } + if (err != KSERR_DECRYPT) return (err); } T( trace(T_KEYSET, "keyset: no matching keys, or incorrect MAC"); ) return (KSERR_DECRYPT);