+/*----- The AEAD transform ------------------------------------------------*
+ *
+ * This transform uses a general authenticated encryption scheme (the
+ * additional data isn't necessary). Good options include
+ * `chacha20-poly1305' or `rijndael-ocb3'.
+ *
+ * To be acceptable, the scheme must accept at least a 40-bit nonce. (All of
+ * Catacomb's current AEAD schemes are suitable.) The low 32 bits are the
+ * sequence number. The type is written to the next 8--32 bytes: if the
+ * nonce size is 64 bits or more (preferred, for compatibility reasons) then
+ * the type is written as 32 bits, and the remaining space is padded with
+ * zero bytes; otherwise, the type is right-aligned in the remaining space.
+ * Both fields are big-endian.
+ *
+ * +--------+--+
+ * | seq |ty|
+ * +--------+--+
+ * 32 8
+ *
+ * +--------+----+
+ * | seq | ty |
+ * +--------+----+
+ * 32 16
+ *
+ * +--------+------+
+ * | seq | type |
+ * +--------+------+
+ * 32 24
+ *
+ * +--------+--------+---...---+
+ * | seq | type | 0 |
+ * +--------+--------+---...---+
+ * 32 32 nsz - 64
+ *
+ * The ciphertext is formatted as
+ *
+ * +---...---+--------+------...------+
+ * | tag | seq | ciphertext |
+ * +---...---+--------+------...------+
+ * tagsz 32 sz
+ *
+ */
+
+#define AEAD_NONCEMAX 64
+
+typedef struct aead_algs {
+ bulkalgs _b;
+ const gcaead *c;
+ size_t ksz, nsz, tsz;
+} aead_algs;
+
+typedef struct aead_ctx {
+ bulkctx _b;
+ struct { gaead_key *k; } d[NDIR];
+ size_t nsz, tsz;
+} aead_ctx;
+
+static bulkalgs *aead_getalgs(const algswitch *asw, dstr *e,
+ key_file *kf, key *k)
+{
+ aead_algs *a = CREATE(aead_algs);
+ const char *p;
+ char *qq;
+ gaead_key *kk = 0;
+ size_t ksz;
+ size_t csz = 0;
+ unsigned long n;
+
+ /* --- Collect the selected cipher and check that it's supported --- */
+
+ p = key_getattr(kf, k, "cipher"); if (!p) p = "rijndael-ocb3";
+ a->c = gaead_byname(p);
+ if (!a->c) { a_format(e, "unknown-cipher", "%s", p, A_END); goto fail; }
+ if (a->c->f&AEADF_NOAAD) {
+ a_format(e, "unsuitable-aead-cipher", "%s", p, "no-aad", A_END);
+ goto fail;
+ }
+ a->nsz = keysz_pad(8, a->c->noncesz);
+ if (!a->nsz) a->nsz = keysz_pad(5, a->c->noncesz);
+ if (!a->nsz) {
+ a_format(e, "unsuitable-aead-cipher", "%s", p, "nonce-too-small", A_END);
+ goto fail;
+ } else if (a->nsz > AEAD_NONCEMAX) {
+ a_format(e, "unsuitable-aead-cipher", "%s", p, "nonce-too-large", A_END);
+ goto fail;
+ }
+
+ /* --- Collect the selected MAC, and check the tag length --- *
+ *
+ * Of course, there isn't a separate MAC, so only accept `aead'.
+ */
+
+ p = key_getattr(kf, k, "tagsz");
+ if (!p) {
+ p = key_getattr(kf, k, "mac");
+ if (!p) ;
+ else if (strncmp(p, "aead", 4) != 0 || (p[4] && p[4] != '/'))
+ { a_format(e, "unknown-mac", "%s", p, A_END); goto fail; }
+ else if (p[4] == '/') p += 5;
+ else p = 0;
+ }
+ if (!p)
+ a->tsz = keysz(0, a->c->tagsz);
+ else {
+ n = strtoul(p, &qq, 0);
+ if (*qq) {
+ a_format(e, "bad-tag-length-string", "%s", p, A_END);
+ goto fail;
+ }
+ if (n%8 || (a->tsz = keysz(n/8, a->c->tagsz)) == 0)
+ { a_format(e, "bad-tag-length", "%lu", n, A_END); goto fail; }
+ }
+
+ /* --- Check that an empty message gives an empty ciphertext --- *
+ *
+ * This is necessary for producing challenges. If the overhead is zero
+ * then we're fine; otherwise, we have to check the hard way.
+ */
+
+ if (a->c->ohd) {
+ ksz = keysz(0, a->c->keysz);
+ memset(buf_t, 0, ksz > a->nsz ? ksz : a->nsz);
+ kk = GAEAD_KEY(a->c, buf_t, ksz);
+ if (gaead_encrypt(kk, buf_t, a->nsz,
+ buf_t, ksz,
+ 0, 0,
+ buf_t, &csz,
+ buf_t, a->tsz)) {
+ a_format(e, "unsuitable-aead-cipher", "%s", a->c->name,
+ "nonempty-ciphertext-for-empty-message", A_END);
+ goto fail;
+ }
+ GAEAD_DESTROY(kk); kk = 0;
+ }
+
+ return (&a->_b);
+fail:
+ if (kk) GAEAD_DESTROY(kk);
+ DESTROY(a);
+ return (0);
+}
+
+#ifndef NTRACE
+static void aead_tracealgs(const bulkalgs *aa)
+{
+ const aead_algs *a = (const aead_algs *)aa;
+
+ trace(T_CRYPTO, "crypto: cipher = %s", a->c->name);
+ trace(T_CRYPTO, "crypto: noncesz = %lu", (unsigned long)a->nsz);
+ trace(T_CRYPTO, "crypto: tagsz = %lu", (unsigned long)a->tsz);
+}
+#endif
+
+static int aead_checkalgs(bulkalgs *aa, const algswitch *asw, dstr *e)
+{
+ aead_algs *a = (aead_algs *)aa;
+
+ if ((a->ksz = keysz(asw->hashsz, a->c->keysz)) == 0) {
+ a_format(e, "cipher", "%s", a->c->name,
+ "no-key-size", "%lu", (unsigned long)asw->hashsz,
+ A_END);
+ return (-1);
+ }
+ return (0);
+}
+
+static int aead_samealgsp(const bulkalgs *aa, const bulkalgs *bb)
+{
+ const aead_algs *a = (const aead_algs *)aa,
+ *b = (const aead_algs *)bb;
+ return (a->c == b->c && a->tsz == b->tsz);
+}
+
+static void aead_alginfo(const bulkalgs *aa, admin *adm)
+{
+ const aead_algs *a = (const aead_algs *)aa;
+ a_info(adm, "cipher=%s", a->c->name,
+ "cipher-keysz=%lu", (unsigned long)a->ksz,
+ A_END);
+ a_info(adm, "mac=aead", "mac-tagsz=%lu", (unsigned long)a->tsz, A_END);
+}
+
+static size_t aead_overhead(const bulkalgs *aa)
+{
+ const aead_algs *a = (const aead_algs *)aa;
+ return (a->tsz + SEQSZ + a->c->ohd);
+}
+
+static size_t aead_expsz(const bulkalgs *aa)
+{
+ const aead_algs *a = (const aead_algs *)aa;
+ return (a->c->blksz < 16 ? MEG(64) : MEG(2048));
+}
+
+static bulkctx *aead_genkeys(const bulkalgs *aa, const deriveargs *da)
+{
+ const aead_algs *a = (const aead_algs *)aa;
+ aead_ctx *bc = CREATE(aead_ctx);
+ octet k[MAXHASHSZ];
+ int i;
+
+ for (i = 0; i < NDIR; i++) {
+ if (!(da->f&(1 << i))) { bc->d[i].k = 0; continue; }
+ derivekey(k, a->ksz, da, i, "encryption");
+ bc->d[i].k = GAEAD_KEY(a->c, k, a->ksz);
+ }
+ bc->nsz = a->nsz; bc->tsz = a->tsz;
+ return (&bc->_b);
+}
+
+typedef struct aead_chal {
+ bulkchal _b;
+ gaead_key *k;
+} aead_chal;
+
+static bulkchal *aead_genchal(const bulkalgs *aa)
+{
+ const aead_algs *a = (const aead_algs *)aa;
+ aead_chal *c = CREATE(aead_chal);
+ rand_get(RAND_GLOBAL, buf_t, a->ksz);
+ c->k = GAEAD_KEY(a->c, buf_t, a->ksz);
+ IF_TRACING(T_CHAL, {
+ trace(T_CHAL, "chal: generated new challenge key");
+ trace_block(T_CRYPTO, "chal: new key", buf_t, a->ksz);
+ })
+ c->_b.tagsz = a->tsz;
+ return (&c->_b);
+}
+
+static int aead_chaltag(bulkchal *bc, const void *m, size_t msz,
+ uint32 seq, void *t)
+{
+ aead_chal *c = (aead_chal *)bc;
+ octet b[AEAD_NONCEMAX];
+ size_t nsz = keysz_pad(4, c->k->ops->c->noncesz);
+ size_t csz = 0;
+ int rc;
+
+ assert(nsz); assert(nsz <= sizeof(b));
+ memset(b, 0, nsz - 4); STORE32(b + nsz - 4, seq);
+ rc = gaead_encrypt(c->k, b, nsz, m, msz, 0, 0,
+ buf_t, &csz, t, c->_b.tagsz);
+ assert(!rc);
+ return (0);
+}
+
+static int aead_chalvrf(bulkchal *bc, const void *m, size_t msz,
+ uint32 seq, const void *t)
+{
+ aead_chal *c = (aead_chal *)bc;
+ octet b[AEAD_NONCEMAX];
+ size_t nsz = keysz(4, c->k->ops->c->noncesz);
+ size_t psz = 0;
+ int rc;
+
+ assert(nsz); assert(nsz <= sizeof(b));
+ memset(b, 0, nsz - 4); STORE32(b + nsz - 4, seq);
+ rc = gaead_decrypt(c->k, b, nsz, m, msz, 0, 0,
+ buf_t, &psz, t, c->_b.tagsz);
+ assert(rc >= 0);
+ return (rc == 1 ? 0 : -1);
+}
+
+static void aead_freechal(bulkchal *bc)
+ { aead_chal *c = (aead_chal *)bc; GAEAD_DESTROY(c->k); DESTROY(c); }
+
+static void aead_freealgs(bulkalgs *aa)
+ { aead_algs *a = (aead_algs *)aa; DESTROY(a); }
+
+static void aead_freectx(bulkctx *bbc)
+{
+ aead_ctx *bc = (aead_ctx *)bbc;
+ int i;
+
+ for (i = 0; i < NDIR; i++) { if (bc->d[i].k) GAEAD_DESTROY(bc->d[i].k); }
+ DESTROY(bc);
+}
+
+static void aead_fmtnonce(aead_ctx *bc, octet *n, uint32 seq, unsigned ty)
+{
+ assert(bc->nsz <= AEAD_NONCEMAX); assert(ty <= 255);
+ STORE32(n, seq);
+ switch (bc->nsz) {
+ case 5: STORE8(n + SEQSZ, ty); break;
+ case 6: STORE16(n + SEQSZ, ty); break;
+ case 7: STORE24(n + SEQSZ, ty); break;
+ default: memset(n + 8, 0, bc->nsz - 8); /* and continue */
+ case 8: STORE32(n + SEQSZ, ty); break;
+ }
+ TRACE_IV(n, bc->nsz);
+}
+
+static int aead_encrypt(bulkctx *bbc, unsigned ty,
+ buf *b, buf *bb, uint32 seq)
+{
+ aead_ctx *bc = (aead_ctx *)bbc;
+ const octet *p = BCUR(b);
+ gaead_key *k = bc->d[DIR_OUT].k;
+ size_t sz = BLEFT(b);
+ size_t csz = sz + k->ops->c->ohd;
+ octet *qmac, *qseq, *qpk;
+ octet n[AEAD_NONCEMAX];
+ int rc;
+
+ assert(k);
+
+ if (buf_ensure(bb, bc->tsz + SEQSZ + csz)) return (0);
+ qmac = BCUR(bb); qseq = qmac + bc->tsz; qpk = qseq + SEQSZ;
+ STORE32(qseq, seq);
+
+ aead_fmtnonce(bc, n, seq, ty);
+ rc = gaead_encrypt(k, n, bc->nsz, 0, 0, p, sz, qpk, &csz, qmac, bc->tsz);
+ assert(!rc);
+ BSTEP(bb, bc->tsz + SEQSZ + csz);
+ TRACE_CT(qpk, csz);
+ TRACE_MAC(qmac, bc->tsz);
+
+ return (0);
+}
+
+static int aead_decrypt(bulkctx *bbc, unsigned ty,
+ buf *b, buf *bb, uint32 *seq_out)
+{
+ aead_ctx *bc = (aead_ctx *)bbc;
+ gaead_key *k = bc->d[DIR_IN].k;
+ const octet *pmac, *pseq, *ppk;
+ uint32 seq;
+ size_t psz = BLEFT(b);
+ size_t sz;
+ octet *q = BCUR(bb);
+ octet n[AEAD_NONCEMAX];
+ int rc;
+
+ assert(k);
+
+ if (psz < bc->tsz + SEQSZ) {
+ T( trace(T_KEYSET, "keyset: block too small for keyset"); )
+ return (KSERR_MALFORMED);
+ }
+ sz = psz - bc->tsz - SEQSZ;
+ pmac = BCUR(b); pseq = pmac + bc->tsz; ppk = pseq + SEQSZ;
+ seq = LOAD32(pseq);
+
+ aead_fmtnonce(bc, n, seq, ty);
+ rc = gaead_decrypt(k, n, bc->nsz, 0, 0, ppk, sz, q, &sz, pmac, bc->tsz);
+ assert(rc >= 0);
+ if (!rc) { TRACE_MACERR(pmac, bc->tsz); return (KSERR_DECRYPT); }
+
+ *seq_out = seq;
+ BSTEP(bb, sz);
+ return (0);
+}
+
+/*----- The NaCl box transform --------------------------------------------*
+ *
+ * This transform is very similar to the NaCl `crypto_secretbox' transform
+ * described in Bernstein, `Cryptography in NaCl', with the difference that,
+ * rather than using XSalsa20, we use either Salsa20/r or ChaChar, because we
+ * have no need of XSalsa20's extended nonce. The default cipher is Salsa20.
+ *
+ * Salsa20 and ChaCha accept a 64-bit nonce. The low 32 bits are the
+ * sequence number, and the high 32 bits are the type, both big-endian.
+ *
+ * +--------+--------+
+ * | seq | type |
+ * +--------+--------+
+ * 32 32
+ *
+ * A stream is generated by concatenating the raw output blocks generated
+ * with this nonce and successive counter values starting from zero. The
+ * first 32 bytes of the stream are used as a key for Poly1305: the first 16
+ * bytes are the universal hash key r, and the second 16 bytes are the mask
+ * value s.
+ *
+ * +------+------+ +------...------+
+ * | r | s | | keystream |
+ * +------+------+ +------...------+
+ * 128 128 sz
+ *
+ * The remainder of the stream is XORed with the incoming plaintext to form a
+ * ciphertext with the same length. The ciphertext (only) is then tagged
+ * using Poly1305. The tag, sequence number, and ciphertext are concatenated
+ * in this order, and transmitted.
+ *
+ *
+ * +---...---+------+------...------+
+ * | tag | seq | ciphertext |
+ * +---...---+------+------...------+
+ * 128 32 sz
+ *
+ * Note that there is no need to authenticate the type separately, since it
+ * was used to select the cipher nonce, and hence the Poly1305 key. The
+ * Poly1305 tag length is fixed.
+ */
+
+typedef struct naclbox_algs {
+ aead_algs _b;
+ const gccipher *c;
+} naclbox_algs;
+
+static bulkalgs *naclbox_getalgs(const algswitch *asw, dstr *e,
+ key_file *kf, key *k)
+{
+ naclbox_algs *a = CREATE(naclbox_algs);
+ const char *p;
+ char *qq;
+ unsigned long n;
+
+ /* --- Collect the selected cipher and check that it's supported --- */
+
+ p = key_getattr(kf, k, "cipher");
+ if (!p || strcmp(p, "salsa20") == 0)
+ { a->_b.c = &salsa20_naclbox; a->c = &salsa20; }
+ else if (strcmp(p, "salsa20/12") == 0)
+ { a->_b.c = &salsa2012_naclbox; a->c = &salsa2012; }
+ else if (strcmp(p, "salsa20/8") == 0)
+ { a->_b.c = &salsa208_naclbox; a->c = &salsa208; }
+ else if (strcmp(p, "chacha20") == 0)
+ { a->_b.c = &chacha20_naclbox; a->c = &chacha20; }
+ else if (strcmp(p, "chacha12") == 0)
+ { a->_b.c = &chacha12_naclbox; a->c = &chacha12; }
+ else if (strcmp(p, "chacha8") == 0)
+ { a->_b.c = &chacha8_naclbox; a->c = &chacha8; }
+ else {
+ a_format(e, "unknown-cipher", "%s", p, A_END);
+ goto fail;
+ }
+ a->_b.nsz = 8;
+
+ /* --- Collect the selected MAC, and check the tag length --- */
+
+ p = key_getattr(kf, k, "mac");
+ if (!p)
+ ;
+ else if (strncmp(p, "poly1305", 8) != 0 || (p[8] && p[8] != '/')) {
+ a_format(e, "unknown-mac", "%s", p, A_END);
+ goto fail;
+ } else if (p[8] == '/') {
+ n = strtoul(p + 9, &qq, 0);
+ if (*qq) {
+ a_format(e, "bad-tag-length-string", "%s", p + 9, A_END);
+ goto fail;
+ }
+ if (n != 128) {
+ a_format(e, "bad-tag-length", "%lu", n, A_END);
+ goto fail;
+ }
+ }
+ a->_b.tsz = 16;
+
+ return (&a->_b._b);
+fail:
+ DESTROY(a);
+ return (0);
+}
+
+#ifndef NTRACE
+static void naclbox_tracealgs(const bulkalgs *aa)
+{
+ const naclbox_algs *a = (const naclbox_algs *)aa;
+
+ trace(T_CRYPTO, "crypto: cipher = %s", a->c->name);
+ trace(T_CRYPTO, "crypto: mac = poly1305/128");
+}
+#endif
+
+#define naclbox_checkalgs aead_checkalgs
+#define naclbox_samealgsp aead_samealgsp
+
+static void naclbox_alginfo(const bulkalgs *aa, admin *adm)
+{
+ const naclbox_algs *a = (const naclbox_algs *)aa;
+ a_info(adm, "cipher=%s", a->c->name, "cipher-keysz=32", A_END);
+ a_info(adm, "mac=poly1305", "mac-tagsz=16", A_END);
+}
+
+#define naclbox_overhead aead_overhead
+#define naclbox_expsz aead_expsz
+#define naclbox_genkeys aead_genkeys
+
+typedef struct naclbox_chal {
+ bulkchal _b;
+ gcipher *c;
+} naclbox_chal;
+
+static bulkchal *naclbox_genchal(const bulkalgs *aa)
+{
+ const naclbox_algs *a = (const naclbox_algs *)aa;
+ naclbox_chal *c = CREATE(naclbox_chal);
+ rand_get(RAND_GLOBAL, buf_t, a->_b.ksz);
+ c->c = GC_INIT(a->c, buf_t, a->_b.ksz);
+ IF_TRACING(T_CHAL, {
+ trace(T_CHAL, "chal: generated new challenge key");
+ trace_block(T_CRYPTO, "chal: new key", buf_t, a->_b.ksz);
+ })
+ c->_b.tagsz = POLY1305_TAGSZ;
+ return (&c->_b);
+}
+
+static int naclbox_chaltag(bulkchal *bc, const void *m, size_t msz,
+ uint32 seq, void *t)
+{
+ naclbox_chal *c = (naclbox_chal *)bc;
+ poly1305_key pk;
+ poly1305_ctx pm;
+ octet b[POLY1305_KEYSZ + POLY1305_MASKSZ];
+
+ STATIC_ASSERT(SALSA20_NONCESZ <= sizeof(b), "Need more space for nonce");
+
+ memset(b, 0, SALSA20_NONCESZ - 4); STORE32(b + SALSA20_NONCESZ - 4, seq);
+ GC_SETIV(c->c, b); GC_ENCRYPT(c->c, 0, b, sizeof(b));
+ poly1305_keyinit(&pk, b, POLY1305_KEYSZ);
+ poly1305_macinit(&pm, &pk, b + POLY1305_KEYSZ);
+ if (msz) poly1305_hash(&pm, m, msz);
+ poly1305_done(&pm, t);
+ return (0);
+}
+
+static int naclbox_chalvrf(bulkchal *bc, const void *m, size_t msz,
+ uint32 seq, const void *t)
+{
+ naclbox_chal *c = (naclbox_chal *)bc;
+ poly1305_key pk;
+ poly1305_ctx pm;
+ octet b[POLY1305_KEYSZ + POLY1305_MASKSZ];
+
+ STATIC_ASSERT(SALSA20_NONCESZ <= sizeof(b), "Need more space for nonce");
+ STATIC_ASSERT(POLY1305_TAGSZ <= sizeof(b), "Need more space for tag");
+
+ memset(b, 0, SALSA20_NONCESZ - 4); STORE32(b + SALSA20_NONCESZ - 4, seq);
+ GC_SETIV(c->c, b); GC_ENCRYPT(c->c, 0, b, sizeof(b));
+ poly1305_keyinit(&pk, b, POLY1305_KEYSZ);
+ poly1305_macinit(&pm, &pk, b + POLY1305_KEYSZ);
+ if (msz) poly1305_hash(&pm, m, msz);
+ poly1305_done(&pm, b);
+ return (ct_memeq(t, b, POLY1305_TAGSZ) ? 0 : -1);
+}
+
+static void naclbox_freechal(bulkchal *bc)
+ { naclbox_chal *c = (naclbox_chal *)bc; GC_DESTROY(c->c); DESTROY(c); }
+
+static void naclbox_freealgs(bulkalgs *aa)
+ { naclbox_algs *a = (naclbox_algs *)aa; DESTROY(a); }
+
+#define naclbox_freectx aead_freectx
+#define naclbox_encrypt aead_encrypt
+#define naclbox_decrypt aead_decrypt
+
~mdw / tripe / blobdiff