3 * Bulk crypto transformations
5 * (c) 2014 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of Trivial IP Encryption (TrIPE).
12 * TrIPE is free software: you can redistribute it and/or modify it under
13 * the terms of the GNU General Public License as published by the Free
14 * Software Foundation; either version 3 of the License, or (at your
15 * option) any later version.
17 * TrIPE is distributed in the hope that it will be useful, but WITHOUT
18 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
19 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
22 * You should have received a copy of the GNU General Public License
23 * along with TrIPE. If not, see <https://www.gnu.org/licenses/>.
26 /*----- Header files ------------------------------------------------------*/
30 /*----- Utilities ---------------------------------------------------------*/
32 #define SEQSZ 4 /* Size of sequence number packet */
34 #define TRACE_IV(qiv, ivsz) do { IF_TRACING(T_KEYSET, { \
35 trace_block(T_CRYPTO, "crypto: initialization vector", \
39 #define TRACE_CT(qpk, sz) do { IF_TRACING(T_KEYSET, { \
40 trace_block(T_CRYPTO, "crypto: encrypted packet", (qpk), (sz)); \
43 #define TRACE_MAC(qmac, tagsz) do { IF_TRACING(T_KEYSET, { \
44 trace_block(T_CRYPTO, "crypto: computed MAC", (qmac), (tagsz)); \
47 #define TRACE_MACERR(pmac, tagsz) do { IF_TRACING(T_KEYSET, { \
48 trace(T_KEYSET, "keyset: incorrect MAC: decryption failed"); \
49 trace_block(T_CRYPTO, "crypto: expected MAC", (pmac), (tagsz)); \
52 /* --- @derivekey@ --- *
54 * Arguments: @octet *k@ = pointer to an output buffer of at least
56 * @size_t ksz@ = actual size wanted (for tracing)
57 * @const deriveargs@ = derivation parameters, as passed into
59 * @int dir@ = direction for the key (@DIR_IN@ or @DIR_OUT@)
60 * @const char *what@ = label for the key (input to derivation)
64 * Use: Derives a session key, for use on incoming or outgoing data.
67 static void derivekey(octet
*k
, size_t ksz
, const deriveargs
*a
,
68 int dir
, const char *what
)
70 const gchash
*hc
= a
->hc
;
73 assert(ksz
<= hc
->hashsz
);
74 assert(hc
->hashsz
<= MAXHASHSZ
);
76 GH_HASH(h
, a
->what
, strlen(a
->what
)); GH_HASH(h
, what
, strlen(what
) + 1);
79 if (a
->x
) GH_HASH(h
, a
->k
, a
->x
);
80 if (a
->y
!= a
->x
) GH_HASH(h
, a
->k
+ a
->x
, a
->y
- a
->x
);
83 if (a
->y
!= a
->x
) GH_HASH(h
, a
->k
+ a
->x
, a
->y
- a
->x
);
84 if (a
->x
) GH_HASH(h
, a
->k
, a
->x
);
89 GH_HASH(h
, a
->k
+ a
->y
, a
->z
- a
->y
);
92 IF_TRACING(T_KEYSET
, { IF_TRACING(T_CRYPTO
, {
94 sprintf(_buf
, "crypto: %s key %s", dir ?
"outgoing" : "incoming", what
);
95 trace_block(T_CRYPTO
, _buf
, k
, ksz
);
99 /*----- Common functionality for generic-composition transforms -----------*/
101 #define CHECK_MAC(h, pmac, tagsz) do { \
103 const octet *_pmac = (pmac); \
104 size_t _tagsz = (tagsz); \
105 octet *_mac = GH_DONE(_h, 0); \
106 int _eq = ct_memeq(_mac, _pmac, _tagsz); \
107 TRACE_MAC(_mac, _tagsz); \
110 TRACE_MACERR(_pmac, _tagsz); \
111 return (KSERR_DECRYPT); \
115 typedef struct gencomp_algs
{
116 const gccipher
*c
; size_t cksz
;
117 const gcmac
*m
; size_t mksz
; size_t tagsz
;
120 typedef struct gencomp_chal
{
125 static int gencomp_getalgs(gencomp_algs
*a
, const algswitch
*asw
,
126 dstr
*e
, key_file
*kf
, key
*k
)
134 /* --- Symmetric encryption --- */
136 if ((p
= key_getattr(kf
, k
, "cipher")) == 0) p
= "blowfish-cbc";
137 if ((a
->c
= gcipher_byname(p
)) == 0) {
138 a_format(e
, "unknown-cipher", "%s", p
, A_END
);
142 /* --- Message authentication --- */
144 if ((p
= key_getattr(kf
, k
, "mac")) != 0) {
147 if ((q
= strrchr(d
.buf
, '/')) != 0)
149 if ((a
->m
= gmac_byname(d
.buf
)) == 0) {
150 a_format(e
, "unknown-mac", "%s", d
.buf
, A_END
);
154 a
->tagsz
= a
->m
->hashsz
;
156 n
= strtoul(q
, &qq
, 0);
158 a_format(e
, "bad-tag-length-string", "%s", q
, A_END
);
161 if (n
%8 || n
/8 > a
->m
->hashsz
) {
162 a_format(e
, "bad-tag-length", "%lu", n
, A_END
);
169 dstr_putf(&d
, "%s-hmac", asw
->h
->name
);
170 if ((a
->m
= gmac_byname(d
.buf
)) == 0) {
171 a_format(e
, "no-hmac-for-hash", "%s", asw
->h
->name
, A_END
);
174 a
->tagsz
= asw
->h
->hashsz
/2;
184 static void gencomp_tracealgs(const gencomp_algs
*a
)
186 trace(T_CRYPTO
, "crypto: cipher = %s", a
->c
->name
);
187 trace(T_CRYPTO
, "crypto: mac = %s/%lu",
188 a
->m
->name
, (unsigned long)a
->tagsz
* 8);
192 static int gencomp_checkalgs(gencomp_algs
*a
, const algswitch
*asw
, dstr
*e
)
194 /* --- Derive the key sizes --- *
196 * Must ensure that we have non-empty keys. This isn't ideal, but it
197 * provides a handy sanity check. Also must be based on a 64- or 128-bit
198 * block cipher or we can't do the data expiry properly.
201 if ((a
->cksz
= keysz(asw
->hashsz
, a
->c
->keysz
)) == 0) {
202 a_format(e
, "cipher", "%s", a
->c
->name
,
203 "no-key-size", "%lu", (unsigned long)asw
->hashsz
,
207 if ((a
->mksz
= keysz(asw
->hashsz
, a
->m
->keysz
)) == 0) {
208 a_format(e
, "mac", "%s", a
->m
->name
,
209 "no-key-size", "%lu", (unsigned long)asw
->hashsz
,
217 static void gencomp_alginfo(const gencomp_algs
*a
, admin
*adm
)
220 "cipher=%s", a
->c
->name
,
221 "cipher-keysz=%lu", (unsigned long)a
->cksz
,
222 "cipher-blksz=%lu", (unsigned long)a
->c
->blksz
,
225 "mac=%s", a
->m
->name
,
226 "mac-keysz=%lu", (unsigned long)a
->mksz
,
227 "mac-tagsz=%lu", (unsigned long)a
->tagsz
,
231 static int gencomp_samealgsp(const gencomp_algs
*a
, const gencomp_algs
*aa
)
233 return (a
->c
== aa
->c
&&
234 a
->m
== aa
->m
&& a
->tagsz
== aa
->tagsz
);
237 static size_t gencomp_expsz(const gencomp_algs
*a
)
238 { return (a
->c
->blksz
< 16 ?
MEG(64) : MEG(2048)); }
240 static bulkchal
*gencomp_genchal(const gencomp_algs
*a
)
242 gencomp_chal
*gc
= CREATE(gencomp_chal
);
244 rand_get(RAND_GLOBAL
, buf_t
, a
->mksz
);
245 gc
->m
= GM_KEY(a
->m
, buf_t
, a
->mksz
);
246 gc
->_b
.tagsz
= a
->tagsz
;
248 trace(T_CHAL
, "chal: generated new challenge key");
249 trace_block(T_CRYPTO
, "chal: new key", buf_t
, a
->mksz
);
254 static int gencomp_chaltag(bulkchal
*bc
, const void *m
, size_t msz
,
257 gencomp_chal
*gc
= (gencomp_chal
*)bc
;
258 ghash
*h
= GM_INIT(gc
->m
);
260 GH_HASHU32(h
, seq
); if (msz
) GH_HASH(h
, m
, msz
);
261 memcpy(t
, GH_DONE(h
, 0), bc
->tagsz
);
266 static int gencomp_chalvrf(bulkchal
*bc
, const void *m
, size_t msz
,
267 uint32 seq
, const void *t
)
269 gencomp_chal
*gc
= (gencomp_chal
*)bc
;
270 ghash
*h
= GM_INIT(gc
->m
);
273 GH_HASHU32(h
, seq
); if (msz
) GH_HASH(h
, m
, msz
);
274 ok
= ct_memeq(GH_DONE(h
, 0), t
, gc
->_b
.tagsz
);
276 return (ok ?
0 : -1);
279 static void gencomp_freechal(bulkchal
*bc
)
280 { gencomp_chal
*gc
= (gencomp_chal
*)bc
; GM_DESTROY(gc
->m
); DESTROY(gc
); }
282 /*----- The original transform --------------------------------------------*
284 * We generate a random initialization vector (if the cipher needs one). We
285 * encrypt the input message with the cipher, and format the type, sequence
286 * number, IV, and ciphertext as follows.
288 * +------+ +------+---...---+------...------+
289 * | type | | seq | iv | ciphertext |
290 * +------+ +------+---...---+------...------+
293 * All of this is fed into the MAC to compute a tag. The type is not
294 * transmitted: the other end knows what type of message it expects, and the
295 * type is only here to prevent us from being confused because some other
296 * kind of ciphertext has been substituted. The tag is prepended to the
297 * remainder, to yield the finished cryptogram, as follows.
299 * +---...---+------+---...---+------...------+
300 * | tag | seq | iv | ciphertext |
301 * +---...---+------+---...---+------...------+
304 * Decryption: checks the overall size, verifies the tag, then decrypts the
305 * ciphertext and extracts the sequence number.
308 typedef struct v0_algs
{
313 typedef struct v0_ctx
{
322 static bulkalgs
*v0_getalgs(const algswitch
*asw
, dstr
*e
,
323 key_file
*kf
, key
*k
)
325 v0_algs
*a
= CREATE(v0_algs
);
326 if (gencomp_getalgs(&a
->ga
, asw
, e
, kf
, k
)) { DESTROY(a
); return (0); }
331 static void v0_tracealgs(const bulkalgs
*aa
)
332 { const v0_algs
*a
= (const v0_algs
*)aa
; gencomp_tracealgs(&a
->ga
); }
335 static int v0_checkalgs(bulkalgs
*aa
, const algswitch
*asw
, dstr
*e
)
337 v0_algs
*a
= (v0_algs
*)aa
;
338 if (gencomp_checkalgs(&a
->ga
, asw
, e
)) return (-1);
342 static int v0_samealgsp(const bulkalgs
*aa
, const bulkalgs
*bb
)
344 const v0_algs
*a
= (const v0_algs
*)aa
, *b
= (const v0_algs
*)bb
;
345 return (gencomp_samealgsp(&a
->ga
, &b
->ga
));
348 static void v0_alginfo(const bulkalgs
*aa
, admin
*adm
)
349 { const v0_algs
*a
= (const v0_algs
*)aa
; gencomp_alginfo(&a
->ga
, adm
); }
351 static size_t v0_overhead(const bulkalgs
*aa
)
353 const v0_algs
*a
= (const v0_algs
*)aa
;
354 return (a
->ga
.tagsz
+ SEQSZ
+ a
->ga
.c
->blksz
);
357 static size_t v0_expsz(const bulkalgs
*aa
)
358 { const v0_algs
*a
= (const v0_algs
*)aa
; return (gencomp_expsz(&a
->ga
)); }
360 static bulkctx
*v0_genkeys(const bulkalgs
*aa
, const deriveargs
*da
)
362 const v0_algs
*a
= (const v0_algs
*)aa
;
363 v0_ctx
*bc
= CREATE(v0_ctx
);
367 bc
->tagsz
= a
->ga
.tagsz
;
368 for (i
= 0; i
< NDIR
; i
++) {
369 if (!(da
->f
&(1 << i
))) { bc
->d
[i
].c
= 0; bc
->d
[i
].m
= 0; continue; }
370 derivekey(k
, a
->ga
.cksz
, da
, i
, "encryption");
371 bc
->d
[i
].c
= GC_INIT(a
->ga
.c
, k
, a
->ga
.cksz
);
372 derivekey(k
, a
->ga
.mksz
, da
, i
, "integrity");
373 bc
->d
[i
].m
= GM_KEY(a
->ga
.m
, k
, a
->ga
.mksz
);
378 static bulkchal
*v0_genchal(const bulkalgs
*aa
)
380 const v0_algs
*a
= (const v0_algs
*)aa
;
381 return (gencomp_genchal(&a
->ga
));
383 #define v0_chaltag gencomp_chaltag
384 #define v0_chalvrf gencomp_chalvrf
385 #define v0_freechal gencomp_freechal
387 static void v0_freealgs(bulkalgs
*aa
)
388 { v0_algs
*a
= (v0_algs
*)aa
; DESTROY(a
); }
390 static void v0_freectx(bulkctx
*bbc
)
392 v0_ctx
*bc
= (v0_ctx
*)bbc
;
395 for (i
= 0; i
< NDIR
; i
++) {
396 if (bc
->d
[i
].c
) GC_DESTROY(bc
->d
[i
].c
);
397 if (bc
->d
[i
].m
) GM_DESTROY(bc
->d
[i
].m
);
402 static int v0_encrypt(bulkctx
*bbc
, unsigned ty
,
403 buf
*b
, buf
*bb
, uint32 seq
)
405 v0_ctx
*bc
= (v0_ctx
*)bbc
;
407 gcipher
*c
= bc
->d
[DIR_OUT
].c
;
408 const octet
*p
= BCUR(b
);
409 size_t sz
= BLEFT(b
);
410 octet
*qmac
, *qseq
, *qiv
, *qpk
;
412 size_t tagsz
= bc
->tagsz
;
416 ivsz
= GC_CLASS(c
)->blksz
;
418 /* --- Determine the ciphertext layout --- */
420 if (buf_ensure(bb
, tagsz
+ SEQSZ
+ ivsz
+ sz
)) return (0);
421 qmac
= BCUR(bb
); qseq
= qmac
+ tagsz
; qiv
= qseq
+ SEQSZ
; qpk
= qiv
+ ivsz
;
422 BSTEP(bb
, tagsz
+ SEQSZ
+ ivsz
+ sz
);
424 /* --- Store the type --- *
426 * This isn't transmitted, but it's covered by the MAC.
431 /* --- Store the sequence number --- */
435 /* --- Establish an initialization vector if necessary --- */
438 rand_get(RAND_GLOBAL
, qiv
, ivsz
);
443 /* --- Encrypt the packet --- */
445 GC_ENCRYPT(c
, p
, qpk
, sz
);
448 /* --- Compute a MAC over type, sequence number, IV, and ciphertext --- */
451 h
= GM_INIT(bc
->d
[DIR_OUT
].m
);
452 GH_HASH(h
, t
, sizeof(t
));
453 GH_HASH(h
, qseq
, SEQSZ
+ ivsz
+ sz
);
454 memcpy(qmac
, GH_DONE(h
, 0), tagsz
);
456 TRACE_MAC(qmac
, tagsz
);
459 /* --- We're done --- */
464 static int v0_decrypt(bulkctx
*bbc
, unsigned ty
,
465 buf
*b
, buf
*bb
, uint32
*seq
)
467 v0_ctx
*bc
= (v0_ctx
*)bbc
;
468 const octet
*pmac
, *piv
, *pseq
, *ppk
;
469 size_t psz
= BLEFT(b
);
473 gcipher
*c
= bc
->d
[DIR_IN
].c
;
475 size_t tagsz
= bc
->tagsz
;
479 ivsz
= GC_CLASS(c
)->blksz
;
481 /* --- Break up the packet into its components --- */
483 if (psz
< ivsz
+ SEQSZ
+ tagsz
) {
484 T( trace(T_KEYSET
, "keyset: block too small for keyset"); )
485 return (KSERR_MALFORMED
);
487 sz
= psz
- ivsz
- SEQSZ
- tagsz
;
488 pmac
= BCUR(b
); pseq
= pmac
+ tagsz
; piv
= pseq
+ SEQSZ
; ppk
= piv
+ ivsz
;
491 /* --- Verify the MAC on the packet --- */
494 h
= GM_INIT(bc
->d
[DIR_IN
].m
);
495 GH_HASH(h
, t
, sizeof(t
));
496 GH_HASH(h
, pseq
, SEQSZ
+ ivsz
+ sz
);
497 CHECK_MAC(h
, pmac
, tagsz
);
500 /* --- Decrypt the packet --- */
506 GC_DECRYPT(c
, ppk
, q
, sz
);
508 /* --- Finished --- */
515 /*----- The implicit-IV transform -----------------------------------------*
517 * The v0 transform makes everything explicit. There's an IV because the
518 * cipher needs an IV; there's a sequence number because replay prevention
519 * needs a sequence number.
521 * This new transform works rather differently. We make use of a block
522 * cipher to encrypt the sequence number, and use that as the IV. We
523 * transmit the sequence number in the clear, as before. This reduces
524 * overhead; and it's not a significant privacy leak because the adversary
525 * can see the order in which the messages are transmitted -- i.e., the
526 * sequence numbers are almost completely predictable anyway.
528 * So, a MAC is computed over
530 * +------+ +------+------...------+
531 * | type | | seq | ciphertext |
532 * +------+ +------+------...------+
535 * and we actually transmit the following as the cryptogram.
537 * +---...---+------+------...------+
538 * | tag | seq | ciphertext |
539 * +---...---+------+------...------+
543 typedef struct iiv_algs
{
546 const gccipher
*b
; size_t bksz
;
549 typedef struct iiv_ctx
{
559 static bulkalgs
*iiv_getalgs(const algswitch
*asw
, dstr
*e
,
560 key_file
*kf
, key
*k
)
562 iiv_algs
*a
= CREATE(iiv_algs
);
563 dstr d
= DSTR_INIT
, dd
= DSTR_INIT
;
567 if (gencomp_getalgs(&a
->ga
, asw
, e
, kf
, k
)) goto fail
;
569 if ((p
= key_getattr(kf
, k
, "blkc")) == 0) {
570 dstr_puts(&dd
, a
->ga
.c
->name
);
571 if ((q
= strrchr(dd
.buf
, '-')) != 0) *q
= 0;
574 dstr_putf(&d
, "%s-ecb", p
);
575 if ((a
->b
= gcipher_byname(d
.buf
)) == 0) {
576 a_format(e
, "unknown-blkc", "%s", p
, A_END
);
580 dstr_destroy(&d
); dstr_destroy(&dd
);
583 dstr_destroy(&d
); dstr_destroy(&dd
);
589 static void iiv_tracealgs(const bulkalgs
*aa
)
591 const iiv_algs
*a
= (const iiv_algs
*)aa
;
593 gencomp_tracealgs(&a
->ga
);
595 "crypto: blkc = %.*s", (int)strlen(a
->b
->name
) - 4, a
->b
->name
);
599 static int iiv_checkalgs(bulkalgs
*aa
, const algswitch
*asw
, dstr
*e
)
601 iiv_algs
*a
= (iiv_algs
*)aa
;
603 if (gencomp_checkalgs(&a
->ga
, asw
, e
)) return (-1);
605 if ((a
->bksz
= keysz(asw
->hashsz
, a
->b
->keysz
)) == 0) {
606 a_format(e
, "blkc", "%.*s", strlen(a
->b
->name
) - 4, a
->b
->name
,
607 "no-key-size", "%lu", (unsigned long)asw
->hashsz
,
611 if (a
->b
->blksz
< a
->ga
.c
->blksz
) {
612 a_format(e
, "blkc", "%.*s", strlen(a
->b
->name
) - 4, a
->b
->name
,
613 "blksz-insufficient", A_END
);
619 static int iiv_samealgsp(const bulkalgs
*aa
, const bulkalgs
*bb
)
621 const iiv_algs
*a
= (const iiv_algs
*)aa
, *b
= (const iiv_algs
*)bb
;
622 return (gencomp_samealgsp(&a
->ga
, &b
->ga
) && a
->b
== b
->b
);
625 static void iiv_alginfo(const bulkalgs
*aa
, admin
*adm
)
627 const iiv_algs
*a
= (const iiv_algs
*)aa
;
628 gencomp_alginfo(&a
->ga
, adm
);
630 "blkc=%.*s", strlen(a
->b
->name
) - 4, a
->b
->name
,
631 "blkc-keysz=%lu", (unsigned long)a
->bksz
,
632 "blkc-blksz=%lu", (unsigned long)a
->b
->blksz
,
636 static size_t iiv_overhead(const bulkalgs
*aa
)
637 { const iiv_algs
*a
= (const iiv_algs
*)aa
; return (a
->ga
.tagsz
+ SEQSZ
); }
639 static size_t iiv_expsz(const bulkalgs
*aa
)
641 const iiv_algs
*a
= (const iiv_algs
*)aa
;
642 return (gencomp_expsz(&a
->ga
));
645 static bulkctx
*iiv_genkeys(const bulkalgs
*aa
, const deriveargs
*da
)
647 const iiv_algs
*a
= (const iiv_algs
*)aa
;
648 iiv_ctx
*bc
= CREATE(iiv_ctx
);
652 bc
->tagsz
= a
->ga
.tagsz
;
653 for (i
= 0; i
< NDIR
; i
++) {
654 if (!(da
->f
&(1 << i
)))
655 { bc
->d
[i
].c
= 0; bc
->d
[i
].b
= 0; bc
->d
[i
].m
= 0; continue; }
656 derivekey(k
, a
->ga
.cksz
, da
, i
, "encryption");
657 bc
->d
[i
].c
= GC_INIT(a
->ga
.c
, k
, a
->ga
.cksz
);
658 derivekey(k
, a
->bksz
, da
, i
, "blkc");
659 bc
->d
[i
].b
= GC_INIT(a
->b
, k
, a
->bksz
);
660 derivekey(k
, a
->ga
.mksz
, da
, i
, "integrity");
661 bc
->d
[i
].m
= GM_KEY(a
->ga
.m
, k
, a
->ga
.mksz
);
666 static bulkchal
*iiv_genchal(const bulkalgs
*aa
)
668 const iiv_algs
*a
= (const iiv_algs
*)aa
;
669 return (gencomp_genchal(&a
->ga
));
671 #define iiv_chaltag gencomp_chaltag
672 #define iiv_chalvrf gencomp_chalvrf
673 #define iiv_freechal gencomp_freechal
675 static void iiv_freealgs(bulkalgs
*aa
)
676 { iiv_algs
*a
= (iiv_algs
*)aa
; DESTROY(a
); }
678 static void iiv_freectx(bulkctx
*bbc
)
680 iiv_ctx
*bc
= (iiv_ctx
*)bbc
;
683 for (i
= 0; i
< NDIR
; i
++) {
684 if (bc
->d
[i
].c
) GC_DESTROY(bc
->d
[i
].c
);
685 if (bc
->d
[i
].b
) GC_DESTROY(bc
->d
[i
].b
);
686 if (bc
->d
[i
].m
) GM_DESTROY(bc
->d
[i
].m
);
691 #define TRACE_PRESEQ(qseq, ivsz) do { IF_TRACING(T_KEYSET, { \
692 trace_block(T_CRYPTO, "crypto: IV derivation input", (qseq), (ivsz)); \
695 static int iiv_encrypt(bulkctx
*bbc
, unsigned ty
,
696 buf
*b
, buf
*bb
, uint32 seq
)
698 iiv_ctx
*bc
= (iiv_ctx
*)bbc
;
700 gcipher
*c
= bc
->d
[DIR_OUT
].c
, *blkc
= bc
->d
[DIR_OUT
].b
;
701 const octet
*p
= BCUR(b
);
702 size_t sz
= BLEFT(b
);
703 octet
*qmac
, *qseq
, *qpk
;
705 size_t tagsz
= bc
->tagsz
;
708 assert(c
); assert(blkc
);
709 ivsz
= GC_CLASS(c
)->blksz
;
710 blkcsz
= GC_CLASS(blkc
)->blksz
;
712 /* --- Determine the ciphertext layout --- */
714 if (buf_ensure(bb
, tagsz
+ SEQSZ
+ sz
)) return (0);
715 qmac
= BCUR(bb
); qseq
= qmac
+ tagsz
; qpk
= qseq
+ SEQSZ
;
716 BSTEP(bb
, tagsz
+ SEQSZ
+ sz
);
718 /* --- Store the type --- *
720 * This isn't transmitted, but it's covered by the MAC.
725 /* --- Store the sequence number --- */
729 /* --- Establish an initialization vector if necessary --- */
732 memset(buf_u
, 0, blkcsz
- SEQSZ
);
733 memcpy(buf_u
+ blkcsz
- SEQSZ
, qseq
, SEQSZ
);
734 TRACE_PRESEQ(buf_u
, ivsz
);
735 GC_ENCRYPT(blkc
, buf_u
, buf_u
, blkcsz
);
737 TRACE_IV(buf_u
, ivsz
);
740 /* --- Encrypt the packet --- */
742 GC_ENCRYPT(c
, p
, qpk
, sz
);
745 /* --- Compute a MAC over type, sequence number, and ciphertext --- */
748 h
= GM_INIT(bc
->d
[DIR_OUT
].m
);
749 GH_HASH(h
, t
, sizeof(t
));
750 GH_HASH(h
, qseq
, SEQSZ
+ sz
);
751 memcpy(qmac
, GH_DONE(h
, 0), tagsz
);
753 TRACE_MAC(qmac
, tagsz
);
756 /* --- We're done --- */
761 static int iiv_decrypt(bulkctx
*bbc
, unsigned ty
,
762 buf
*b
, buf
*bb
, uint32
*seq
)
764 iiv_ctx
*bc
= (iiv_ctx
*)bbc
;
765 const octet
*pmac
, *pseq
, *ppk
;
766 size_t psz
= BLEFT(b
);
770 gcipher
*c
= bc
->d
[DIR_IN
].c
, *blkc
= bc
->d
[DIR_IN
].b
;
772 size_t tagsz
= bc
->tagsz
;
775 assert(c
); assert(blkc
);
776 ivsz
= GC_CLASS(c
)->blksz
;
777 blkcsz
= GC_CLASS(blkc
)->blksz
;
779 /* --- Break up the packet into its components --- */
781 if (psz
< SEQSZ
+ tagsz
) {
782 T( trace(T_KEYSET
, "keyset: block too small for keyset"); )
783 return (KSERR_MALFORMED
);
785 sz
= psz
- SEQSZ
- tagsz
;
786 pmac
= BCUR(b
); pseq
= pmac
+ tagsz
; ppk
= pseq
+ SEQSZ
;
789 /* --- Verify the MAC on the packet --- */
792 h
= GM_INIT(bc
->d
[DIR_IN
].m
);
793 GH_HASH(h
, t
, sizeof(t
));
794 GH_HASH(h
, pseq
, SEQSZ
+ sz
);
795 CHECK_MAC(h
, pmac
, tagsz
);
798 /* --- Decrypt the packet --- */
801 memset(buf_u
, 0, blkcsz
- SEQSZ
);
802 memcpy(buf_u
+ blkcsz
- SEQSZ
, pseq
, SEQSZ
);
803 TRACE_PRESEQ(buf_u
, ivsz
);
804 GC_ENCRYPT(blkc
, buf_u
, buf_u
, blkcsz
);
806 TRACE_IV(buf_u
, ivsz
);
808 GC_DECRYPT(c
, ppk
, q
, sz
);
810 /* --- Finished --- */
817 /*----- The NaCl box transform --------------------------------------------*
819 * This transform is very similar to the NaCl `crypto_secretbox' transform
820 * described in Bernstein, `Cryptography in NaCl', with the difference that,
821 * rather than using XSalsa20, we use either Salsa20/r or ChaChar, because we
822 * have no need of XSalsa20's extended nonce. The default cipher is Salsa20.
824 * Salsa20 and ChaCha accept a 64-bit nonce. The low 32 bits are the
825 * sequence number, and the high 32 bits are the type, both big-endian.
832 * A stream is generated by concatenating the raw output blocks generated
833 * with this nonce and successive counter values starting from zero. The
834 * first 32 bytes of the stream are used as a key for Poly1305: the first 16
835 * bytes are the universal hash key r, and the second 16 bytes are the mask
838 * +------+------+ +------...------+
839 * | r | s | | keystream |
840 * +------+------+ +------...------+
843 * The remainder of the stream is XORed with the incoming plaintext to form a
844 * ciphertext with the same length. The ciphertext (only) is then tagged
845 * using Poly1305. The tag, sequence number, and ciphertext are concatenated
846 * in this order, and transmitted.
849 * +---...---+------+------...------+
850 * | tag | seq | ciphertext |
851 * +---...---+------+------...------+
854 * Note that there is no need to authenticate the type separately, since it
855 * was used to select the cipher nonce, and hence the Poly1305 key. The
856 * Poly1305 tag length is fixed.
859 typedef struct naclbox_algs
{
861 const gccipher
*c
; size_t cksz
;
864 typedef struct naclbox_ctx
{
866 struct { gcipher
*c
; } d
[NDIR
];
870 static bulkalgs
*naclbox_getalgs(const algswitch
*asw
, dstr
*e
,
871 key_file
*kf
, key
*k
)
873 naclbox_algs
*a
= CREATE(naclbox_algs
);
878 /* --- Collect the selected cipher and check that it's supported --- */
880 p
= key_getattr(kf
, k
, "cipher");
881 if (!p
|| strcmp(p
, "salsa20") == 0) a
->c
= &salsa20
;
882 else if (strcmp(p
, "salsa20/12") == 0) a
->c
= &salsa2012
;
883 else if (strcmp(p
, "salsa20/8") == 0) a
->c
= &salsa208
;
884 else if (strcmp(p
, "chacha20") == 0) a
->c
= &chacha20
;
885 else if (strcmp(p
, "chacha12") == 0) a
->c
= &chacha12
;
886 else if (strcmp(p
, "chacha8") == 0) a
->c
= &chacha8
;
888 a_format(e
, "unknown-cipher", "%s", p
, A_END
);
892 /* --- Collect the selected MAC, and check the tag length --- */
894 p
= key_getattr(kf
, k
, "mac");
897 else if (strncmp(p
, "poly1305", 8) != 0 || (p
[8] && p
[8] != '/')) {
898 a_format(e
, "unknown-mac", "%s", p
, A_END
);
900 } else if (p
[8] == '/') {
901 n
= strtoul(p
+ 9, &qq
, 0);
903 a_format(e
, "bad-tag-length-string", "%s", p
+ 9, A_END
);
907 a_format(e
, "bad-tag-length", "%lu", n
, A_END
);
919 static void naclbox_tracealgs(const bulkalgs
*aa
)
921 const naclbox_algs
*a
= (const naclbox_algs
*)aa
;
923 trace(T_CRYPTO
, "crypto: cipher = %s", a
->c
->name
);
924 trace(T_CRYPTO
, "crypto: mac = poly1305/128");
928 static int naclbox_checkalgs(bulkalgs
*aa
, const algswitch
*asw
, dstr
*e
)
930 naclbox_algs
*a
= (naclbox_algs
*)aa
;
932 if ((a
->cksz
= keysz(asw
->hashsz
, a
->c
->keysz
)) == 0) {
933 a_format(e
, "cipher", "%s", a
->c
->name
,
934 "no-key-size", "%lu", (unsigned long)asw
->hashsz
,
941 static int naclbox_samealgsp(const bulkalgs
*aa
, const bulkalgs
*bb
)
943 const naclbox_algs
*a
= (const naclbox_algs
*)aa
,
944 *b
= (const naclbox_algs
*)bb
;
945 return (a
->c
== b
->c
);
948 static void naclbox_alginfo(const bulkalgs
*aa
, admin
*adm
)
950 const naclbox_algs
*a
= (const naclbox_algs
*)aa
;
951 a_info(adm
, "cipher=%s", a
->c
->name
, "cipher-keysz=32", A_END
);
952 a_info(adm
, "mac=poly1305", "mac-tagsz=16", A_END
);
955 static size_t naclbox_overhead(const bulkalgs
*aa
)
956 { return (POLY1305_TAGSZ
+ SEQSZ
); }
958 static size_t naclbox_expsz(const bulkalgs
*aa
)
959 { return (MEG(2048)); }
961 static bulkctx
*naclbox_genkeys(const bulkalgs
*aa
, const deriveargs
*da
)
963 const naclbox_algs
*a
= (const naclbox_algs
*)aa
;
964 naclbox_ctx
*bc
= CREATE(naclbox_ctx
);
968 for (i
= 0; i
< NDIR
; i
++) {
969 if (!(da
->f
&(1 << i
))) { bc
->d
[i
].c
= 0; continue; }
970 derivekey(k
, a
->cksz
, da
, i
, "encryption");
971 bc
->d
[i
].c
= GC_INIT(a
->c
, k
, a
->cksz
);
976 typedef struct naclbox_chal
{
981 static bulkchal
*naclbox_genchal(const bulkalgs
*aa
)
983 const naclbox_algs
*a
= (const naclbox_algs
*)aa
;
984 naclbox_chal
*c
= CREATE(naclbox_chal
);
985 rand_get(RAND_GLOBAL
, buf_t
, a
->cksz
);
986 c
->c
= GC_INIT(a
->c
, buf_t
, a
->cksz
);
988 trace(T_CHAL
, "chal: generated new challenge key");
989 trace_block(T_CRYPTO
, "chal: new key", buf_t
, a
->cksz
);
991 c
->_b
.tagsz
= POLY1305_TAGSZ
;
995 static int naclbox_chaltag(bulkchal
*bc
, const void *m
, size_t msz
,
998 naclbox_chal
*c
= (naclbox_chal
*)bc
;
1001 octet b
[POLY1305_KEYSZ
+ POLY1305_MASKSZ
];
1003 assert(SALSA20_NONCESZ
<= sizeof(b
));
1004 memset(b
, 0, SALSA20_NONCESZ
- 4); STORE32(b
+ SALSA20_NONCESZ
- 4, seq
);
1005 GC_SETIV(c
->c
, b
); GC_ENCRYPT(c
->c
, 0, b
, sizeof(b
));
1006 poly1305_keyinit(&pk
, b
, POLY1305_KEYSZ
);
1007 poly1305_macinit(&pm
, &pk
, b
+ POLY1305_KEYSZ
);
1008 if (msz
) poly1305_hash(&pm
, m
, msz
);
1009 poly1305_done(&pm
, t
);
1013 static int naclbox_chalvrf(bulkchal
*bc
, const void *m
, size_t msz
,
1014 uint32 seq
, const void *t
)
1016 naclbox_chal
*c
= (naclbox_chal
*)bc
;
1019 octet b
[POLY1305_KEYSZ
+ POLY1305_MASKSZ
];
1021 assert(SALSA20_NONCESZ
<= sizeof(b
));
1022 memset(b
, 0, SALSA20_NONCESZ
- 4); STORE32(b
+ SALSA20_NONCESZ
- 4, seq
);
1023 GC_SETIV(c
->c
, b
); GC_ENCRYPT(c
->c
, 0, b
, sizeof(b
));
1024 poly1305_keyinit(&pk
, b
, POLY1305_KEYSZ
);
1025 poly1305_macinit(&pm
, &pk
, b
+ POLY1305_KEYSZ
);
1026 if (msz
) poly1305_hash(&pm
, m
, msz
);
1027 assert(POLY1305_TAGSZ
<= sizeof(b
)); poly1305_done(&pm
, b
);
1028 return (ct_memeq(t
, b
, POLY1305_TAGSZ
) ?
0 : -1);
1031 static void naclbox_freechal(bulkchal
*bc
)
1032 { naclbox_chal
*c
= (naclbox_chal
*)bc
; GC_DESTROY(c
->c
); DESTROY(c
); }
1034 static void naclbox_freealgs(bulkalgs
*aa
)
1035 { naclbox_algs
*a
= (naclbox_algs
*)aa
; DESTROY(a
); }
1037 static void naclbox_freectx(bulkctx
*bbc
)
1039 naclbox_ctx
*bc
= (naclbox_ctx
*)bbc
;
1042 for (i
= 0; i
< NDIR
; i
++) { if (bc
->d
[i
].c
) GC_DESTROY(bc
->d
[i
].c
); }
1046 static int naclbox_encrypt(bulkctx
*bbc
, unsigned ty
,
1047 buf
*b
, buf
*bb
, uint32 seq
)
1049 naclbox_ctx
*bc
= (naclbox_ctx
*)bbc
;
1050 gcipher
*c
= bc
->d
[DIR_OUT
].c
;
1053 const octet
*p
= BCUR(b
);
1054 size_t sz
= BLEFT(b
);
1055 octet
*qmac
, *qseq
, *qpk
;
1059 /* --- Determine the ciphertext layout --- */
1061 if (buf_ensure(bb
, POLY1305_TAGSZ
+ SEQSZ
+ sz
)) return (0);
1062 qmac
= BCUR(bb
); qseq
= qmac
+ POLY1305_TAGSZ
; qpk
= qseq
+ SEQSZ
;
1063 BSTEP(bb
, POLY1305_TAGSZ
+ SEQSZ
+ sz
);
1065 /* --- Construct and set the nonce --- */
1068 memcpy(buf_u
, qseq
, SEQSZ
); STORE32(buf_u
+ SEQSZ
, ty
);
1070 TRACE_IV(buf_u
, SALSA20_NONCESZ
);
1072 /* --- Determine the MAC key --- */
1074 GC_ENCRYPT(c
, 0, buf_u
, POLY1305_KEYSZ
+ POLY1305_MASKSZ
);
1075 poly1305_keyinit(&polyk
, buf_u
, POLY1305_KEYSZ
);
1076 poly1305_macinit(&poly
, &polyk
, buf_u
+ POLY1305_KEYSZ
);
1078 /* --- Encrypt the message --- */
1080 GC_ENCRYPT(c
, p
, qpk
, sz
);
1083 /* --- Compute the MAC --- */
1085 poly1305_hash(&poly
, qpk
, sz
);
1086 poly1305_done(&poly
, qmac
);
1087 TRACE_MAC(qmac
, POLY1305_TAGSZ
);
1089 /* --- We're done --- */
1094 static int naclbox_decrypt(bulkctx
*bbc
, unsigned ty
,
1095 buf
*b
, buf
*bb
, uint32
*seq
)
1097 naclbox_ctx
*bc
= (naclbox_ctx
*)bbc
;
1098 gcipher
*c
= bc
->d
[DIR_IN
].c
;
1101 const octet
*pmac
, *pseq
, *ppk
;
1102 size_t psz
= BLEFT(b
);
1104 octet
*q
= BCUR(bb
);
1108 /* --- Break up the packet into its components --- */
1110 if (psz
< SEQSZ
+ POLY1305_TAGSZ
) {
1111 T( trace(T_KEYSET
, "keyset: block too small for keyset"); )
1112 return (KSERR_MALFORMED
);
1114 sz
= psz
- SEQSZ
- POLY1305_TAGSZ
;
1115 pmac
= BCUR(b
); pseq
= pmac
+ POLY1305_TAGSZ
; ppk
= pseq
+ SEQSZ
;
1117 /* --- Construct and set the nonce --- */
1119 memcpy(buf_u
, pseq
, SEQSZ
); STORE32(buf_u
+ SEQSZ
, ty
);
1121 TRACE_IV(buf_u
, SALSA20_NONCESZ
);
1123 /* --- Determine the MAC key --- */
1125 GC_ENCRYPT(c
, 0, buf_u
, POLY1305_KEYSZ
+ POLY1305_MASKSZ
);
1126 poly1305_keyinit(&polyk
, buf_u
, POLY1305_KEYSZ
);
1127 poly1305_macinit(&poly
, &polyk
, buf_u
+ POLY1305_KEYSZ
);
1129 /* --- Verify the MAC on the packet --- */
1131 poly1305_hash(&poly
, ppk
, sz
);
1132 poly1305_done(&poly
, buf_u
);
1133 TRACE_MAC(buf_u
, POLY1305_TAGSZ
);
1134 if (!ct_memeq(buf_u
, pmac
, POLY1305_TAGSZ
)) {
1135 TRACE_MACERR(pmac
, POLY1305_TAGSZ
);
1136 return (KSERR_DECRYPT
);
1139 /* --- Decrypt the packet --- */
1141 GC_DECRYPT(c
, ppk
, q
, sz
);
1143 /* --- Finished --- */
1145 *seq
= LOAD32(pseq
);
1150 /*----- Bulk crypto transform table ---------------------------------------*/
1152 const bulkops bulktab
[] = {
1156 #define BULK(name, pre) \
1157 { name, pre##_getalgs, T( pre##_tracealgs COMMA ) \
1158 pre##_checkalgs, pre##_samealgsp, \
1159 pre##_alginfo, pre##_overhead, pre##_expsz, \
1160 pre##_genkeys, pre##_genchal, pre##_freealgs, \
1161 pre##_encrypt, pre##_decrypt, pre##_freectx, \
1162 pre##_chaltag, pre##_chalvrf, pre##_freechal }
1166 BULK("naclbox", naclbox
),
1172 /*----- That's all, folks -------------------------------------------------*/