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
, void *t
)
256 gencomp_chal
*gc
= (gencomp_chal
*)bc
;
257 ghash
*h
= GM_INIT(gc
->m
);
260 memcpy(t
, GH_DONE(h
, 0), bc
->tagsz
);
265 static int gencomp_chalvrf(bulkchal
*bc
, const void *m
, size_t msz
,
268 gencomp_chal
*gc
= (gencomp_chal
*)bc
;
269 ghash
*h
= GM_INIT(gc
->m
);
273 ok
= ct_memeq(GH_DONE(h
, 0), t
, gc
->_b
.tagsz
);
275 return (ok ?
0 : -1);
278 static void gencomp_freechal(bulkchal
*bc
)
279 { gencomp_chal
*gc
= (gencomp_chal
*)bc
; GM_DESTROY(gc
->m
); DESTROY(gc
); }
281 /*----- The original transform --------------------------------------------*
283 * We generate a random initialization vector (if the cipher needs one). We
284 * encrypt the input message with the cipher, and format the type, sequence
285 * number, IV, and ciphertext as follows.
287 * +------+ +------+---...---+------...------+
288 * | type | | seq | iv | ciphertext |
289 * +------+ +------+---...---+------...------+
292 * All of this is fed into the MAC to compute a tag. The type is not
293 * transmitted: the other end knows what type of message it expects, and the
294 * type is only here to prevent us from being confused because some other
295 * kind of ciphertext has been substituted. The tag is prepended to the
296 * remainder, to yield the finished cryptogram, as follows.
298 * +---...---+------+---...---+------...------+
299 * | tag | seq | iv | ciphertext |
300 * +---...---+------+---...---+------...------+
303 * Decryption: checks the overall size, verifies the tag, then decrypts the
304 * ciphertext and extracts the sequence number.
307 typedef struct v0_algs
{
312 typedef struct v0_ctx
{
321 static bulkalgs
*v0_getalgs(const algswitch
*asw
, dstr
*e
,
322 key_file
*kf
, key
*k
)
324 v0_algs
*a
= CREATE(v0_algs
);
325 if (gencomp_getalgs(&a
->ga
, asw
, e
, kf
, k
)) { DESTROY(a
); return (0); }
330 static void v0_tracealgs(const bulkalgs
*aa
)
331 { const v0_algs
*a
= (const v0_algs
*)aa
; gencomp_tracealgs(&a
->ga
); }
334 static int v0_checkalgs(bulkalgs
*aa
, const algswitch
*asw
, dstr
*e
)
336 v0_algs
*a
= (v0_algs
*)aa
;
337 if (gencomp_checkalgs(&a
->ga
, asw
, e
)) return (-1);
341 static int v0_samealgsp(const bulkalgs
*aa
, const bulkalgs
*bb
)
343 const v0_algs
*a
= (const v0_algs
*)aa
, *b
= (const v0_algs
*)bb
;
344 return (gencomp_samealgsp(&a
->ga
, &b
->ga
));
347 static void v0_alginfo(const bulkalgs
*aa
, admin
*adm
)
348 { const v0_algs
*a
= (const v0_algs
*)aa
; gencomp_alginfo(&a
->ga
, adm
); }
350 static size_t v0_overhead(const bulkalgs
*aa
)
352 const v0_algs
*a
= (const v0_algs
*)aa
;
353 return (a
->ga
.tagsz
+ SEQSZ
+ a
->ga
.c
->blksz
);
356 static size_t v0_expsz(const bulkalgs
*aa
)
357 { const v0_algs
*a
= (const v0_algs
*)aa
; return (gencomp_expsz(&a
->ga
)); }
359 static bulkctx
*v0_genkeys(const bulkalgs
*aa
, const deriveargs
*da
)
361 const v0_algs
*a
= (const v0_algs
*)aa
;
362 v0_ctx
*bc
= CREATE(v0_ctx
);
366 bc
->tagsz
= a
->ga
.tagsz
;
367 for (i
= 0; i
< NDIR
; i
++) {
368 if (!(da
->f
&(1 << i
))) { bc
->d
[i
].c
= 0; bc
->d
[i
].m
= 0; continue; }
369 derivekey(k
, a
->ga
.cksz
, da
, i
, "encryption");
370 bc
->d
[i
].c
= GC_INIT(a
->ga
.c
, k
, a
->ga
.cksz
);
371 derivekey(k
, a
->ga
.mksz
, da
, i
, "integrity");
372 bc
->d
[i
].m
= GM_KEY(a
->ga
.m
, k
, a
->ga
.mksz
);
377 static bulkchal
*v0_genchal(const bulkalgs
*aa
)
379 const v0_algs
*a
= (const v0_algs
*)aa
;
380 return (gencomp_genchal(&a
->ga
));
382 #define v0_chaltag gencomp_chaltag
383 #define v0_chalvrf gencomp_chalvrf
384 #define v0_freechal gencomp_freechal
386 static void v0_freealgs(bulkalgs
*aa
)
387 { v0_algs
*a
= (v0_algs
*)aa
; DESTROY(a
); }
389 static void v0_freectx(bulkctx
*bbc
)
391 v0_ctx
*bc
= (v0_ctx
*)bbc
;
394 for (i
= 0; i
< NDIR
; i
++) {
395 if (bc
->d
[i
].c
) GC_DESTROY(bc
->d
[i
].c
);
396 if (bc
->d
[i
].m
) GM_DESTROY(bc
->d
[i
].m
);
401 static int v0_encrypt(bulkctx
*bbc
, unsigned ty
,
402 buf
*b
, buf
*bb
, uint32 seq
)
404 v0_ctx
*bc
= (v0_ctx
*)bbc
;
406 gcipher
*c
= bc
->d
[DIR_OUT
].c
;
407 const octet
*p
= BCUR(b
);
408 size_t sz
= BLEFT(b
);
409 octet
*qmac
, *qseq
, *qiv
, *qpk
;
411 size_t tagsz
= bc
->tagsz
;
415 ivsz
= GC_CLASS(c
)->blksz
;
417 /* --- Determine the ciphertext layout --- */
419 if (buf_ensure(bb
, tagsz
+ SEQSZ
+ ivsz
+ sz
)) return (0);
420 qmac
= BCUR(bb
); qseq
= qmac
+ tagsz
; qiv
= qseq
+ SEQSZ
; qpk
= qiv
+ ivsz
;
421 BSTEP(bb
, tagsz
+ SEQSZ
+ ivsz
+ sz
);
423 /* --- Store the type --- *
425 * This isn't transmitted, but it's covered by the MAC.
430 /* --- Store the sequence number --- */
434 /* --- Establish an initialization vector if necessary --- */
437 rand_get(RAND_GLOBAL
, qiv
, ivsz
);
442 /* --- Encrypt the packet --- */
444 GC_ENCRYPT(c
, p
, qpk
, sz
);
447 /* --- Compute a MAC over type, sequence number, IV, and ciphertext --- */
450 h
= GM_INIT(bc
->d
[DIR_OUT
].m
);
451 GH_HASH(h
, t
, sizeof(t
));
452 GH_HASH(h
, qseq
, SEQSZ
+ ivsz
+ sz
);
453 memcpy(qmac
, GH_DONE(h
, 0), tagsz
);
455 TRACE_MAC(qmac
, tagsz
);
458 /* --- We're done --- */
463 static int v0_decrypt(bulkctx
*bbc
, unsigned ty
,
464 buf
*b
, buf
*bb
, uint32
*seq
)
466 v0_ctx
*bc
= (v0_ctx
*)bbc
;
467 const octet
*pmac
, *piv
, *pseq
, *ppk
;
468 size_t psz
= BLEFT(b
);
472 gcipher
*c
= bc
->d
[DIR_IN
].c
;
474 size_t tagsz
= bc
->tagsz
;
478 ivsz
= GC_CLASS(c
)->blksz
;
480 /* --- Break up the packet into its components --- */
482 if (psz
< ivsz
+ SEQSZ
+ tagsz
) {
483 T( trace(T_KEYSET
, "keyset: block too small for keyset"); )
484 return (KSERR_MALFORMED
);
486 sz
= psz
- ivsz
- SEQSZ
- tagsz
;
487 pmac
= BCUR(b
); pseq
= pmac
+ tagsz
; piv
= pseq
+ SEQSZ
; ppk
= piv
+ ivsz
;
490 /* --- Verify the MAC on the packet --- */
493 h
= GM_INIT(bc
->d
[DIR_IN
].m
);
494 GH_HASH(h
, t
, sizeof(t
));
495 GH_HASH(h
, pseq
, SEQSZ
+ ivsz
+ sz
);
496 CHECK_MAC(h
, pmac
, tagsz
);
499 /* --- Decrypt the packet --- */
505 GC_DECRYPT(c
, ppk
, q
, sz
);
507 /* --- Finished --- */
514 /*----- The implicit-IV transform -----------------------------------------*
516 * The v0 transform makes everything explicit. There's an IV because the
517 * cipher needs an IV; there's a sequence number because replay prevention
518 * needs a sequence number.
520 * This new transform works rather differently. We make use of a block
521 * cipher to encrypt the sequence number, and use that as the IV. We
522 * transmit the sequence number in the clear, as before. This reduces
523 * overhead; and it's not a significant privacy leak because the adversary
524 * can see the order in which the messages are transmitted -- i.e., the
525 * sequence numbers are almost completely predictable anyway.
527 * So, a MAC is computed over
529 * +------+ +------+------...------+
530 * | type | | seq | ciphertext |
531 * +------+ +------+------...------+
534 * and we actually transmit the following as the cryptogram.
536 * +---...---+------+------...------+
537 * | tag | seq | ciphertext |
538 * +---...---+------+------...------+
542 typedef struct iiv_algs
{
545 const gccipher
*b
; size_t bksz
;
548 typedef struct iiv_ctx
{
558 static bulkalgs
*iiv_getalgs(const algswitch
*asw
, dstr
*e
,
559 key_file
*kf
, key
*k
)
561 iiv_algs
*a
= CREATE(iiv_algs
);
562 dstr d
= DSTR_INIT
, dd
= DSTR_INIT
;
566 if (gencomp_getalgs(&a
->ga
, asw
, e
, kf
, k
)) goto fail
;
568 if ((p
= key_getattr(kf
, k
, "blkc")) == 0) {
569 dstr_puts(&dd
, a
->ga
.c
->name
);
570 if ((q
= strrchr(dd
.buf
, '-')) != 0) *q
= 0;
573 dstr_putf(&d
, "%s-ecb", p
);
574 if ((a
->b
= gcipher_byname(d
.buf
)) == 0) {
575 a_format(e
, "unknown-blkc", "%s", p
, A_END
);
579 dstr_destroy(&d
); dstr_destroy(&dd
);
582 dstr_destroy(&d
); dstr_destroy(&dd
);
588 static void iiv_tracealgs(const bulkalgs
*aa
)
590 const iiv_algs
*a
= (const iiv_algs
*)aa
;
592 gencomp_tracealgs(&a
->ga
);
594 "crypto: blkc = %.*s", (int)strlen(a
->b
->name
) - 4, a
->b
->name
);
598 static int iiv_checkalgs(bulkalgs
*aa
, const algswitch
*asw
, dstr
*e
)
600 iiv_algs
*a
= (iiv_algs
*)aa
;
602 if (gencomp_checkalgs(&a
->ga
, asw
, e
)) return (-1);
604 if ((a
->bksz
= keysz(asw
->hashsz
, a
->b
->keysz
)) == 0) {
605 a_format(e
, "blkc", "%.*s", strlen(a
->b
->name
) - 4, a
->b
->name
,
606 "no-key-size", "%lu", (unsigned long)asw
->hashsz
,
610 if (a
->b
->blksz
< a
->ga
.c
->blksz
) {
611 a_format(e
, "blkc", "%.*s", strlen(a
->b
->name
) - 4, a
->b
->name
,
612 "blksz-insufficient", A_END
);
618 static int iiv_samealgsp(const bulkalgs
*aa
, const bulkalgs
*bb
)
620 const iiv_algs
*a
= (const iiv_algs
*)aa
, *b
= (const iiv_algs
*)bb
;
621 return (gencomp_samealgsp(&a
->ga
, &b
->ga
) && a
->b
== b
->b
);
624 static void iiv_alginfo(const bulkalgs
*aa
, admin
*adm
)
626 const iiv_algs
*a
= (const iiv_algs
*)aa
;
627 gencomp_alginfo(&a
->ga
, adm
);
629 "blkc=%.*s", strlen(a
->b
->name
) - 4, a
->b
->name
,
630 "blkc-keysz=%lu", (unsigned long)a
->bksz
,
631 "blkc-blksz=%lu", (unsigned long)a
->b
->blksz
,
635 static size_t iiv_overhead(const bulkalgs
*aa
)
636 { const iiv_algs
*a
= (const iiv_algs
*)aa
; return (a
->ga
.tagsz
+ SEQSZ
); }
638 static size_t iiv_expsz(const bulkalgs
*aa
)
640 const iiv_algs
*a
= (const iiv_algs
*)aa
;
641 return (gencomp_expsz(&a
->ga
));
644 static bulkctx
*iiv_genkeys(const bulkalgs
*aa
, const deriveargs
*da
)
646 const iiv_algs
*a
= (const iiv_algs
*)aa
;
647 iiv_ctx
*bc
= CREATE(iiv_ctx
);
651 bc
->tagsz
= a
->ga
.tagsz
;
652 for (i
= 0; i
< NDIR
; i
++) {
653 if (!(da
->f
&(1 << i
)))
654 { bc
->d
[i
].c
= 0; bc
->d
[i
].b
= 0; bc
->d
[i
].m
= 0; continue; }
655 derivekey(k
, a
->ga
.cksz
, da
, i
, "encryption");
656 bc
->d
[i
].c
= GC_INIT(a
->ga
.c
, k
, a
->ga
.cksz
);
657 derivekey(k
, a
->bksz
, da
, i
, "blkc");
658 bc
->d
[i
].b
= GC_INIT(a
->b
, k
, a
->bksz
);
659 derivekey(k
, a
->ga
.mksz
, da
, i
, "integrity");
660 bc
->d
[i
].m
= GM_KEY(a
->ga
.m
, k
, a
->ga
.mksz
);
665 static bulkchal
*iiv_genchal(const bulkalgs
*aa
)
667 const iiv_algs
*a
= (const iiv_algs
*)aa
;
668 return (gencomp_genchal(&a
->ga
));
670 #define iiv_chaltag gencomp_chaltag
671 #define iiv_chalvrf gencomp_chalvrf
672 #define iiv_freechal gencomp_freechal
674 static void iiv_freealgs(bulkalgs
*aa
)
675 { iiv_algs
*a
= (iiv_algs
*)aa
; DESTROY(a
); }
677 static void iiv_freectx(bulkctx
*bbc
)
679 iiv_ctx
*bc
= (iiv_ctx
*)bbc
;
682 for (i
= 0; i
< NDIR
; i
++) {
683 if (bc
->d
[i
].c
) GC_DESTROY(bc
->d
[i
].c
);
684 if (bc
->d
[i
].b
) GC_DESTROY(bc
->d
[i
].b
);
685 if (bc
->d
[i
].m
) GM_DESTROY(bc
->d
[i
].m
);
690 #define TRACE_PRESEQ(qseq, ivsz) do { IF_TRACING(T_KEYSET, { \
691 trace_block(T_CRYPTO, "crypto: IV derivation input", (qseq), (ivsz)); \
694 static int iiv_encrypt(bulkctx
*bbc
, unsigned ty
,
695 buf
*b
, buf
*bb
, uint32 seq
)
697 iiv_ctx
*bc
= (iiv_ctx
*)bbc
;
699 gcipher
*c
= bc
->d
[DIR_OUT
].c
, *blkc
= bc
->d
[DIR_OUT
].b
;
700 const octet
*p
= BCUR(b
);
701 size_t sz
= BLEFT(b
);
702 octet
*qmac
, *qseq
, *qpk
;
704 size_t tagsz
= bc
->tagsz
;
707 assert(c
); assert(blkc
);
708 ivsz
= GC_CLASS(c
)->blksz
;
709 blkcsz
= GC_CLASS(blkc
)->blksz
;
711 /* --- Determine the ciphertext layout --- */
713 if (buf_ensure(bb
, tagsz
+ SEQSZ
+ sz
)) return (0);
714 qmac
= BCUR(bb
); qseq
= qmac
+ tagsz
; qpk
= qseq
+ SEQSZ
;
715 BSTEP(bb
, tagsz
+ SEQSZ
+ sz
);
717 /* --- Store the type --- *
719 * This isn't transmitted, but it's covered by the MAC.
724 /* --- Store the sequence number --- */
728 /* --- Establish an initialization vector if necessary --- */
731 memset(buf_u
, 0, blkcsz
- SEQSZ
);
732 memcpy(buf_u
+ blkcsz
- SEQSZ
, qseq
, SEQSZ
);
733 TRACE_PRESEQ(buf_u
, ivsz
);
734 GC_ENCRYPT(blkc
, buf_u
, buf_u
, blkcsz
);
736 TRACE_IV(buf_u
, ivsz
);
739 /* --- Encrypt the packet --- */
741 GC_ENCRYPT(c
, p
, qpk
, sz
);
744 /* --- Compute a MAC over type, sequence number, and ciphertext --- */
747 h
= GM_INIT(bc
->d
[DIR_OUT
].m
);
748 GH_HASH(h
, t
, sizeof(t
));
749 GH_HASH(h
, qseq
, SEQSZ
+ sz
);
750 memcpy(qmac
, GH_DONE(h
, 0), tagsz
);
752 TRACE_MAC(qmac
, tagsz
);
755 /* --- We're done --- */
760 static int iiv_decrypt(bulkctx
*bbc
, unsigned ty
,
761 buf
*b
, buf
*bb
, uint32
*seq
)
763 iiv_ctx
*bc
= (iiv_ctx
*)bbc
;
764 const octet
*pmac
, *pseq
, *ppk
;
765 size_t psz
= BLEFT(b
);
769 gcipher
*c
= bc
->d
[DIR_IN
].c
, *blkc
= bc
->d
[DIR_IN
].b
;
771 size_t tagsz
= bc
->tagsz
;
774 assert(c
); assert(blkc
);
775 ivsz
= GC_CLASS(c
)->blksz
;
776 blkcsz
= GC_CLASS(blkc
)->blksz
;
778 /* --- Break up the packet into its components --- */
780 if (psz
< SEQSZ
+ tagsz
) {
781 T( trace(T_KEYSET
, "keyset: block too small for keyset"); )
782 return (KSERR_MALFORMED
);
784 sz
= psz
- SEQSZ
- tagsz
;
785 pmac
= BCUR(b
); pseq
= pmac
+ tagsz
; ppk
= pseq
+ SEQSZ
;
788 /* --- Verify the MAC on the packet --- */
791 h
= GM_INIT(bc
->d
[DIR_IN
].m
);
792 GH_HASH(h
, t
, sizeof(t
));
793 GH_HASH(h
, pseq
, SEQSZ
+ sz
);
794 CHECK_MAC(h
, pmac
, tagsz
);
797 /* --- Decrypt the packet --- */
800 memset(buf_u
, 0, blkcsz
- SEQSZ
);
801 memcpy(buf_u
+ blkcsz
- SEQSZ
, pseq
, SEQSZ
);
802 TRACE_PRESEQ(buf_u
, ivsz
);
803 GC_ENCRYPT(blkc
, buf_u
, buf_u
, blkcsz
);
805 TRACE_IV(buf_u
, ivsz
);
807 GC_DECRYPT(c
, ppk
, q
, sz
);
809 /* --- Finished --- */
816 /*----- The NaCl box transform --------------------------------------------*
818 * This transform is very similar to the NaCl `crypto_secretbox' transform
819 * described in Bernstein, `Cryptography in NaCl', with the difference that,
820 * rather than using XSalsa20, we use either Salsa20/r or ChaChar, because we
821 * have no need of XSalsa20's extended nonce. The default cipher is Salsa20.
823 * Salsa20 and ChaCha accept a 64-bit nonce. The low 32 bits are the
824 * sequence number, and the high 32 bits are the type, both big-endian.
831 * A stream is generated by concatenating the raw output blocks generated
832 * with this nonce and successive counter values starting from zero. The
833 * first 32 bytes of the stream are used as a key for Poly1305: the first 16
834 * bytes are the universal hash key r, and the second 16 bytes are the mask
837 * +------+------+ +------...------+
838 * | r | s | | keystream |
839 * +------+------+ +------...------+
842 * The remainder of the stream is XORed with the incoming plaintext to form a
843 * ciphertext with the same length. The ciphertext (only) is then tagged
844 * using Poly1305. The tag, sequence number, and ciphertext are concatenated
845 * in this order, and transmitted.
848 * +---...---+------+------...------+
849 * | tag | seq | ciphertext |
850 * +---...---+------+------...------+
853 * Note that there is no need to authenticate the type separately, since it
854 * was used to select the cipher nonce, and hence the Poly1305 key. The
855 * Poly1305 tag length is fixed.
858 typedef struct naclbox_algs
{
860 const gccipher
*c
; size_t cksz
;
863 typedef struct naclbox_ctx
{
865 struct { gcipher
*c
; } d
[NDIR
];
869 static bulkalgs
*naclbox_getalgs(const algswitch
*asw
, dstr
*e
,
870 key_file
*kf
, key
*k
)
872 naclbox_algs
*a
= CREATE(naclbox_algs
);
877 /* --- Collect the selected cipher and check that it's supported --- */
879 p
= key_getattr(kf
, k
, "cipher");
880 if (!p
|| strcmp(p
, "salsa20") == 0) a
->c
= &salsa20
;
881 else if (strcmp(p
, "salsa20/12") == 0) a
->c
= &salsa2012
;
882 else if (strcmp(p
, "salsa20/8") == 0) a
->c
= &salsa208
;
883 else if (strcmp(p
, "chacha20") == 0) a
->c
= &chacha20
;
884 else if (strcmp(p
, "chacha12") == 0) a
->c
= &chacha12
;
885 else if (strcmp(p
, "chacha8") == 0) a
->c
= &chacha8
;
887 a_format(e
, "unknown-cipher", "%s", p
, A_END
);
891 /* --- Collect the selected MAC, and check the tag length --- */
893 p
= key_getattr(kf
, k
, "mac");
896 else if (strncmp(p
, "poly1305", 8) != 0 || (p
[8] && p
[8] != '/')) {
897 a_format(e
, "unknown-mac", "%s", p
, A_END
);
899 } else if (p
[8] == '/') {
900 n
= strtoul(p
+ 9, &qq
, 0);
902 a_format(e
, "bad-tag-length-string", "%s", p
+ 9, A_END
);
906 a_format(e
, "bad-tag-length", "%lu", n
, A_END
);
918 static void naclbox_tracealgs(const bulkalgs
*aa
)
920 const naclbox_algs
*a
= (const naclbox_algs
*)aa
;
922 trace(T_CRYPTO
, "crypto: cipher = %s", a
->c
->name
);
923 trace(T_CRYPTO
, "crypto: mac = poly1305/128");
927 static int naclbox_checkalgs(bulkalgs
*aa
, const algswitch
*asw
, dstr
*e
)
929 naclbox_algs
*a
= (naclbox_algs
*)aa
;
931 if ((a
->cksz
= keysz(asw
->hashsz
, a
->c
->keysz
)) == 0) {
932 a_format(e
, "cipher", "%s", a
->c
->name
,
933 "no-key-size", "%lu", (unsigned long)asw
->hashsz
,
940 static int naclbox_samealgsp(const bulkalgs
*aa
, const bulkalgs
*bb
)
942 const naclbox_algs
*a
= (const naclbox_algs
*)aa
,
943 *b
= (const naclbox_algs
*)bb
;
944 return (a
->c
== b
->c
);
947 static void naclbox_alginfo(const bulkalgs
*aa
, admin
*adm
)
949 const naclbox_algs
*a
= (const naclbox_algs
*)aa
;
950 a_info(adm
, "cipher=%s", a
->c
->name
, "cipher-keysz=32", A_END
);
951 a_info(adm
, "mac=poly1305", "mac-tagsz=16", A_END
);
954 static size_t naclbox_overhead(const bulkalgs
*aa
)
955 { return (POLY1305_TAGSZ
+ SEQSZ
); }
957 static size_t naclbox_expsz(const bulkalgs
*aa
)
958 { return (MEG(2048)); }
960 static bulkctx
*naclbox_genkeys(const bulkalgs
*aa
, const deriveargs
*da
)
962 const naclbox_algs
*a
= (const naclbox_algs
*)aa
;
963 naclbox_ctx
*bc
= CREATE(naclbox_ctx
);
967 for (i
= 0; i
< NDIR
; i
++) {
968 if (!(da
->f
&(1 << i
))) { bc
->d
[i
].c
= 0; continue; }
969 derivekey(k
, a
->cksz
, da
, i
, "encryption");
970 bc
->d
[i
].c
= GC_INIT(a
->c
, k
, a
->cksz
);
975 typedef struct naclbox_chal
{
980 static bulkchal
*naclbox_genchal(const bulkalgs
*aa
)
982 const naclbox_algs
*a
= (const naclbox_algs
*)aa
;
983 naclbox_chal
*c
= CREATE(naclbox_chal
);
984 rand_get(RAND_GLOBAL
, buf_t
, a
->cksz
);
985 c
->c
= GC_INIT(a
->c
, buf_t
, a
->cksz
);
987 trace(T_CHAL
, "chal: generated new challenge key");
988 trace_block(T_CRYPTO
, "chal: new key", buf_t
, a
->cksz
);
994 static int naclbox_chaltag(bulkchal
*bc
, const void *m
, size_t msz
, void *t
)
996 naclbox_chal
*c
= (naclbox_chal
*)bc
;
997 octet b0
[SALSA20_NONCESZ
];
998 assert(msz
<= sizeof(b0
));
999 memcpy(b0
, m
, msz
); memset(b0
+ msz
, 0, sizeof(b0
) - msz
);
1001 GC_ENCRYPT(c
->c
, 0, t
, c
->_b
.tagsz
);
1005 static int naclbox_chalvrf(bulkchal
*bc
, const void *m
, size_t msz
,
1008 naclbox_chal
*c
= (naclbox_chal
*)bc
;
1009 octet b0
[SALSA20_NONCESZ
], b1
[16];
1010 assert(msz
<= sizeof(b0
)); assert(c
->_b
.tagsz
<= sizeof(b1
));
1011 memcpy(b0
, m
, msz
); memset(b0
+ msz
, 0, sizeof(b0
) - msz
);
1013 GC_ENCRYPT(c
->c
, 0, b1
, c
->_b
.tagsz
);
1014 return (ct_memeq(t
, b1
, c
->_b
.tagsz
) ?
0 : -1);
1017 static void naclbox_freechal(bulkchal
*bc
)
1018 { naclbox_chal
*c
= (naclbox_chal
*)bc
; GC_DESTROY(c
->c
); DESTROY(c
); }
1020 static void naclbox_freealgs(bulkalgs
*aa
)
1021 { naclbox_algs
*a
= (naclbox_algs
*)aa
; DESTROY(a
); }
1023 static void naclbox_freectx(bulkctx
*bbc
)
1025 naclbox_ctx
*bc
= (naclbox_ctx
*)bbc
;
1028 for (i
= 0; i
< NDIR
; i
++) { if (bc
->d
[i
].c
) GC_DESTROY(bc
->d
[i
].c
); }
1032 static int naclbox_encrypt(bulkctx
*bbc
, unsigned ty
,
1033 buf
*b
, buf
*bb
, uint32 seq
)
1035 naclbox_ctx
*bc
= (naclbox_ctx
*)bbc
;
1036 gcipher
*c
= bc
->d
[DIR_OUT
].c
;
1039 const octet
*p
= BCUR(b
);
1040 size_t sz
= BLEFT(b
);
1041 octet
*qmac
, *qseq
, *qpk
;
1045 /* --- Determine the ciphertext layout --- */
1047 if (buf_ensure(bb
, POLY1305_TAGSZ
+ SEQSZ
+ sz
)) return (0);
1048 qmac
= BCUR(bb
); qseq
= qmac
+ POLY1305_TAGSZ
; qpk
= qseq
+ SEQSZ
;
1049 BSTEP(bb
, POLY1305_TAGSZ
+ SEQSZ
+ sz
);
1051 /* --- Construct and set the nonce --- */
1054 memcpy(buf_u
, qseq
, SEQSZ
); STORE32(buf_u
+ SEQSZ
, ty
);
1056 TRACE_IV(buf_u
, SALSA20_NONCESZ
);
1058 /* --- Determine the MAC key --- */
1060 GC_ENCRYPT(c
, 0, buf_u
, POLY1305_KEYSZ
+ POLY1305_MASKSZ
);
1061 poly1305_keyinit(&polyk
, buf_u
, POLY1305_KEYSZ
);
1062 poly1305_macinit(&poly
, &polyk
, buf_u
+ POLY1305_KEYSZ
);
1064 /* --- Encrypt the message --- */
1066 GC_ENCRYPT(c
, p
, qpk
, sz
);
1069 /* --- Compute the MAC --- */
1071 poly1305_hash(&poly
, qpk
, sz
);
1072 poly1305_done(&poly
, qmac
);
1073 TRACE_MAC(qmac
, POLY1305_TAGSZ
);
1075 /* --- We're done --- */
1080 static int naclbox_decrypt(bulkctx
*bbc
, unsigned ty
,
1081 buf
*b
, buf
*bb
, uint32
*seq
)
1083 naclbox_ctx
*bc
= (naclbox_ctx
*)bbc
;
1084 gcipher
*c
= bc
->d
[DIR_IN
].c
;
1087 const octet
*pmac
, *pseq
, *ppk
;
1088 size_t psz
= BLEFT(b
);
1090 octet
*q
= BCUR(bb
);
1094 /* --- Break up the packet into its components --- */
1096 if (psz
< SEQSZ
+ POLY1305_TAGSZ
) {
1097 T( trace(T_KEYSET
, "keyset: block too small for keyset"); )
1098 return (KSERR_MALFORMED
);
1100 sz
= psz
- SEQSZ
- POLY1305_TAGSZ
;
1101 pmac
= BCUR(b
); pseq
= pmac
+ POLY1305_TAGSZ
; ppk
= pseq
+ SEQSZ
;
1103 /* --- Construct and set the nonce --- */
1105 memcpy(buf_u
, pseq
, SEQSZ
); STORE32(buf_u
+ SEQSZ
, ty
);
1107 TRACE_IV(buf_u
, SALSA20_NONCESZ
);
1109 /* --- Determine the MAC key --- */
1111 GC_ENCRYPT(c
, 0, buf_u
, POLY1305_KEYSZ
+ POLY1305_MASKSZ
);
1112 poly1305_keyinit(&polyk
, buf_u
, POLY1305_KEYSZ
);
1113 poly1305_macinit(&poly
, &polyk
, buf_u
+ POLY1305_KEYSZ
);
1115 /* --- Verify the MAC on the packet --- */
1117 poly1305_hash(&poly
, ppk
, sz
);
1118 poly1305_done(&poly
, buf_u
);
1119 TRACE_MAC(buf_u
, POLY1305_TAGSZ
);
1120 if (!ct_memeq(buf_u
, pmac
, POLY1305_TAGSZ
)) {
1121 TRACE_MACERR(pmac
, POLY1305_TAGSZ
);
1122 return (KSERR_DECRYPT
);
1125 /* --- Decrypt the packet --- */
1127 GC_DECRYPT(c
, ppk
, q
, sz
);
1129 /* --- Finished --- */
1131 *seq
= LOAD32(pseq
);
1136 /*----- Bulk crypto transform table ---------------------------------------*/
1138 const bulkops bulktab
[] = {
1142 #define BULK(name, pre) \
1143 { name, pre##_getalgs, T( pre##_tracealgs COMMA ) \
1144 pre##_checkalgs, pre##_samealgsp, \
1145 pre##_alginfo, pre##_overhead, pre##_expsz, \
1146 pre##_genkeys, pre##_genchal, pre##_freealgs, \
1147 pre##_encrypt, pre##_decrypt, pre##_freectx, \
1148 pre##_chaltag, pre##_chalvrf, pre##_freechal }
1152 BULK("naclbox", naclbox
),
1158 /*----- That's all, folks -------------------------------------------------*/