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 /*----- Common functionality for generic-composition transforms -----------*/
54 #define CHECK_MAC(h, pmac, tagsz) do { \
56 const octet *_pmac = (pmac); \
57 size_t _tagsz = (tagsz); \
58 octet *_mac = GH_DONE(_h, 0); \
59 int _eq = ct_memeq(_mac, _pmac, _tagsz); \
60 TRACE_MAC(_mac, _tagsz); \
63 TRACE_MACERR(_pmac, _tagsz); \
64 return (KSERR_DECRYPT); \
68 typedef struct gencomp_algs
{
69 const gccipher
*c
; size_t cksz
;
70 const gcmac
*m
; size_t mksz
; size_t tagsz
;
73 typedef struct gencomp_chal
{
78 static int gencomp_getalgs(gencomp_algs
*a
, const algswitch
*asw
,
79 dstr
*e
, key_file
*kf
, key
*k
)
87 /* --- Symmetric encryption --- */
89 if ((p
= key_getattr(kf
, k
, "cipher")) == 0) p
= "blowfish-cbc";
90 if ((a
->c
= gcipher_byname(p
)) == 0) {
91 a_format(e
, "unknown-cipher", "%s", p
, A_END
);
95 /* --- Message authentication --- */
97 if ((p
= key_getattr(kf
, k
, "mac")) != 0) {
100 if ((q
= strrchr(d
.buf
, '/')) != 0)
102 if ((a
->m
= gmac_byname(d
.buf
)) == 0) {
103 a_format(e
, "unknown-mac", "%s", d
.buf
, A_END
);
107 a
->tagsz
= a
->m
->hashsz
;
109 n
= strtoul(q
, &qq
, 0);
111 a_format(e
, "bad-tag-length-string", "%s", q
, A_END
);
114 if (n
%8 || n
/8 > a
->m
->hashsz
) {
115 a_format(e
, "bad-tag-length", "%lu", n
, A_END
);
122 dstr_putf(&d
, "%s-hmac", asw
->h
->name
);
123 if ((a
->m
= gmac_byname(d
.buf
)) == 0) {
124 a_format(e
, "no-hmac-for-hash", "%s", asw
->h
->name
, A_END
);
127 a
->tagsz
= asw
->h
->hashsz
/2;
137 static void gencomp_tracealgs(const gencomp_algs
*a
)
139 trace(T_CRYPTO
, "crypto: cipher = %s", a
->c
->name
);
140 trace(T_CRYPTO
, "crypto: mac = %s/%lu",
141 a
->m
->name
, (unsigned long)a
->tagsz
* 8);
145 static int gencomp_checkalgs(gencomp_algs
*a
, const algswitch
*asw
, dstr
*e
)
147 /* --- Derive the key sizes --- *
149 * Must ensure that we have non-empty keys. This isn't ideal, but it
150 * provides a handy sanity check. Also must be based on a 64- or 128-bit
151 * block cipher or we can't do the data expiry properly.
154 if ((a
->cksz
= keysz(asw
->hashsz
, a
->c
->keysz
)) == 0) {
155 a_format(e
, "cipher", "%s", a
->c
->name
,
156 "no-key-size", "%lu", (unsigned long)asw
->hashsz
,
160 if ((a
->mksz
= keysz(asw
->hashsz
, a
->m
->keysz
)) == 0) {
161 a_format(e
, "mac", "%s", a
->m
->name
,
162 "no-key-size", "%lu", (unsigned long)asw
->hashsz
,
170 static void gencomp_alginfo(const gencomp_algs
*a
, admin
*adm
)
173 "cipher=%s", a
->c
->name
,
174 "cipher-keysz=%lu", (unsigned long)a
->cksz
,
175 "cipher-blksz=%lu", (unsigned long)a
->c
->blksz
,
178 "mac=%s", a
->m
->name
,
179 "mac-keysz=%lu", (unsigned long)a
->mksz
,
180 "mac-tagsz=%lu", (unsigned long)a
->tagsz
,
184 static int gencomp_samealgsp(const gencomp_algs
*a
, const gencomp_algs
*aa
)
186 return (a
->c
== aa
->c
&&
187 a
->m
== aa
->m
&& a
->tagsz
== aa
->tagsz
);
190 static size_t gencomp_expsz(const gencomp_algs
*a
)
191 { return (a
->c
->blksz
< 16 ?
MEG(64) : MEG(2048)); }
193 static bulkchal
*gencomp_genchal(const gencomp_algs
*a
)
195 gencomp_chal
*gc
= CREATE(gencomp_chal
);
197 rand_get(RAND_GLOBAL
, buf_t
, a
->mksz
);
198 gc
->m
= GM_KEY(a
->m
, buf_t
, a
->mksz
);
199 gc
->_b
.tagsz
= a
->tagsz
;
201 trace(T_CHAL
, "chal: generated new challenge key");
202 trace_block(T_CRYPTO
, "chal: new key", buf_t
, a
->mksz
);
207 static int gencomp_chaltag(bulkchal
*bc
, const void *m
, size_t msz
, void *t
)
209 gencomp_chal
*gc
= (gencomp_chal
*)bc
;
210 ghash
*h
= GM_INIT(gc
->m
);
213 memcpy(t
, GH_DONE(h
, 0), bc
->tagsz
);
218 static int gencomp_chalvrf(bulkchal
*bc
, const void *m
, size_t msz
,
221 gencomp_chal
*gc
= (gencomp_chal
*)bc
;
222 ghash
*h
= GM_INIT(gc
->m
);
226 ok
= ct_memeq(GH_DONE(h
, 0), t
, gc
->_b
.tagsz
);
228 return (ok ?
0 : -1);
231 static void gencomp_freechal(bulkchal
*bc
)
232 { gencomp_chal
*gc
= (gencomp_chal
*)bc
; GM_DESTROY(gc
->m
); DESTROY(gc
); }
234 /*----- The original transform --------------------------------------------*
236 * We generate a random initialization vector (if the cipher needs one). We
237 * encrypt the input message with the cipher, and format the type, sequence
238 * number, IV, and ciphertext as follows.
240 * +------+ +------+---...---+------...------+
241 * | type | | seq | iv | ciphertext |
242 * +------+ +------+---...---+------...------+
245 * All of this is fed into the MAC to compute a tag. The type is not
246 * transmitted: the other end knows what type of message it expects, and the
247 * type is only here to prevent us from being confused because some other
248 * kind of ciphertext has been substituted. The tag is prepended to the
249 * remainder, to yield the finished cryptogram, as follows.
251 * +---...---+------+---...---+------...------+
252 * | tag | seq | iv | ciphertext |
253 * +---...---+------+---...---+------...------+
256 * Decryption: checks the overall size, verifies the tag, then decrypts the
257 * ciphertext and extracts the sequence number.
260 typedef struct v0_algs
{
265 typedef struct v0_ctx
{
274 static bulkalgs
*v0_getalgs(const algswitch
*asw
, dstr
*e
,
275 key_file
*kf
, key
*k
)
277 v0_algs
*a
= CREATE(v0_algs
);
278 if (gencomp_getalgs(&a
->ga
, asw
, e
, kf
, k
)) { DESTROY(a
); return (0); }
283 static void v0_tracealgs(const bulkalgs
*aa
)
284 { const v0_algs
*a
= (const v0_algs
*)aa
; gencomp_tracealgs(&a
->ga
); }
287 static int v0_checkalgs(bulkalgs
*aa
, const algswitch
*asw
, dstr
*e
)
289 v0_algs
*a
= (v0_algs
*)aa
;
290 if (gencomp_checkalgs(&a
->ga
, asw
, e
)) return (-1);
294 static int v0_samealgsp(const bulkalgs
*aa
, const bulkalgs
*bb
)
296 const v0_algs
*a
= (const v0_algs
*)aa
, *b
= (const v0_algs
*)bb
;
297 return (gencomp_samealgsp(&a
->ga
, &b
->ga
));
300 static void v0_alginfo(const bulkalgs
*aa
, admin
*adm
)
301 { const v0_algs
*a
= (const v0_algs
*)aa
; gencomp_alginfo(&a
->ga
, adm
); }
303 static size_t v0_overhead(const bulkalgs
*aa
)
305 const v0_algs
*a
= (const v0_algs
*)aa
;
306 return (a
->ga
.tagsz
+ SEQSZ
+ a
->ga
.c
->blksz
);
309 static size_t v0_expsz(const bulkalgs
*aa
)
310 { const v0_algs
*a
= (const v0_algs
*)aa
; return (gencomp_expsz(&a
->ga
)); }
312 static bulkctx
*v0_genkeys(const bulkalgs
*aa
, const struct rawkey
*rk
)
314 const v0_algs
*a
= (const v0_algs
*)aa
;
315 v0_ctx
*bc
= CREATE(v0_ctx
);
319 bc
->tagsz
= a
->ga
.tagsz
;
320 for (i
= 0; i
< NDIR
; i
++) {
321 ks_derivekey(k
, a
->ga
.cksz
, rk
, i
, "encryption");
322 bc
->d
[i
].c
= GC_INIT(a
->ga
.c
, k
, a
->ga
.cksz
);
323 ks_derivekey(k
, a
->ga
.mksz
, rk
, i
, "integrity");
324 bc
->d
[i
].m
= GM_KEY(a
->ga
.m
, k
, a
->ga
.mksz
);
329 static bulkchal
*v0_genchal(const bulkalgs
*aa
)
331 const v0_algs
*a
= (const v0_algs
*)aa
;
332 return (gencomp_genchal(&a
->ga
));
334 #define v0_chaltag gencomp_chaltag
335 #define v0_chalvrf gencomp_chalvrf
336 #define v0_freechal gencomp_freechal
338 static void v0_freealgs(bulkalgs
*aa
)
339 { v0_algs
*a
= (v0_algs
*)aa
; DESTROY(a
); }
341 static void v0_freectx(bulkctx
*bbc
)
343 v0_ctx
*bc
= (v0_ctx
*)bbc
;
346 for (i
= 0; i
< NDIR
; i
++) {
347 GC_DESTROY(bc
->d
[i
].c
);
348 GM_DESTROY(bc
->d
[i
].m
);
353 static int v0_encrypt(bulkctx
*bbc
, unsigned ty
,
354 buf
*b
, buf
*bb
, uint32 seq
)
356 v0_ctx
*bc
= (v0_ctx
*)bbc
;
358 gcipher
*c
= bc
->d
[DIR_OUT
].c
;
359 const octet
*p
= BCUR(b
);
360 size_t sz
= BLEFT(b
);
361 octet
*qmac
, *qseq
, *qiv
, *qpk
;
362 size_t ivsz
= GC_CLASS(c
)->blksz
;
363 size_t tagsz
= bc
->tagsz
;
366 /* --- Determine the ciphertext layout --- */
368 if (buf_ensure(bb
, tagsz
+ SEQSZ
+ ivsz
+ sz
)) return (0);
369 qmac
= BCUR(bb
); qseq
= qmac
+ tagsz
; qiv
= qseq
+ SEQSZ
; qpk
= qiv
+ ivsz
;
370 BSTEP(bb
, tagsz
+ SEQSZ
+ ivsz
+ sz
);
372 /* --- Store the type --- *
374 * This isn't transmitted, but it's covered by the MAC.
379 /* --- Store the sequence number --- */
383 /* --- Establish an initialization vector if necessary --- */
386 rand_get(RAND_GLOBAL
, qiv
, ivsz
);
391 /* --- Encrypt the packet --- */
393 GC_ENCRYPT(c
, p
, qpk
, sz
);
396 /* --- Compute a MAC over type, sequence number, IV, and ciphertext --- */
399 h
= GM_INIT(bc
->d
[DIR_OUT
].m
);
400 GH_HASH(h
, t
, sizeof(t
));
401 GH_HASH(h
, qseq
, SEQSZ
+ ivsz
+ sz
);
402 memcpy(qmac
, GH_DONE(h
, 0), tagsz
);
404 TRACE_MAC(qmac
, tagsz
);
407 /* --- We're done --- */
412 static int v0_decrypt(bulkctx
*bbc
, unsigned ty
,
413 buf
*b
, buf
*bb
, uint32
*seq
)
415 v0_ctx
*bc
= (v0_ctx
*)bbc
;
416 const octet
*pmac
, *piv
, *pseq
, *ppk
;
417 size_t psz
= BLEFT(b
);
421 gcipher
*c
= bc
->d
[DIR_IN
].c
;
422 size_t ivsz
= GC_CLASS(c
)->blksz
;
423 size_t tagsz
= bc
->tagsz
;
426 /* --- Break up the packet into its components --- */
428 if (psz
< ivsz
+ SEQSZ
+ tagsz
) {
429 T( trace(T_KEYSET
, "keyset: block too small for keyset"); )
430 return (KSERR_MALFORMED
);
432 sz
= psz
- ivsz
- SEQSZ
- tagsz
;
433 pmac
= BCUR(b
); pseq
= pmac
+ tagsz
; piv
= pseq
+ SEQSZ
; ppk
= piv
+ ivsz
;
436 /* --- Verify the MAC on the packet --- */
439 h
= GM_INIT(bc
->d
[DIR_IN
].m
);
440 GH_HASH(h
, t
, sizeof(t
));
441 GH_HASH(h
, pseq
, SEQSZ
+ ivsz
+ sz
);
442 CHECK_MAC(h
, pmac
, tagsz
);
445 /* --- Decrypt the packet --- */
451 GC_DECRYPT(c
, ppk
, q
, sz
);
453 /* --- Finished --- */
460 /*----- The implicit-IV transform -----------------------------------------*
462 * The v0 transform makes everything explicit. There's an IV because the
463 * cipher needs an IV; there's a sequence number because replay prevention
464 * needs a sequence number.
466 * This new transform works rather differently. We make use of a block
467 * cipher to encrypt the sequence number, and use that as the IV. We
468 * transmit the sequence number in the clear, as before. This reduces
469 * overhead; and it's not a significant privacy leak because the adversary
470 * can see the order in which the messages are transmitted -- i.e., the
471 * sequence numbers are almost completely predictable anyway.
473 * So, a MAC is computed over
475 * +------+ +------+------...------+
476 * | type | | seq | ciphertext |
477 * +------+ +------+------...------+
480 * and we actually transmit the following as the cryptogram.
482 * +---...---+------+------...------+
483 * | tag | seq | ciphertext |
484 * +---...---+------+------...------+
488 typedef struct iiv_algs
{
491 const gccipher
*b
; size_t bksz
;
494 typedef struct iiv_ctx
{
504 static bulkalgs
*iiv_getalgs(const algswitch
*asw
, dstr
*e
,
505 key_file
*kf
, key
*k
)
507 iiv_algs
*a
= CREATE(iiv_algs
);
508 dstr d
= DSTR_INIT
, dd
= DSTR_INIT
;
512 if (gencomp_getalgs(&a
->ga
, asw
, e
, kf
, k
)) goto fail
;
514 if ((p
= key_getattr(kf
, k
, "blkc")) == 0) {
515 dstr_puts(&dd
, a
->ga
.c
->name
);
516 if ((q
= strrchr(dd
.buf
, '-')) != 0) *q
= 0;
519 dstr_putf(&d
, "%s-ecb", p
);
520 if ((a
->b
= gcipher_byname(d
.buf
)) == 0) {
521 a_format(e
, "unknown-blkc", "%s", p
, A_END
);
525 dstr_destroy(&d
); dstr_destroy(&dd
);
528 dstr_destroy(&d
); dstr_destroy(&dd
);
534 static void iiv_tracealgs(const bulkalgs
*aa
)
536 const iiv_algs
*a
= (const iiv_algs
*)aa
;
538 gencomp_tracealgs(&a
->ga
);
540 "crypto: blkc = %.*s", (int)strlen(a
->b
->name
) - 4, a
->b
->name
);
544 static int iiv_checkalgs(bulkalgs
*aa
, const algswitch
*asw
, dstr
*e
)
546 iiv_algs
*a
= (iiv_algs
*)aa
;
548 if (gencomp_checkalgs(&a
->ga
, asw
, e
)) return (-1);
550 if ((a
->bksz
= keysz(asw
->hashsz
, a
->b
->keysz
)) == 0) {
551 a_format(e
, "blkc", "%.*s", strlen(a
->b
->name
) - 4, a
->b
->name
,
552 "no-key-size", "%lu", (unsigned long)asw
->hashsz
,
556 if (a
->b
->blksz
< a
->ga
.c
->blksz
) {
557 a_format(e
, "blkc", "%.*s", strlen(a
->b
->name
) - 4, a
->b
->name
,
558 "blksz-insufficient", A_END
);
564 static int iiv_samealgsp(const bulkalgs
*aa
, const bulkalgs
*bb
)
566 const iiv_algs
*a
= (const iiv_algs
*)aa
, *b
= (const iiv_algs
*)bb
;
567 return (gencomp_samealgsp(&a
->ga
, &b
->ga
) && a
->b
== b
->b
);
570 static void iiv_alginfo(const bulkalgs
*aa
, admin
*adm
)
572 const iiv_algs
*a
= (const iiv_algs
*)aa
;
573 gencomp_alginfo(&a
->ga
, adm
);
575 "blkc=%.*s", strlen(a
->b
->name
) - 4, a
->b
->name
,
576 "blkc-keysz=%lu", (unsigned long)a
->bksz
,
577 "blkc-blksz=%lu", (unsigned long)a
->b
->blksz
,
581 static size_t iiv_overhead(const bulkalgs
*aa
)
582 { const iiv_algs
*a
= (const iiv_algs
*)aa
; return (a
->ga
.tagsz
+ SEQSZ
); }
584 static size_t iiv_expsz(const bulkalgs
*aa
)
586 const iiv_algs
*a
= (const iiv_algs
*)aa
;
587 return (gencomp_expsz(&a
->ga
));
590 static bulkctx
*iiv_genkeys(const bulkalgs
*aa
, const struct rawkey
*rk
)
592 const iiv_algs
*a
= (const iiv_algs
*)aa
;
593 iiv_ctx
*bc
= CREATE(iiv_ctx
);
597 bc
->tagsz
= a
->ga
.tagsz
;
598 for (i
= 0; i
< NDIR
; i
++) {
599 ks_derivekey(k
, a
->ga
.cksz
, rk
, i
, "encryption");
600 bc
->d
[i
].c
= GC_INIT(a
->ga
.c
, k
, a
->ga
.cksz
);
601 ks_derivekey(k
, a
->bksz
, rk
, i
, "blkc");
602 bc
->d
[i
].b
= GC_INIT(a
->b
, k
, a
->bksz
);
603 ks_derivekey(k
, a
->ga
.mksz
, rk
, i
, "integrity");
604 bc
->d
[i
].m
= GM_KEY(a
->ga
.m
, k
, a
->ga
.mksz
);
609 static bulkchal
*iiv_genchal(const bulkalgs
*aa
)
611 const iiv_algs
*a
= (const iiv_algs
*)aa
;
612 return (gencomp_genchal(&a
->ga
));
614 #define iiv_chaltag gencomp_chaltag
615 #define iiv_chalvrf gencomp_chalvrf
616 #define iiv_freechal gencomp_freechal
618 static void iiv_freealgs(bulkalgs
*aa
)
619 { iiv_algs
*a
= (iiv_algs
*)aa
; DESTROY(a
); }
621 static void iiv_freectx(bulkctx
*bbc
)
623 iiv_ctx
*bc
= (iiv_ctx
*)bbc
;
626 for (i
= 0; i
< NDIR
; i
++) {
627 GC_DESTROY(bc
->d
[i
].c
);
628 GC_DESTROY(bc
->d
[i
].b
);
629 GM_DESTROY(bc
->d
[i
].m
);
634 #define TRACE_PRESEQ(qseq, ivsz) do { IF_TRACING(T_KEYSET, { \
635 trace_block(T_CRYPTO, "crypto: IV derivation input", (qseq), (ivsz)); \
638 static int iiv_encrypt(bulkctx
*bbc
, unsigned ty
,
639 buf
*b
, buf
*bb
, uint32 seq
)
641 iiv_ctx
*bc
= (iiv_ctx
*)bbc
;
643 gcipher
*c
= bc
->d
[DIR_OUT
].c
, *blkc
= bc
->d
[DIR_OUT
].b
;
644 const octet
*p
= BCUR(b
);
645 size_t sz
= BLEFT(b
);
646 octet
*qmac
, *qseq
, *qpk
;
647 size_t ivsz
= GC_CLASS(c
)->blksz
, blkcsz
= GC_CLASS(blkc
)->blksz
;
648 size_t tagsz
= bc
->tagsz
;
651 /* --- Determine the ciphertext layout --- */
653 if (buf_ensure(bb
, tagsz
+ SEQSZ
+ sz
)) return (0);
654 qmac
= BCUR(bb
); qseq
= qmac
+ tagsz
; qpk
= qseq
+ SEQSZ
;
655 BSTEP(bb
, tagsz
+ SEQSZ
+ sz
);
657 /* --- Store the type --- *
659 * This isn't transmitted, but it's covered by the MAC.
664 /* --- Store the sequence number --- */
668 /* --- Establish an initialization vector if necessary --- */
671 memset(buf_u
, 0, blkcsz
- SEQSZ
);
672 memcpy(buf_u
+ blkcsz
- SEQSZ
, qseq
, SEQSZ
);
673 TRACE_PRESEQ(buf_u
, ivsz
);
674 GC_ENCRYPT(blkc
, buf_u
, buf_u
, blkcsz
);
676 TRACE_IV(buf_u
, ivsz
);
679 /* --- Encrypt the packet --- */
681 GC_ENCRYPT(c
, p
, qpk
, sz
);
684 /* --- Compute a MAC over type, sequence number, and ciphertext --- */
687 h
= GM_INIT(bc
->d
[DIR_OUT
].m
);
688 GH_HASH(h
, t
, sizeof(t
));
689 GH_HASH(h
, qseq
, SEQSZ
+ sz
);
690 memcpy(qmac
, GH_DONE(h
, 0), tagsz
);
692 TRACE_MAC(qmac
, tagsz
);
695 /* --- We're done --- */
700 static int iiv_decrypt(bulkctx
*bbc
, unsigned ty
,
701 buf
*b
, buf
*bb
, uint32
*seq
)
703 iiv_ctx
*bc
= (iiv_ctx
*)bbc
;
704 const octet
*pmac
, *pseq
, *ppk
;
705 size_t psz
= BLEFT(b
);
709 gcipher
*c
= bc
->d
[DIR_IN
].c
, *blkc
= bc
->d
[DIR_IN
].b
;
710 size_t ivsz
= GC_CLASS(c
)->blksz
, blkcsz
= GC_CLASS(blkc
)->blksz
;
711 size_t tagsz
= bc
->tagsz
;
714 /* --- Break up the packet into its components --- */
716 if (psz
< SEQSZ
+ tagsz
) {
717 T( trace(T_KEYSET
, "keyset: block too small for keyset"); )
718 return (KSERR_MALFORMED
);
720 sz
= psz
- SEQSZ
- tagsz
;
721 pmac
= BCUR(b
); pseq
= pmac
+ tagsz
; ppk
= pseq
+ SEQSZ
;
724 /* --- Verify the MAC on the packet --- */
727 h
= GM_INIT(bc
->d
[DIR_IN
].m
);
728 GH_HASH(h
, t
, sizeof(t
));
729 GH_HASH(h
, pseq
, SEQSZ
+ sz
);
730 CHECK_MAC(h
, pmac
, tagsz
);
733 /* --- Decrypt the packet --- */
736 memset(buf_u
, 0, blkcsz
- SEQSZ
);
737 memcpy(buf_u
+ blkcsz
- SEQSZ
, pseq
, SEQSZ
);
738 TRACE_PRESEQ(buf_u
, ivsz
);
739 GC_ENCRYPT(blkc
, buf_u
, buf_u
, blkcsz
);
741 TRACE_IV(buf_u
, ivsz
);
743 GC_DECRYPT(c
, ppk
, q
, sz
);
745 /* --- Finished --- */
752 /*----- The NaCl box transform --------------------------------------------*
754 * This transform is very similar to the NaCl `crypto_secretbox' transform
755 * described in Bernstein, `Cryptography in NaCl', with the difference that,
756 * rather than using XSalsa20, we use either Salsa20/r or ChaChar, because we
757 * have no need of XSalsa20's extended nonce. The default cipher is Salsa20.
759 * Salsa20 and ChaCha accept a 64-bit nonce. The low 32 bits are the
760 * sequence number, and the high 32 bits are the type, both big-endian.
767 * A stream is generated by concatenating the raw output blocks generated
768 * with this nonce and successive counter values starting from zero. The
769 * first 32 bytes of the stream are used as a key for Poly1305: the first 16
770 * bytes are the universal hash key r, and the second 16 bytes are the mask
773 * +------+------+ +------...------+
774 * | r | s | | keystream |
775 * +------+------+ +------...------+
778 * The remainder of the stream is XORed with the incoming plaintext to form a
779 * ciphertext with the same length. The ciphertext (only) is then tagged
780 * using Poly1305. The tag, sequence number, and ciphertext are concatenated
781 * in this order, and transmitted.
784 * +---...---+------+------...------+
785 * | tag | seq | ciphertext |
786 * +---...---+------+------...------+
789 * Note that there is no need to authenticate the type separately, since it
790 * was used to select the cipher nonce, and hence the Poly1305 key. The
791 * Poly1305 tag length is fixed.
794 typedef struct naclbox_algs
{
796 const gccipher
*c
; size_t cksz
;
799 typedef struct naclbox_ctx
{
801 struct { gcipher
*c
; } d
[NDIR
];
805 static bulkalgs
*naclbox_getalgs(const algswitch
*asw
, dstr
*e
,
806 key_file
*kf
, key
*k
)
808 naclbox_algs
*a
= CREATE(naclbox_algs
);
813 /* --- Collect the selected cipher and check that it's supported --- */
815 p
= key_getattr(kf
, k
, "cipher");
816 if (!p
|| strcmp(p
, "salsa20") == 0) a
->c
= &salsa20
;
817 else if (strcmp(p
, "salsa20/12") == 0) a
->c
= &salsa2012
;
818 else if (strcmp(p
, "salsa20/8") == 0) a
->c
= &salsa208
;
819 else if (strcmp(p
, "chacha20") == 0) a
->c
= &chacha20
;
820 else if (strcmp(p
, "chacha12") == 0) a
->c
= &chacha12
;
821 else if (strcmp(p
, "chacha8") == 0) a
->c
= &chacha8
;
823 a_format(e
, "unknown-cipher", "%s", p
, A_END
);
827 /* --- Collect the selected MAC, and check the tag length --- */
829 p
= key_getattr(kf
, k
, "mac");
832 else if (strncmp(p
, "poly1305", 8) != 0 || (p
[8] && p
[8] != '/')) {
833 a_format(e
, "unknown-mac", "%s", p
, A_END
);
835 } else if (p
[8] == '/') {
836 n
= strtoul(p
+ 9, &qq
, 0);
838 a_format(e
, "bad-tag-length-string", "%s", p
+ 9, A_END
);
842 a_format(e
, "bad-tag-length", "%lu", n
, A_END
);
854 static void naclbox_tracealgs(const bulkalgs
*aa
)
856 const naclbox_algs
*a
= (const naclbox_algs
*)aa
;
858 trace(T_CRYPTO
, "crypto: cipher = %s", a
->c
->name
);
859 trace(T_CRYPTO
, "crypto: mac = poly1305/128");
863 static int naclbox_checkalgs(bulkalgs
*aa
, const algswitch
*asw
, dstr
*e
)
865 naclbox_algs
*a
= (naclbox_algs
*)aa
;
867 if ((a
->cksz
= keysz(asw
->hashsz
, a
->c
->keysz
)) == 0) {
868 a_format(e
, "cipher", "%s", a
->c
->name
,
869 "no-key-size", "%lu", (unsigned long)asw
->hashsz
,
876 static int naclbox_samealgsp(const bulkalgs
*aa
, const bulkalgs
*bb
)
878 const naclbox_algs
*a
= (const naclbox_algs
*)aa
,
879 *b
= (const naclbox_algs
*)bb
;
880 return (a
->c
== b
->c
);
883 static void naclbox_alginfo(const bulkalgs
*aa
, admin
*adm
)
885 const naclbox_algs
*a
= (const naclbox_algs
*)aa
;
886 a_info(adm
, "cipher=%s", a
->c
->name
, "cipher-keysz=32", A_END
);
887 a_info(adm
, "mac=poly1305", "mac-tagsz=16", A_END
);
890 static size_t naclbox_overhead(const bulkalgs
*aa
)
891 { return (POLY1305_TAGSZ
+ SEQSZ
); }
893 static size_t naclbox_expsz(const bulkalgs
*aa
)
894 { return (MEG(2048)); }
896 static bulkctx
*naclbox_genkeys(const bulkalgs
*aa
, const struct rawkey
*rk
)
898 const naclbox_algs
*a
= (const naclbox_algs
*)aa
;
899 naclbox_ctx
*bc
= CREATE(naclbox_ctx
);
903 for (i
= 0; i
< NDIR
; i
++) {
904 ks_derivekey(k
, a
->cksz
, rk
, i
, "encryption");
905 bc
->d
[i
].c
= GC_INIT(a
->c
, k
, a
->cksz
);
910 typedef struct naclbox_chal
{
915 static bulkchal
*naclbox_genchal(const bulkalgs
*aa
)
917 const naclbox_algs
*a
= (const naclbox_algs
*)aa
;
918 naclbox_chal
*c
= CREATE(naclbox_chal
);
919 rand_get(RAND_GLOBAL
, buf_t
, a
->cksz
);
920 c
->c
= GC_INIT(a
->c
, buf_t
, a
->cksz
);
922 trace(T_CHAL
, "chal: generated new challenge key");
923 trace_block(T_CRYPTO
, "chal: new key", buf_t
, a
->cksz
);
929 static int naclbox_chaltag(bulkchal
*bc
, const void *m
, size_t msz
, void *t
)
931 naclbox_chal
*c
= (naclbox_chal
*)bc
;
932 octet b0
[SALSA20_NONCESZ
];
933 assert(msz
<= sizeof(b0
));
934 memcpy(b0
, m
, msz
); memset(b0
+ msz
, 0, sizeof(b0
) - msz
);
936 GC_ENCRYPT(c
->c
, 0, t
, c
->_b
.tagsz
);
940 static int naclbox_chalvrf(bulkchal
*bc
, const void *m
, size_t msz
,
943 naclbox_chal
*c
= (naclbox_chal
*)bc
;
944 octet b0
[SALSA20_NONCESZ
], b1
[16];
945 assert(msz
<= sizeof(b0
)); assert(c
->_b
.tagsz
<= sizeof(b1
));
946 memcpy(b0
, m
, msz
); memset(b0
+ msz
, 0, sizeof(b0
) - msz
);
948 GC_ENCRYPT(c
->c
, 0, b1
, c
->_b
.tagsz
);
949 return (ct_memeq(t
, b1
, c
->_b
.tagsz
) ?
0 : -1);
952 static void naclbox_freechal(bulkchal
*bc
)
953 { naclbox_chal
*c
= (naclbox_chal
*)bc
; GC_DESTROY(c
->c
); DESTROY(c
); }
955 static void naclbox_freealgs(bulkalgs
*aa
)
956 { naclbox_algs
*a
= (naclbox_algs
*)aa
; DESTROY(a
); }
958 static void naclbox_freectx(bulkctx
*bbc
)
960 naclbox_ctx
*bc
= (naclbox_ctx
*)bbc
;
963 for (i
= 0; i
< NDIR
; i
++) GC_DESTROY(bc
->d
[i
].c
);
967 static int naclbox_encrypt(bulkctx
*bbc
, unsigned ty
,
968 buf
*b
, buf
*bb
, uint32 seq
)
970 naclbox_ctx
*bc
= (naclbox_ctx
*)bbc
;
971 gcipher
*c
= bc
->d
[DIR_OUT
].c
;
974 const octet
*p
= BCUR(b
);
975 size_t sz
= BLEFT(b
);
976 octet
*qmac
, *qseq
, *qpk
;
978 /* --- Determine the ciphertext layout --- */
980 if (buf_ensure(bb
, POLY1305_TAGSZ
+ SEQSZ
+ sz
)) return (0);
981 qmac
= BCUR(bb
); qseq
= qmac
+ POLY1305_TAGSZ
; qpk
= qseq
+ SEQSZ
;
982 BSTEP(bb
, POLY1305_TAGSZ
+ SEQSZ
+ sz
);
984 /* --- Construct and set the nonce --- */
987 memcpy(buf_u
, qseq
, SEQSZ
); STORE32(buf_u
+ SEQSZ
, ty
);
989 TRACE_IV(buf_u
, SALSA20_NONCESZ
);
991 /* --- Determine the MAC key --- */
993 GC_ENCRYPT(c
, 0, buf_u
, POLY1305_KEYSZ
+ POLY1305_MASKSZ
);
994 poly1305_keyinit(&polyk
, buf_u
, POLY1305_KEYSZ
);
995 poly1305_macinit(&poly
, &polyk
, buf_u
+ POLY1305_KEYSZ
);
997 /* --- Encrypt the message --- */
999 GC_ENCRYPT(c
, p
, qpk
, sz
);
1002 /* --- Compute the MAC --- */
1004 poly1305_hash(&poly
, qpk
, sz
);
1005 poly1305_done(&poly
, qmac
);
1006 TRACE_MAC(qmac
, POLY1305_TAGSZ
);
1008 /* --- We're done --- */
1013 static int naclbox_decrypt(bulkctx
*bbc
, unsigned ty
,
1014 buf
*b
, buf
*bb
, uint32
*seq
)
1016 naclbox_ctx
*bc
= (naclbox_ctx
*)bbc
;
1017 gcipher
*c
= bc
->d
[DIR_IN
].c
;
1020 const octet
*pmac
, *pseq
, *ppk
;
1021 size_t psz
= BLEFT(b
);
1023 octet
*q
= BCUR(bb
);
1025 /* --- Break up the packet into its components --- */
1027 if (psz
< SEQSZ
+ POLY1305_TAGSZ
) {
1028 T( trace(T_KEYSET
, "keyset: block too small for keyset"); )
1029 return (KSERR_MALFORMED
);
1031 sz
= psz
- SEQSZ
- POLY1305_TAGSZ
;
1032 pmac
= BCUR(b
); pseq
= pmac
+ POLY1305_TAGSZ
; ppk
= pseq
+ SEQSZ
;
1034 /* --- Construct and set the nonce --- */
1036 memcpy(buf_u
, pseq
, SEQSZ
); STORE32(buf_u
+ SEQSZ
, ty
);
1038 TRACE_IV(buf_u
, SALSA20_NONCESZ
);
1040 /* --- Determine the MAC key --- */
1042 GC_ENCRYPT(c
, 0, buf_u
, POLY1305_KEYSZ
+ POLY1305_MASKSZ
);
1043 poly1305_keyinit(&polyk
, buf_u
, POLY1305_KEYSZ
);
1044 poly1305_macinit(&poly
, &polyk
, buf_u
+ POLY1305_KEYSZ
);
1046 /* --- Verify the MAC on the packet --- */
1048 poly1305_hash(&poly
, ppk
, sz
);
1049 poly1305_done(&poly
, buf_u
);
1050 TRACE_MAC(buf_u
, POLY1305_TAGSZ
);
1051 if (!ct_memeq(buf_u
, pmac
, POLY1305_TAGSZ
)) {
1052 TRACE_MACERR(pmac
, POLY1305_TAGSZ
);
1053 return (KSERR_DECRYPT
);
1056 /* --- Decrypt the packet --- */
1058 GC_DECRYPT(c
, ppk
, q
, sz
);
1060 /* --- Finished --- */
1062 *seq
= LOAD32(pseq
);
1067 /*----- Bulk crypto transform table ---------------------------------------*/
1069 const bulkops bulktab
[] = {
1073 #define BULK(name, pre) \
1074 { name, pre##_getalgs, T( pre##_tracealgs COMMA ) \
1075 pre##_checkalgs, pre##_samealgsp, \
1076 pre##_alginfo, pre##_overhead, pre##_expsz, \
1077 pre##_genkeys, pre##_genchal, pre##_freealgs, \
1078 pre##_encrypt, pre##_decrypt, pre##_freectx, \
1079 pre##_chaltag, pre##_chalvrf, pre##_freechal }
1083 BULK("naclbox", naclbox
),
1089 /*----- That's all, folks -------------------------------------------------*/