1 \ Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
3 \ Permission is hereby granted, free of charge, to any person obtaining
4 \ a copy of this software and associated documentation files (the
5 \ "Software"), to deal in the Software without restriction, including
6 \ without limitation the rights to use, copy, modify, merge, publish,
7 \ distribute, sublicense, and/or sell copies of the Software, and to
8 \ permit persons to whom the Software is furnished to do so, subject to
9 \ the following conditions:
11 \ The above copyright notice and this permission notice shall be
12 \ included in all copies or substantial portions of the Software.
14 \ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
15 \ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
16 \ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
17 \ NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
18 \ BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
19 \ ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
20 \ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
28 * Implementation Notes
29 * --------------------
31 * The C code pushes the data by chunks; all decoding is done in the
32 * T0 code. The cert_length value is set to the certificate length when
33 * a new certificate is started; the T0 code picks it up as outer limit,
34 * and decoding functions use it to ensure that no attempt is made at
35 * reading past it. The T0 code also checks that once the certificate is
36 * decoded, there are no trailing bytes.
38 * The T0 code sets cert_length to 0 when the certificate is fully
41 * The C code must still perform two checks:
43 * -- If the certificate length is 0, then the T0 code will not be
44 * invoked at all. This invalid condition must thus be reported by the
47 * -- When reaching the end of certificate, the C code must verify that
48 * the certificate length has been set to 0, thereby signaling that
49 * the T0 code properly decoded a certificate.
51 * Processing of a chain works in the following way:
53 * -- The error flag is set to a non-zero value when validation is
54 * finished. The value is either BR_ERR_X509_OK (validation is
55 * successful) or another non-zero error code. When a non-zero error
56 * code is obtained, the remaining bytes in the current certificate and
57 * the subsequent certificates (if any) are completely ignored.
59 * -- Each certificate is decoded in due course, with the following
60 * "interesting points":
62 * -- Start of the TBS: the multihash engine is reset and activated.
64 * -- Start of the issuer DN: the secondary hash engine is started,
65 * to process the encoded issuer DN.
67 * -- End of the issuer DN: the secondary hash engine is stopped. The
68 * resulting hash value is computed and then copied into the
69 * next_dn_hash[] buffer.
71 * -- Start of the subject DN: the secondary hash engine is started,
72 * to process the encoded subject DN.
74 * -- For the EE certificate only: the Common Name, if any, is matched
75 * against the expected server name.
77 * -- End of the subject DN: the secondary hash engine is stopped. The
78 * resulting hash value is computed into the pad. It is then processed:
80 * -- If this is the EE certificate, then the hash is ignored
81 * (except for direct trust processing, see later; the hash is
82 * simply left in current_dn_hash[]).
84 * -- Otherwise, the hashed subject DN is compared with the saved
85 * hash value (in saved_dn_hash[]). They must match.
87 * Either way, the next_dn_hash[] value is then copied into the
88 * saved_dn_hash[] value. Thus, at that point, saved_dn_hash[]
89 * contains the hash of the issuer DN for the current certificate,
90 * and current_dn_hash[] contains the hash of the subject DN for the
91 * current certificate.
93 * -- Public key: it is decoded into the cert_pkey[] buffer. Unknown
94 * key types are reported at that point.
96 * -- If this is the EE certificate, then the key type is compared
97 * with the expected key type (initialization parameter). The public
98 * key data is copied to ee_pkey_data[]. The key and hashed subject
99 * DN are also compared with the "direct trust" keys; if the key
100 * and DN are matched, then validation ends with a success.
102 * -- Otherwise, the saved signature (cert_sig[]) is verified
103 * against the saved TBS hash (tbs_hash[]) and that freshly
104 * decoded public key. Failure here ends validation with an error.
106 * -- Extensions: extension values are processed in due order.
108 * -- Basic Constraints: for all certificates except EE, must be
109 * present, indicate a CA, and have a path legnth compatible with
110 * the chain length so far.
112 * -- Key Usage: for the EE, if present, must allow signatures
113 * or encryption/key exchange, as required for the cipher suite.
114 * For non-EE, if present, must have the "certificate sign" bit.
116 * -- Subject Alt Name: for the EE, dNSName names are matched
117 * against the server name. Ignored for non-EE.
119 * -- Authority Key Identifier, Subject Key Identifier, Issuer
120 * Alt Name, Subject Directory Attributes, CRL Distribution Points
121 * Freshest CRL, Authority Info Access and Subject Info Access
122 * extensions are always ignored: they either contain only
123 * informative data, or they relate to revocation processing, which
124 * we explicitly do not support.
126 * -- All other extensions are ignored if non-critical. If a
127 * critical extension other than the ones above is encountered,
128 * then a failure is reported.
130 * -- End of the TBS: the multihash engine is stopped.
132 * -- Signature algorithm: the signature algorithm on the
133 * certificate is decoded. A failure is reported if that algorithm
134 * is unknown. The hashed TBS corresponding to the signature hash
135 * function is computed and stored in tbs_hash[] (if not supported,
136 * then a failure is reported). The hash OID and length are stored
137 * in cert_sig_hash_oid and cert_sig_hash_len.
139 * -- Signature value: the signature value is copied into the
142 * -- Certificate end: the hashed issuer DN (saved_dn_hash[]) is
143 * looked up in the trust store (CA trust anchors only); for all
144 * that match, the signature (cert_sig[]) is verified against the
145 * anchor public key (hashed TBS is in tbs_hash[]). If one of these
146 * signatures is valid, then validation ends with a success.
148 * -- If the chain end is reached without obtaining a validation success,
149 * then validation is reported as failed.
156 #if BR_USE_WIN32_TIME
161 * The T0 compiler will produce these prototypes declarations in the
164 void br_x509_minimal_init_main(void *ctx);
165 void br_x509_minimal_run(void *ctx);
168 /* see bearssl_x509.h */
170 br_x509_minimal_init(br_x509_minimal_context *ctx,
171 const br_hash_class *dn_hash_impl,
172 const br_x509_trust_anchor *trust_anchors, size_t trust_anchors_num)
174 memset(ctx, 0, sizeof *ctx);
175 ctx->vtable = &br_x509_minimal_vtable;
176 ctx->dn_hash_impl = dn_hash_impl;
177 ctx->trust_anchors = trust_anchors;
178 ctx->trust_anchors_num = trust_anchors_num;
182 xm_start_chain(const br_x509_class **ctx, const char *server_name)
184 br_x509_minimal_context *cc;
187 cc = (br_x509_minimal_context *)(void *)ctx;
188 for (u = 0; u < cc->num_name_elts; u ++) {
189 cc->name_elts[u].status = 0;
190 cc->name_elts[u].buf[0] = 0;
192 memset(&cc->pkey, 0, sizeof cc->pkey);
195 cc->cpu.dp = cc->dp_stack;
196 cc->cpu.rp = cc->rp_stack;
197 br_x509_minimal_init_main(&cc->cpu);
198 if (server_name == NULL || *server_name == 0) {
199 cc->server_name = NULL;
201 cc->server_name = server_name;
206 xm_start_cert(const br_x509_class **ctx, uint32_t length)
208 br_x509_minimal_context *cc;
210 cc = (br_x509_minimal_context *)(void *)ctx;
215 cc->err = BR_ERR_X509_TRUNCATED;
218 cc->cert_length = length;
222 xm_append(const br_x509_class **ctx, const unsigned char *buf, size_t len)
224 br_x509_minimal_context *cc;
226 cc = (br_x509_minimal_context *)(void *)ctx;
232 br_x509_minimal_run(&cc->cpu);
236 xm_end_cert(const br_x509_class **ctx)
238 br_x509_minimal_context *cc;
240 cc = (br_x509_minimal_context *)(void *)ctx;
241 if (cc->err == 0 && cc->cert_length != 0) {
242 cc->err = BR_ERR_X509_TRUNCATED;
248 xm_end_chain(const br_x509_class **ctx)
250 br_x509_minimal_context *cc;
252 cc = (br_x509_minimal_context *)(void *)ctx;
254 if (cc->num_certs == 0) {
255 cc->err = BR_ERR_X509_EMPTY_CHAIN;
257 cc->err = BR_ERR_X509_NOT_TRUSTED;
259 } else if (cc->err == BR_ERR_X509_OK) {
262 return (unsigned)cc->err;
265 static const br_x509_pkey *
266 xm_get_pkey(const br_x509_class *const *ctx, unsigned *usages)
268 br_x509_minimal_context *cc;
270 cc = (br_x509_minimal_context *)(void *)ctx;
271 if (cc->err == BR_ERR_X509_OK
272 || cc->err == BR_ERR_X509_NOT_TRUSTED)
274 if (usages != NULL) {
275 *usages = cc->key_usages;
277 return &((br_x509_minimal_context *)(void *)ctx)->pkey;
283 /* see bearssl_x509.h */
284 const br_x509_class br_x509_minimal_vtable = {
285 sizeof(br_x509_minimal_context),
294 #define CTX ((br_x509_minimal_context *)(void *)((unsigned char *)t0ctx - offsetof(br_x509_minimal_context, cpu)))
295 #define CONTEXT_NAME br_x509_minimal_context
297 #define DNHASH_LEN ((CTX->dn_hash_impl->desc >> BR_HASHDESC_OUT_OFF) & BR_HASHDESC_OUT_MASK)
300 * Hash a DN (from a trust anchor) into the provided buffer. This uses the
301 * DN hash implementation and context structure from the X.509 engine
305 hash_dn(br_x509_minimal_context *ctx, const void *dn, size_t len,
308 ctx->dn_hash_impl->init(&ctx->dn_hash.vtable);
309 ctx->dn_hash_impl->update(&ctx->dn_hash.vtable, dn, len);
310 ctx->dn_hash_impl->out(&ctx->dn_hash.vtable, out);
314 * Compare two big integers for equality. The integers use unsigned big-endian
315 * encoding; extra leading bytes (of value 0) are allowed.
318 eqbigint(const unsigned char *b1, size_t len1,
319 const unsigned char *b2, size_t len2)
321 while (len1 > 0 && *b1 == 0) {
325 while (len2 > 0 && *b2 == 0) {
332 return memcmp(b1, b2, len1) == 0;
336 * Compare two strings for equality, in a case-insensitive way. This
337 * function handles casing only for ASCII letters.
340 eqnocase(const void *s1, const void *s2, size_t len)
342 const unsigned char *buf1, *buf2;
351 if (x1 >= 'A' && x1 <= 'Z') {
354 if (x2 >= 'A' && x2 <= 'Z') {
364 static int verify_signature(br_x509_minimal_context *ctx,
365 const br_x509_pkey *pk);
372 * Verify the signature on the certificate with the provided public key.
373 * This function checks the public key type with regards to the expected
374 * type. Returned value is either 0 on success, or a non-zero error code.
377 verify_signature(br_x509_minimal_context *ctx, const br_x509_pkey *pk)
381 kt = ctx->cert_signer_key_type;
382 if ((pk->key_type & 0x0F) != kt) {
383 return BR_ERR_X509_WRONG_KEY_TYPE;
386 unsigned char tmp[64];
389 if (ctx->irsa == 0) {
390 return BR_ERR_X509_UNSUPPORTED;
392 if (!ctx->irsa(ctx->cert_sig, ctx->cert_sig_len,
393 &t0_datablock[ctx->cert_sig_hash_oid],
394 ctx->cert_sig_hash_len, &pk->key.rsa, tmp))
396 return BR_ERR_X509_BAD_SIGNATURE;
398 if (memcmp(ctx->tbs_hash, tmp, ctx->cert_sig_hash_len) != 0) {
399 return BR_ERR_X509_BAD_SIGNATURE;
404 if (ctx->iecdsa == 0) {
405 return BR_ERR_X509_UNSUPPORTED;
407 if (!ctx->iecdsa(ctx->iec, ctx->tbs_hash,
408 ctx->cert_sig_hash_len, &pk->key.ec,
409 ctx->cert_sig, ctx->cert_sig_len))
411 return BR_ERR_X509_BAD_SIGNATURE;
416 return BR_ERR_X509_UNSUPPORTED;
422 cc: read8-low ( -- x ) {
423 if (CTX->hlen == 0) {
426 unsigned char x = *CTX->hbuf ++;
428 br_multihash_update(&CTX->mhash, &x, 1);
430 if (CTX->do_dn_hash) {
431 CTX->dn_hash_impl->update(&CTX->dn_hash.vtable, &x, 1);
441 cc: read-blob-inner ( addr len -- addr len ) {
442 uint32_t len = T0_POP();
443 uint32_t addr = T0_POP();
444 size_t clen = CTX->hlen;
449 memcpy((unsigned char *)CTX + addr, CTX->hbuf, clen);
452 br_multihash_update(&CTX->mhash, CTX->hbuf, clen);
454 if (CTX->do_dn_hash) {
455 CTX->dn_hash_impl->update(
456 &CTX->dn_hash.vtable, CTX->hbuf, clen);
460 T0_PUSH(addr + clen);
464 \ Compute the TBS hash, using the provided hash ID. The hash value is
465 \ written in the tbs_hash[] array, and the hash length is returned. If
466 \ the requested hash function is not supported, then 0 is returned.
467 cc: compute-tbs-hash ( id -- hashlen ) {
470 len = br_multihash_out(&CTX->mhash, id, CTX->tbs_hash);
474 \ Push true (-1) if no server name is expected in the EE certificate.
475 cc: zero-server-name ( -- bool ) {
476 T0_PUSHi(-(CTX->server_name == NULL));
482 addr: cert_signer_key_type
483 addr: cert_sig_hash_oid
484 addr: cert_sig_hash_len
488 \ Start TBS hash computation. The hash functions are reinitialised.
489 cc: start-tbs-hash ( -- ) {
490 br_multihash_init(&CTX->mhash);
494 \ Stop TBS hash computation.
495 cc: stop-tbs-hash ( -- ) {
499 \ Start DN hash computation.
500 cc: start-dn-hash ( -- ) {
501 CTX->dn_hash_impl->init(&CTX->dn_hash.vtable);
505 \ Terminate DN hash computation and write the DN hash into the
506 \ current_dn_hash buffer.
507 cc: compute-dn-hash ( -- ) {
508 CTX->dn_hash_impl->out(&CTX->dn_hash.vtable, CTX->current_dn_hash);
512 \ Get the length of hash values obtained with the DN hasher.
513 cc: dn-hash-length ( -- len ) {
517 \ Copy data between two areas in the context.
518 cc: blobcopy ( addr-dst addr-src len -- ) {
519 size_t len = T0_POP();
520 unsigned char *src = (unsigned char *)CTX + T0_POP();
521 unsigned char *dst = (unsigned char *)CTX + T0_POP();
522 memcpy(dst, src, len);
525 addr: current_dn_hash
529 \ Read a DN, hashing it into current_dn_hash. The DN contents are not
530 \ inspected (only the outer tag, for SEQUENCE, is checked).
531 : read-DN ( lim -- lim )
533 read-sequence-open skip-close-elt
536 cc: offset-name-element ( san -- n ) {
537 unsigned san = T0_POP();
540 for (u = 0; u < CTX->num_name_elts; u ++) {
541 if (CTX->name_elts[u].status == 0) {
542 const unsigned char *oid;
545 oid = CTX->name_elts[u].oid;
547 if (oid[0] != 0 || oid[1] != 0) {
555 if (len != 0 && len == CTX->pad[0]
556 && memcmp(oid + off + 1,
557 CTX->pad + 1, len) == 0)
567 cc: copy-name-element ( bool offbuf -- ) {
569 int32_t off = T0_POPi();
573 br_name_element *ne = &CTX->name_elts[off];
578 memcpy(ne->buf, CTX->pad + 1, len);
590 cc: copy-name-SAN ( bool tag -- ) {
591 unsigned tag = T0_POP();
592 unsigned ok = T0_POP();
596 for (u = 0; u < CTX->num_name_elts; u ++) {
599 ne = &CTX->name_elts[u];
600 if (ne->status == 0 && ne->oid[0] == 0 && ne->oid[1] == tag) {
601 if (ok && ne->len > len) {
602 memcpy(ne->buf, CTX->pad + 1, len);
613 \ Read a value, decoding string types. If the string type is recognised
614 \ and the value could be converted to UTF-8 into the pad, then true (-1)
615 \ is returned; in all other cases, false (0) is returned. Either way, the
616 \ object is consumed.
617 : read-string ( lim -- lim bool )
620 12 of check-primitive read-value-UTF8 endof
622 18 of check-primitive read-value-latin1 endof
624 19 of check-primitive read-value-latin1 endof
626 20 of check-primitive read-value-latin1 endof
628 22 of check-primitive read-value-latin1 endof
630 30 of check-primitive read-value-UTF16 endof
631 2drop read-length-skip 0 0
634 \ Read a DN for the EE. The normalized DN hash is computed and stored in the
636 \ Name elements are gathered. Also, the Common Name is matched against the
637 \ intended server name.
638 \ Returned value is true (-1) if the CN matches the intended server name,
639 \ false (0) otherwise.
640 : read-DN-EE ( lim -- lim bool )
641 \ Flag will be set to true if there is a CN and it matches the
642 \ intended server name.
645 \ Activate DN hashing.
648 \ Parse the DN structure: it is a SEQUENCE of SET of
649 \ AttributeTypeAndValue. Each AttributeTypeAndValue is a
650 \ SEQUENCE { OBJECT IDENTIFIER, ANY }.
655 read-tag 0x11 check-tag-constructed read-length-open-elt
656 dup ifnot ERR_X509_BAD_DN fail then
662 \ Read the OID. If the OID could not be read (too
663 \ long) then the first pad byte will be 0.
666 \ If it is the Common Name then we'll need to
667 \ match it against the intended server name (if
669 id-at-commonName eqOID { isCN }
671 \ Get offset for reception buffer for that element
673 0 offset-name-element { offbuf }
675 \ Try to read the value as a string.
678 \ If the value could be decoded as a string,
679 \ copy it and/or match it, as appropriate.
685 offbuf copy-name-element
695 \ Compute DN hash and deactivate DN hashing.
698 \ Return the CN match flag.
701 \ Get the validation date and time from the context or system.
702 cc: get-system-date ( -- days seconds ) {
703 if (CTX->days == 0 && CTX->seconds == 0) {
705 time_t x = time(NULL);
707 T0_PUSH((uint32_t)(x / 86400) + 719528);
708 T0_PUSH((uint32_t)(x % 86400));
709 #elif BR_USE_WIN32_TIME
713 GetSystemTimeAsFileTime(&ft);
714 x = ((uint64_t)ft.dwHighDateTime << 32)
715 + (uint64_t)ft.dwLowDateTime;
717 T0_PUSH((uint32_t)(x / 86400) + 584754);
718 T0_PUSH((uint32_t)(x % 86400));
720 CTX->err = BR_ERR_X509_TIME_UNKNOWN;
725 T0_PUSH(CTX->seconds);
729 \ Compare two dates (days+seconds) together.
730 : before ( days1 seconds1 days2 seconds2 -- bool )
732 d1 d2 = if s1 s2 < else d1 d2 < then ;
734 : after ( days1 seconds1 days2 seconds2 -- bool )
737 \ Swap the top two elements with the two elements immediately below.
738 : swap2 ( a b c d -- c d a b )
741 \ Match the name in the pad with the expected server name. Returned value
742 \ is true (-1) on match, false (0) otherwise. If there is no expected
743 \ server name, then 0 is returned.
744 \ Match conditions: either an exact match (case insensitive), or a
745 \ wildcard match, if the found name starts with "*.". We only match a
746 \ starting wildcard, and only against a complete DN name component.
747 cc: match-server-name ( -- bool ) {
750 if (CTX->server_name == NULL) {
754 n1 = strlen(CTX->server_name);
756 if (n1 == n2 && eqnocase(&CTX->pad[1], CTX->server_name, n1)) {
760 if (n2 >= 2 && CTX->pad[1] == '*' && CTX->pad[2] == '.') {
764 while (u < n1 && CTX->server_name[u] != '.') {
770 && eqnocase(&CTX->pad[3], CTX->server_name + u, n1))
779 \ Get the address and length for the pkey_data buffer.
780 : addr-len-pkey_data ( -- addr len )
781 CX 0 8191 { offsetof(br_x509_minimal_context, pkey_data) }
782 CX 0 8191 { BR_X509_BUFSIZE_KEY } ;
784 \ Copy the EE public key to the permanent buffer (RSA).
785 cc: copy-ee-rsa-pkey ( nlen elen -- ) {
786 size_t elen = T0_POP();
787 size_t nlen = T0_POP();
788 memcpy(CTX->ee_pkey_data, CTX->pkey_data, nlen + elen);
789 CTX->pkey.key_type = BR_KEYTYPE_RSA;
790 CTX->pkey.key.rsa.n = CTX->ee_pkey_data;
791 CTX->pkey.key.rsa.nlen = nlen;
792 CTX->pkey.key.rsa.e = CTX->ee_pkey_data + nlen;
793 CTX->pkey.key.rsa.elen = elen;
796 \ Copy the EE public key to the permanent buffer (EC).
797 cc: copy-ee-ec-pkey ( curve qlen -- ) {
798 size_t qlen = T0_POP();
799 uint32_t curve = T0_POP();
800 memcpy(CTX->ee_pkey_data, CTX->pkey_data, qlen);
801 CTX->pkey.key_type = BR_KEYTYPE_EC;
802 CTX->pkey.key.ec.curve = curve;
803 CTX->pkey.key.ec.q = CTX->ee_pkey_data;
804 CTX->pkey.key.ec.qlen = qlen;
807 \ Check whether the current certificate (EE) is directly trusted.
808 cc: check-direct-trust ( -- ) {
811 for (u = 0; u < CTX->trust_anchors_num; u ++) {
812 const br_x509_trust_anchor *ta;
813 unsigned char hashed_DN[64];
816 ta = &CTX->trust_anchors[u];
817 if (ta->flags & BR_X509_TA_CA) {
820 hash_dn(CTX, ta->dn.data, ta->dn.len, hashed_DN);
821 if (memcmp(hashed_DN, CTX->current_dn_hash, DNHASH_LEN)) {
824 kt = CTX->pkey.key_type;
825 if ((ta->pkey.key_type & 0x0F) != kt) {
831 if (!eqbigint(CTX->pkey.key.rsa.n,
832 CTX->pkey.key.rsa.nlen,
834 ta->pkey.key.rsa.nlen)
835 || !eqbigint(CTX->pkey.key.rsa.e,
836 CTX->pkey.key.rsa.elen,
838 ta->pkey.key.rsa.elen))
845 if (CTX->pkey.key.ec.curve != ta->pkey.key.ec.curve
846 || CTX->pkey.key.ec.qlen != ta->pkey.key.ec.qlen
847 || memcmp(CTX->pkey.key.ec.q,
849 ta->pkey.key.ec.qlen) != 0)
860 * Direct trust match!
862 CTX->err = BR_ERR_X509_OK;
867 \ Check the signature on the certificate with regards to all trusted CA.
868 \ We use the issuer hash (in saved_dn_hash[]) as CA identifier.
869 cc: check-trust-anchor-CA ( -- ) {
872 for (u = 0; u < CTX->trust_anchors_num; u ++) {
873 const br_x509_trust_anchor *ta;
874 unsigned char hashed_DN[64];
876 ta = &CTX->trust_anchors[u];
877 if (!(ta->flags & BR_X509_TA_CA)) {
880 hash_dn(CTX, ta->dn.data, ta->dn.len, hashed_DN);
881 if (memcmp(hashed_DN, CTX->saved_dn_hash, DNHASH_LEN)) {
884 if (verify_signature(CTX, &ta->pkey) == 0) {
885 CTX->err = BR_ERR_X509_OK;
891 \ Verify RSA signature. This uses the public key that was just decoded
892 \ into CTX->pkey_data; the modulus and exponent length are provided as
893 \ parameters. The resulting hash value is compared with the one in
894 \ tbs_hash. Returned value is 0 on success, or a non-zero error code.
895 cc: do-rsa-vrfy ( nlen elen -- err ) {
896 size_t elen = T0_POP();
897 size_t nlen = T0_POP();
900 pk.key_type = BR_KEYTYPE_RSA;
901 pk.key.rsa.n = CTX->pkey_data;
902 pk.key.rsa.nlen = nlen;
903 pk.key.rsa.e = CTX->pkey_data + nlen;
904 pk.key.rsa.elen = elen;
905 T0_PUSH(verify_signature(CTX, &pk));
908 \ Verify ECDSA signature. This uses the public key that was just decoded
909 \ into CTX->pkey_dayta; the curve ID and public point length are provided
910 \ as parameters. The hash value in tbs_hash is used. Returned value is 0
911 \ on success, or non-zero error code.
912 cc: do-ecdsa-vrfy ( curve qlen -- err ) {
913 size_t qlen = T0_POP();
914 int curve = T0_POP();
917 pk.key_type = BR_KEYTYPE_EC;
918 pk.key.ec.curve = curve;
919 pk.key.ec.q = CTX->pkey_data;
920 pk.key.ec.qlen = qlen;
921 T0_PUSH(verify_signature(CTX, &pk));
924 cc: print-bytes ( addr len -- ) {
925 extern int printf(const char *fmt, ...);
926 size_t len = T0_POP();
927 unsigned char *buf = (unsigned char *)CTX + T0_POP();
930 for (u = 0; u < len; u ++) {
931 printf("%02X", buf[u]);
935 cc: printOID ( -- ) {
936 extern int printf(const char *fmt, ...);
944 printf("%u.%u", CTX->pad[1] / 40, CTX->pad[1] % 40);
958 ul = (ul << 7) + (x & 0x7F);
967 \ Extensions with specific processing.
968 OID: basicConstraints 2.5.29.19
969 OID: keyUsage 2.5.29.15
970 OID: subjectAltName 2.5.29.17
971 OID: certificatePolicies 2.5.29.32
973 \ Policy qualifier "pointer to CPS"
974 OID: id-qt-cps 1.3.6.1.5.5.7.2.1
976 \ Extensions which are ignored when encountered, even if critical.
977 OID: authorityKeyIdentifier 2.5.29.35
978 OID: subjectKeyIdentifier 2.5.29.14
979 OID: issuerAltName 2.5.29.18
980 OID: subjectDirectoryAttributes 2.5.29.9
981 OID: crlDistributionPoints 2.5.29.31
982 OID: freshestCRL 2.5.29.46
983 OID: authorityInfoAccess 1.3.6.1.5.5.7.1.1
984 OID: subjectInfoAccess 1.3.6.1.5.5.7.1.11
986 \ Process a Basic Constraints extension. This should be called only if
987 \ the certificate is not the EE. We check that the extension contains
988 \ the "CA" flag, and that the path length, if specified, is compatible
989 \ with the current chain length.
990 : process-basicConstraints ( lim -- lim )
994 read-boolean ifnot ERR_X509_NOT_CA fail then
1000 drop check-primitive read-small-int-value
1001 addr-num_certs get32 1- < if ERR_X509_NOT_CA fail then
1004 -1 <> if ERR_X509_UNEXPECTED fail then
1009 \ Process a Key Usage extension.
1010 \ For the EE certificate:
1011 \ -- if the key usage contains keyEncipherment (2), dataEncipherment (3)
1012 \ or keyAgreement (4), then the "key exchange" usage is allowed;
1013 \ -- if the key usage contains digitalSignature (0) or nonRepudiation (1),
1014 \ then the "signature" usage is allowed.
1015 \ For CA certificates, the extension must contain keyCertSign (5).
1016 : process-keyUsage ( lim ee -- lim )
1019 \ Read tag for the BIT STRING and open it.
1020 read-tag 0x03 check-tag-primitive
1021 read-length-open-elt
1022 \ First byte indicates number of ignored bits in the last byte. It
1023 \ must be between 0 and 7.
1025 ign 7 > if ERR_X509_UNEXPECTED fail then
1026 \ Depending on length, we have either 0, 1 or more bytes to read.
1028 0 of ERR_X509_FORBIDDEN_KEY_USAGE fail endof
1029 1 of read8 ign >> ign << endof
1037 over 0x38 and if 0x10 or then
1038 swap 0xC0 and if 0x20 or then
1039 addr-key_usages set8
1041 \ Not EE: keyCertSign must be set.
1042 0x04 and ifnot ERR_X509_FORBIDDEN_KEY_USAGE fail then
1045 \ We don't care about subsequent bytes.
1048 \ Process a Certificate Policies extension.
1050 \ Since we don't actually support full policies processing, this function
1051 \ only checks that the extension contents can be safely ignored. Indeed,
1052 \ we don't validate against a specific set of policies (in RFC 5280
1053 \ terminology, user-initial-policy-set only contains the special value
1054 \ any-policy). Moreover, we don't support policy constraints (if a
1055 \ critical Policy Constraints extension is encountered, the validation
1056 \ will fail). Therefore, we can safely ignore the contents of this
1057 \ extension, except if it is critical AND one of the policy OID has a
1058 \ qualifier which is distinct from id-qt-cps (because id-qt-cps is
1059 \ specially designated by RFC 5280 has having no mandated action).
1061 \ This function is called only if the extension is critical.
1062 : process-certPolicies ( lim -- lim )
1063 \ Extension value is a SEQUENCE OF PolicyInformation.
1066 \ PolicyInformation ::= SEQUENCE {
1067 \ policyIdentifier OBJECT IDENTIFIER,
1068 \ policyQualifiers SEQUENCE OF PolicyQualifierInfo OPTIONAL
1075 \ PolicyQualifierInfo ::= SEQUENCE {
1076 \ policyQualifierId OBJECT IDENTIFIER,
1080 read-OID drop id-qt-cps eqOID ifnot
1081 ERR_X509_CRITICAL_EXTENSION fail
1091 \ Process a Subject Alt Name extension. Returned value is a boolean set
1092 \ to true if the expected server name was matched against a dNSName in
1094 : process-SAN ( lim -- lim bool )
1098 \ Read the tag. If the tag is context-0, then parse an
1099 \ 'otherName'. If the tag is context-2, then parse a
1100 \ dNSName. If the tag is context-1 or context-6,
1105 \ OtherName ::= SEQUENCE {
1106 \ type-id OBJECT IDENTIFIER,
1107 \ value [0] EXPLICIT ANY
1109 check-constructed read-length-open-elt
1111 -1 offset-name-element { offbuf }
1112 read-tag 0x20 check-tag-constructed
1113 read-length-open-elt
1114 read-string offbuf copy-name-element
1118 \ rfc822Name (IA5String)
1121 read-value-UTF8 1 copy-name-SAN
1123 \ dNSName (IA5String)
1127 dup if match-server-name m or >m then
1130 \ uniformResourceIdentifier (IA5String)
1133 read-value-UTF8 6 copy-name-SAN
1135 2drop read-length-skip 0
1138 \ We check only names of type dNSName; they use IA5String,
1139 \ which is basically ASCII.
1140 \ read-tag 0x22 = if
1142 \ read-small-value drop
1143 \ match-server-name m or >m
1145 \ drop read-length-skip
1151 \ Decode a certificate. The "ee" boolean must be true for the EE.
1152 : decode-certificate ( ee -- )
1155 \ Obtain the total certificate length.
1156 addr-cert_length get32
1158 \ Open the outer SEQUENCE.
1166 \ First element may be an explicit version. We accept only
1167 \ versions 0 to 2 (certificates v1 to v3).
1168 read-tag dup 0x20 = if
1169 drop check-constructed read-length-open-elt
1171 0x02 check-tag-primitive
1172 read-small-int-value
1173 2 > if ERR_X509_UNSUPPORTED fail then
1178 \ Serial number. We just check that the tag is correct.
1179 0x02 check-tag-primitive
1182 \ Signature algorithm. This structure is redundant with the one
1183 \ on the outside; we just skip it.
1184 read-sequence-open skip-close-elt
1186 \ Issuer name: hashed, then copied into next_dn_hash[].
1188 addr-next_dn_hash addr-current_dn_hash dn-hash-length blobcopy
1192 read-date get-system-date after if ERR_X509_EXPIRED fail then
1193 read-date get-system-date before if ERR_X509_EXPIRED fail then
1198 \ For the EE, we must check whether the Common Name, if
1199 \ any, matches the expected server name.
1200 read-DN-EE { eename }
1202 \ For a non-EE certificate, the hashed subject DN must match
1203 \ the saved hashed issuer DN from the previous certificate.
1205 addr-current_dn_hash addr-saved_dn_hash dn-hash-length eqblob
1206 ifnot ERR_X509_DN_MISMATCH fail then
1208 \ Move the hashed issuer DN for this certificate into the
1209 \ saved_dn_hash[] array.
1210 addr-saved_dn_hash addr-next_dn_hash dn-hash-length blobcopy
1214 \ Algorithm Identifier. Right now we are only interested in the
1215 \ OID, since we only support RSA keys.
1217 read-OID ifnot ERR_X509_UNSUPPORTED fail then
1221 rsaEncryption eqOID uf
1223 \ Public key itself: the BIT STRING contains bytes
1224 \ (no partial byte) and these bytes encode the
1227 \ RSA public key is a SEQUENCE of two
1228 \ INTEGER. We get both INTEGER values into
1229 \ the pkey_data[] buffer, if they fit.
1232 read-integer { nlen }
1233 addr-len-pkey_data swap nlen + swap nlen -
1234 read-integer { elen }
1237 \ Check that the public key fits our minimal
1238 \ size requirements. Note that the integer
1239 \ decoder already skipped the leading bytes
1240 \ of value 0, so we are working on the true
1241 \ modulus length here.
1242 addr-min_rsa_size get16 128 + nlen > if
1243 ERR_X509_WEAK_PUBLIC_KEY fail
1246 KEYTYPE_RSA >pkey-type
1250 id-ecPublicKey eqOID uf
1251 \ We support only named curves, for which the
1252 \ "parameters" field in the AlgorithmIdentifier
1253 \ field should be an OID.
1254 read-OID ifnot ERR_X509_UNSUPPORTED fail then
1256 ansix9p256r1 eqOID uf 23 enduf
1257 ansix9p384r1 eqOID uf 24 enduf
1258 ansix9p521r1 eqOID uf 25 enduf
1259 ERR_X509_UNSUPPORTED fail
1265 dup addr-len-pkey_data rot < if
1266 ERR_X509_LIMIT_EXCEEDED fail
1269 KEYTYPE_EC >pkey-type
1272 \ Not a recognised public key type.
1273 ERR_X509_UNSUPPORTED fail
1277 \ Process public key.
1279 \ For the EE certificate, copy the key data to the
1282 KEYTYPE_RSA of nlen elen copy-ee-rsa-pkey endof
1283 KEYTYPE_EC of curve qlen copy-ee-ec-pkey endof
1284 ERR_X509_UNSUPPORTED fail
1287 \ Verify signature on previous certificate. We invoke
1288 \ the RSA implementation.
1290 KEYTYPE_RSA of nlen elen do-rsa-vrfy endof
1291 KEYTYPE_EC of curve qlen do-ecdsa-vrfy endof
1292 ERR_X509_UNSUPPORTED fail
1298 \ This flag will be set to true if the Basic Constraints extension
1302 \ Skip issuerUniqueID and subjectUniqueID, and process extensions
1303 \ if present. Extensions are an explicit context tag of value 3
1304 \ around a SEQUENCE OF extensions. Each extension is a SEQUENCE
1305 \ with an OID, an optional boolean, and a value; the value is
1312 check-constructed read-length-open-elt
1318 read-tag dup 0x01 = if
1319 read-boolean >critical
1322 0x04 check-tag-primitive read-length-open-elt
1324 \ Extensions with specific processing.
1325 basicConstraints eqOID uf
1329 process-basicConstraints
1336 subjectAltName eqOID uf
1345 \ We don't implement full processing of
1346 \ policies. The call below mostly checks
1347 \ that the contents of the Certificate
1348 \ Policies extension can be safely ignored.
1349 certificatePolicies eqOID uf
1351 process-certPolicies
1357 \ Extensions which are always ignored,
1359 authorityKeyIdentifier eqOID uf
1362 subjectKeyIdentifier eqOID uf
1365 issuerAltName eqOID uf
1368 subjectDirectoryAttributes eqOID uf
1371 crlDistributionPoints eqOID uf
1374 freshestCRL eqOID uf
1377 authorityInfoAccess eqOID uf
1380 subjectInfoAccess eqOID uf
1384 \ Unrecognized extensions trigger a failure
1385 \ if critical; otherwise, they are just
1388 ERR_X509_CRITICAL_EXTENSION fail
1398 -1 = ifnot ERR_X509_UNEXPECTED fail then
1403 \ Terminate hashing.
1406 \ For the EE certificate, verify that the intended server name
1409 eename zero-server-name or ifnot
1410 ERR_X509_BAD_SERVER_NAME fail
1414 \ If this is the EE certificate, then direct trust may apply.
1415 \ Note: we do this at this point, not immediately after decoding
1416 \ the public key, because even in case of direct trust we still
1417 \ want to check the server name with regards to the SAN extension.
1418 \ However, we want to check direct trust before trying to decode
1419 \ the signature algorithm, because it should work even if that
1420 \ algorithm is not supported.
1421 ee if check-direct-trust then
1423 \ Non-EE certificates MUST have a Basic Constraints extension
1424 \ (that marks them as being CA).
1425 ee seenBC or ifnot ERR_X509_NOT_CA fail then
1427 \ signature algorithm
1428 read-tag check-sequence read-length-open-elt
1429 \ Read and understand the OID. Right now, we support only
1430 \ RSA with PKCS#1 v1.5 padding, and hash functions SHA-1,
1431 \ SHA-224, SHA-256, SHA-384 and SHA-512. We purposely do NOT
1433 \ TODO: add support for RSA/PSS
1435 \ Based on the signature OID, we get:
1436 \ -- the signing key type
1437 \ -- the hash function numeric identifier
1438 \ -- the hash function OID
1440 sha1WithRSAEncryption eqOID
1441 uf 2 KEYTYPE_RSA id-sha1 enduf
1442 sha224WithRSAEncryption eqOID
1443 uf 3 KEYTYPE_RSA id-sha224 enduf
1444 sha256WithRSAEncryption eqOID
1445 uf 4 KEYTYPE_RSA id-sha256 enduf
1446 sha384WithRSAEncryption eqOID
1447 uf 5 KEYTYPE_RSA id-sha384 enduf
1448 sha512WithRSAEncryption eqOID
1449 uf 6 KEYTYPE_RSA id-sha512 enduf
1451 ecdsa-with-SHA1 eqOID
1452 uf 2 KEYTYPE_EC id-sha1 enduf
1453 ecdsa-with-SHA224 eqOID
1454 uf 3 KEYTYPE_EC id-sha224 enduf
1455 ecdsa-with-SHA256 eqOID
1456 uf 4 KEYTYPE_EC id-sha256 enduf
1457 ecdsa-with-SHA384 eqOID
1458 uf 5 KEYTYPE_EC id-sha384 enduf
1459 ecdsa-with-SHA512 eqOID
1460 uf 6 KEYTYPE_EC id-sha512 enduf
1461 ERR_X509_UNSUPPORTED fail
1463 addr-cert_sig_hash_oid set16
1464 addr-cert_signer_key_type set8
1466 \ Compute the TBS hash into tbs_hash.
1468 dup ifnot ERR_X509_UNSUPPORTED fail then
1469 addr-cert_sig_hash_len set8
1471 ERR_X509_UNSUPPORTED fail
1473 \ We ignore the parameters, whether they are present or not,
1474 \ because we got all the information from the OID.
1479 dup CX 0 8191 { BR_X509_BUFSIZE_SIG } > if
1480 ERR_X509_LIMIT_EXCEEDED fail
1482 dup addr-cert_sig_len set16
1483 addr-cert_sig read-blob
1485 \ Close the outer SEQUENCE.
1488 \ Close the advertised total certificate length. This checks that
1489 \ there is no trailing garbage after the certificate.
1492 \ Flag the certificate as fully processed.
1493 0 addr-cert_length set32
1495 \ Check whether the issuer for the current certificate is known
1496 \ as a trusted CA; in which case, verify the signature.
1497 check-trust-anchor-CA ;
1500 \ Unless restricted by a Key Usage extension, all usages are
1502 0x30 addr-key_usages set8
1503 -1 decode-certificate
1506 0 decode-certificate co