2 * PDKIM - a RFC4871 (DKIM) implementation
4 * Copyright (C) 1995 - 2020 Exim maintainers
6 * signing/verification interface
10 #include "crypt_ver.h"
15 # include "../macro_predef.h"
20 # ifdef SIGN_HAVE_ED25519
21 builtin_macro_create(US"_CRYPTO_SIGN_ED25519");
23 # ifdef EXIM_HAVE_SHA3
24 builtin_macro_create(US"_CRYPTO_HASH_SHA3");
29 #ifndef DISABLE_DKIM /* rest of file */
32 # error Must no DISABLE_TLS, for DKIM
36 /******************************************************************************/
38 # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL 3
41 /* Logging function which can be registered with
42 * gnutls_global_set_log_function()
43 * gnutls_global_set_log_level() 0..9
45 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
47 exim_gnutls_logger_cb(int level, const char *message)
49 size_t len = strlen(message);
52 DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level);
55 DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message,
56 message[len-1] == '\n' ? "" : "\n");
65 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
68 gnutls_global_set_log_function(exim_gnutls_logger_cb);
69 /* arbitrarily chosen level; bump upto 9 for more */
70 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL);
76 /* accumulate data (gnutls-only). String to be appended must be nul-terminated. */
78 exim_dkim_data_append(gstring * g, uschar * s)
80 return string_cat(g, s);
85 /* import private key from PEM string in memory.
86 Return: NULL for success, or an error string */
89 exim_dkim_signing_init(const uschar * privkey_pem, es_ctx * sign_ctx)
91 gnutls_datum_t k = { .data = (void *)privkey_pem, .size = Ustrlen(privkey_pem) };
92 gnutls_x509_privkey_t x509_key;
96 if ( (where = US"internal init", rc = gnutls_x509_privkey_init(&x509_key))
97 || (rc = gnutls_privkey_init(&sign_ctx->key))
98 || (where = US"privkey PEM-block import",
99 rc = gnutls_x509_privkey_import(x509_key, &k, GNUTLS_X509_FMT_PEM))
100 || (where = US"internal privkey transfer",
101 rc = gnutls_privkey_import_x509(sign_ctx->key, x509_key, 0))
103 return string_sprintf("%s: %s", where, gnutls_strerror(rc));
105 switch (rc = gnutls_privkey_get_pk_algorithm(sign_ctx->key, NULL))
107 case GNUTLS_PK_RSA: sign_ctx->keytype = KEYTYPE_RSA; break;
108 #ifdef SIGN_HAVE_ED25519
109 case GNUTLS_PK_EDDSA_ED25519: sign_ctx->keytype = KEYTYPE_ED25519; break;
111 default: return rc < 0
112 ? CUS gnutls_strerror(rc)
113 : string_sprintf("Unhandled key type: %d '%s'", rc, gnutls_pk_get_name(rc));
121 /* allocate mem for signature (when signing) */
122 /* hash & sign data. No way to do incremental.
124 Return: NULL for success, or an error string */
127 exim_dkim_sign(es_ctx * sign_ctx, hashmethod hash, blob * data, blob * sig)
129 gnutls_datum_t k_data = { .data = data->data, .size = data->len };
130 gnutls_digest_algorithm_t dig;
131 gnutls_datum_t k_sig;
136 case HASH_SHA1: dig = GNUTLS_DIG_SHA1; break;
137 case HASH_SHA2_256: dig = GNUTLS_DIG_SHA256; break;
138 case HASH_SHA2_512: dig = GNUTLS_DIG_SHA512; break;
139 default: return US"nonhandled hash type";
142 if ((rc = gnutls_privkey_sign_data(sign_ctx->key, dig, 0, &k_data, &k_sig)))
143 return CUS gnutls_strerror(rc);
145 /* Don't care about deinit for the key; shortlived process */
147 sig->data = k_sig.data;
148 sig->len = k_sig.size;
154 /* import public key (from blob in memory)
155 Return: NULL for success, or an error string */
158 exim_dkim_verify_init(blob * pubkey, keyformat fmt, ev_ctx * verify_ctx,
163 const uschar * ret = NULL;
165 gnutls_pubkey_init(&verify_ctx->key);
166 k.data = pubkey->data;
167 k.size = pubkey->len;
172 if ((rc = gnutls_pubkey_import(verify_ctx->key, &k, GNUTLS_X509_FMT_DER)))
173 ret = US gnutls_strerror(rc);
175 #ifdef SIGN_HAVE_ED25519
176 case KEYFMT_ED25519_BARE:
177 if ((rc = gnutls_pubkey_import_ecc_raw(verify_ctx->key,
178 GNUTLS_ECC_CURVE_ED25519, &k, NULL)))
179 ret = US gnutls_strerror(rc);
183 ret = US"pubkey format not handled";
186 if (!ret && bits) gnutls_pubkey_get_pk_algorithm(verify_ctx->key, bits);
191 /* verify signature (of hash if RSA sig, of data if EC sig. No way to do incremental)
192 (given pubkey & alleged sig)
193 Return: NULL for success, or an error string */
196 exim_dkim_verify(ev_ctx * verify_ctx, hashmethod hash, blob * data_hash, blob * sig)
198 gnutls_datum_t k = { .data = data_hash->data, .size = data_hash->len };
199 gnutls_datum_t s = { .data = sig->data, .size = sig->len };
201 const uschar * ret = NULL;
203 #ifdef SIGN_HAVE_ED25519
204 if (verify_ctx->keytype == KEYTYPE_ED25519)
206 if ((rc = gnutls_pubkey_verify_data2(verify_ctx->key,
207 GNUTLS_SIGN_EDDSA_ED25519, 0, &k, &s)) < 0)
208 ret = US gnutls_strerror(rc);
213 gnutls_sign_algorithm_t algo;
216 case HASH_SHA1: algo = GNUTLS_SIGN_RSA_SHA1; break;
217 case HASH_SHA2_256: algo = GNUTLS_SIGN_RSA_SHA256; break;
218 case HASH_SHA2_512: algo = GNUTLS_SIGN_RSA_SHA512; break;
219 default: return US"nonhandled hash type";
222 if ((rc = gnutls_pubkey_verify_hash2(verify_ctx->key, algo,
223 GNUTLS_VERIFY_ALLOW_BROKEN, &k, &s)) < 0)
224 ret = US gnutls_strerror(rc);
227 gnutls_pubkey_deinit(verify_ctx->key);
234 #elif defined(SIGN_GCRYPT)
235 /******************************************************************************/
236 /* This variant is used under pre-3.0.0 GnuTLS. Only rsa-sha1 and rsa-sha256 */
239 /* Internal service routine:
240 Read and move past an asn.1 header, checking class & tag,
241 optionally returning the data-length */
244 as_tag(blob * der, uschar req_cls, long req_tag, long * alen)
251 debug_printf_indent("as_tag: %02x %02x %02x %02x\n",
252 der->data[0], der->data[1], der->data[2], der->data[3]);
254 if ((rc = asn1_get_tag_der(der->data++, der->len--, &tag_class, &taglen, &tag))
258 if (tag_class != req_cls || tag != req_tag) return ASN1_ELEMENT_NOT_FOUND;
260 if ((len = asn1_get_length_der(der->data, der->len, &taglen)) < 0)
261 return ASN1_DER_ERROR;
262 if (alen) *alen = len;
264 /* debug_printf_indent("as_tag: tlen %d dlen %d\n", taglen, (int)len); */
271 /* Internal service routine:
272 Read and move over an asn.1 integer, setting an MPI to the value
276 as_mpi(blob * der, gcry_mpi_t * mpi)
282 debug_printf_indent("%s\n", __FUNCTION__);
284 /* integer; move past the header */
285 if ((rc = as_tag(der, 0, ASN1_TAG_INTEGER, &alen)) != ASN1_SUCCESS)
286 return US asn1_strerror(rc);
289 if ((gerr = gcry_mpi_scan(mpi, GCRYMPI_FMT_STD, der->data, alen, NULL)))
290 return US gcry_strerror(gerr);
292 /* move over the data */
293 der->data += alen; der->len -= alen;
302 /* Version check should be the very first call because it
303 makes sure that important subsystems are initialized. */
304 if (!gcry_check_version (GCRYPT_VERSION))
306 fputs ("libgcrypt version mismatch\n", stderr);
310 /* We don't want to see any warnings, e.g. because we have not yet
311 parsed program options which might be used to suppress such
313 gcry_control (GCRYCTL_SUSPEND_SECMEM_WARN);
315 /* ... If required, other initialization goes here. Note that the
316 process might still be running with increased privileges and that
317 the secure memory has not been initialized. */
319 /* Allocate a pool of 16k secure memory. This make the secure memory
320 available and also drops privileges where needed. */
321 gcry_control (GCRYCTL_INIT_SECMEM, 16384, 0);
323 /* It is now okay to let Libgcrypt complain when there was/is
324 a problem with the secure memory. */
325 gcry_control (GCRYCTL_RESUME_SECMEM_WARN);
327 /* ... If required, other initialization goes here. */
329 /* Tell Libgcrypt that initialization has completed. */
330 gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);
338 /* Accumulate data (gnutls-only).
339 String to be appended must be nul-terminated. */
342 exim_dkim_data_append(gstring * g, uschar * s)
349 /* import private key from PEM string in memory.
350 Only handles RSA keys.
351 Return: NULL for success, or an error string */
354 exim_dkim_signing_init(const uschar * privkey_pem, es_ctx * sign_ctx)
361 /*XXX will need extension to _spot_ as well as handle a
362 non-RSA key? I think...
363 So... this is not a PrivateKeyInfo - which would have a field
364 identifying the keytype - PrivateKeyAlgorithmIdentifier -
365 but a plain RSAPrivateKey (wrapped in PEM-headers. Can we
366 use those as a type tag? What forms are there? "BEGIN EC PRIVATE KEY" (cf. ec(1ssl))
368 How does OpenSSL PEM_read_bio_PrivateKey() deal with it?
369 gnutls_x509_privkey_import() ?
373 * RSAPrivateKey ::= SEQUENCE
375 * modulus INTEGER, -- n
376 * publicExponent INTEGER, -- e
377 * privateExponent INTEGER, -- d
378 * prime1 INTEGER, -- p
379 * prime2 INTEGER, -- q
380 * exponent1 INTEGER, -- d mod (p-1)
381 * exponent2 INTEGER, -- d mod (q-1)
382 * coefficient INTEGER, -- (inverse of q) mod p
383 * otherPrimeInfos OtherPrimeInfos OPTIONAL
385 * ECPrivateKey ::= SEQUENCE {
386 * version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),
387 * privateKey OCTET STRING,
388 * parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,
389 * publicKey [1] BIT STRING OPTIONAL
391 * Hmm, only 1 useful item, and not even an integer? Wonder how we might use it...
393 - actually, gnutls_x509_privkey_import() appears to require a curve name parameter
394 value for that is an OID? a local-only integer (it's an enum in GnuTLS)?
398 ssh-keygen -t ecdsa -f foo.privkey
399 ssh-keygen -t ecdsa -b384 -f foo.privkey
400 ssh-keygen -t ecdsa -b521 -f foo.privkey
401 ssh-keygen -t ed25519 -f foo.privkey
403 < foo openssl pkcs8 -in /dev/stdin -inform PEM -nocrypt -topk8 -outform DER | od -x
405 openssl asn1parse -in foo -inform PEM -dump
406 openssl asn1parse -in foo -inform PEM -dump -stroffset 24 (??)
407 (not good for ed25519)
411 if ( !(s1 = Ustrstr(CS privkey_pem, "-----BEGIN RSA PRIVATE KEY-----"))
412 || !(s2 = Ustrstr(CS (s1+=31), "-----END RSA PRIVATE KEY-----" ))
414 return US"Bad PEM wrapper";
418 if ((rc = b64decode(s1, &der.data) < 0))
419 return US"Bad PEM-DER b64 decode";
424 /* sequence; just move past the header */
425 if ((rc = as_tag(&der, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL))
426 != ASN1_SUCCESS) goto asn_err;
428 /* integer version; move past the header, check is zero */
429 if ((rc = as_tag(&der, 0, ASN1_TAG_INTEGER, &alen)) != ASN1_SUCCESS)
431 if (alen != 1 || *der.data != 0)
432 return US"Bad version number";
433 der.data++; der.len--;
435 if ( (s1 = as_mpi(&der, &sign_ctx->n))
436 || (s1 = as_mpi(&der, &sign_ctx->e))
437 || (s1 = as_mpi(&der, &sign_ctx->d))
438 || (s1 = as_mpi(&der, &sign_ctx->p))
439 || (s1 = as_mpi(&der, &sign_ctx->q))
440 || (s1 = as_mpi(&der, &sign_ctx->dp))
441 || (s1 = as_mpi(&der, &sign_ctx->dq))
442 || (s1 = as_mpi(&der, &sign_ctx->qp))
447 DEBUG(D_acl) debug_printf_indent("rsa_signing_init:\n");
450 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->n);
451 debug_printf_indent(" N : %s\n", s);
452 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->e);
453 debug_printf_indent(" E : %s\n", s);
454 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->d);
455 debug_printf_indent(" D : %s\n", s);
456 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->p);
457 debug_printf_indent(" P : %s\n", s);
458 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->q);
459 debug_printf_indent(" Q : %s\n", s);
460 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->dp);
461 debug_printf_indent(" DP: %s\n", s);
462 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->dq);
463 debug_printf_indent(" DQ: %s\n", s);
464 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->qp);
465 debug_printf_indent(" QP: %s\n", s);
469 sign_ctx->keytype = KEYTYPE_RSA;
472 asn_err: return US asn1_strerror(rc);
477 /* allocate mem for signature (when signing) */
478 /* sign already-hashed data.
480 Return: NULL for success, or an error string */
483 exim_dkim_sign(es_ctx * sign_ctx, hashmethod hash, blob * data, blob * sig)
486 gcry_sexp_t s_hash = NULL, s_key = NULL, s_sig = NULL;
491 /*XXX will need extension for hash types (though, possibly, should
492 be re-specced to not rehash but take an already-hashed value? Actually
493 current impl looks WRONG - it _is_ given a hash so should not be
494 re-hashing. Has this been tested?
496 Will need extension for non-RSA sugning algos. */
500 case HASH_SHA1: sexp_hash = "(data(flags pkcs1)(hash sha1 %b))"; break;
501 case HASH_SHA2_256: sexp_hash = "(data(flags pkcs1)(hash sha256 %b))"; break;
502 default: return US"nonhandled hash type";
506 sig->data = store_get(SIGSPACE, FALSE);
508 if (gcry_mpi_cmp (sign_ctx->p, sign_ctx->q) > 0)
510 gcry_mpi_swap (sign_ctx->p, sign_ctx->q);
511 gcry_mpi_invm (sign_ctx->qp, sign_ctx->p, sign_ctx->q);
514 if ( (gerr = gcry_sexp_build (&s_key, NULL,
515 "(private-key (rsa (n%m)(e%m)(d%m)(p%m)(q%m)(u%m)))",
516 sign_ctx->n, sign_ctx->e,
517 sign_ctx->d, sign_ctx->p,
518 sign_ctx->q, sign_ctx->qp))
519 || (gerr = gcry_sexp_build (&s_hash, NULL, sexp_hash,
520 (int) data->len, CS data->data))
521 || (gerr = gcry_pk_sign (&s_sig, s_hash, s_key))
523 return US gcry_strerror(gerr);
525 /* gcry_sexp_dump(s_sig); */
527 if ( !(s_sig = gcry_sexp_find_token(s_sig, "s", 0))
529 return US"no sig result";
531 m_sig = gcry_sexp_nth_mpi(s_sig, 1, GCRYMPI_FMT_USG);
537 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, m_sig);
538 debug_printf_indent(" SG: %s\n", s);
542 gerr = gcry_mpi_print(GCRYMPI_FMT_USG, sig->data, SIGSPACE, &sig->len, m_sig);
545 debug_printf_indent("signature conversion from MPI to buffer failed\n");
546 return US gcry_strerror(gerr);
554 /* import public key (from blob in memory)
555 Return: NULL for success, or an error string */
558 exim_dkim_verify_init(blob * pubkey, keyformat fmt, ev_ctx * verify_ctx,
562 in code sequence per b81207d2bfa92 rsa_parse_public_key() and asn1_get_mpi()
571 uschar * stage = US"S1";
573 if (fmt != KEYFMT_DER) return US"pubkey format not handled";
580 BIT STRING:RSAPublicKey
582 INTEGER:Public modulus
583 INTEGER:Public exponent
585 openssl rsa -in aux-fixed/dkim/dkim.private -pubout -outform DER | od -t x1 | head;
586 openssl rsa -in aux-fixed/dkim/dkim.private -pubout | openssl asn1parse -dump;
587 openssl rsa -in aux-fixed/dkim/dkim.private -pubout | openssl asn1parse -dump -offset 22;
590 /* sequence; just move past the header */
591 if ((rc = as_tag(pubkey, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL))
592 != ASN1_SUCCESS) goto asn_err;
594 /* sequence; skip the entire thing */
595 DEBUG(D_acl) stage = US"S2";
596 if ((rc = as_tag(pubkey, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, &alen))
597 != ASN1_SUCCESS) goto asn_err;
598 pubkey->data += alen; pubkey->len -= alen;
601 /* bitstring: limit range to size of bitstring;
602 move over header + content wrapper */
603 DEBUG(D_acl) stage = US"BS";
604 if ((rc = as_tag(pubkey, 0, ASN1_TAG_BIT_STRING, &alen)) != ASN1_SUCCESS)
607 pubkey->data++; pubkey->len--;
609 /* sequence; just move past the header */
610 DEBUG(D_acl) stage = US"S3";
611 if ((rc = as_tag(pubkey, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL))
612 != ASN1_SUCCESS) goto asn_err;
614 /* read two integers */
615 DEBUG(D_acl) stage = US"MPI";
617 if ((errstr = as_mpi(pubkey, &verify_ctx->n))) return errstr;
618 nbits = (nbits - pubkey->len) * 8;
619 if ((errstr = as_mpi(pubkey, &verify_ctx->e))) return errstr;
622 DEBUG(D_acl) debug_printf_indent("rsa_verify_init:\n");
625 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, verify_ctx->n);
626 debug_printf_indent(" N : %s\n", s);
627 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, verify_ctx->e);
628 debug_printf_indent(" E : %s\n", s);
632 if (bits) *bits = nbits;
636 DEBUG(D_acl) return string_sprintf("%s: %s", stage, asn1_strerror(rc));
637 return US asn1_strerror(rc);
641 /* verify signature (of hash)
642 XXX though we appear to be doing a hash, too!
643 (given pubkey & alleged sig)
644 Return: NULL for success, or an error string */
647 exim_dkim_verify(ev_ctx * verify_ctx, hashmethod hash, blob * data_hash, blob * sig)
650 cf. libgnutls 2.8.5 _wrap_gcry_pk_verify()
654 gcry_sexp_t s_sig = NULL, s_hash = NULL, s_pkey = NULL;
658 /*XXX needs extension for SHA512 */
661 case HASH_SHA1: sexp_hash = "(data(flags pkcs1)(hash sha1 %b))"; break;
662 case HASH_SHA2_256: sexp_hash = "(data(flags pkcs1)(hash sha256 %b))"; break;
663 default: return US"nonhandled hash type";
666 if ( (stage = US"pkey sexp build",
667 gerr = gcry_sexp_build (&s_pkey, NULL, "(public-key(rsa(n%m)(e%m)))",
668 verify_ctx->n, verify_ctx->e))
669 || (stage = US"data sexp build",
670 gerr = gcry_sexp_build (&s_hash, NULL, sexp_hash,
671 (int) data_hash->len, CS data_hash->data))
672 || (stage = US"sig mpi scan",
673 gerr = gcry_mpi_scan(&m_sig, GCRYMPI_FMT_USG, sig->data, sig->len, NULL))
674 || (stage = US"sig sexp build",
675 gerr = gcry_sexp_build (&s_sig, NULL, "(sig-val(rsa(s%m)))", m_sig))
676 || (stage = US"verify",
677 gerr = gcry_pk_verify (s_sig, s_hash, s_pkey))
680 DEBUG(D_acl) debug_printf_indent("verify: error in stage '%s'\n", stage);
681 return US gcry_strerror(gerr);
684 if (s_sig) gcry_sexp_release (s_sig);
685 if (s_hash) gcry_sexp_release (s_hash);
686 if (s_pkey) gcry_sexp_release (s_pkey);
687 gcry_mpi_release (m_sig);
688 gcry_mpi_release (verify_ctx->n);
689 gcry_mpi_release (verify_ctx->e);
697 #elif defined(SIGN_OPENSSL)
698 /******************************************************************************/
703 ERR_load_crypto_strings();
707 /* accumulate data (was gnutls-only but now needed for OpenSSL non-EC too
708 because now using hash-and-sign interface) */
710 exim_dkim_data_append(gstring * g, uschar * s)
712 return string_cat(g, s);
716 /* import private key from PEM string in memory.
717 Return: NULL for success, or an error string */
720 exim_dkim_signing_init(const uschar * privkey_pem, es_ctx * sign_ctx)
722 BIO * bp = BIO_new_mem_buf((void *)privkey_pem, -1);
724 if (!(sign_ctx->key = PEM_read_bio_PrivateKey(bp, NULL, NULL, NULL)))
725 return string_sprintf("privkey PEM-block import: %s",
726 ERR_error_string(ERR_get_error(), NULL));
729 #ifdef SIGN_HAVE_ED25519
730 EVP_PKEY_type(EVP_PKEY_id(sign_ctx->key)) == EVP_PKEY_ED25519
731 ? KEYTYPE_ED25519 : KEYTYPE_RSA;
740 /* allocate mem for signature (when signing) */
741 /* hash & sign data. Incremental not supported.
743 Return: NULL for success with the signaature in the sig blob, or an error string */
746 exim_dkim_sign(es_ctx * sign_ctx, hashmethod hash, blob * data, blob * sig)
754 case HASH_NULL: md = NULL; break; /* Ed25519 signing */
755 case HASH_SHA1: md = EVP_sha1(); break;
756 case HASH_SHA2_256: md = EVP_sha256(); break;
757 case HASH_SHA2_512: md = EVP_sha512(); break;
758 default: return US"nonhandled hash type";
761 #ifdef SIGN_HAVE_ED25519
762 if ( (ctx = EVP_MD_CTX_new())
763 && EVP_DigestSignInit(ctx, NULL, md, NULL, sign_ctx->key) > 0
764 && EVP_DigestSign(ctx, NULL, &siglen, NULL, 0) > 0
765 && (sig->data = store_get(siglen, FALSE))
767 /* Obtain the signature (slen could change here!) */
768 && EVP_DigestSign(ctx, sig->data, &siglen, data->data, data->len) > 0
771 EVP_MD_CTX_destroy(ctx);
776 /*XXX renamed to EVP_MD_CTX_new() in 1.1.0 */
777 if ( (ctx = EVP_MD_CTX_create())
778 && EVP_DigestSignInit(ctx, NULL, md, NULL, sign_ctx->key) > 0
779 && EVP_DigestSignUpdate(ctx, data->data, data->len) > 0
780 && EVP_DigestSignFinal(ctx, NULL, &siglen) > 0
781 && (sig->data = store_get(siglen, FALSE))
783 /* Obtain the signature (slen could change here!) */
784 && EVP_DigestSignFinal(ctx, sig->data, &siglen) > 0
787 EVP_MD_CTX_destroy(ctx);
793 if (ctx) EVP_MD_CTX_destroy(ctx);
794 return US ERR_error_string(ERR_get_error(), NULL);
799 /* import public key (from blob in memory)
800 Return: NULL for success, or an error string */
803 exim_dkim_verify_init(blob * pubkey, keyformat fmt, ev_ctx * verify_ctx,
806 const uschar * s = pubkey->data;
812 /*XXX hmm, we never free this */
813 if (!(verify_ctx->key = d2i_PUBKEY(NULL, &s, pubkey->len)))
814 ret = US ERR_error_string(ERR_get_error(), NULL);
816 #ifdef SIGN_HAVE_ED25519
817 case KEYFMT_ED25519_BARE:
818 if (!(verify_ctx->key = EVP_PKEY_new_raw_public_key(EVP_PKEY_ED25519, NULL,
820 ret = US ERR_error_string(ERR_get_error(), NULL);
824 ret = US"pubkey format not handled";
828 if (!ret && bits) *bits = EVP_PKEY_bits(verify_ctx->key);
835 /* verify signature (of hash, except Ed25519 where of-data)
836 (given pubkey & alleged sig)
837 Return: NULL for success, or an error string */
840 exim_dkim_verify(ev_ctx * verify_ctx, hashmethod hash, blob * data, blob * sig)
846 case HASH_NULL: md = NULL; break;
847 case HASH_SHA1: md = EVP_sha1(); break;
848 case HASH_SHA2_256: md = EVP_sha256(); break;
849 case HASH_SHA2_512: md = EVP_sha512(); break;
850 default: return US"nonhandled hash type";
853 #ifdef SIGN_HAVE_ED25519
858 if ((ctx = EVP_MD_CTX_new()))
860 if ( EVP_DigestVerifyInit(ctx, NULL, md, NULL, verify_ctx->key) > 0
861 && EVP_DigestVerify(ctx, sig->data, sig->len, data->data, data->len) > 0
863 { EVP_MD_CTX_free(ctx); return NULL; }
864 EVP_MD_CTX_free(ctx);
872 if ((ctx = EVP_PKEY_CTX_new(verify_ctx->key, NULL)))
874 if ( EVP_PKEY_verify_init(ctx) > 0
875 && EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) > 0
876 && EVP_PKEY_CTX_set_signature_md(ctx, md) > 0
877 && EVP_PKEY_verify(ctx, sig->data, sig->len,
878 data->data, data->len) == 1
880 { EVP_PKEY_CTX_free(ctx); return NULL; }
881 EVP_PKEY_CTX_free(ctx);
884 if (Ustrcmp(ERR_reason_error_string(ERR_peek_error()), "wrong signature length") == 0)
885 debug_printf("sig len (from msg hdr): %d, expected (from dns pubkey) %d\n",
886 (int) sig->len, EVP_PKEY_size(verify_ctx->key));
890 return US ERR_error_string(ERR_get_error(), NULL);
896 /******************************************************************************/
898 #endif /*DISABLE_DKIM*/
899 #endif /*MACRO_PREDEF*/