2 * PDKIM - a RFC4871 (DKIM) implementation
3 * Copyright (c) The Exim Maintainers 1995 - 2022
5 * signing/verification interface
14 # include "../macro_predef.h"
19 # ifdef SIGN_HAVE_ED25519
20 builtin_macro_create(US"_CRYPTO_SIGN_ED25519");
22 # ifdef EXIM_HAVE_SHA3
23 builtin_macro_create(US"_CRYPTO_HASH_SHA3");
28 #ifndef DISABLE_DKIM /* rest of file */
31 # error Must no DISABLE_TLS, for DKIM
35 /******************************************************************************/
37 # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL 3
39 # ifndef GNUTLS_VERIFY_ALLOW_BROKEN
40 # define GNUTLS_VERIFY_ALLOW_BROKEN 0
44 /* Logging function which can be registered with
45 * gnutls_global_set_log_function()
46 * gnutls_global_set_log_level() 0..9
48 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
50 exim_gnutls_logger_cb(int level, const char *message)
52 size_t len = strlen(message);
55 DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level);
58 DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message,
59 message[len-1] == '\n' ? "" : "\n");
68 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
71 gnutls_global_set_log_function(exim_gnutls_logger_cb);
72 /* arbitrarily chosen level; bump upto 9 for more */
73 gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL);
79 /* accumulate data (gnutls-only). String to be appended must be nul-terminated. */
81 exim_dkim_data_append(gstring * g, uschar * s)
83 return string_cat(g, s);
88 /* import private key from PEM string in memory.
89 Return: NULL for success, or an error string */
92 exim_dkim_signing_init(const uschar * privkey_pem, es_ctx * sign_ctx)
94 gnutls_datum_t k = { .data = (void *)privkey_pem, .size = Ustrlen(privkey_pem) };
95 gnutls_x509_privkey_t x509_key;
99 if ( (where = US"internal init", rc = gnutls_x509_privkey_init(&x509_key))
100 || (rc = gnutls_privkey_init(&sign_ctx->key))
101 || (where = US"privkey PEM-block import",
102 rc = gnutls_x509_privkey_import(x509_key, &k, GNUTLS_X509_FMT_PEM))
103 || (where = US"internal privkey transfer",
104 rc = gnutls_privkey_import_x509(sign_ctx->key, x509_key, 0))
106 return string_sprintf("%s: %s", where, gnutls_strerror(rc));
108 switch (rc = gnutls_privkey_get_pk_algorithm(sign_ctx->key, NULL))
110 case GNUTLS_PK_RSA: sign_ctx->keytype = KEYTYPE_RSA; break;
111 #ifdef SIGN_HAVE_ED25519
112 case GNUTLS_PK_EDDSA_ED25519: sign_ctx->keytype = KEYTYPE_ED25519; break;
114 default: return rc < 0
115 ? CUS gnutls_strerror(rc)
116 : string_sprintf("Unhandled key type: %d '%s'", rc, gnutls_pk_get_name(rc));
124 /* allocate mem for signature (when signing) */
125 /* hash & sign data. No way to do incremental.
127 Return: NULL for success, or an error string */
130 exim_dkim_sign(es_ctx * sign_ctx, hashmethod hash, blob * data, blob * sig)
132 gnutls_datum_t k_data = { .data = data->data, .size = data->len };
133 gnutls_digest_algorithm_t dig;
134 gnutls_datum_t k_sig;
139 case HASH_SHA1: dig = GNUTLS_DIG_SHA1; break;
140 case HASH_SHA2_256: dig = GNUTLS_DIG_SHA256; break;
141 case HASH_SHA2_512: dig = GNUTLS_DIG_SHA512; break;
142 default: return US"nonhandled hash type";
145 if ((rc = gnutls_privkey_sign_data(sign_ctx->key, dig, 0, &k_data, &k_sig)))
146 return CUS gnutls_strerror(rc);
148 /* Don't care about deinit for the key; shortlived process */
150 sig->data = k_sig.data;
151 sig->len = k_sig.size;
157 /* import public key (from blob in memory)
158 Return: NULL for success, or an error string */
161 exim_dkim_verify_init(blob * pubkey, keyformat fmt, ev_ctx * verify_ctx,
166 const uschar * ret = NULL;
168 gnutls_pubkey_init(&verify_ctx->key);
169 k.data = pubkey->data;
170 k.size = pubkey->len;
175 if ((rc = gnutls_pubkey_import(verify_ctx->key, &k, GNUTLS_X509_FMT_DER)))
176 ret = US gnutls_strerror(rc);
178 #ifdef SIGN_HAVE_ED25519
179 case KEYFMT_ED25519_BARE:
180 if ((rc = gnutls_pubkey_import_ecc_raw(verify_ctx->key,
181 GNUTLS_ECC_CURVE_ED25519, &k, NULL)))
182 ret = US gnutls_strerror(rc);
186 ret = US"pubkey format not handled";
189 if (!ret && bits) gnutls_pubkey_get_pk_algorithm(verify_ctx->key, bits);
194 /* verify signature (of hash if RSA sig, of data if EC sig. No way to do incremental)
195 (given pubkey & alleged sig)
196 Return: NULL for success, or an error string */
199 exim_dkim_verify(ev_ctx * verify_ctx, hashmethod hash, blob * data_hash, blob * sig)
201 gnutls_datum_t k = { .data = data_hash->data, .size = data_hash->len };
202 gnutls_datum_t s = { .data = sig->data, .size = sig->len };
204 const uschar * ret = NULL;
206 #ifdef SIGN_HAVE_ED25519
207 if (verify_ctx->keytype == KEYTYPE_ED25519)
209 if ((rc = gnutls_pubkey_verify_data2(verify_ctx->key,
210 GNUTLS_SIGN_EDDSA_ED25519, 0, &k, &s)) < 0)
211 ret = US gnutls_strerror(rc);
216 gnutls_sign_algorithm_t algo;
219 case HASH_SHA1: algo = GNUTLS_SIGN_RSA_SHA1; break;
220 case HASH_SHA2_256: algo = GNUTLS_SIGN_RSA_SHA256; break;
221 case HASH_SHA2_512: algo = GNUTLS_SIGN_RSA_SHA512; break;
222 default: return US"nonhandled hash type";
225 if ((rc = gnutls_pubkey_verify_hash2(verify_ctx->key, algo,
226 GNUTLS_VERIFY_ALLOW_BROKEN, &k, &s)) < 0)
227 ret = US gnutls_strerror(rc);
230 gnutls_pubkey_deinit(verify_ctx->key);
237 #elif defined(SIGN_GCRYPT)
238 /******************************************************************************/
239 /* This variant is used under pre-3.0.0 GnuTLS. Only rsa-sha1 and rsa-sha256 */
242 /* Internal service routine:
243 Read and move past an asn.1 header, checking class & tag,
244 optionally returning the data-length */
247 as_tag(blob * der, uschar req_cls, long req_tag, long * alen)
254 debug_printf_indent("as_tag: %02x %02x %02x %02x\n",
255 der->data[0], der->data[1], der->data[2], der->data[3]);
257 if ((rc = asn1_get_tag_der(der->data++, der->len--, &tag_class, &taglen, &tag))
261 if (tag_class != req_cls || tag != req_tag) return ASN1_ELEMENT_NOT_FOUND;
263 if ((len = asn1_get_length_der(der->data, der->len, &taglen)) < 0)
264 return ASN1_DER_ERROR;
265 if (alen) *alen = len;
267 /* debug_printf_indent("as_tag: tlen %d dlen %d\n", taglen, (int)len); */
274 /* Internal service routine:
275 Read and move over an asn.1 integer, setting an MPI to the value
279 as_mpi(blob * der, gcry_mpi_t * mpi)
285 debug_printf_indent("%s\n", __FUNCTION__);
287 /* integer; move past the header */
288 if ((rc = as_tag(der, 0, ASN1_TAG_INTEGER, &alen)) != ASN1_SUCCESS)
289 return US asn1_strerror(rc);
292 if ((gerr = gcry_mpi_scan(mpi, GCRYMPI_FMT_STD, der->data, alen, NULL)))
293 return US gcry_strerror(gerr);
295 /* move over the data */
296 der->data += alen; der->len -= alen;
305 /* Version check should be the very first call because it
306 makes sure that important subsystems are initialized. */
307 if (!gcry_check_version (GCRYPT_VERSION))
309 fputs ("libgcrypt version mismatch\n", stderr);
313 /* We don't want to see any warnings, e.g. because we have not yet
314 parsed program options which might be used to suppress such
316 gcry_control (GCRYCTL_SUSPEND_SECMEM_WARN);
318 /* ... If required, other initialization goes here. Note that the
319 process might still be running with increased privileges and that
320 the secure memory has not been initialized. */
322 /* Allocate a pool of 16k secure memory. This make the secure memory
323 available and also drops privileges where needed. */
324 gcry_control (GCRYCTL_INIT_SECMEM, 16384, 0);
326 /* It is now okay to let Libgcrypt complain when there was/is
327 a problem with the secure memory. */
328 gcry_control (GCRYCTL_RESUME_SECMEM_WARN);
330 /* ... If required, other initialization goes here. */
332 /* Tell Libgcrypt that initialization has completed. */
333 gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);
341 /* Accumulate data (gnutls-only).
342 String to be appended must be nul-terminated. */
345 exim_dkim_data_append(gstring * g, uschar * s)
352 /* import private key from PEM string in memory.
353 Only handles RSA keys.
354 Return: NULL for success, or an error string */
357 exim_dkim_signing_init(const uschar * privkey_pem, es_ctx * sign_ctx)
364 /*XXX will need extension to _spot_ as well as handle a
365 non-RSA key? I think...
366 So... this is not a PrivateKeyInfo - which would have a field
367 identifying the keytype - PrivateKeyAlgorithmIdentifier -
368 but a plain RSAPrivateKey (wrapped in PEM-headers. Can we
369 use those as a type tag? What forms are there? "BEGIN EC PRIVATE KEY" (cf. ec(1ssl))
371 How does OpenSSL PEM_read_bio_PrivateKey() deal with it?
372 gnutls_x509_privkey_import() ?
376 * RSAPrivateKey ::= SEQUENCE
378 * modulus INTEGER, -- n
379 * publicExponent INTEGER, -- e
380 * privateExponent INTEGER, -- d
381 * prime1 INTEGER, -- p
382 * prime2 INTEGER, -- q
383 * exponent1 INTEGER, -- d mod (p-1)
384 * exponent2 INTEGER, -- d mod (q-1)
385 * coefficient INTEGER, -- (inverse of q) mod p
386 * otherPrimeInfos OtherPrimeInfos OPTIONAL
388 * ECPrivateKey ::= SEQUENCE {
389 * version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),
390 * privateKey OCTET STRING,
391 * parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,
392 * publicKey [1] BIT STRING OPTIONAL
394 * Hmm, only 1 useful item, and not even an integer? Wonder how we might use it...
396 - actually, gnutls_x509_privkey_import() appears to require a curve name parameter
397 value for that is an OID? a local-only integer (it's an enum in GnuTLS)?
401 ssh-keygen -t ecdsa -f foo.privkey
402 ssh-keygen -t ecdsa -b384 -f foo.privkey
403 ssh-keygen -t ecdsa -b521 -f foo.privkey
404 ssh-keygen -t ed25519 -f foo.privkey
406 < foo openssl pkcs8 -in /dev/stdin -inform PEM -nocrypt -topk8 -outform DER | od -x
408 openssl asn1parse -in foo -inform PEM -dump
409 openssl asn1parse -in foo -inform PEM -dump -stroffset 24 (??)
410 (not good for ed25519)
414 if ( !(s1 = Ustrstr(CS privkey_pem, "-----BEGIN RSA PRIVATE KEY-----"))
415 || !(s2 = Ustrstr(CS (s1+=31), "-----END RSA PRIVATE KEY-----" ))
417 return US"Bad PEM wrapper";
421 if ((rc = b64decode(s1, &der.data) < 0))
422 return US"Bad PEM-DER b64 decode";
427 /* sequence; just move past the header */
428 if ((rc = as_tag(&der, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL))
429 != ASN1_SUCCESS) goto asn_err;
431 /* integer version; move past the header, check is zero */
432 if ((rc = as_tag(&der, 0, ASN1_TAG_INTEGER, &alen)) != ASN1_SUCCESS)
434 if (alen != 1 || *der.data != 0)
435 return US"Bad version number";
436 der.data++; der.len--;
438 if ( (s1 = as_mpi(&der, &sign_ctx->n))
439 || (s1 = as_mpi(&der, &sign_ctx->e))
440 || (s1 = as_mpi(&der, &sign_ctx->d))
441 || (s1 = as_mpi(&der, &sign_ctx->p))
442 || (s1 = as_mpi(&der, &sign_ctx->q))
443 || (s1 = as_mpi(&der, &sign_ctx->dp))
444 || (s1 = as_mpi(&der, &sign_ctx->dq))
445 || (s1 = as_mpi(&der, &sign_ctx->qp))
450 DEBUG(D_acl) debug_printf_indent("rsa_signing_init:\n");
453 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->n);
454 debug_printf_indent(" N : %s\n", s);
455 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->e);
456 debug_printf_indent(" E : %s\n", s);
457 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->d);
458 debug_printf_indent(" D : %s\n", s);
459 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->p);
460 debug_printf_indent(" P : %s\n", s);
461 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->q);
462 debug_printf_indent(" Q : %s\n", s);
463 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->dp);
464 debug_printf_indent(" DP: %s\n", s);
465 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->dq);
466 debug_printf_indent(" DQ: %s\n", s);
467 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->qp);
468 debug_printf_indent(" QP: %s\n", s);
472 sign_ctx->keytype = KEYTYPE_RSA;
475 asn_err: return US asn1_strerror(rc);
480 /* allocate mem for signature (when signing) */
481 /* sign already-hashed data.
483 Return: NULL for success, or an error string */
486 exim_dkim_sign(es_ctx * sign_ctx, hashmethod hash, blob * data, blob * sig)
489 gcry_sexp_t s_hash = NULL, s_key = NULL, s_sig = NULL;
494 /*XXX will need extension for hash types (though, possibly, should
495 be re-specced to not rehash but take an already-hashed value? Actually
496 current impl looks WRONG - it _is_ given a hash so should not be
497 re-hashing. Has this been tested?
499 Will need extension for non-RSA sugning algos. */
503 case HASH_SHA1: sexp_hash = "(data(flags pkcs1)(hash sha1 %b))"; break;
504 case HASH_SHA2_256: sexp_hash = "(data(flags pkcs1)(hash sha256 %b))"; break;
505 default: return US"nonhandled hash type";
509 sig->data = store_get(SIGSPACE, GET_UNTAINTED);
511 if (gcry_mpi_cmp (sign_ctx->p, sign_ctx->q) > 0)
513 gcry_mpi_swap (sign_ctx->p, sign_ctx->q);
514 gcry_mpi_invm (sign_ctx->qp, sign_ctx->p, sign_ctx->q);
517 if ( (gerr = gcry_sexp_build (&s_key, NULL,
518 "(private-key (rsa (n%m)(e%m)(d%m)(p%m)(q%m)(u%m)))",
519 sign_ctx->n, sign_ctx->e,
520 sign_ctx->d, sign_ctx->p,
521 sign_ctx->q, sign_ctx->qp))
522 || (gerr = gcry_sexp_build (&s_hash, NULL, sexp_hash,
523 (int) data->len, CS data->data))
524 || (gerr = gcry_pk_sign (&s_sig, s_hash, s_key))
526 return US gcry_strerror(gerr);
528 /* gcry_sexp_dump(s_sig); */
530 if ( !(s_sig = gcry_sexp_find_token(s_sig, "s", 0))
532 return US"no sig result";
534 m_sig = gcry_sexp_nth_mpi(s_sig, 1, GCRYMPI_FMT_USG);
540 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, m_sig);
541 debug_printf_indent(" SG: %s\n", s);
545 gerr = gcry_mpi_print(GCRYMPI_FMT_USG, sig->data, SIGSPACE, &sig->len, m_sig);
548 debug_printf_indent("signature conversion from MPI to buffer failed\n");
549 return US gcry_strerror(gerr);
557 /* import public key (from blob in memory)
558 Return: NULL for success, or an error string */
561 exim_dkim_verify_init(blob * pubkey, keyformat fmt, ev_ctx * verify_ctx,
565 in code sequence per b81207d2bfa92 rsa_parse_public_key() and asn1_get_mpi()
574 uschar * stage = US"S1";
576 if (fmt != KEYFMT_DER) return US"pubkey format not handled";
583 BIT STRING:RSAPublicKey
585 INTEGER:Public modulus
586 INTEGER:Public exponent
588 openssl rsa -in aux-fixed/dkim/dkim.private -pubout -outform DER | od -t x1 | head;
589 openssl rsa -in aux-fixed/dkim/dkim.private -pubout | openssl asn1parse -dump;
590 openssl rsa -in aux-fixed/dkim/dkim.private -pubout | openssl asn1parse -dump -offset 22;
593 /* sequence; just move past the header */
594 if ((rc = as_tag(pubkey, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL))
595 != ASN1_SUCCESS) goto asn_err;
597 /* sequence; skip the entire thing */
598 DEBUG(D_acl) stage = US"S2";
599 if ((rc = as_tag(pubkey, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, &alen))
600 != ASN1_SUCCESS) goto asn_err;
601 pubkey->data += alen; pubkey->len -= alen;
604 /* bitstring: limit range to size of bitstring;
605 move over header + content wrapper */
606 DEBUG(D_acl) stage = US"BS";
607 if ((rc = as_tag(pubkey, 0, ASN1_TAG_BIT_STRING, &alen)) != ASN1_SUCCESS)
610 pubkey->data++; pubkey->len--;
612 /* sequence; just move past the header */
613 DEBUG(D_acl) stage = US"S3";
614 if ((rc = as_tag(pubkey, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL))
615 != ASN1_SUCCESS) goto asn_err;
617 /* read two integers */
618 DEBUG(D_acl) stage = US"MPI";
620 if ((errstr = as_mpi(pubkey, &verify_ctx->n))) return errstr;
621 nbits = (nbits - pubkey->len) * 8;
622 if ((errstr = as_mpi(pubkey, &verify_ctx->e))) return errstr;
625 DEBUG(D_acl) debug_printf_indent("rsa_verify_init:\n");
628 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, verify_ctx->n);
629 debug_printf_indent(" N : %s\n", s);
630 gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, verify_ctx->e);
631 debug_printf_indent(" E : %s\n", s);
635 if (bits) *bits = nbits;
639 DEBUG(D_acl) return string_sprintf("%s: %s", stage, asn1_strerror(rc));
640 return US asn1_strerror(rc);
644 /* verify signature (of hash)
645 XXX though we appear to be doing a hash, too!
646 (given pubkey & alleged sig)
647 Return: NULL for success, or an error string */
650 exim_dkim_verify(ev_ctx * verify_ctx, hashmethod hash, blob * data_hash, blob * sig)
653 cf. libgnutls 2.8.5 _wrap_gcry_pk_verify()
657 gcry_sexp_t s_sig = NULL, s_hash = NULL, s_pkey = NULL;
661 /*XXX needs extension for SHA512 */
664 case HASH_SHA1: sexp_hash = "(data(flags pkcs1)(hash sha1 %b))"; break;
665 case HASH_SHA2_256: sexp_hash = "(data(flags pkcs1)(hash sha256 %b))"; break;
666 default: return US"nonhandled hash type";
669 if ( (stage = US"pkey sexp build",
670 gerr = gcry_sexp_build (&s_pkey, NULL, "(public-key(rsa(n%m)(e%m)))",
671 verify_ctx->n, verify_ctx->e))
672 || (stage = US"data sexp build",
673 gerr = gcry_sexp_build (&s_hash, NULL, sexp_hash,
674 (int) data_hash->len, CS data_hash->data))
675 || (stage = US"sig mpi scan",
676 gerr = gcry_mpi_scan(&m_sig, GCRYMPI_FMT_USG, sig->data, sig->len, NULL))
677 || (stage = US"sig sexp build",
678 gerr = gcry_sexp_build (&s_sig, NULL, "(sig-val(rsa(s%m)))", m_sig))
679 || (stage = US"verify",
680 gerr = gcry_pk_verify (s_sig, s_hash, s_pkey))
683 DEBUG(D_acl) debug_printf_indent("verify: error in stage '%s'\n", stage);
684 return US gcry_strerror(gerr);
687 if (s_sig) gcry_sexp_release (s_sig);
688 if (s_hash) gcry_sexp_release (s_hash);
689 if (s_pkey) gcry_sexp_release (s_pkey);
690 gcry_mpi_release (m_sig);
691 gcry_mpi_release (verify_ctx->n);
692 gcry_mpi_release (verify_ctx->e);
700 #elif defined(SIGN_OPENSSL)
701 /******************************************************************************/
706 ERR_load_crypto_strings();
710 /* accumulate data (was gnutls-only but now needed for OpenSSL non-EC too
711 because now using hash-and-sign interface) */
713 exim_dkim_data_append(gstring * g, uschar * s)
715 return string_cat(g, s);
719 /* import private key from PEM string in memory.
720 Return: NULL for success, or an error string */
723 exim_dkim_signing_init(const uschar * privkey_pem, es_ctx * sign_ctx)
725 BIO * bp = BIO_new_mem_buf((void *)privkey_pem, -1);
727 if (!(sign_ctx->key = PEM_read_bio_PrivateKey(bp, NULL, NULL, NULL)))
728 return string_sprintf("privkey PEM-block import: %s",
729 ERR_error_string(ERR_get_error(), NULL));
732 #ifdef SIGN_HAVE_ED25519
733 EVP_PKEY_type(EVP_PKEY_id(sign_ctx->key)) == EVP_PKEY_ED25519
734 ? KEYTYPE_ED25519 : KEYTYPE_RSA;
743 /* allocate mem for signature (when signing) */
744 /* hash & sign data. Incremental not supported.
746 Return: NULL for success with the signaature in the sig blob, or an error string */
749 exim_dkim_sign(es_ctx * sign_ctx, hashmethod hash, blob * data, blob * sig)
757 case HASH_NULL: md = NULL; break; /* Ed25519 signing */
758 case HASH_SHA1: md = EVP_sha1(); break;
759 case HASH_SHA2_256: md = EVP_sha256(); break;
760 case HASH_SHA2_512: md = EVP_sha512(); break;
761 default: return US"nonhandled hash type";
764 #ifdef SIGN_HAVE_ED25519
765 if ( (ctx = EVP_MD_CTX_new())
766 && EVP_DigestSignInit(ctx, NULL, md, NULL, sign_ctx->key) > 0
767 && EVP_DigestSign(ctx, NULL, &siglen, NULL, 0) > 0
768 && (sig->data = store_get(siglen, GET_UNTAINTED))
770 /* Obtain the signature (slen could change here!) */
771 && EVP_DigestSign(ctx, sig->data, &siglen, data->data, data->len) > 0
774 EVP_MD_CTX_destroy(ctx);
779 /*XXX renamed to EVP_MD_CTX_new() in 1.1.0 */
780 if ( (ctx = EVP_MD_CTX_create())
781 && EVP_DigestSignInit(ctx, NULL, md, NULL, sign_ctx->key) > 0
782 && EVP_DigestSignUpdate(ctx, data->data, data->len) > 0
783 && EVP_DigestSignFinal(ctx, NULL, &siglen) > 0
784 && (sig->data = store_get(siglen, GET_UNTAINTED))
786 /* Obtain the signature (slen could change here!) */
787 && EVP_DigestSignFinal(ctx, sig->data, &siglen) > 0
790 EVP_MD_CTX_destroy(ctx);
796 if (ctx) EVP_MD_CTX_destroy(ctx);
797 return US ERR_error_string(ERR_get_error(), NULL);
802 /* import public key (from blob in memory)
803 Return: NULL for success, or an error string */
806 exim_dkim_verify_init(blob * pubkey, keyformat fmt, ev_ctx * verify_ctx,
809 const uschar * s = pubkey->data;
815 /*XXX hmm, we never free this */
816 if (!(verify_ctx->key = d2i_PUBKEY(NULL, &s, pubkey->len)))
817 ret = US ERR_error_string(ERR_get_error(), NULL);
819 #ifdef SIGN_HAVE_ED25519
820 case KEYFMT_ED25519_BARE:
821 if (!(verify_ctx->key = EVP_PKEY_new_raw_public_key(EVP_PKEY_ED25519, NULL,
823 ret = US ERR_error_string(ERR_get_error(), NULL);
827 ret = US"pubkey format not handled";
831 if (!ret && bits) *bits = EVP_PKEY_bits(verify_ctx->key);
838 /* verify signature (of hash, except Ed25519 where of-data)
839 (given pubkey & alleged sig)
840 Return: NULL for success, or an error string */
843 exim_dkim_verify(ev_ctx * verify_ctx, hashmethod hash, blob * data, blob * sig)
849 case HASH_NULL: md = NULL; break;
850 case HASH_SHA1: md = EVP_sha1(); break;
851 case HASH_SHA2_256: md = EVP_sha256(); break;
852 case HASH_SHA2_512: md = EVP_sha512(); break;
853 default: return US"nonhandled hash type";
856 #ifdef SIGN_HAVE_ED25519
861 if ((ctx = EVP_MD_CTX_new()))
863 if ( EVP_DigestVerifyInit(ctx, NULL, md, NULL, verify_ctx->key) > 0
864 && EVP_DigestVerify(ctx, sig->data, sig->len, data->data, data->len) > 0
866 { EVP_MD_CTX_free(ctx); return NULL; }
867 EVP_MD_CTX_free(ctx);
875 if ((ctx = EVP_PKEY_CTX_new(verify_ctx->key, NULL)))
877 if ( EVP_PKEY_verify_init(ctx) > 0
878 && EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) > 0
879 && EVP_PKEY_CTX_set_signature_md(ctx, md) > 0
880 && EVP_PKEY_verify(ctx, sig->data, sig->len,
881 data->data, data->len) == 1
883 { EVP_PKEY_CTX_free(ctx); return NULL; }
884 EVP_PKEY_CTX_free(ctx);
887 if (Ustrcmp(ERR_reason_error_string(ERR_peek_error()), "wrong signature length") == 0)
888 debug_printf("sig len (from msg hdr): %d, expected (from dns pubkey) %d\n",
889 (int) sig->len, EVP_PKEY_size(verify_ctx->key));
893 return US ERR_error_string(ERR_get_error(), NULL);
899 /******************************************************************************/
901 #endif /*DISABLE_DKIM*/
902 #endif /*MACRO_PREDEF*/