/* * PDKIM - a RFC4871 (DKIM) implementation * * Copyright (C) 1995 - 2020 Exim maintainers * * signing/verification interface */ #include "../exim.h" #include "crypt_ver.h" #include "signing.h" #ifdef MACRO_PREDEF # include "../macro_predef.h" void features_crypto(void) { # ifdef SIGN_HAVE_ED25519 builtin_macro_create(US"_CRYPTO_SIGN_ED25519"); # endif # ifdef EXIM_HAVE_SHA3 builtin_macro_create(US"_CRYPTO_HASH_SHA3"); # endif } #else #ifndef DISABLE_DKIM /* rest of file */ #ifdef DISABLE_TLS # error Must no DISABLE_TLS, for DKIM #endif /******************************************************************************/ #ifdef SIGN_GNUTLS # define EXIM_GNUTLS_LIBRARY_LOG_LEVEL 3 /* Logging function which can be registered with * gnutls_global_set_log_function() * gnutls_global_set_log_level() 0..9 */ #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 static void exim_gnutls_logger_cb(int level, const char *message) { size_t len = strlen(message); if (len < 1) { DEBUG(D_tls) debug_printf("GnuTLS<%d> empty debug message\n", level); return; } DEBUG(D_tls) debug_printf("GnuTLS<%d>: %s%s", level, message, message[len-1] == '\n' ? "" : "\n"); } #endif void exim_dkim_init(void) { #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0 DEBUG(D_tls) { gnutls_global_set_log_function(exim_gnutls_logger_cb); /* arbitrarily chosen level; bump upto 9 for more */ gnutls_global_set_log_level(EXIM_GNUTLS_LIBRARY_LOG_LEVEL); } #endif } /* accumulate data (gnutls-only). String to be appended must be nul-terminated. */ gstring * exim_dkim_data_append(gstring * g, uschar * s) { return string_cat(g, s); } /* import private key from PEM string in memory. Return: NULL for success, or an error string */ const uschar * exim_dkim_signing_init(const uschar * privkey_pem, es_ctx * sign_ctx) { gnutls_datum_t k = { .data = (void *)privkey_pem, .size = Ustrlen(privkey_pem) }; gnutls_x509_privkey_t x509_key; const uschar * where; int rc; if ( (where = US"internal init", rc = gnutls_x509_privkey_init(&x509_key)) || (rc = gnutls_privkey_init(&sign_ctx->key)) || (where = US"privkey PEM-block import", rc = gnutls_x509_privkey_import(x509_key, &k, GNUTLS_X509_FMT_PEM)) || (where = US"internal privkey transfer", rc = gnutls_privkey_import_x509(sign_ctx->key, x509_key, 0)) ) return string_sprintf("%s: %s", where, gnutls_strerror(rc)); switch (rc = gnutls_privkey_get_pk_algorithm(sign_ctx->key, NULL)) { case GNUTLS_PK_RSA: sign_ctx->keytype = KEYTYPE_RSA; break; #ifdef SIGN_HAVE_ED25519 case GNUTLS_PK_EDDSA_ED25519: sign_ctx->keytype = KEYTYPE_ED25519; break; #endif default: return rc < 0 ? CUS gnutls_strerror(rc) : string_sprintf("Unhandled key type: %d '%s'", rc, gnutls_pk_get_name(rc)); } return NULL; } /* allocate mem for signature (when signing) */ /* hash & sign data. No way to do incremental. Return: NULL for success, or an error string */ const uschar * exim_dkim_sign(es_ctx * sign_ctx, hashmethod hash, blob * data, blob * sig) { gnutls_datum_t k_data = { .data = data->data, .size = data->len }; gnutls_digest_algorithm_t dig; gnutls_datum_t k_sig; int rc; switch (hash) { case HASH_SHA1: dig = GNUTLS_DIG_SHA1; break; case HASH_SHA2_256: dig = GNUTLS_DIG_SHA256; break; case HASH_SHA2_512: dig = GNUTLS_DIG_SHA512; break; default: return US"nonhandled hash type"; } if ((rc = gnutls_privkey_sign_data(sign_ctx->key, dig, 0, &k_data, &k_sig))) return CUS gnutls_strerror(rc); /* Don't care about deinit for the key; shortlived process */ sig->data = k_sig.data; sig->len = k_sig.size; return NULL; } /* import public key (from blob in memory) Return: NULL for success, or an error string */ const uschar * exim_dkim_verify_init(blob * pubkey, keyformat fmt, ev_ctx * verify_ctx, unsigned * bits) { gnutls_datum_t k; int rc; const uschar * ret = NULL; gnutls_pubkey_init(&verify_ctx->key); k.data = pubkey->data; k.size = pubkey->len; switch(fmt) { case KEYFMT_DER: if ((rc = gnutls_pubkey_import(verify_ctx->key, &k, GNUTLS_X509_FMT_DER))) ret = US gnutls_strerror(rc); break; #ifdef SIGN_HAVE_ED25519 case KEYFMT_ED25519_BARE: if ((rc = gnutls_pubkey_import_ecc_raw(verify_ctx->key, GNUTLS_ECC_CURVE_ED25519, &k, NULL))) ret = US gnutls_strerror(rc); break; #endif default: ret = US"pubkey format not handled"; break; } if (!ret && bits) gnutls_pubkey_get_pk_algorithm(verify_ctx->key, bits); return ret; } /* verify signature (of hash if RSA sig, of data if EC sig. No way to do incremental) (given pubkey & alleged sig) Return: NULL for success, or an error string */ const uschar * exim_dkim_verify(ev_ctx * verify_ctx, hashmethod hash, blob * data_hash, blob * sig) { gnutls_datum_t k = { .data = data_hash->data, .size = data_hash->len }; gnutls_datum_t s = { .data = sig->data, .size = sig->len }; int rc; const uschar * ret = NULL; #ifdef SIGN_HAVE_ED25519 if (verify_ctx->keytype == KEYTYPE_ED25519) { if ((rc = gnutls_pubkey_verify_data2(verify_ctx->key, GNUTLS_SIGN_EDDSA_ED25519, 0, &k, &s)) < 0) ret = US gnutls_strerror(rc); } else #endif { gnutls_sign_algorithm_t algo; switch (hash) { case HASH_SHA1: algo = GNUTLS_SIGN_RSA_SHA1; break; case HASH_SHA2_256: algo = GNUTLS_SIGN_RSA_SHA256; break; case HASH_SHA2_512: algo = GNUTLS_SIGN_RSA_SHA512; break; default: return US"nonhandled hash type"; } if ((rc = gnutls_pubkey_verify_hash2(verify_ctx->key, algo, 0, &k, &s)) < 0) ret = US gnutls_strerror(rc); } gnutls_pubkey_deinit(verify_ctx->key); return ret; } #elif defined(SIGN_GCRYPT) /******************************************************************************/ /* This variant is used under pre-3.0.0 GnuTLS. Only rsa-sha1 and rsa-sha256 */ /* Internal service routine: Read and move past an asn.1 header, checking class & tag, optionally returning the data-length */ static int as_tag(blob * der, uschar req_cls, long req_tag, long * alen) { int rc; uschar tag_class; int taglen; long tag, len; debug_printf_indent("as_tag: %02x %02x %02x %02x\n", der->data[0], der->data[1], der->data[2], der->data[3]); if ((rc = asn1_get_tag_der(der->data++, der->len--, &tag_class, &taglen, &tag)) != ASN1_SUCCESS) return rc; if (tag_class != req_cls || tag != req_tag) return ASN1_ELEMENT_NOT_FOUND; if ((len = asn1_get_length_der(der->data, der->len, &taglen)) < 0) return ASN1_DER_ERROR; if (alen) *alen = len; /* debug_printf_indent("as_tag: tlen %d dlen %d\n", taglen, (int)len); */ der->data += taglen; der->len -= taglen; return rc; } /* Internal service routine: Read and move over an asn.1 integer, setting an MPI to the value */ static uschar * as_mpi(blob * der, gcry_mpi_t * mpi) { long alen; int rc; gcry_error_t gerr; debug_printf_indent("%s\n", __FUNCTION__); /* integer; move past the header */ if ((rc = as_tag(der, 0, ASN1_TAG_INTEGER, &alen)) != ASN1_SUCCESS) return US asn1_strerror(rc); /* read to an MPI */ if ((gerr = gcry_mpi_scan(mpi, GCRYMPI_FMT_STD, der->data, alen, NULL))) return US gcry_strerror(gerr); /* move over the data */ der->data += alen; der->len -= alen; return NULL; } void exim_dkim_init(void) { /* Version check should be the very first call because it makes sure that important subsystems are initialized. */ if (!gcry_check_version (GCRYPT_VERSION)) { fputs ("libgcrypt version mismatch\n", stderr); exit (2); } /* We don't want to see any warnings, e.g. because we have not yet parsed program options which might be used to suppress such warnings. */ gcry_control (GCRYCTL_SUSPEND_SECMEM_WARN); /* ... If required, other initialization goes here. Note that the process might still be running with increased privileges and that the secure memory has not been initialized. */ /* Allocate a pool of 16k secure memory. This make the secure memory available and also drops privileges where needed. */ gcry_control (GCRYCTL_INIT_SECMEM, 16384, 0); /* It is now okay to let Libgcrypt complain when there was/is a problem with the secure memory. */ gcry_control (GCRYCTL_RESUME_SECMEM_WARN); /* ... If required, other initialization goes here. */ /* Tell Libgcrypt that initialization has completed. */ gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0); return; } /* Accumulate data (gnutls-only). String to be appended must be nul-terminated. */ gstring * exim_dkim_data_append(gstring * g, uschar * s) { return g; /*dummy*/ } /* import private key from PEM string in memory. Only handles RSA keys. Return: NULL for success, or an error string */ const uschar * exim_dkim_signing_init(const uschar * privkey_pem, es_ctx * sign_ctx) { uschar * s1, * s2; blob der; long alen; int rc; /*XXX will need extension to _spot_ as well as handle a non-RSA key? I think... So... this is not a PrivateKeyInfo - which would have a field identifying the keytype - PrivateKeyAlgorithmIdentifier - but a plain RSAPrivateKey (wrapped in PEM-headers. Can we use those as a type tag? What forms are there? "BEGIN EC PRIVATE KEY" (cf. ec(1ssl)) How does OpenSSL PEM_read_bio_PrivateKey() deal with it? gnutls_x509_privkey_import() ? */ /* * RSAPrivateKey ::= SEQUENCE * version Version, * modulus INTEGER, -- n * publicExponent INTEGER, -- e * privateExponent INTEGER, -- d * prime1 INTEGER, -- p * prime2 INTEGER, -- q * exponent1 INTEGER, -- d mod (p-1) * exponent2 INTEGER, -- d mod (q-1) * coefficient INTEGER, -- (inverse of q) mod p * otherPrimeInfos OtherPrimeInfos OPTIONAL * ECPrivateKey ::= SEQUENCE { * version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1), * privateKey OCTET STRING, * parameters [0] ECParameters {{ NamedCurve }} OPTIONAL, * publicKey [1] BIT STRING OPTIONAL * } * Hmm, only 1 useful item, and not even an integer? Wonder how we might use it... - actually, gnutls_x509_privkey_import() appears to require a curve name parameter value for that is an OID? a local-only integer (it's an enum in GnuTLS)? Useful cmds: ssh-keygen -t ecdsa -f foo.privkey ssh-keygen -t ecdsa -b384 -f foo.privkey ssh-keygen -t ecdsa -b521 -f foo.privkey ssh-keygen -t ed25519 -f foo.privkey < foo openssl pkcs8 -in /dev/stdin -inform PEM -nocrypt -topk8 -outform DER | od -x openssl asn1parse -in foo -inform PEM -dump openssl asn1parse -in foo -inform PEM -dump -stroffset 24 (??) (not good for ed25519) */ if ( !(s1 = Ustrstr(CS privkey_pem, "-----BEGIN RSA PRIVATE KEY-----")) || !(s2 = Ustrstr(CS (s1+=31), "-----END RSA PRIVATE KEY-----" )) ) return US"Bad PEM wrapper"; *s2 = '\0'; if ((rc = b64decode(s1, &der.data) < 0)) return US"Bad PEM-DER b64 decode"; der.len = rc; /* untangle asn.1 */ /* sequence; just move past the header */ if ((rc = as_tag(&der, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL)) != ASN1_SUCCESS) goto asn_err; /* integer version; move past the header, check is zero */ if ((rc = as_tag(&der, 0, ASN1_TAG_INTEGER, &alen)) != ASN1_SUCCESS) goto asn_err; if (alen != 1 || *der.data != 0) return US"Bad version number"; der.data++; der.len--; if ( (s1 = as_mpi(&der, &sign_ctx->n)) || (s1 = as_mpi(&der, &sign_ctx->e)) || (s1 = as_mpi(&der, &sign_ctx->d)) || (s1 = as_mpi(&der, &sign_ctx->p)) || (s1 = as_mpi(&der, &sign_ctx->q)) || (s1 = as_mpi(&der, &sign_ctx->dp)) || (s1 = as_mpi(&der, &sign_ctx->dq)) || (s1 = as_mpi(&der, &sign_ctx->qp)) ) return s1; #ifdef extreme_debug DEBUG(D_acl) debug_printf_indent("rsa_signing_init:\n"); { uschar * s; gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->n); debug_printf_indent(" N : %s\n", s); gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->e); debug_printf_indent(" E : %s\n", s); gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->d); debug_printf_indent(" D : %s\n", s); gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->p); debug_printf_indent(" P : %s\n", s); gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->q); debug_printf_indent(" Q : %s\n", s); gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->dp); debug_printf_indent(" DP: %s\n", s); gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->dq); debug_printf_indent(" DQ: %s\n", s); gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, sign_ctx->qp); debug_printf_indent(" QP: %s\n", s); } #endif sign_ctx->keytype = KEYTYPE_RSA; return NULL; asn_err: return US asn1_strerror(rc); } /* allocate mem for signature (when signing) */ /* sign already-hashed data. Return: NULL for success, or an error string */ const uschar * exim_dkim_sign(es_ctx * sign_ctx, hashmethod hash, blob * data, blob * sig) { char * sexp_hash; gcry_sexp_t s_hash = NULL, s_key = NULL, s_sig = NULL; gcry_mpi_t m_sig; uschar * errstr; gcry_error_t gerr; /*XXX will need extension for hash types (though, possibly, should be re-specced to not rehash but take an already-hashed value? Actually current impl looks WRONG - it _is_ given a hash so should not be re-hashing. Has this been tested? Will need extension for non-RSA sugning algos. */ switch (hash) { case HASH_SHA1: sexp_hash = "(data(flags pkcs1)(hash sha1 %b))"; break; case HASH_SHA2_256: sexp_hash = "(data(flags pkcs1)(hash sha256 %b))"; break; default: return US"nonhandled hash type"; } #define SIGSPACE 128 sig->data = store_get(SIGSPACE, FALSE); if (gcry_mpi_cmp (sign_ctx->p, sign_ctx->q) > 0) { gcry_mpi_swap (sign_ctx->p, sign_ctx->q); gcry_mpi_invm (sign_ctx->qp, sign_ctx->p, sign_ctx->q); } if ( (gerr = gcry_sexp_build (&s_key, NULL, "(private-key (rsa (n%m)(e%m)(d%m)(p%m)(q%m)(u%m)))", sign_ctx->n, sign_ctx->e, sign_ctx->d, sign_ctx->p, sign_ctx->q, sign_ctx->qp)) || (gerr = gcry_sexp_build (&s_hash, NULL, sexp_hash, (int) data->len, CS data->data)) || (gerr = gcry_pk_sign (&s_sig, s_hash, s_key)) ) return US gcry_strerror(gerr); /* gcry_sexp_dump(s_sig); */ if ( !(s_sig = gcry_sexp_find_token(s_sig, "s", 0)) ) return US"no sig result"; m_sig = gcry_sexp_nth_mpi(s_sig, 1, GCRYMPI_FMT_USG); #ifdef extreme_debug DEBUG(D_acl) { uschar * s; gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, m_sig); debug_printf_indent(" SG: %s\n", s); } #endif gerr = gcry_mpi_print(GCRYMPI_FMT_USG, sig->data, SIGSPACE, &sig->len, m_sig); if (gerr) { debug_printf_indent("signature conversion from MPI to buffer failed\n"); return US gcry_strerror(gerr); } #undef SIGSPACE return NULL; } /* import public key (from blob in memory) Return: NULL for success, or an error string */ const uschar * exim_dkim_verify_init(blob * pubkey, keyformat fmt, ev_ctx * verify_ctx, unsigned * bits) { /* in code sequence per b81207d2bfa92 rsa_parse_public_key() and asn1_get_mpi() */ uschar tag_class; int taglen; long alen; unsigned nbits; int rc; uschar * errstr; gcry_error_t gerr; uschar * stage = US"S1"; if (fmt != KEYFMT_DER) return US"pubkey format not handled"; /* sequence sequence OBJECT:rsaEncryption NULL BIT STRING:RSAPublicKey sequence INTEGER:Public modulus INTEGER:Public exponent openssl rsa -in aux-fixed/dkim/dkim.private -pubout -outform DER | od -t x1 | head; openssl rsa -in aux-fixed/dkim/dkim.private -pubout | openssl asn1parse -dump; openssl rsa -in aux-fixed/dkim/dkim.private -pubout | openssl asn1parse -dump -offset 22; */ /* sequence; just move past the header */ if ((rc = as_tag(pubkey, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL)) != ASN1_SUCCESS) goto asn_err; /* sequence; skip the entire thing */ DEBUG(D_acl) stage = US"S2"; if ((rc = as_tag(pubkey, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, &alen)) != ASN1_SUCCESS) goto asn_err; pubkey->data += alen; pubkey->len -= alen; /* bitstring: limit range to size of bitstring; move over header + content wrapper */ DEBUG(D_acl) stage = US"BS"; if ((rc = as_tag(pubkey, 0, ASN1_TAG_BIT_STRING, &alen)) != ASN1_SUCCESS) goto asn_err; pubkey->len = alen; pubkey->data++; pubkey->len--; /* sequence; just move past the header */ DEBUG(D_acl) stage = US"S3"; if ((rc = as_tag(pubkey, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL)) != ASN1_SUCCESS) goto asn_err; /* read two integers */ DEBUG(D_acl) stage = US"MPI"; nbits = pubkey->len; if ((errstr = as_mpi(pubkey, &verify_ctx->n))) return errstr; nbits = (nbits - pubkey->len) * 8; if ((errstr = as_mpi(pubkey, &verify_ctx->e))) return errstr; #ifdef extreme_debug DEBUG(D_acl) debug_printf_indent("rsa_verify_init:\n"); { uschar * s; gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, verify_ctx->n); debug_printf_indent(" N : %s\n", s); gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, verify_ctx->e); debug_printf_indent(" E : %s\n", s); } #endif if (bits) *bits = nbits; return NULL; asn_err: DEBUG(D_acl) return string_sprintf("%s: %s", stage, asn1_strerror(rc)); return US asn1_strerror(rc); } /* verify signature (of hash) XXX though we appear to be doing a hash, too! (given pubkey & alleged sig) Return: NULL for success, or an error string */ const uschar * exim_dkim_verify(ev_ctx * verify_ctx, hashmethod hash, blob * data_hash, blob * sig) { /* cf. libgnutls 2.8.5 _wrap_gcry_pk_verify() */ char * sexp_hash; gcry_mpi_t m_sig; gcry_sexp_t s_sig = NULL, s_hash = NULL, s_pkey = NULL; gcry_error_t gerr; uschar * stage; /*XXX needs extension for SHA512 */ switch (hash) { case HASH_SHA1: sexp_hash = "(data(flags pkcs1)(hash sha1 %b))"; break; case HASH_SHA2_256: sexp_hash = "(data(flags pkcs1)(hash sha256 %b))"; break; default: return US"nonhandled hash type"; } if ( (stage = US"pkey sexp build", gerr = gcry_sexp_build (&s_pkey, NULL, "(public-key(rsa(n%m)(e%m)))", verify_ctx->n, verify_ctx->e)) || (stage = US"data sexp build", gerr = gcry_sexp_build (&s_hash, NULL, sexp_hash, (int) data_hash->len, CS data_hash->data)) || (stage = US"sig mpi scan", gerr = gcry_mpi_scan(&m_sig, GCRYMPI_FMT_USG, sig->data, sig->len, NULL)) || (stage = US"sig sexp build", gerr = gcry_sexp_build (&s_sig, NULL, "(sig-val(rsa(s%m)))", m_sig)) || (stage = US"verify", gerr = gcry_pk_verify (s_sig, s_hash, s_pkey)) ) { DEBUG(D_acl) debug_printf_indent("verify: error in stage '%s'\n", stage); return US gcry_strerror(gerr); } if (s_sig) gcry_sexp_release (s_sig); if (s_hash) gcry_sexp_release (s_hash); if (s_pkey) gcry_sexp_release (s_pkey); gcry_mpi_release (m_sig); gcry_mpi_release (verify_ctx->n); gcry_mpi_release (verify_ctx->e); return NULL; } #elif defined(SIGN_OPENSSL) /******************************************************************************/ void exim_dkim_init(void) { ERR_load_crypto_strings(); } /* accumulate data (was gnutls-only but now needed for OpenSSL non-EC too because now using hash-and-sign interface) */ gstring * exim_dkim_data_append(gstring * g, uschar * s) { return string_cat(g, s); } /* import private key from PEM string in memory. Return: NULL for success, or an error string */ const uschar * exim_dkim_signing_init(const uschar * privkey_pem, es_ctx * sign_ctx) { BIO * bp = BIO_new_mem_buf((void *)privkey_pem, -1); if (!(sign_ctx->key = PEM_read_bio_PrivateKey(bp, NULL, NULL, NULL))) return string_sprintf("privkey PEM-block import: %s", ERR_error_string(ERR_get_error(), NULL)); sign_ctx->keytype = #ifdef SIGN_HAVE_ED25519 EVP_PKEY_type(EVP_PKEY_id(sign_ctx->key)) == EVP_PKEY_ED25519 ? KEYTYPE_ED25519 : KEYTYPE_RSA; #else KEYTYPE_RSA; #endif return NULL; } /* allocate mem for signature (when signing) */ /* hash & sign data. Incremental not supported. Return: NULL for success with the signaature in the sig blob, or an error string */ const uschar * exim_dkim_sign(es_ctx * sign_ctx, hashmethod hash, blob * data, blob * sig) { const EVP_MD * md; EVP_MD_CTX * ctx; size_t siglen; switch (hash) { case HASH_NULL: md = NULL; break; /* Ed25519 signing */ case HASH_SHA1: md = EVP_sha1(); break; case HASH_SHA2_256: md = EVP_sha256(); break; case HASH_SHA2_512: md = EVP_sha512(); break; default: return US"nonhandled hash type"; } #ifdef SIGN_HAVE_ED25519 if ( (ctx = EVP_MD_CTX_new()) && EVP_DigestSignInit(ctx, NULL, md, NULL, sign_ctx->key) > 0 && EVP_DigestSign(ctx, NULL, &siglen, NULL, 0) > 0 && (sig->data = store_get(siglen, FALSE)) /* Obtain the signature (slen could change here!) */ && EVP_DigestSign(ctx, sig->data, &siglen, data->data, data->len) > 0 ) { EVP_MD_CTX_destroy(ctx); sig->len = siglen; return NULL; } #else /*XXX renamed to EVP_MD_CTX_new() in 1.1.0 */ if ( (ctx = EVP_MD_CTX_create()) && EVP_DigestSignInit(ctx, NULL, md, NULL, sign_ctx->key) > 0 && EVP_DigestSignUpdate(ctx, data->data, data->len) > 0 && EVP_DigestSignFinal(ctx, NULL, &siglen) > 0 && (sig->data = store_get(siglen, FALSE)) /* Obtain the signature (slen could change here!) */ && EVP_DigestSignFinal(ctx, sig->data, &siglen) > 0 ) { EVP_MD_CTX_destroy(ctx); sig->len = siglen; return NULL; } #endif if (ctx) EVP_MD_CTX_destroy(ctx); return US ERR_error_string(ERR_get_error(), NULL); } /* import public key (from blob in memory) Return: NULL for success, or an error string */ const uschar * exim_dkim_verify_init(blob * pubkey, keyformat fmt, ev_ctx * verify_ctx, unsigned * bits) { const uschar * s = pubkey->data; uschar * ret = NULL; switch(fmt) { case KEYFMT_DER: /*XXX hmm, we never free this */ if (!(verify_ctx->key = d2i_PUBKEY(NULL, &s, pubkey->len))) ret = US ERR_error_string(ERR_get_error(), NULL); break; #ifdef SIGN_HAVE_ED25519 case KEYFMT_ED25519_BARE: if (!(verify_ctx->key = EVP_PKEY_new_raw_public_key(EVP_PKEY_ED25519, NULL, s, pubkey->len))) ret = US ERR_error_string(ERR_get_error(), NULL); break; #endif default: ret = US"pubkey format not handled"; break; } if (!ret && bits) *bits = EVP_PKEY_bits(verify_ctx->key); return ret; } /* verify signature (of hash, except Ed25519 where of-data) (given pubkey & alleged sig) Return: NULL for success, or an error string */ const uschar * exim_dkim_verify(ev_ctx * verify_ctx, hashmethod hash, blob * data, blob * sig) { const EVP_MD * md; switch (hash) { case HASH_NULL: md = NULL; break; case HASH_SHA1: md = EVP_sha1(); break; case HASH_SHA2_256: md = EVP_sha256(); break; case HASH_SHA2_512: md = EVP_sha512(); break; default: return US"nonhandled hash type"; } #ifdef SIGN_HAVE_ED25519 if (!md) { EVP_MD_CTX * ctx; if ((ctx = EVP_MD_CTX_new())) { if ( EVP_DigestVerifyInit(ctx, NULL, md, NULL, verify_ctx->key) > 0 && EVP_DigestVerify(ctx, sig->data, sig->len, data->data, data->len) > 0 ) { EVP_MD_CTX_free(ctx); return NULL; } EVP_MD_CTX_free(ctx); } } else #endif { EVP_PKEY_CTX * ctx; if ((ctx = EVP_PKEY_CTX_new(verify_ctx->key, NULL))) { if ( EVP_PKEY_verify_init(ctx) > 0 && EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) > 0 && EVP_PKEY_CTX_set_signature_md(ctx, md) > 0 && EVP_PKEY_verify(ctx, sig->data, sig->len, data->data, data->len) == 1 ) { EVP_PKEY_CTX_free(ctx); return NULL; } EVP_PKEY_CTX_free(ctx); DEBUG(D_tls) if (Ustrcmp(ERR_reason_error_string(ERR_peek_error()), "wrong signature length") == 0) debug_printf("sig len (from msg hdr): %d, expected (from dns pubkey) %d\n", (int) sig->len, EVP_PKEY_size(verify_ctx->key)); } } return US ERR_error_string(ERR_get_error(), NULL); } #endif /******************************************************************************/ #endif /*DISABLE_DKIM*/ #endif /*MACRO_PREDEF*/ /* End of File */