mkdir pdkim
cd pdkim
for f in README Makefile crypt_ver.h pdkim.c \
- pdkim.h hash.c hash.h rsa.c rsa.h blob.h
+ pdkim.h hash.c hash.h signing.c signing.h blob.h
do
ln -s ../../src/pdkim/$f $f
done
dkim_private_key_expanded = big_buffer;
}
+/*XXX so we currently nail signing to RSA + SHA256. Need to extract algo
+from privkey, and provide means for selecting hash-method.
+Check for disallowed combos.
+Will need new dkim_ transport option for hash. */
+
if (!(ctx = pdkim_init_sign(CS dkim_signing_domain,
CS dkim_signing_selector,
CS dkim_private_key_expanded,
BOOL
exim_sha_init(hctx * h, hashmethod m)
{
+/*XXX extend for sha512 */
switch (h->method = m)
{
case HASH_SHA1: h->hashlen = 20; SHA1_Init (&h->u.sha1); break;
BOOL
exim_sha_init(hctx * h, hashmethod m)
{
+/*XXX extend for sha512 */
switch (h->method = m)
{
case HASH_SHA1: h->hashlen = 20; gnutls_hash_init(&h->sha, GNUTLS_DIG_SHA1); break;
BOOL
exim_sha_init(hctx * h, hashmethod m)
{
+/*XXX extend for sha512 */
switch (h->method = m)
{
case HASH_SHA1: h->hashlen = 20; gcry_md_open(&h->sha, GCRY_MD_SHA1, 0); break;
BOOL
exim_sha_init(hctx * h, hashmethod m)
{
+/*XXX extend for sha512 */
switch (h->method = m)
{
case HASH_SHA1: h->hashlen = 20; sha1_starts(&h->u.sha1); break;
# Make file for building the pdkim library.
-OBJ = pdkim.o rsa.o
+OBJ = pdkim.o signing.o
pdkim.a: $(OBJ)
@$(RM_COMMAND) -f pdkim.a
$(FE)$(CC) -c $(CFLAGS) $(INCLUDE) -I. $*.c
pdkim.o: $(HDRS) crypt_ver.h pdkim.h pdkim.c
-rsa.o: $(HDRS) crypt_ver.h rsa.h rsa.c
+signing.o: $(HDRS) crypt_ver.h signing.h signing.c
# End
#endif
#include "pdkim.h"
-#include "rsa.h"
+#include "signing.h"
#define PDKIM_SIGNATURE_VERSION "1"
#define PDKIM_PUB_RECORD_VERSION US "DKIM1"
US"relaxed",
NULL
};
+/*XXX currently unused */
const uschar * pdkim_hashes[] = {
US"sha256",
US"sha1",
NULL
};
+/*XXX currently unused */
const uschar * pdkim_keytypes[] = {
US"rsa",
NULL
Ustrcmp(cur_val, PDKIM_SIGNATURE_VERSION) == 0 ? 1 : -1;
break;
case 'a':
+/*XXX this searches a list of combined (algo + hash-method)s */
for (i = 0; pdkim_algos[i]; i++)
if (Ustrcmp(cur_val, pdkim_algos[i]) == 0)
{
"PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
}
+/*XXX hash method: extend for sha512 */
if (!exim_sha_init(&sig->body_hash_ctx,
sig->algo == PDKIM_ALGO_RSA_SHA1 ? HASH_SHA1 : HASH_SHA256))
{
/* Required and static bits */
hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"a=",
+/*XXX this is a combo of algo and hash-method */
pdkim_algos[sig->algo]);
hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"q=",
pdkim_querymethods[sig->querymethod]);
"PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
/* Import public key */
-if ((*errstr = exim_rsa_verify_init(&p->key, vctx)))
+if ((*errstr = exim_dkim_verify_init(&p->key, vctx)))
{
DEBUG(D_acl) debug_printf("verify_init: %s\n", *errstr);
sig->verify_status = PDKIM_VERIFY_INVALID;
while (sig)
{
+/*XXX bool probably not enough */
BOOL is_sha1 = sig->algo == PDKIM_ALGO_RSA_SHA1;
hctx hhash_ctx;
uschar * sig_hdr = US"";
exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh));
/* Remember headers block for signing (when the library cannot do incremental) */
- (void) exim_rsa_data_append(&hdata, &hdata_alloc, rh);
+ (void) exim_dkim_data_append(&hdata, &hdata_alloc, rh);
DEBUG(D_acl) pdkim_quoteprint(rh, Ustrlen(rh));
}
}
/* Remember headers block for signing (when the library cannot do incremental) */
+/*XXX is this assuing algo == RSA? */
if (ctx->flags & PDKIM_MODE_SIGN)
- (void) exim_rsa_data_append(&hdata, &hdata_alloc, US sig_hdr);
+ (void) exim_dkim_data_append(&hdata, &hdata_alloc, US sig_hdr);
/* SIGNING ---------------------------------------------------------------- */
if (ctx->flags & PDKIM_MODE_SIGN)
es_ctx sctx;
/* Import private key */
- if ((*err = exim_rsa_signing_init(US sig->rsa_privkey, &sctx)))
+/*XXX extend for non-RSA algos */
+ if ((*err = exim_dkim_signing_init(US sig->rsa_privkey, &sctx)))
{
DEBUG(D_acl) debug_printf("signing_init: %s\n", *err);
return PDKIM_ERR_RSA_PRIVKEY;
hdata = hhash;
#endif
- if ((*err = exim_rsa_sign(&sctx, is_sha1, &hdata, &sig->sighash)))
+/*XXX extend for non-RSA algos */
+/*XXX oddly the dkim rfc does _not_ say what variant (sha1 or sha256) of
+RSA signing should be done. We use the same variant as the hash-method. */
+
+ if ((*err = exim_dkim_sign(&sctx, is_sha1, &hdata, &sig->sighash)))
{
DEBUG(D_acl) debug_printf("signing: %s\n", *err);
return PDKIM_ERR_RSA_SIGNING;
}
/* Check the signature */
- if ((*err = exim_rsa_verify(&vctx, is_sha1, &hhash, &sig->sighash)))
+/*XXX needs extension for non-RSA */
+ if ((*err = exim_dkim_verify(&vctx, is_sha1, &hhash, &sig->sighash)))
{
DEBUG(D_acl) debug_printf("headers verify: %s\n", *err);
sig->verify_status = PDKIM_VERIFY_FAIL;
/* -------------------------------------------------------------------------- */
+/*XXX ? needs extension to cover non-RSA algo? Currently the "algo" is actually
+the combo of algo and hash-method */
+
DLLEXPORT pdkim_ctx *
pdkim_init_sign(char * domain, char * selector, char * rsa_privkey, int algo,
BOOL dot_stuffed, int(*dns_txt_callback)(char *, char *),
sig->rsa_privkey = string_copy(US rsa_privkey);
sig->algo = algo;
+/*XXX extend for sha512 */
if (!exim_sha_init(&sig->body_hash_ctx,
algo == PDKIM_ALGO_RSA_SHA1 ? HASH_SHA1 : HASH_SHA256))
{
void
pdkim_init(void)
{
-exim_rsa_init();
+exim_dkim_init();
}
+++ /dev/null
-/*
- * PDKIM - a RFC4871 (DKIM) implementation
- *
- * Copyright (C) 2016 Exim maintainers
- *
- * RSA signing/verification interface
- */
-
-#include "../exim.h"
-
-#ifndef DISABLE_DKIM /* entire file */
-
-#ifndef SUPPORT_TLS
-# error Need SUPPORT_TLS for DKIM
-#endif
-
-#include "crypt_ver.h"
-#include "rsa.h"
-
-
-/******************************************************************************/
-#ifdef RSA_GNUTLS
-
-void
-exim_rsa_init(void)
-{
-}
-
-
-/* accumulate data (gnutls-only). String to be appended must be nul-terminated. */
-blob *
-exim_rsa_data_append(blob * b, int * alloc, uschar * s)
-{
-int len = b->len;
-b->data = string_append(b->data, alloc, &len, 1, s);
-b->len = len;
-return b;
-}
-
-
-
-/* import private key from PEM string in memory.
-Return: NULL for success, or an error string */
-
-const uschar *
-exim_rsa_signing_init(uschar * privkey_pem, es_ctx * sign_ctx)
-{
-gnutls_datum_t k;
-int rc;
-
-k.data = privkey_pem;
-k.size = strlen(privkey_pem);
-
-if ( (rc = gnutls_x509_privkey_init(&sign_ctx->rsa)) != GNUTLS_E_SUCCESS
- /*|| (rc = gnutls_x509_privkey_import(sign_ctx->rsa, &k,
- GNUTLS_X509_FMT_PEM)) != GNUTLS_E_SUCCESS */
- )
- return gnutls_strerror(rc);
-
-if ( /* (rc = gnutls_x509_privkey_init(&sign_ctx->rsa)) != GNUTLS_E_SUCCESS
- ||*/ (rc = gnutls_x509_privkey_import(sign_ctx->rsa, &k,
- GNUTLS_X509_FMT_PEM)) != GNUTLS_E_SUCCESS
- )
- return gnutls_strerror(rc);
-
-return NULL;
-}
-
-
-
-/* allocate mem for signature (when signing) */
-/* sign data (gnutls_only)
-OR
-sign hash.
-
-Return: NULL for success, or an error string */
-
-const uschar *
-exim_rsa_sign(es_ctx * sign_ctx, BOOL is_sha1, blob * data, blob * sig)
-{
-gnutls_datum_t k;
-size_t sigsize = 0;
-int rc;
-const uschar * ret = NULL;
-
-/* Allocate mem for signature */
-k.data = data->data;
-k.size = data->len;
-(void) gnutls_x509_privkey_sign_data(sign_ctx->rsa,
- is_sha1 ? GNUTLS_DIG_SHA1 : GNUTLS_DIG_SHA256,
- 0, &k, NULL, &sigsize);
-
-sig->data = store_get(sigsize);
-sig->len = sigsize;
-
-/* Do signing */
-if ((rc = gnutls_x509_privkey_sign_data(sign_ctx->rsa,
- is_sha1 ? GNUTLS_DIG_SHA1 : GNUTLS_DIG_SHA256,
- 0, &k, sig->data, &sigsize)) != GNUTLS_E_SUCCESS
- )
- ret = gnutls_strerror(rc);
-
-gnutls_x509_privkey_deinit(sign_ctx->rsa);
-return ret;
-}
-
-
-
-/* import public key (from DER in memory)
-Return: NULL for success, or an error string */
-
-const uschar *
-exim_rsa_verify_init(blob * pubkey_der, ev_ctx * verify_ctx)
-{
-gnutls_datum_t k;
-int rc;
-const uschar * ret = NULL;
-
-gnutls_pubkey_init(&verify_ctx->rsa);
-
-k.data = pubkey_der->data;
-k.size = pubkey_der->len;
-
-if ((rc = gnutls_pubkey_import(verify_ctx->rsa, &k, GNUTLS_X509_FMT_DER))
- != GNUTLS_E_SUCCESS)
- ret = gnutls_strerror(rc);
-return ret;
-}
-
-
-/* verify signature (of hash) (given pubkey & alleged sig)
-Return: NULL for success, or an error string */
-
-const uschar *
-exim_rsa_verify(ev_ctx * verify_ctx, BOOL is_sha1, blob * data_hash, blob * sig)
-{
-gnutls_datum_t k, s;
-int rc;
-const uschar * ret = NULL;
-
-k.data = data_hash->data;
-k.size = data_hash->len;
-s.data = sig->data;
-s.size = sig->len;
-if ((rc = gnutls_pubkey_verify_hash2(verify_ctx->rsa,
- is_sha1 ? GNUTLS_SIGN_RSA_SHA1 : GNUTLS_SIGN_RSA_SHA256,
- 0, &k, &s)) < 0)
- ret = gnutls_strerror(rc);
-
-gnutls_pubkey_deinit(verify_ctx->rsa);
-return ret;
-}
-
-
-
-
-#elif defined(RSA_GCRYPT)
-/******************************************************************************/
-
-
-/* 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;
-
-/* 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_rsa_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. */
-
-blob *
-exim_rsa_data_append(blob * b, int * alloc, uschar * s)
-{
-return b; /*dummy*/
-}
-
-
-
-/* import private key from PEM string in memory.
-Return: NULL for success, or an error string */
-
-const uschar *
-exim_rsa_signing_init(uschar * privkey_pem, es_ctx * sign_ctx)
-{
-uschar * s1, * s2;
-blob der;
-long alen;
-int rc;
-
-/*
- * 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
- */
-
-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 ((der.len = b64decode(s1, &der.data)) < 0)
- return US"Bad PEM-DER b64 decode";
-
-/* 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;
-
-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);
- }
-return NULL;
-
-asn_err: return US asn1_strerror(rc);
-}
-
-
-
-/* allocate mem for signature (when signing) */
-/* sign data (gnutls_only)
-OR
-sign hash.
-
-Return: NULL for success, or an error string */
-
-const uschar *
-exim_rsa_sign(es_ctx * sign_ctx, BOOL is_sha1, blob * data, blob * sig)
-{
-gcry_sexp_t s_hash = NULL, s_key = NULL, s_sig = NULL;
-gcry_mpi_t m_sig;
-uschar * errstr;
-gcry_error_t gerr;
-
-#define SIGSPACE 128
-sig->data = store_get(SIGSPACE);
-
-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,
- is_sha1
- ? "(data(flags pkcs1)(hash sha1 %b))"
- : "(data(flags pkcs1)(hash sha256 %b))",
- (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);
-
-DEBUG(D_acl)
- {
- uschar * s;
- gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, m_sig);
- debug_printf_indent(" SG: %s\n", s);
- }
-
-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 DER in memory)
-Return: NULL for success, or an error string */
-
-const uschar *
-exim_rsa_verify_init(blob * pubkey_der, ev_ctx * verify_ctx)
-{
-/*
-in code sequence per b81207d2bfa92 rsa_parse_public_key() and asn1_get_mpi()
-*/
-uschar tag_class;
-int taglen;
-long alen;
-int rc;
-uschar * errstr;
-gcry_error_t gerr;
-uschar * stage = US"S1";
-
-/*
-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_der, 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_der, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, &alen))
- != ASN1_SUCCESS) goto asn_err;
-pubkey_der->data += alen; pubkey_der->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_der, 0, ASN1_TAG_BIT_STRING, &alen)) != ASN1_SUCCESS)
- goto asn_err;
-pubkey_der->len = alen;
-pubkey_der->data++; pubkey_der->len--;
-
-/* sequence; just move past the header */
-DEBUG(D_acl) stage = US"S3";
-if ((rc = as_tag(pubkey_der, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL))
- != ASN1_SUCCESS) goto asn_err;
-
-/* read two integers */
-DEBUG(D_acl) stage = US"MPI";
-if ( (errstr = as_mpi(pubkey_der, &verify_ctx->n))
- || (errstr = as_mpi(pubkey_der, &verify_ctx->e))
- )
- return errstr;
-
-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);
- }
-
-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) (given pubkey & alleged sig)
-Return: NULL for success, or an error string */
-
-const uschar *
-exim_rsa_verify(ev_ctx * verify_ctx, BOOL is_sha1, blob * data_hash, blob * sig)
-{
-/*
-cf. libgnutls 2.8.5 _wrap_gcry_pk_verify()
-*/
-gcry_mpi_t m_sig;
-gcry_sexp_t s_sig = NULL, s_hash = NULL, s_pkey = NULL;
-gcry_error_t gerr;
-uschar * stage;
-
-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,
- is_sha1
- ? "(data(flags pkcs1)(hash sha1 %b))"
- : "(data(flags pkcs1)(hash sha256 %b))",
- (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(RSA_OPENSSL)
-/******************************************************************************/
-
-void
-exim_rsa_init(void)
-{
-}
-
-
-/* accumulate data (gnutls-only) */
-blob *
-exim_rsa_data_append(blob * b, int * alloc, uschar * s)
-{
-return b; /*dummy*/
-}
-
-
-/* import private key from PEM string in memory.
-Return: NULL for success, or an error string */
-
-const uschar *
-exim_rsa_signing_init(uschar * privkey_pem, es_ctx * sign_ctx)
-{
-uschar * p, * q;
-int len;
-
-/* Convert PEM to DER */
-if ( !(p = Ustrstr(privkey_pem, "-----BEGIN RSA PRIVATE KEY-----"))
- || !(q = Ustrstr(p+=31, "-----END RSA PRIVATE KEY-----"))
- )
- return US"Bad PEM wrapping";
-
-*q = '\0';
-if ((len = b64decode(p, &p)) < 0)
- return US"b64decode failed";
-
-if (!(sign_ctx->rsa = d2i_RSAPrivateKey(NULL, CUSS &p, len)))
- {
- char ssl_errstring[256];
- ERR_load_crypto_strings(); /*XXX move to a startup routine */
- ERR_error_string(ERR_get_error(), ssl_errstring);
- return string_copy(US ssl_errstring);
- }
-
-return NULL;
-}
-
-
-
-/* allocate mem for signature (when signing) */
-/* sign data (gnutls_only)
-OR
-sign hash.
-
-Return: NULL for success, or an error string */
-
-const uschar *
-exim_rsa_sign(es_ctx * sign_ctx, BOOL is_sha1, blob * data, blob * sig)
-{
-uint len;
-const uschar * ret = NULL;
-
-/* Allocate mem for signature */
-len = RSA_size(sign_ctx->rsa);
-sig->data = store_get(len);
-sig->len = len;
-
-/* Do signing */
-if (RSA_sign(is_sha1 ? NID_sha1 : NID_sha256,
- CUS data->data, data->len,
- US sig->data, &len, sign_ctx->rsa) != 1)
- {
- char ssl_errstring[256];
- ERR_load_crypto_strings(); /*XXX move to a startup routine */
- ERR_error_string(ERR_get_error(), ssl_errstring);
- ret = string_copy(US ssl_errstring);
- }
-
-RSA_free(sign_ctx->rsa);
-return ret;;
-}
-
-
-
-/* import public key (from DER in memory)
-Return: nULL for success, or an error string */
-
-const uschar *
-exim_rsa_verify_init(blob * pubkey_der, ev_ctx * verify_ctx)
-{
-const uschar * p = CUS pubkey_der->data;
-const uschar * ret = NULL;
-
-if (!(verify_ctx->rsa = d2i_RSA_PUBKEY(NULL, &p, (long) pubkey_der->len)))
- {
- char ssl_errstring[256];
- ERR_load_crypto_strings(); /*XXX move to a startup routine */
- ERR_error_string(ERR_get_error(), ssl_errstring);
- ret = string_copy(CUS ssl_errstring);
- }
-return ret;
-}
-
-
-
-
-/* verify signature (of hash) (given pubkey & alleged sig)
-Return: NULL for success, or an error string */
-
-const uschar *
-exim_rsa_verify(ev_ctx * verify_ctx, BOOL is_sha1, blob * data_hash, blob * sig)
-{
-const uschar * ret = NULL;
-
-if (RSA_verify(is_sha1 ? NID_sha1 : NID_sha256,
- CUS data_hash->data, data_hash->len,
- US sig->data, (uint) sig->len, verify_ctx->rsa) != 1)
- {
- char ssl_errstring[256];
- ERR_load_crypto_strings(); /*XXX move to a startup routine */
- ERR_error_string(ERR_get_error(), ssl_errstring);
- ret = string_copy(US ssl_errstring);
- }
-return ret;
-}
-
-
-#endif
-/******************************************************************************/
-
-#endif /*DISABLE_DKIM*/
-/* End of File */
+++ /dev/null
-/*
- * PDKIM - a RFC4871 (DKIM) implementation
- *
- * Copyright (C) 2016 Exim maintainers
- *
- * RSA signing/verification interface
- */
-
-#include "../exim.h"
-
-#ifndef DISABLE_DKIM /* entire file */
-
-#include "crypt_ver.h"
-
-#ifdef RSA_OPENSSL
-# include <openssl/rsa.h>
-# include <openssl/ssl.h>
-# include <openssl/err.h>
-#elif defined(RSA_GNUTLS)
-# include <gnutls/gnutls.h>
-# include <gnutls/x509.h>
-# include <gnutls/abstract.h>
-#elif defined(RSA_GCRYPT)
-# include <gcrypt.h>
-# include <libtasn1.h>
-#endif
-
-#include "../blob.h"
-
-
-#ifdef RSA_OPENSSL
-
-typedef struct {
- RSA * rsa;
-} es_ctx;
-
-typedef struct {
- RSA * rsa;
-} ev_ctx;
-
-#elif defined(RSA_GNUTLS)
-
-typedef struct {
- gnutls_x509_privkey_t rsa;
-} es_ctx;
-
-typedef struct {
- gnutls_pubkey_t rsa;
-} ev_ctx;
-
-#elif defined(RSA_GCRYPT)
-
-typedef struct {
- gcry_mpi_t n;
- gcry_mpi_t e;
- gcry_mpi_t d;
- gcry_mpi_t p;
- gcry_mpi_t q;
- gcry_mpi_t dp;
- gcry_mpi_t dq;
- gcry_mpi_t qp;
-} es_ctx;
-
-typedef struct {
- gcry_mpi_t n;
- gcry_mpi_t e;
-} ev_ctx;
-
-#endif
-
-
-extern void exim_rsa_init(void);
-extern blob * exim_rsa_data_append(blob *, int *, uschar *);
-
-extern const uschar * exim_rsa_signing_init(uschar *, es_ctx *);
-extern const uschar * exim_rsa_sign(es_ctx *, BOOL, blob *, blob *);
-extern const uschar * exim_rsa_verify_init(blob *, ev_ctx *);
-extern const uschar * exim_rsa_verify(ev_ctx *, BOOL, blob *, blob *);
-
-#endif /*DISABLE_DKIM*/
-/* End of File */
--- /dev/null
+/*
+ * PDKIM - a RFC4871 (DKIM) implementation
+ *
+ * Copyright (C) 2016 Exim maintainers
+ *
+ * RSA signing/verification interface
+XXX rename interfaces to cover all signature methods.
+the method (algo) needs to be extracted from the supplied private-key
+and not only stashed as needed in the sign- or verify- context, but
+indicated to caller for protocol tag construction.
+ */
+
+#include "../exim.h"
+
+#ifndef DISABLE_DKIM /* entire file */
+
+#ifndef SUPPORT_TLS
+# error Need SUPPORT_TLS for DKIM
+#endif
+
+#include "crypt_ver.h"
+#include "signing.h"
+
+
+/******************************************************************************/
+#ifdef RSA_GNUTLS
+
+void
+exim_dkim_init(void)
+{
+}
+
+
+/* accumulate data (gnutls-only). String to be appended must be nul-terminated. */
+blob *
+exim_dkim_data_append(blob * b, int * alloc, uschar * s)
+{
+int len = b->len;
+b->data = string_append(b->data, alloc, &len, 1, s);
+b->len = len;
+return b;
+}
+
+
+
+/* import private key from PEM string in memory.
+Return: NULL for success, or an error string */
+
+const uschar *
+exim_dkim_signing_init(uschar * privkey_pem, es_ctx * sign_ctx)
+{
+gnutls_datum_t k;
+int rc;
+
+k.data = privkey_pem;
+k.size = strlen(privkey_pem);
+
+if ( (rc = gnutls_x509_privkey_init(&sign_ctx->rsa)) != GNUTLS_E_SUCCESS
+ || (rc = gnutls_x509_privkey_import(sign_ctx->rsa, &k,
+ GNUTLS_X509_FMT_PEM)) != GNUTLS_E_SUCCESS
+ )
+ return gnutls_strerror(rc);
+
+return NULL;
+}
+
+
+
+/* allocate mem for signature (when signing) */
+/* sign data (gnutls_only)
+OR
+sign hash.
+
+Return: NULL for success, or an error string */
+
+const uschar *
+exim_dkim_sign(es_ctx * sign_ctx, BOOL is_sha1, blob * data, blob * sig)
+{
+gnutls_datum_t k;
+size_t sigsize = 0;
+int rc;
+const uschar * ret = NULL;
+
+/* Allocate mem for signature */
+k.data = data->data;
+k.size = data->len;
+(void) gnutls_x509_privkey_sign_data(sign_ctx->rsa,
+ is_sha1 ? GNUTLS_DIG_SHA1 : GNUTLS_DIG_SHA256,
+ 0, &k, NULL, &sigsize);
+
+sig->data = store_get(sigsize);
+sig->len = sigsize;
+
+/* Do signing */
+/*XXX will need extension for hash type; looks ok for non-RSA algos
+so long as the privkey_import stage got them. */
+if ((rc = gnutls_x509_privkey_sign_data(sign_ctx->rsa,
+ is_sha1 ? GNUTLS_DIG_SHA1 : GNUTLS_DIG_SHA256,
+ 0, &k, sig->data, &sigsize)) != GNUTLS_E_SUCCESS
+ )
+ ret = gnutls_strerror(rc);
+
+gnutls_x509_privkey_deinit(sign_ctx->rsa);
+return ret;
+}
+
+
+
+/* import public key (from DER in memory)
+Return: NULL for success, or an error string */
+
+const uschar *
+exim_dkim_verify_init(blob * pubkey_der, ev_ctx * verify_ctx)
+{
+gnutls_datum_t k;
+int rc;
+const uschar * ret = NULL;
+
+gnutls_pubkey_init(&verify_ctx->rsa);
+
+k.data = pubkey_der->data;
+k.size = pubkey_der->len;
+
+if ((rc = gnutls_pubkey_import(verify_ctx->rsa, &k, GNUTLS_X509_FMT_DER))
+ != GNUTLS_E_SUCCESS)
+ ret = gnutls_strerror(rc);
+return ret;
+}
+
+
+/* verify signature (of hash) (given pubkey & alleged sig)
+Return: NULL for success, or an error string */
+
+const uschar *
+exim_dkim_verify(ev_ctx * verify_ctx, BOOL is_sha1, blob * data_hash, blob * sig)
+{
+gnutls_datum_t k, s;
+int rc;
+const uschar * ret = NULL;
+
+k.data = data_hash->data;
+k.size = data_hash->len;
+s.data = sig->data;
+s.size = sig->len;
+if ((rc = gnutls_pubkey_verify_hash2(verify_ctx->rsa,
+/*XXX needs extension for SHA512 */
+ is_sha1 ? GNUTLS_SIGN_RSA_SHA1 : GNUTLS_SIGN_RSA_SHA256,
+ 0, &k, &s)) < 0)
+ ret = gnutls_strerror(rc);
+
+gnutls_pubkey_deinit(verify_ctx->rsa);
+return ret;
+}
+
+
+
+
+#elif defined(RSA_GCRYPT)
+/******************************************************************************/
+
+
+/* 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;
+
+/* 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. */
+
+blob *
+exim_dkim_data_append(blob * b, int * alloc, uschar * s)
+{
+return b; /*dummy*/
+}
+
+
+
+/* import private key from PEM string in memory.
+Return: NULL for success, or an error string */
+
+const uschar *
+exim_dkim_signing_init(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... */
+
+/*
+ * 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
+ */
+
+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 ((der.len = b64decode(s1, &der.data)) < 0)
+ return US"Bad PEM-DER b64 decode";
+
+/* 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;
+
+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);
+ }
+return NULL;
+
+asn_err: return US asn1_strerror(rc);
+}
+
+
+
+/* allocate mem for signature (when signing) */
+/* sign data (gnutls_only)
+OR
+sign hash.
+
+Return: NULL for success, or an error string */
+
+const uschar *
+exim_dkim_sign(es_ctx * sign_ctx, BOOL is_sha1, blob * data, blob * sig)
+{
+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 has so should not be
+re-hashing. Has this been tested?
+
+Will need extension for non-RSA sugning algos. */
+
+#define SIGSPACE 128
+sig->data = store_get(SIGSPACE);
+
+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,
+ is_sha1
+ ? "(data(flags pkcs1)(hash sha1 %b))"
+ : "(data(flags pkcs1)(hash sha256 %b))",
+ (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);
+
+DEBUG(D_acl)
+ {
+ uschar * s;
+ gcry_mpi_aprint (GCRYMPI_FMT_HEX, &s, NULL, m_sig);
+ debug_printf_indent(" SG: %s\n", s);
+ }
+
+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 DER in memory)
+Return: NULL for success, or an error string */
+
+const uschar *
+exim_dkim_verify_init(blob * pubkey_der, ev_ctx * verify_ctx)
+{
+/*
+in code sequence per b81207d2bfa92 rsa_parse_public_key() and asn1_get_mpi()
+*/
+uschar tag_class;
+int taglen;
+long alen;
+int rc;
+uschar * errstr;
+gcry_error_t gerr;
+uschar * stage = US"S1";
+
+/*
+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_der, 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_der, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, &alen))
+ != ASN1_SUCCESS) goto asn_err;
+pubkey_der->data += alen; pubkey_der->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_der, 0, ASN1_TAG_BIT_STRING, &alen)) != ASN1_SUCCESS)
+ goto asn_err;
+pubkey_der->len = alen;
+pubkey_der->data++; pubkey_der->len--;
+
+/* sequence; just move past the header */
+DEBUG(D_acl) stage = US"S3";
+if ((rc = as_tag(pubkey_der, ASN1_CLASS_STRUCTURED, ASN1_TAG_SEQUENCE, NULL))
+ != ASN1_SUCCESS) goto asn_err;
+
+/* read two integers */
+DEBUG(D_acl) stage = US"MPI";
+if ( (errstr = as_mpi(pubkey_der, &verify_ctx->n))
+ || (errstr = as_mpi(pubkey_der, &verify_ctx->e))
+ )
+ return errstr;
+
+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);
+ }
+
+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) (given pubkey & alleged sig)
+Return: NULL for success, or an error string */
+
+const uschar *
+exim_dkim_verify(ev_ctx * verify_ctx, BOOL is_sha1, blob * data_hash, blob * sig)
+{
+/*
+cf. libgnutls 2.8.5 _wrap_gcry_pk_verify()
+*/
+gcry_mpi_t m_sig;
+gcry_sexp_t s_sig = NULL, s_hash = NULL, s_pkey = NULL;
+gcry_error_t gerr;
+uschar * stage;
+
+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,
+/*XXX needs extension for SHA512 */
+ is_sha1
+ ? "(data(flags pkcs1)(hash sha1 %b))"
+ : "(data(flags pkcs1)(hash sha256 %b))",
+ (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(RSA_OPENSSL)
+/******************************************************************************/
+
+void
+exim_dkim_init(void)
+{
+}
+
+
+/* accumulate data (gnutls-only) */
+blob *
+exim_dkim_data_append(blob * b, int * alloc, uschar * s)
+{
+return b; /*dummy*/
+}
+
+
+/* import private key from PEM string in memory.
+Return: NULL for success, or an error string */
+
+const uschar *
+exim_dkim_signing_init(uschar * privkey_pem, es_ctx * sign_ctx)
+{
+uschar * p, * q;
+int len;
+
+/*XXX maybe use PEM_read_bio_PrivateKey() ???
+The sign_ctx would need to have an EVP_PKEY* */
+
+/* Convert PEM to DER */
+if ( !(p = Ustrstr(privkey_pem, "-----BEGIN RSA PRIVATE KEY-----"))
+ || !(q = Ustrstr(p+=31, "-----END RSA PRIVATE KEY-----"))
+ )
+ return US"Bad PEM wrapping";
+
+*q = '\0';
+if ((len = b64decode(p, &p)) < 0)
+ return US"b64decode failed";
+
+if (!(sign_ctx->rsa = d2i_RSAPrivateKey(NULL, CUSS &p, len)))
+ {
+ char ssl_errstring[256];
+ ERR_load_crypto_strings(); /*XXX move to a startup routine */
+ ERR_error_string(ERR_get_error(), ssl_errstring);
+ return string_copy(US ssl_errstring);
+ }
+
+return NULL;
+}
+
+
+
+/* allocate mem for signature (when signing) */
+/* sign data (gnutls_only)
+OR
+sign hash.
+
+Return: NULL for success, or an error string */
+
+const uschar *
+exim_dkim_sign(es_ctx * sign_ctx, BOOL is_sha1, blob * data, blob * sig)
+{
+uint len;
+const uschar * ret = NULL;
+
+/*XXX will need extension for non-RSA signing algo. Maybe use
+https://www.openssl.org/docs/man1.0.2/crypto/EVP_PKEY_sign.html ??? */
+
+/* Allocate mem for signature */
+len = RSA_size(sign_ctx->rsa);
+sig->data = store_get(len);
+sig->len = len;
+
+/* Do signing */
+if (RSA_sign(is_sha1 ? NID_sha1 : NID_sha256,
+ CUS data->data, data->len,
+ US sig->data, &len, sign_ctx->rsa) != 1)
+ {
+ char ssl_errstring[256];
+ ERR_load_crypto_strings(); /*XXX move to a startup routine */
+ ERR_error_string(ERR_get_error(), ssl_errstring);
+ ret = string_copy(US ssl_errstring);
+ }
+
+RSA_free(sign_ctx->rsa);
+return ret;;
+}
+
+
+
+/* import public key (from DER in memory)
+Return: NULL for success, or an error string */
+
+const uschar *
+exim_dkim_verify_init(blob * pubkey_der, ev_ctx * verify_ctx)
+{
+const uschar * p = CUS pubkey_der->data;
+const uschar * ret = NULL;
+
+/*XXX d2i_X509_PUBKEY, X509_get_pubkey(), and an EVP_PKEY* in verify_ctx. */
+
+if (!(verify_ctx->rsa = d2i_RSA_PUBKEY(NULL, &p, (long) pubkey_der->len)))
+ {
+ char ssl_errstring[256];
+ ERR_load_crypto_strings(); /*XXX move to a startup routine */
+ ERR_error_string(ERR_get_error(), ssl_errstring);
+ ret = string_copy(CUS ssl_errstring);
+ }
+return ret;
+}
+
+
+
+
+/* verify signature (of hash) (given pubkey & alleged sig)
+Return: NULL for success, or an error string */
+
+const uschar *
+exim_dkim_verify(ev_ctx * verify_ctx, BOOL is_sha1, blob * data_hash, blob * sig)
+{
+const uschar * ret = NULL;
+
+/*XXX needs extension for SHA512, Possibly EVP_PKEY_verify() is all we need??? */
+/* with EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING)
+- see example code at https://www.openssl.org/docs/man1.0.2/crypto/EVP_PKEY_verify.html
+and maybe also EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) though unclear
+if that only sets a pad/type field byte value, or sets up for an actual hash operation...
+Same on the signing side.
+https://www.openssl.org/docs/manmaster/man3/EVP_PKEY_CTX_set_rsa_padding.html says it does what we want. */
+
+if (RSA_verify(is_sha1 ? NID_sha1 : NID_sha256,
+ CUS data_hash->data, data_hash->len,
+ US sig->data, (uint) sig->len, verify_ctx->rsa) != 1)
+ {
+ char ssl_errstring[256];
+ ERR_load_crypto_strings(); /*XXX move to a startup routine */
+ ERR_error_string(ERR_get_error(), ssl_errstring);
+ ret = string_copy(US ssl_errstring);
+ }
+return ret;
+}
+
+
+#endif
+/******************************************************************************/
+
+#endif /*DISABLE_DKIM*/
+/* End of File */
--- /dev/null
+/*
+ * PDKIM - a RFC4871 (DKIM) implementation
+ *
+ * Copyright (C) 2016 Exim maintainers
+ *
+ * RSA signing/verification interface
+ */
+
+#include "../exim.h"
+
+#ifndef DISABLE_DKIM /* entire file */
+
+#include "crypt_ver.h"
+
+#ifdef RSA_OPENSSL
+# include <openssl/rsa.h>
+# include <openssl/ssl.h>
+# include <openssl/err.h>
+#elif defined(RSA_GNUTLS)
+# include <gnutls/gnutls.h>
+# include <gnutls/x509.h>
+# include <gnutls/abstract.h>
+#elif defined(RSA_GCRYPT)
+# include <gcrypt.h>
+# include <libtasn1.h>
+#endif
+
+#include "../blob.h"
+
+
+#ifdef RSA_OPENSSL
+
+typedef struct {
+ RSA * rsa;
+} es_ctx;
+
+typedef struct {
+ RSA * rsa;
+} ev_ctx;
+
+#elif defined(RSA_GNUTLS)
+
+typedef struct {
+ gnutls_x509_privkey_t rsa;
+} es_ctx;
+
+typedef struct {
+ gnutls_pubkey_t rsa;
+} ev_ctx;
+
+#elif defined(RSA_GCRYPT)
+
+typedef struct {
+ gcry_mpi_t n;
+ gcry_mpi_t e;
+ gcry_mpi_t d;
+ gcry_mpi_t p;
+ gcry_mpi_t q;
+ gcry_mpi_t dp;
+ gcry_mpi_t dq;
+ gcry_mpi_t qp;
+} es_ctx;
+
+typedef struct {
+ gcry_mpi_t n;
+ gcry_mpi_t e;
+} ev_ctx;
+
+#endif
+
+
+extern void exim_dkim_init(void);
+extern blob * exim_dkim_data_append(blob *, int *, uschar *);
+
+extern const uschar * exim_dkim_signing_init(uschar *, es_ctx *);
+extern const uschar * exim_dkim_sign(es_ctx *, BOOL, blob *, blob *);
+extern const uschar * exim_dkim_verify_init(blob *, ev_ctx *);
+extern const uschar * exim_dkim_verify(ev_ctx *, BOOL, blob *, blob *);
+
+#endif /*DISABLE_DKIM*/
+/* End of File */
git://git.exim.org / exim.git / commitdiff