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gpgsm: Create binary detached sigs with definite form length octets.
* sm/sign.c: Include tlv.h. (write_detached_signature): New, (gpgsm_sign): Fixup binary detached signatures. -- This helps some other software to verify detached signatures.
This commit is contained in:
Werner Koch
parent
4b9346492e
commit
8996b0b655
16
NEWS
16
NEWS
@ -1,15 +1,21 @@
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Noteworthy changes in version 2.4.1 (unreleased)
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------------------------------------------------
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* gpg: New option --add-desig-revoker.
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* gpg: New option --add-desig-revoker. [rG3d094e2bcf]
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* gpg: New list-option "show-unusable-sigs".
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* gpg: New list-option "show-unusable-sigs". Also show
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"[self-signature]" instead of the user-id in key signature
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listings. [rG103acfe9ca]
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* gpg: Show "[self-signature]" instead of the user-id in key
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signature listings.
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* gpgsm: Verification of detached signatures does now strip trailing
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zeroes from the input if --assume-binary is used. [rG2a13f7f9dc]
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* gpgsm: Non-armored detached signature are now created without
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using indefinite form length octets. This improves compatibility
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with some PDF signature verification software.
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* gpg: Make list-options "show-sig-subpackets" work again.
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Fixes regression in 2.4.0.
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Fixes regression in 2.4.0. [rG5a223303d7]
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255
sm/sign.c
255
sm/sign.c
@ -1,6 +1,8 @@
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/* sign.c - Sign a message
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* Copyright (C) 2001, 2002, 2003, 2008,
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* 2010 Free Software Foundation, Inc.
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* Copyright (C) 2003-2012, 2016-2017, 2019,
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* 2020, 2022-2023 g10 Code GmbH
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*
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* This file is part of GnuPG.
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*
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@ -16,6 +18,7 @@
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <https://www.gnu.org/licenses/>.
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* SPDX-License-Identifier: GPL-3.0-or-later
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*/
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#include <config.h>
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@ -32,6 +35,7 @@
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#include "keydb.h"
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#include "../common/i18n.h"
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#include "../common/tlv.h"
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/* Hash the data and return if something was hashed. Return -1 on error. */
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@ -397,6 +401,216 @@ add_signed_attribute (ksba_cms_t cms, const char *attrstr)
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}
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/* This function takes a binary detached signature in (BLOB,BLOBLEN)
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* and writes it to OUT_FP. The core of the function is to replace
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* NDEF length sequences in the input to those with fixed inputs.
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* This helps certain other implementations to properly verify
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* detached signature. Moreover, it allows our own trailing zero
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* stripping code - which we need for PDF signatures - to work
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* correctly.
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*
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* Example start of a detached signature as created by us:
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* 0 NDEF: SEQUENCE { -- 1st sequence
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* 2 9: OBJECT IDENTIFIER signedData (1 2 840 113549 1 7 2)
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* 13 NDEF: [0] { -- 2nd sequence
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* 15 NDEF: SEQUENCE { -- 3rd sequence
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* 17 1: INTEGER 1 -- version
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* 20 15: SET { -- set of algorithms
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* 22 13: SEQUENCE {
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* 24 9: OBJECT IDENTIFIER sha-256 (2 16 840 1 101 3 4 2 1)
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* 35 0: NULL
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* : }
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* : }
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* 37 NDEF: SEQUENCE { -- 4th pretty short sequence
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* 39 9: OBJECT IDENTIFIER data (1 2 840 113549 1 7 1)
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* : }
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* 52 869: [0] {
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* Our goal is to replace the NDEF by fixed length tags.
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*/
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static gpg_error_t
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write_detached_signature (ctrl_t ctrl, const void *blob, size_t bloblen,
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estream_t out_fp)
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{
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gpg_error_t err;
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const unsigned char *p, *psave;
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size_t n, nsave, objlen, objlensave, hdrlen;
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int class, tag, cons, ndef;
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const unsigned char *p_ctoid, *p_version, *p_algoset, *p_dataoid;
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size_t n_ctoid, n_version, n_algoset, n_dataoid;
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const unsigned char *p_certset, *p_signerinfos;
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size_t n_certset, n_signerinfos;
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int i;
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ksba_der_t dbld;
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unsigned char *finalder = NULL;
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size_t finalderlen;
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p = blob;
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n = bloblen;
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if ((err=parse_ber_header (&p,&n,&class,&tag,&cons,&ndef,&objlen,&hdrlen)))
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return err;
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if (!(class == CLASS_UNIVERSAL && tag == TAG_SEQUENCE && cons))
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return gpg_error (GPG_ERR_INV_CMS_OBJ); /* No 1st sequence. */
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if ((err=parse_ber_header (&p,&n,&class,&tag,&cons,&ndef,&objlen,&hdrlen)))
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return err;
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if (!(class == CLASS_UNIVERSAL && tag == TAG_OBJECT_ID && !cons))
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return gpg_error (GPG_ERR_INV_CMS_OBJ); /* No signedData OID. */
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if (objlen > n)
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return gpg_error (GPG_ERR_BAD_BER); /* Object larger than data. */
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p_ctoid = p;
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n_ctoid = objlen;
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p += objlen;
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n -= objlen;
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if ((err=parse_ber_header (&p,&n,&class,&tag,&cons,&ndef,&objlen,&hdrlen)))
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return err;
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if (!(class == CLASS_CONTEXT && tag == 0 && cons))
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return gpg_error (GPG_ERR_INV_CMS_OBJ); /* No 2nd sequence. */
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if ((err=parse_ber_header (&p,&n,&class,&tag,&cons,&ndef,&objlen,&hdrlen)))
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return err;
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if (!(class == CLASS_UNIVERSAL && tag == TAG_SEQUENCE && cons))
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return gpg_error (GPG_ERR_INV_CMS_OBJ); /* No 3rd sequence. */
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if ((err=parse_ber_header (&p,&n,&class,&tag,&cons,&ndef,&objlen,&hdrlen)))
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return err;
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if (!(class == CLASS_UNIVERSAL && tag == TAG_INTEGER))
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return gpg_error (GPG_ERR_INV_CMS_OBJ); /* No version. */
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if (objlen > n)
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return gpg_error (GPG_ERR_BAD_BER); /* Object larger than data. */
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p_version = p;
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n_version = objlen;
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p += objlen;
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n -= objlen;
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p_algoset = p;
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if ((err=parse_ber_header (&p,&n,&class,&tag,&cons,&ndef,&objlen,&hdrlen)))
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return err;
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if (!(class == CLASS_UNIVERSAL && tag == TAG_SET && cons && !ndef))
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return gpg_error (GPG_ERR_INV_CMS_OBJ); /* No set of algorithms. */
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if (objlen > n)
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return gpg_error (GPG_ERR_BAD_BER); /* Object larger than data. */
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n_algoset = hdrlen + objlen;
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p += objlen;
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n -= objlen;
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if ((err=parse_ber_header (&p,&n,&class,&tag,&cons,&ndef,&objlen,&hdrlen)))
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return err;
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if (!(class == CLASS_UNIVERSAL && tag == TAG_SEQUENCE && cons))
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return gpg_error (GPG_ERR_INV_CMS_OBJ); /* No 4th sequence. */
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if ((err=parse_ber_header (&p,&n,&class,&tag,&cons,&ndef,&objlen,&hdrlen)))
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return err;
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if (!(class == CLASS_UNIVERSAL && tag == TAG_OBJECT_ID && !cons))
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return gpg_error (GPG_ERR_INV_CMS_OBJ); /* No data OID. */
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if (objlen > n)
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return gpg_error (GPG_ERR_BAD_BER); /* Object larger than data. */
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p_dataoid = p;
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n_dataoid = objlen;
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p += objlen;
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n -= objlen;
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if ((err=parse_ber_header (&p,&n,&class,&tag,&cons,&ndef,&objlen,&hdrlen)))
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return err;
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if (!(class == CLASS_UNIVERSAL && tag == TAG_NONE && !cons && !objlen))
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return gpg_error (GPG_ERR_INV_CMS_OBJ); /* No End tag. */
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/* certificates [0] IMPLICIT CertificateSet OPTIONAL,
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* Note: We ignore the following
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* crls [1] IMPLICIT CertificateRevocationLists OPTIONAL
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* because gpgsm does not create them. */
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if ((err=parse_ber_header (&p,&n,&class,&tag,&cons,&ndef,&objlen,&hdrlen)))
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return err;
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if (class == CLASS_CONTEXT && tag == 0 && cons)
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{
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if (objlen > n)
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return gpg_error (GPG_ERR_BAD_BER); /* Object larger than data. */
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p_certset = p;
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n_certset = objlen;
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p += objlen;
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n -= objlen;
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if ((err=parse_ber_header (&p,&n,&class,&tag,&cons,&ndef,
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&objlen,&hdrlen)))
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return err;
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}
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else
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{
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p_certset = NULL;
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n_certset = 0;
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}
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/* SignerInfos ::= SET OF SignerInfo */
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if (!(class == CLASS_UNIVERSAL && tag == TAG_SET && cons && !ndef))
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return gpg_error (GPG_ERR_INV_CMS_OBJ); /* No set of signerInfos. */
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if (objlen > n)
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return gpg_error (GPG_ERR_BAD_BER); /* Object larger than data. */
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p_signerinfos = p;
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n_signerinfos = objlen;
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p += objlen;
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n -= objlen;
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/* For the fun of it check the 3 end tags. */
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for (i=0; i < 3; i++)
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{
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if ((err=parse_ber_header (&p,&n,&class,&tag,&cons,&ndef,
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&objlen,&hdrlen)))
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return err;
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if (!(class == CLASS_UNIVERSAL && tag == TAG_NONE && !cons && !objlen))
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return gpg_error (GPG_ERR_INV_CMS_OBJ); /* No End tag. */
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}
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if (n)
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return gpg_error (GPG_ERR_INV_CMS_OBJ); /* Garbage */
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/*---- From here on we jump to leave on error. ----*/
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/* Now create a new object from the collected data. */
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dbld = ksba_der_builder_new (16); /* (pre-allocate 16 items) */
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if (!dbld)
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{
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err = gpg_error_from_syserror ();
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goto leave;
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}
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ksba_der_add_tag (dbld, 0, KSBA_TYPE_SEQUENCE);
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ksba_der_add_val ( dbld, 0, KSBA_TYPE_OBJECT_ID, p_ctoid, n_ctoid);
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ksba_der_add_tag ( dbld, KSBA_CLASS_CONTEXT, 0);
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ksba_der_add_tag ( dbld, 0, KSBA_TYPE_SEQUENCE);
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ksba_der_add_val ( dbld, 0, KSBA_TYPE_INTEGER, p_version, n_version);
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ksba_der_add_der ( dbld, p_algoset, n_algoset);
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ksba_der_add_tag ( dbld, 0, KSBA_TYPE_SEQUENCE);
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ksba_der_add_val ( dbld, 0, KSBA_TYPE_OBJECT_ID, p_dataoid, n_dataoid);
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ksba_der_add_end ( dbld);
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if (p_certset)
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{
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ksba_der_add_tag ( dbld, KSBA_CLASS_CONTEXT, 0);
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ksba_der_add_der ( dbld, p_certset, n_certset);
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ksba_der_add_end ( dbld);
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}
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ksba_der_add_tag ( dbld, 0, KSBA_TYPE_SET);
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ksba_der_add_der ( dbld, p_signerinfos, n_signerinfos);
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ksba_der_add_end ( dbld);
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ksba_der_add_end ( dbld);
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ksba_der_add_end ( dbld);
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ksba_der_add_end (dbld);
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err = ksba_der_builder_get (dbld, &finalder, &finalderlen);
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if (err)
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goto leave;
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if (es_fwrite (finalder, finalderlen, 1, out_fp) != 1)
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{
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err = gpg_error_from_syserror ();
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goto leave;
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}
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leave:
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ksba_der_release (dbld);
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ksba_free (finalder);
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return err;
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}
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/* Perform a sign operation.
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@ -412,6 +626,7 @@ gpgsm_sign (ctrl_t ctrl, certlist_t signerlist,
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gpg_error_t err;
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gnupg_ksba_io_t b64writer = NULL;
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ksba_writer_t writer;
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estream_t sig_fp = NULL; /* Used for detached signatures. */
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ksba_cms_t cms = NULL;
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ksba_stop_reason_t stopreason;
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KEYDB_HANDLE kh = NULL;
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@ -422,6 +637,7 @@ gpgsm_sign (ctrl_t ctrl, certlist_t signerlist,
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ksba_isotime_t signed_at;
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certlist_t cl;
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int release_signerlist = 0;
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int binary_detached = detached && !ctrl->create_pem && !ctrl->create_base64;
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audit_set_type (ctrl->audit, AUDIT_TYPE_SIGN);
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@ -444,11 +660,25 @@ gpgsm_sign (ctrl_t ctrl, certlist_t signerlist,
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goto leave;
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}
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/* Note that in detached mode the b64 write is actually a binary
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* writer because we need to fixup the created signature later.
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* Note that we do this only for binary output because we have no
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* PEM writer interface outside of the ksba create writer code. */
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ctrl->pem_name = "SIGNED MESSAGE";
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rc = gnupg_ksba_create_writer
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(&b64writer, ((ctrl->create_pem? GNUPG_KSBA_IO_PEM : 0)
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| (ctrl->create_base64? GNUPG_KSBA_IO_BASE64 : 0)),
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ctrl->pem_name, out_fp, &writer);
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if (binary_detached)
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{
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sig_fp = es_fopenmem (0, "w+");
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rc = sig_fp? 0 : gpg_error_from_syserror ();
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if (!rc)
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rc = gnupg_ksba_create_writer (&b64writer, 0, NULL, sig_fp, &writer);
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}
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else
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{
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rc = gnupg_ksba_create_writer
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(&b64writer, ((ctrl->create_pem? GNUPG_KSBA_IO_PEM : 0)
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| (ctrl->create_base64? GNUPG_KSBA_IO_BASE64 : 0)),
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ctrl->pem_name, out_fp, &writer);
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}
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if (rc)
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{
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log_error ("can't create writer: %s\n", gpg_strerror (rc));
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@ -944,6 +1174,22 @@ gpgsm_sign (ctrl_t ctrl, certlist_t signerlist,
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goto leave;
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}
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if (binary_detached)
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{
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void *blob = NULL;
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size_t bloblen;
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rc = es_fclose_snatch (sig_fp, &blob, &bloblen);
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sig_fp = NULL;
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if (rc)
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goto leave;
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rc = write_detached_signature (ctrl, blob, bloblen, out_fp);
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xfree (blob);
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if (rc)
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goto leave;
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}
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audit_log (ctrl->audit, AUDIT_SIGNING_DONE);
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log_info ("signature created\n");
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@ -957,5 +1203,6 @@ gpgsm_sign (ctrl_t ctrl, certlist_t signerlist,
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gnupg_ksba_destroy_writer (b64writer);
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keydb_release (kh);
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gcry_md_close (data_md);
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es_fclose (sig_fp);
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return rc;
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}
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