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47c1c329ed
* agent/Makefile.am: Add sexp-secret.c. * agent/agent.h: New function declarations. * agent/sexp-secret.c: New. * agent/findkey.c (agent_key_from_file): Use sexp_sscan_private_key. * agent/protect-tool.c (read_and_unprotect): Fix up private part, calling fixup_when_ecc_private_key. Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>
129 lines
3.4 KiB
C
129 lines
3.4 KiB
C
/* sexp-secret.c - SEXP handling of the secret key
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* Copyright (C) 2020 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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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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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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*/
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#include <config.h>
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#include "agent.h"
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#include "../common/sexp-parse.h"
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/*
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* When it's for ECC, fixup private key part in the cannonical SEXP
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* representation in BUF. If not ECC, do nothing.
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*/
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gpg_error_t
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fixup_when_ecc_private_key (unsigned char *buf, size_t *buflen_p)
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{
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const unsigned char *s;
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size_t n;
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size_t buflen = *buflen_p;
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s = buf;
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if (*s != '(')
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return gpg_error (GPG_ERR_INV_SEXP);
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s++;
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n = snext (&s);
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if (!n)
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return gpg_error (GPG_ERR_INV_SEXP);
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if (!smatch (&s, n, "private-key"))
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return gpg_error (GPG_ERR_UNKNOWN_SEXP);
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if (*s != '(')
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return gpg_error (GPG_ERR_UNKNOWN_SEXP);
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s++;
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n = snext (&s);
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if (!smatch (&s, n, "ecc"))
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return 0;
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/* It's ECC */
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while (*s == '(')
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{
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s++;
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n = snext (&s);
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if (!n)
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return gpg_error (GPG_ERR_INV_SEXP);
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if (n == 1 && *s == 'd')
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{
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unsigned char *s0;
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size_t n0;
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s += n;
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s0 = (unsigned char *)s;
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n = snext (&s);
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n0 = s - s0;
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if (!n)
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return gpg_error (GPG_ERR_INV_SEXP);
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else if ((n & 1) && !*s)
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/* Detect wrongly added 0x00. */
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/* For all existing curves in libgcrypt-1.9 (so far), the
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size of private part should be even. */
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{
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size_t numsize;
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n--;
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buflen--;
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numsize = snprintf (s0, s-s0+1, "%u:", (unsigned int)n);
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memmove (s0+numsize, s+1, buflen - (s - buf));
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memset (s0+numsize+buflen - (s - buf), 0, (n0 - numsize) + 1);
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buflen -= (n0 - numsize);
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s = s0+numsize+n;
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*buflen_p = buflen;
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}
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else
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s += n;
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}
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else
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{
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s += n;
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n = snext (&s);
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if (!n)
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return gpg_error (GPG_ERR_INV_SEXP);
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s += n;
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}
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if ( *s != ')' )
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return gpg_error (GPG_ERR_INV_SEXP);
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s++;
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}
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if (*s != ')')
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return gpg_error (GPG_ERR_INV_SEXP);
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s++;
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return 0;
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}
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/*
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* Scan BUF to get SEXP, put into RESULT. Error offset will be in the
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* pointer at R_ERROFF. For ECC, the private part 'd' will be fixed
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* up; That part may have 0x00 prefix of signed MPI encoding, which is
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* incompatible to opaque MPI handling.
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*/
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gpg_error_t
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sexp_sscan_private_key (gcry_sexp_t *result, size_t *r_erroff,
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unsigned char *buf)
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{
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gpg_error_t err;
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size_t buflen, buflen0;
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buflen = buflen0 = gcry_sexp_canon_len (buf, 0, NULL, NULL);
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err = fixup_when_ecc_private_key (buf, &buflen);
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if (!err)
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err = gcry_sexp_sscan (result, r_erroff, (char*)buf, buflen0);
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wipememory (buf, buflen0);
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return err;
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}
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