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/* pkdecrypt.c - public key decryption (well, acually using a secret key)
* Copyright (C) 2001 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* GnuPG is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include <config.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>
#include <unistd.h>
#include <sys/stat.h>
#include "agent.h"
/* DECRYPT the stuff in ciphertext which is expected to be a S-Exp.
Try to get the key from CTRL and write the decoded stuff back to
OUTFP. */
int
agent_pkdecrypt (CTRL ctrl, const char *ciphertext, size_t ciphertextlen,
FILE *outfp)
{
GCRY_SEXP s_skey = NULL, s_cipher = NULL, s_plain = NULL;
unsigned char *shadow_info = NULL;
int rc;
char *buf = NULL;
size_t len;
if (!ctrl->have_keygrip)
{
log_error ("speculative decryption not yet supported\n");
rc = seterr (No_Secret_Key);
goto leave;
}
rc = gcry_sexp_sscan (&s_cipher, NULL, ciphertext, ciphertextlen);
if (rc)
{
log_error ("failed to convert ciphertext: %s\n", gcry_strerror (rc));
rc = seterr (Invalid_Data);
goto leave;
}
if (DBG_CRYPTO)
{
log_printhex ("keygrip:", ctrl->keygrip, 20);
log_printhex ("cipher: ", ciphertext, ciphertextlen);
}
s_skey = agent_key_from_file (ctrl->keygrip, &shadow_info, 0);
if (!s_skey && !shadow_info)
{
log_error ("failed to read the secret key\n");
rc = seterr (No_Secret_Key);
goto leave;
}
if (!s_skey)
{ /* divert operation to the smartcard */
if (!gcry_sexp_canon_len (ciphertext, ciphertextlen, NULL, NULL))
{
rc = GNUPG_Invalid_Sexp;
goto leave;
}
rc = divert_pkdecrypt (ciphertext, shadow_info, &buf, &len );
if (rc)
{
log_error ("smartcard decryption failed: %s\n", gnupg_strerror (rc));
goto leave;
}
/* FIXME: don't use buffering and change the protocol to return
a complete S-expression and not just a part. */
fprintf (outfp, "%u:", (unsigned int)len);
fwrite (buf, 1, len, outfp);
putc (0, outfp);
}
else
{ /* no smartcard, but a private key */
if (DBG_CRYPTO)
{
log_debug ("skey: ");
gcry_sexp_dump (s_skey);
}
rc = gcry_pk_decrypt (&s_plain, s_cipher, s_skey);
if (rc)
{
log_error ("decryption failed: %s\n", gcry_strerror (rc));
rc = map_gcry_err (rc);
goto leave;
}
if (DBG_CRYPTO)
{
log_debug ("plain: ");
gcry_sexp_dump (s_plain);
}
len = gcry_sexp_sprint (s_plain, GCRYSEXP_FMT_CANON, NULL, 0);
assert (len);
buf = xmalloc (len);
len = gcry_sexp_sprint (s_plain, GCRYSEXP_FMT_CANON, buf, len);
assert (len);
/* FIXME: we must make sure that no buffering takes place or we are
in full control of the buffer memory (easy to do) - should go
into assuan. */
fwrite (buf, 1, len, outfp);
}
leave:
gcry_sexp_release (s_skey);
gcry_sexp_release (s_plain);
gcry_sexp_release (s_cipher);
xfree (buf);
xfree (shadow_info);
return rc;
}
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