mirror of
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139 lines
3.8 KiB
C
139 lines
3.8 KiB
C
/* pkdecrypt.c - public key decryption (well, acually using a secret key)
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* Copyright (C) 2001 Free Software Foundation, Inc.
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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 2 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, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#include <config.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <ctype.h>
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#include <assert.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include "agent.h"
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/* DECRYPT the stuff in ciphertext which is expected to be a S-Exp.
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Try to get the key from CTRL and write the decoded stuff back to
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OUTFP. */
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int
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agent_pkdecrypt (CTRL ctrl, const char *ciphertext, size_t ciphertextlen,
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FILE *outfp)
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{
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GCRY_SEXP s_skey = NULL, s_cipher = NULL, s_plain = NULL;
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unsigned char *shadow_info = NULL;
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int rc;
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char *buf = NULL;
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size_t len;
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if (!ctrl->have_keygrip)
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{
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log_error ("speculative decryption not yet supported\n");
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rc = seterr (No_Secret_Key);
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goto leave;
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}
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rc = gcry_sexp_sscan (&s_cipher, NULL, ciphertext, ciphertextlen);
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if (rc)
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{
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log_error ("failed to convert ciphertext: %s\n", gcry_strerror (rc));
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rc = seterr (Invalid_Data);
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goto leave;
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}
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if (DBG_CRYPTO)
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{
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log_printhex ("keygrip:", ctrl->keygrip, 20);
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log_printhex ("cipher: ", ciphertext, ciphertextlen);
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}
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s_skey = agent_key_from_file (ctrl->keygrip, &shadow_info, 0);
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if (!s_skey && !shadow_info)
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{
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log_error ("failed to read the secret key\n");
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rc = seterr (No_Secret_Key);
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goto leave;
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}
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if (!s_skey)
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{ /* divert operation to the smartcard */
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if (!gcry_sexp_canon_len (ciphertext, ciphertextlen, NULL, NULL))
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{
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rc = GNUPG_Invalid_Sexp;
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goto leave;
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}
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rc = divert_pkdecrypt (ciphertext, shadow_info, &buf, &len );
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if (rc)
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{
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log_error ("smartcard decryption failed: %s\n", gnupg_strerror (rc));
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goto leave;
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}
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/* FIXME: don't use buffering and change the protocol to return
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a complete S-expression and not just a part. */
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fprintf (outfp, "%u:", (unsigned int)len);
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fwrite (buf, 1, len, outfp);
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putc (0, outfp);
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}
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else
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{ /* no smartcard, but a private key */
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if (DBG_CRYPTO)
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{
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log_debug ("skey: ");
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gcry_sexp_dump (s_skey);
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}
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rc = gcry_pk_decrypt (&s_plain, s_cipher, s_skey);
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if (rc)
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{
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log_error ("decryption failed: %s\n", gcry_strerror (rc));
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rc = map_gcry_err (rc);
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goto leave;
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}
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if (DBG_CRYPTO)
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{
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log_debug ("plain: ");
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gcry_sexp_dump (s_plain);
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}
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len = gcry_sexp_sprint (s_plain, GCRYSEXP_FMT_CANON, NULL, 0);
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assert (len);
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buf = xmalloc (len);
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len = gcry_sexp_sprint (s_plain, GCRYSEXP_FMT_CANON, buf, len);
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assert (len);
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/* FIXME: we must make sure that no buffering takes place or we are
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in full control of the buffer memory (easy to do) - should go
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into assuan. */
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fwrite (buf, 1, len, outfp);
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}
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leave:
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gcry_sexp_release (s_skey);
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gcry_sexp_release (s_plain);
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gcry_sexp_release (s_cipher);
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xfree (buf);
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xfree (shadow_info);
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return rc;
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}
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