diff options
Diffstat (limited to 'agent/pkdecrypt.c')
| -rw-r--r-- | agent/pkdecrypt.c | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/agent/pkdecrypt.c b/agent/pkdecrypt.c new file mode 100644 index 000000000..543a82737 --- /dev/null +++ b/agent/pkdecrypt.c @@ -0,0 +1,138 @@ +/* pkdecrypt.c - public key decryption (well, acually using a secret key) + * Copyright (C) 2001, 2003 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_t 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 = gpg_error (GPG_ERR_NO_SECKEY); + goto leave; + } + + rc = gcry_sexp_sscan (&s_cipher, NULL, ciphertext, ciphertextlen); + if (rc) + { + log_error ("failed to convert ciphertext: %s\n", gpg_strerror (rc)); + rc = gpg_error (GPG_ERR_INV_DATA); + goto leave; + } + + if (DBG_CRYPTO) + { + log_printhex ("keygrip:", ctrl->keygrip, 20); + log_printhex ("cipher: ", ciphertext, ciphertextlen); + } + s_skey = agent_key_from_file (ctrl, ctrl->keygrip, &shadow_info, 0); + if (!s_skey && !shadow_info) + { + log_error ("failed to read the secret key\n"); + rc = gpg_error (GPG_ERR_NO_SECKEY); + goto leave; + } + + if (!s_skey) + { /* divert operation to the smartcard */ + + if (!gcry_sexp_canon_len (ciphertext, ciphertextlen, NULL, NULL)) + { + rc = gpg_error (GPG_ERR_INV_SEXP); + goto leave; + } + + rc = divert_pkdecrypt (ctrl, ciphertext, shadow_info, &buf, &len ); + if (rc) + { + log_error ("smartcard decryption failed: %s\n", gpg_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", gpg_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; +} + + |