1 /* pkdecrypt.c - public key decryption (well, acually using a secret key)
2 * Copyright (C) 2001, 2003 Free Software Foundation, Inc.
4 * This file is part of GnuPG.
6 * GnuPG is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 3 of the License, or
9 * (at your option) any later version.
11 * GnuPG is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, see <https://www.gnu.org/licenses/>.
33 /* DECRYPT the stuff in ciphertext which is expected to be a S-Exp.
34 Try to get the key from CTRL and write the decoded stuff back to
35 OUTFP. The padding information is stored at R_PADDING with -1
38 agent_pkdecrypt (ctrl_t ctrl, const char *desc_text,
39 const unsigned char *ciphertext, size_t ciphertextlen,
40 membuf_t *outbuf, int *r_padding)
42 gcry_sexp_t s_skey = NULL, s_cipher = NULL, s_plain = NULL;
43 unsigned char *shadow_info = NULL;
50 if (!ctrl->have_keygrip)
52 log_error ("speculative decryption not yet supported\n");
53 rc = gpg_error (GPG_ERR_NO_SECKEY);
57 rc = gcry_sexp_sscan (&s_cipher, NULL, (char*)ciphertext, ciphertextlen);
60 log_error ("failed to convert ciphertext: %s\n", gpg_strerror (rc));
61 rc = gpg_error (GPG_ERR_INV_DATA);
67 log_printhex ("keygrip:", ctrl->keygrip, 20);
68 log_printhex ("cipher: ", ciphertext, ciphertextlen);
70 rc = agent_key_from_file (ctrl, NULL, desc_text,
71 ctrl->keygrip, &shadow_info,
72 CACHE_MODE_NORMAL, NULL, &s_skey, NULL);
75 if (gpg_err_code (rc) != GPG_ERR_NO_SECKEY)
76 log_error ("failed to read the secret key\n");
81 { /* divert operation to the smartcard */
83 if (!gcry_sexp_canon_len (ciphertext, ciphertextlen, NULL, NULL))
85 rc = gpg_error (GPG_ERR_INV_SEXP);
89 rc = divert_pkdecrypt (ctrl, ciphertext, shadow_info,
90 &buf, &len, r_padding);
93 log_error ("smartcard decryption failed: %s\n", gpg_strerror (rc));
97 put_membuf_printf (outbuf, "(5:value%u:", (unsigned int)len);
98 put_membuf (outbuf, buf, len);
99 put_membuf (outbuf, ")", 2);
102 { /* No smartcard, but a private key */
103 /* if (DBG_CRYPTO ) */
105 /* log_debug ("skey: "); */
106 /* gcry_sexp_dump (s_skey); */
109 rc = gcry_pk_decrypt (&s_plain, s_cipher, s_skey);
112 log_error ("decryption failed: %s\n", gpg_strerror (rc));
118 log_debug ("plain: ");
119 gcry_sexp_dump (s_plain);
121 len = gcry_sexp_sprint (s_plain, GCRYSEXP_FMT_CANON, NULL, 0);
124 len = gcry_sexp_sprint (s_plain, GCRYSEXP_FMT_CANON, buf, len);
127 put_membuf (outbuf, buf, len);
130 /* Old style libgcrypt: This is only an S-expression
131 part. Turn it into a complete S-expression. */
132 put_membuf (outbuf, "(5:value", 8);
133 put_membuf (outbuf, buf, len);
134 put_membuf (outbuf, ")", 2);
140 gcry_sexp_release (s_skey);
141 gcry_sexp_release (s_plain);
142 gcry_sexp_release (s_cipher);