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-rw-r--r--agent/pkdecrypt.c147
1 files changed, 147 insertions, 0 deletions
diff --git a/agent/pkdecrypt.c b/agent/pkdecrypt.c
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--- /dev/null
+++ b/agent/pkdecrypt.c
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+/* pkdecrypt.c - public key decryption (well, actually 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 3 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, see <https://www.gnu.org/licenses/>.
+ */
+
+#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. The padding information is stored at R_PADDING with -1
+ for not known. */
+int
+agent_pkdecrypt (ctrl_t ctrl, const char *desc_text,
+ const unsigned char *ciphertext, size_t ciphertextlen,
+ membuf_t *outbuf, int *r_padding)
+{
+ 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;
+
+ *r_padding = -1;
+
+ 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, (char*)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 (ctrl->keygrip, 20, "keygrip:");
+ log_printhex (ciphertext, ciphertextlen, "cipher: ");
+ }
+ rc = agent_key_from_file (ctrl, NULL, desc_text,
+ ctrl->keygrip, &shadow_info,
+ CACHE_MODE_NORMAL, NULL, &s_skey, NULL);
+ if (rc)
+ {
+ if (gpg_err_code (rc) != GPG_ERR_NO_SECKEY)
+ log_error ("failed to read the secret key\n");
+ goto leave;
+ }
+
+ if (shadow_info)
+ { /* 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, desc_text, ciphertext,
+ ctrl->keygrip, shadow_info,
+ &buf, &len, r_padding);
+ if (rc)
+ {
+ log_error ("smartcard decryption failed: %s\n", gpg_strerror (rc));
+ goto leave;
+ }
+
+ put_membuf_printf (outbuf, "(5:value%u:", (unsigned int)len);
+ put_membuf (outbuf, buf, len);
+ put_membuf (outbuf, ")", 2);
+ }
+ 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));
+ 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);
+ if (*buf == '(')
+ put_membuf (outbuf, buf, len);
+ else
+ {
+ /* Old style libgcrypt: This is only an S-expression
+ part. Turn it into a complete S-expression. */
+ put_membuf (outbuf, "(5:value", 8);
+ put_membuf (outbuf, buf, len);
+ put_membuf (outbuf, ")", 2);
+ }
+ }
+
+
+ leave:
+ gcry_sexp_release (s_skey);
+ gcry_sexp_release (s_plain);
+ gcry_sexp_release (s_cipher);
+ xfree (buf);
+ xfree (shadow_info);
+ return rc;
+}