1 files changed, 112 insertions, 0 deletions
diff --git a/agent/pkdecrypt.c b/agent/pkdecrypt.c
new file mode 100644
index 000000000..78f70ad52
--- /dev/null
+++ b/agent/pkdecrypt.c
@@ -0,0 +1,112 @@
+/* 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;
+  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);
+  if (!s_skey)
+    {
+      log_error ("failed to read the secret key\n");
+      rc = seterr (No_Secret_Key);
+      goto leave;
+    }
+
+  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);
+  return rc;
+}
+
+