From d8f031aec2ee84c753ef282577c7f4fcf0123d2f Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Tue, 1 Sep 2015 10:41:02 -0400
Subject: [PATCH] Add a new --newpass option to add or remove secret key
 passphrases.

---
 changes/feature16769 |  3 +++
 src/or/config.c      | 10 ++++++++++
 src/or/or.h          |  1 +
 src/or/routerkeys.c  | 23 ++++++++++++++++++-----
 4 files changed, 32 insertions(+), 5 deletions(-)
 create mode 100644 changes/feature16769

diff --git a/changes/feature16769 b/changes/feature16769
new file mode 100644
index 0000000000..62d373e5cc
--- /dev/null
+++ b/changes/feature16769
@@ -0,0 +1,3 @@
+  o Minor features (ed25519):
+    - Add a --newpass option to allow changing or removing the
+      passphrase of an encrypted key.
\ No newline at end of file
diff --git a/src/or/config.c b/src/or/config.c
index 6e782de0e0..b4a490c70f 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -1918,6 +1918,7 @@ static const struct {
   { "--dump-config",          ARGUMENT_OPTIONAL },
   { "--list-fingerprint",     TAKES_NO_ARGUMENT },
   { "--keygen",               TAKES_NO_ARGUMENT },
+  { "--newpass",              TAKES_NO_ARGUMENT },
   { "--no-passphrase",        TAKES_NO_ARGUMENT },
   { "--passphrase-fd",        ARGUMENT_NECESSARY },
   { "--verify-config",        TAKES_NO_ARGUMENT },
@@ -4512,6 +4513,15 @@ options_init_from_torrc(int argc, char **argv)
     }
   }
 
+  if (config_line_find(cmdline_only_options, "--newpass")) {
+    if (command == CMD_KEYGEN) {
+      get_options_mutable()->change_key_passphrase = 1;
+    } else {
+      log_err(LD_CONFIG, "--newpass specified without --keygen!");
+      exit(1);
+    }
+  }
+
   {
     const config_line_t *fd_line = config_line_find(cmdline_only_options,
                                                     "--passphrase-fd");
diff --git a/src/or/or.h b/src/or/or.h
index 8c40f1ab67..0637325b24 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -4302,6 +4302,7 @@ typedef struct {
   } keygen_force_passphrase;
   int use_keygen_passphrase_fd;
   int keygen_passphrase_fd;
+  int change_key_passphrase;
 } or_options_t;
 
 /** Persistent state for an onion router, as saved to disk. */
diff --git a/src/or/routerkeys.c b/src/or/routerkeys.c
index 50659fcb69..be5c2c33a1 100644
--- a/src/or/routerkeys.c
+++ b/src/or/routerkeys.c
@@ -200,8 +200,17 @@ write_secret_key(const ed25519_secret_key_t *key, int encrypted,
 {
   if (encrypted) {
     int r = write_encrypted_secret_key(key, encrypted_fname);
-    if (r != 0)
-      return r; /* Either succeeded or failed unrecoverably */
+    if (r == 1) {
+      /* Success! */
+
+      /* Try to unlink the unencrypted key, if any existed before */
+      if (strcmp(fname, encrypted_fname))
+        unlink(fname);
+      return r;
+    } else if (r != 0) {
+      /* Unrecoverable failure! */
+      return r;
+    }
 
     fprintf(stderr, "Not encrypting the secret key.\n");
   }
@@ -432,7 +441,7 @@ ed_key_init_from_file(const char *fname, uint32_t flags,
     goto err;
   }
 
-  /* if it's absent, make a new keypair and save it. */
+  /* if it's absent, make a new keypair... */
   if (!have_secret && !found_public) {
     tor_free(keypair);
     keypair = ed_key_new(signing_key, flags, now, lifetime,
@@ -441,8 +450,12 @@ ed_key_init_from_file(const char *fname, uint32_t flags,
       tor_log(severity, LD_OR, "Couldn't create keypair");
       goto err;
     }
-
     created_pk = created_sk = created_cert = 1;
+  }
+
+  /* Write it to disk if we're supposed to do with a new passphrase, or if
+   * we just created it. */
+  if (created_sk || (have_secret && get_options()->change_key_passphrase)) {
     if (write_secret_key(&keypair->seckey,
                          encrypt_key,
                          secret_fname, tag, encrypted_secret_fname) < 0
@@ -671,7 +684,7 @@ load_ed_keys(const or_options_t *options, time_t now)
   const int need_new_signing_key =
     NULL == use_signing ||
     EXPIRES_SOON(check_signing_cert, 0) ||
-    options->command == CMD_KEYGEN;
+    (options->command == CMD_KEYGEN && ! options->change_key_passphrase);
   const int want_new_signing_key =
     need_new_signing_key ||
     EXPIRES_SOON(check_signing_cert, options->TestingSigningKeySlop);