From e72a5b3c070451e7762b1d22553cf077c50eb123 Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Thu, 28 Aug 2014 12:04:22 -0400
Subject: [PATCH] Move secret-to-key functionality into a separate module

I'm about to add more of these, so we might as well trudge forward.
---
 src/common/crypto.c     | 44 ----------------------------------
 src/common/crypto_s2k.c | 53 +++++++++++++++++++++++++++++++++++++++++
 src/common/include.am   |  1 +
 3 files changed, 54 insertions(+), 44 deletions(-)
 create mode 100644 src/common/crypto_s2k.c

diff --git a/src/common/crypto.c b/src/common/crypto.c
index a3e767e6f5..fa91f6dd82 100644
--- a/src/common/crypto.c
+++ b/src/common/crypto.c
@@ -3001,50 +3001,6 @@ base32_decode(char *dest, size_t destlen, const char *src, size_t srclen)
   return 0;
 }
 
-/** Implement RFC2440-style iterated-salted S2K conversion: convert the
- * <b>secret_len</b>-byte <b>secret</b> into a <b>key_out_len</b> byte
- * <b>key_out</b>.  As in RFC2440, the first 8 bytes of s2k_specifier
- * are a salt; the 9th byte describes how much iteration to do.
- * Does not support <b>key_out_len</b> &gt; DIGEST_LEN.
- */
-void
-secret_to_key_rfc2440(char *key_out, size_t key_out_len, const char *secret,
-              size_t secret_len, const char *s2k_specifier)
-{
-  crypto_digest_t *d;
-  uint8_t c;
-  size_t count, tmplen;
-  char *tmp;
-  tor_assert(key_out_len < SIZE_T_CEILING);
-
-#define EXPBIAS 6
-  c = s2k_specifier[8];
-  count = ((uint32_t)16 + (c & 15)) << ((c >> 4) + EXPBIAS);
-#undef EXPBIAS
-
-  tor_assert(key_out_len <= DIGEST_LEN);
-
-  d = crypto_digest_new();
-  tmplen = 8+secret_len;
-  tmp = tor_malloc(tmplen);
-  memcpy(tmp,s2k_specifier,8);
-  memcpy(tmp+8,secret,secret_len);
-  secret_len += 8;
-  while (count) {
-    if (count >= secret_len) {
-      crypto_digest_add_bytes(d, tmp, secret_len);
-      count -= secret_len;
-    } else {
-      crypto_digest_add_bytes(d, tmp, count);
-      count = 0;
-    }
-  }
-  crypto_digest_get_digest(d, key_out, key_out_len);
-  memwipe(tmp, 0, tmplen);
-  tor_free(tmp);
-  crypto_digest_free(d);
-}
-
 /**
  * Destroy the <b>sz</b> bytes of data stored at <b>mem</b>, setting them to
  * the value <b>byte</b>.
diff --git a/src/common/crypto_s2k.c b/src/common/crypto_s2k.c
new file mode 100644
index 0000000000..669ee5301b
--- /dev/null
+++ b/src/common/crypto_s2k.c
@@ -0,0 +1,53 @@
+/* Copyright (c) 2001, Matej Pfajfar.
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2013, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+#include "crypto.h"
+#include "util.h"
+#include "compat.h"
+
+/** Implement RFC2440-style iterated-salted S2K conversion: convert the
+ * <b>secret_len</b>-byte <b>secret</b> into a <b>key_out_len</b> byte
+ * <b>key_out</b>.  As in RFC2440, the first 8 bytes of s2k_specifier
+ * are a salt; the 9th byte describes how much iteration to do.
+ * Does not support <b>key_out_len</b> &gt; DIGEST_LEN.
+ */
+void
+secret_to_key_rfc2440(char *key_out, size_t key_out_len, const char *secret,
+              size_t secret_len, const char *s2k_specifier)
+{
+  crypto_digest_t *d;
+  uint8_t c;
+  size_t count, tmplen;
+  char *tmp;
+  tor_assert(key_out_len < SIZE_T_CEILING);
+
+#define EXPBIAS 6
+  c = s2k_specifier[8];
+  count = ((uint32_t)16 + (c & 15)) << ((c >> 4) + EXPBIAS);
+#undef EXPBIAS
+
+  tor_assert(key_out_len <= DIGEST_LEN);
+
+  d = crypto_digest_new();
+  tmplen = 8+secret_len;
+  tmp = tor_malloc(tmplen);
+  memcpy(tmp,s2k_specifier,8);
+  memcpy(tmp+8,secret,secret_len);
+  secret_len += 8;
+  while (count) {
+    if (count >= secret_len) {
+      crypto_digest_add_bytes(d, tmp, secret_len);
+      count -= secret_len;
+    } else {
+      crypto_digest_add_bytes(d, tmp, count);
+      count = 0;
+    }
+  }
+  crypto_digest_get_digest(d, key_out, key_out_len);
+  memwipe(tmp, 0, tmplen);
+  tor_free(tmp);
+  crypto_digest_free(d);
+}
diff --git a/src/common/include.am b/src/common/include.am
index 68e0110c26..7a8cc5ce8b 100644
--- a/src/common/include.am
+++ b/src/common/include.am
@@ -75,6 +75,7 @@ LIBOR_A_SOURCES = \
 LIBOR_CRYPTO_A_SOURCES = \
   src/common/aes.c		\
   src/common/crypto.c		\
+  src/common/crypto_s2k.c	\
   src/common/crypto_format.c	\
   src/common/torgzip.c		\
   src/common/tortls.c		\