Imported Upstream version 2.3_rc1

1 files changed, 1451 insertions, 0 deletions

diff --git a/src/openvpn/crypto.c b/src/openvpn/crypto.c
new file mode 100644
index 0000000..ac2eecd
--- /dev/null
+++ b/src/openvpn/crypto.c
@@ -0,0 +1,1451 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
+ *  Copyright (C) 2010 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program 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 (see the file COPYING included with this
+ *  distribution); if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef ENABLE_CRYPTO
+
+#include "crypto.h"
+#include "error.h"
+#include "misc.h"
+
+#include "memdbg.h"
+
+/*
+ * Encryption and Compression Routines.
+ *
+ * On entry, buf contains the input data and length.
+ * On exit, it should be set to the output data and length.
+ *
+ * If buf->len is <= 0 we should return
+ * If buf->len is set to 0 on exit it tells the caller to ignore the packet.
+ *
+ * work is a workspace buffer we are given of size BUF_SIZE.
+ * work may be used to return output data, or the input buffer
+ * may be modified and returned as output.  If output data is
+ * returned in work, the data should start after FRAME_HEADROOM bytes
+ * of padding to leave room for downstream routines to prepend.
+ *
+ * Up to a total of FRAME_HEADROOM bytes may be prepended to the input buf
+ * by all routines (encryption, decryption, compression, and decompression).
+ *
+ * Note that the buf_prepend return will assert if we try to
+ * make a header bigger than FRAME_HEADROOM.  This should not
+ * happen unless the frame parameters are wrong.
+ */
+
+#define CRYPT_ERROR(format) \
+  do { msg (D_CRYPT_ERRORS, "%s: " format, error_prefix); goto error_exit; } while (false)
+
+void
+openvpn_encrypt (struct buffer *buf, struct buffer work,
+		 const struct crypto_options *opt,
+		 const struct frame* frame)
+{
+  struct gc_arena gc;
+  gc_init (&gc);
+
+  if (buf->len > 0 && opt->key_ctx_bi)
+    {
+      struct key_ctx *ctx = &opt->key_ctx_bi->encrypt;
+
+      /* Do Encrypt from buf -> work */
+      if (ctx->cipher)
+	{
+	  uint8_t iv_buf[OPENVPN_MAX_IV_LENGTH];
+	  const int iv_size = cipher_ctx_iv_length (ctx->cipher);
+	  const unsigned int mode = cipher_ctx_mode (ctx->cipher);
+	  int outlen;
+
+	  if (mode == OPENVPN_MODE_CBC)
+	    {
+	      CLEAR (iv_buf);
+
+	      /* generate pseudo-random IV */
+	      if (opt->flags & CO_USE_IV)
+		prng_bytes (iv_buf, iv_size);
+
+	      /* Put packet ID in plaintext buffer or IV, depending on cipher mode */
+	      if (opt->packet_id)
+		{
+		  struct packet_id_net pin;
+		  packet_id_alloc_outgoing (&opt->packet_id->send, &pin, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM));
+		  ASSERT (packet_id_write (&pin, buf, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM), true));
+		}
+	    }
+	  else if (mode == OPENVPN_MODE_CFB || mode == OPENVPN_MODE_OFB)
+	    {
+	      struct packet_id_net pin;
+	      struct buffer b;
+
+	      ASSERT (opt->flags & CO_USE_IV);    /* IV and packet-ID required */
+	      ASSERT (opt->packet_id); /*  for this mode. */
+
+	      packet_id_alloc_outgoing (&opt->packet_id->send, &pin, true);
+	      memset (iv_buf, 0, iv_size);
+	      buf_set_write (&b, iv_buf, iv_size);
+	      ASSERT (packet_id_write (&pin, &b, true, false));
+	    }
+	  else /* We only support CBC, CFB, or OFB modes right now */
+	    {
+	      ASSERT (0);
+	    }
+
+	  /* initialize work buffer with FRAME_HEADROOM bytes of prepend capacity */
+	  ASSERT (buf_init (&work, FRAME_HEADROOM (frame)));
+
+	  /* set the IV pseudo-randomly */
+	  if (opt->flags & CO_USE_IV)
+	    dmsg (D_PACKET_CONTENT, "ENCRYPT IV: %s", format_hex (iv_buf, iv_size, 0, &gc));
+
+	  dmsg (D_PACKET_CONTENT, "ENCRYPT FROM: %s",
+	       format_hex (BPTR (buf), BLEN (buf), 80, &gc));
+
+	  /* cipher_ctx was already initialized with key & keylen */
+	  ASSERT (cipher_ctx_reset(ctx->cipher, iv_buf));
+
+	  /* Buffer overflow check */
+	  if (!buf_safe (&work, buf->len + cipher_ctx_block_size(ctx->cipher)))
+	    {
+	      msg (D_CRYPT_ERRORS, "ENCRYPT: buffer size error, bc=%d bo=%d bl=%d wc=%d wo=%d wl=%d cbs=%d",
+		   buf->capacity,
+		   buf->offset,
+		   buf->len,
+		   work.capacity,
+		   work.offset,
+		   work.len,
+		   cipher_ctx_block_size (ctx->cipher));
+	      goto err;
+	    }
+
+	  /* Encrypt packet ID, payload */
+	  ASSERT (cipher_ctx_update (ctx->cipher, BPTR (&work), &outlen, BPTR (buf), BLEN (buf)));
+	  work.len += outlen;
+
+	  /* Flush the encryption buffer */
+	  ASSERT(cipher_ctx_final(ctx->cipher, BPTR (&work) + outlen, &outlen));
+	  work.len += outlen;
+	  ASSERT (outlen == iv_size);
+
+	  /* prepend the IV to the ciphertext */
+	  if (opt->flags & CO_USE_IV)
+	    {
+	      uint8_t *output = buf_prepend (&work, iv_size);
+	      ASSERT (output);
+	      memcpy (output, iv_buf, iv_size);
+	    }
+
+	  dmsg (D_PACKET_CONTENT, "ENCRYPT TO: %s",
+	       format_hex (BPTR (&work), BLEN (&work), 80, &gc));
+	}
+      else				/* No Encryption */
+	{
+	  if (opt->packet_id)
+	    {
+	      struct packet_id_net pin;
+	      packet_id_alloc_outgoing (&opt->packet_id->send, &pin, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM));
+	      ASSERT (packet_id_write (&pin, buf, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM), true));
+	    }
+	  work = *buf;
+	}
+
+      /* HMAC the ciphertext (or plaintext if !cipher) */
+      if (ctx->hmac)
+	{
+	  uint8_t *output = NULL;
+
+	  hmac_ctx_reset (ctx->hmac);
+	  hmac_ctx_update (ctx->hmac, BPTR(&work), BLEN(&work));
+	  output = buf_prepend (&work, hmac_ctx_size(ctx->hmac));
+	  ASSERT (output);
+	  hmac_ctx_final (ctx->hmac, output);
+	}
+
+      *buf = work;
+    }
+
+  gc_free (&gc);
+  return;
+
+err:
+  crypto_clear_error();
+  buf->len = 0;
+  gc_free (&gc);
+  return;
+}
+
+/*
+ * If (opt->flags & CO_USE_IV) is not NULL, we will read an IV from the packet.
+ *
+ * Set buf->len to 0 and return false on decrypt error.
+ *
+ * On success, buf is set to point to plaintext, true
+ * is returned.
+ */
+bool
+openvpn_decrypt (struct buffer *buf, struct buffer work,
+		 const struct crypto_options *opt,
+		 const struct frame* frame)
+{
+  static const char error_prefix[] = "Authenticate/Decrypt packet error";
+  struct gc_arena gc;
+  gc_init (&gc);
+
+  if (buf->len > 0 && opt->key_ctx_bi)
+    {
+      struct key_ctx *ctx = &opt->key_ctx_bi->decrypt;
+      struct packet_id_net pin;
+      bool have_pin = false;
+
+      /* Verify the HMAC */
+      if (ctx->hmac)
+	{
+	  int hmac_len;
+	  uint8_t local_hmac[MAX_HMAC_KEY_LENGTH]; /* HMAC of ciphertext computed locally */
+
+	  hmac_ctx_reset(ctx->hmac);
+
+	  /* Assume the length of the input HMAC */
+	  hmac_len = hmac_ctx_size (ctx->hmac);
+
+	  /* Authentication fails if insufficient data in packet for HMAC */
+	  if (buf->len < hmac_len)
+	    CRYPT_ERROR ("missing authentication info");
+
+	  hmac_ctx_update (ctx->hmac, BPTR (buf) + hmac_len, BLEN (buf) - hmac_len);
+	  hmac_ctx_final (ctx->hmac, local_hmac);
+
+	  /* Compare locally computed HMAC with packet HMAC */
+	  if (memcmp (local_hmac, BPTR (buf), hmac_len))
+	    CRYPT_ERROR ("packet HMAC authentication failed");
+
+	  ASSERT (buf_advance (buf, hmac_len));
+	}
+
+      /* Decrypt packet ID + payload */
+
+      if (ctx->cipher)
+	{
+	  const unsigned int mode = cipher_ctx_mode (ctx->cipher);
+	  const int iv_size = cipher_ctx_iv_length (ctx->cipher);
+	  uint8_t iv_buf[OPENVPN_MAX_IV_LENGTH];
+	  int outlen;
+
+	  /* initialize work buffer with FRAME_HEADROOM bytes of prepend capacity */
+	  ASSERT (buf_init (&work, FRAME_HEADROOM_ADJ (frame, FRAME_HEADROOM_MARKER_DECRYPT)));
+
+	  /* use IV if user requested it */
+	  CLEAR (iv_buf);
+	  if (opt->flags & CO_USE_IV)
+	    {
+	      if (buf->len < iv_size)
+		CRYPT_ERROR ("missing IV info");
+	      memcpy (iv_buf, BPTR (buf), iv_size);
+	      ASSERT (buf_advance (buf, iv_size));
+	    }
+
+	  /* show the IV's initial state */
+	  if (opt->flags & CO_USE_IV)
+	    dmsg (D_PACKET_CONTENT, "DECRYPT IV: %s", format_hex (iv_buf, iv_size, 0, &gc));
+
+	  if (buf->len < 1)
+	    CRYPT_ERROR ("missing payload");
+
+	  /* ctx->cipher was already initialized with key & keylen */
+	  if (!cipher_ctx_reset (ctx->cipher, iv_buf))
+	    CRYPT_ERROR ("cipher init failed");
+
+	  /* Buffer overflow check (should never happen) */
+	  if (!buf_safe (&work, buf->len))
+	    CRYPT_ERROR ("buffer overflow");
+
+	  /* Decrypt packet ID, payload */
+	  if (!cipher_ctx_update (ctx->cipher, BPTR (&work), &outlen, BPTR (buf), BLEN (buf)))
+	    CRYPT_ERROR ("cipher update failed");
+	  work.len += outlen;
+
+	  /* Flush the decryption buffer */
+	  if (!cipher_ctx_final (ctx->cipher, BPTR (&work) + outlen, &outlen))
+	    CRYPT_ERROR ("cipher final failed");
+	  work.len += outlen;
+
+	  dmsg (D_PACKET_CONTENT, "DECRYPT TO: %s",
+	       format_hex (BPTR (&work), BLEN (&work), 80, &gc));
+
+	  /* Get packet ID from plaintext buffer or IV, depending on cipher mode */
+	  {
+	    if (mode == OPENVPN_MODE_CBC)
+	      {
+		if (opt->packet_id)
+		  {
+		    if (!packet_id_read (&pin, &work, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM)))
+		      CRYPT_ERROR ("error reading CBC packet-id");
+		    have_pin = true;
+		  }
+	      }
+	    else if (mode == OPENVPN_MODE_CFB || mode == OPENVPN_MODE_OFB)
+	      {
+		struct buffer b;
+
+		ASSERT (opt->flags & CO_USE_IV);    /* IV and packet-ID required */
+		ASSERT (opt->packet_id); /*  for this mode. */
+
+		buf_set_read (&b, iv_buf, iv_size);
+		if (!packet_id_read (&pin, &b, true))
+		  CRYPT_ERROR ("error reading CFB/OFB packet-id");
+		have_pin = true;
+	      }
+	    else /* We only support CBC, CFB, or OFB modes right now */
+	      {
+		ASSERT (0);
+	      }
+	  }
+	}
+      else
+	{
+	  work = *buf;
+	  if (opt->packet_id)
+	    {
+	      if (!packet_id_read (&pin, &work, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM)))
+		CRYPT_ERROR ("error reading packet-id");
+	      have_pin = !BOOL_CAST (opt->flags & CO_IGNORE_PACKET_ID);
+	    }
+	}
+      
+      if (have_pin)
+	{
+	  packet_id_reap_test (&opt->packet_id->rec);
+	  if (packet_id_test (&opt->packet_id->rec, &pin))
+	    {
+	      packet_id_add (&opt->packet_id->rec, &pin);
+	      if (opt->pid_persist && (opt->flags & CO_PACKET_ID_LONG_FORM))
+		packet_id_persist_save_obj (opt->pid_persist, opt->packet_id);
+	    }
+	  else
+	    {
+	      if (!(opt->flags & CO_MUTE_REPLAY_WARNINGS))
+	      msg (D_REPLAY_ERRORS, "%s: bad packet ID (may be a replay): %s -- see the man page entry for --no-replay and --replay-window for more info or silence this warning with --mute-replay-warnings",
+		   error_prefix, packet_id_net_print (&pin, true, &gc));
+	      goto error_exit;
+	    }
+	}
+      *buf = work;
+    }
+
+  gc_free (&gc);
+  return true;
+
+ error_exit:
+  crypto_clear_error();
+  buf->len = 0;
+  gc_free (&gc);
+  return false;
+}
+
+/*
+ * How many bytes will we add to frame buffer for a given
+ * set of crypto options?
+ */
+void
+crypto_adjust_frame_parameters(struct frame *frame,
+			       const struct key_type* kt,
+			       bool cipher_defined,
+			       bool use_iv,
+			       bool packet_id,
+			       bool packet_id_long_form)
+{
+  frame_add_to_extra_frame (frame,
+			    (packet_id ? packet_id_size (packet_id_long_form) : 0) +
+			    ((cipher_defined && use_iv) ? cipher_kt_iv_size (kt->cipher) : 0) +
+			    (cipher_defined ? cipher_kt_block_size (kt->cipher) : 0) + /* worst case padding expansion */
+			    kt->hmac_length);
+}
+
+/*
+ * Build a struct key_type.
+ */
+void
+init_key_type (struct key_type *kt, const char *ciphername,
+	       bool ciphername_defined, const char *authname,
+	       bool authname_defined, int keysize,
+	       bool cfb_ofb_allowed, bool warn)
+{
+  CLEAR (*kt);
+  if (ciphername && ciphername_defined)
+    {
+      kt->cipher = cipher_kt_get (ciphername);
+      kt->cipher_length = cipher_kt_key_size (kt->cipher);
+      if (keysize > 0 && keysize <= MAX_CIPHER_KEY_LENGTH)
+	kt->cipher_length = keysize;
+
+      /* check legal cipher mode */
+      {
+	const unsigned int mode = cipher_kt_mode (kt->cipher);
+	if (!(mode == OPENVPN_MODE_CBC
+#ifdef ALLOW_NON_CBC_CIPHERS
+	      || (cfb_ofb_allowed && (mode == OPENVPN_MODE_CFB || mode == OPENVPN_MODE_OFB))
+#endif
+	      ))
+#ifdef ENABLE_SMALL
+	  msg (M_FATAL, "Cipher '%s' mode not supported", ciphername);
+#else
+	  msg (M_FATAL, "Cipher '%s' uses a mode not supported by " PACKAGE_NAME " in your current configuration.  CBC mode is always supported, while CFB and OFB modes are supported only when using SSL/TLS authentication and key exchange mode, and when " PACKAGE_NAME " has been built with ALLOW_NON_CBC_CIPHERS.", ciphername);
+#endif
+      }
+    }
+  else
+    {
+      if (warn)
+	msg (M_WARN, "******* WARNING *******: null cipher specified, no encryption will be used");
+    }
+  if (authname && authname_defined)
+    {
+      kt->digest = md_kt_get (authname);
+      kt->hmac_length = md_kt_size (kt->digest);
+    }
+  else
+    {
+      if (warn)
+	msg (M_WARN, "******* WARNING *******: null MAC specified, no authentication will be used");
+    }
+}
+
+/* given a key and key_type, build a key_ctx */
+void
+init_key_ctx (struct key_ctx *ctx, struct key *key,
+	      const struct key_type *kt, int enc,
+	      const char *prefix)
+{
+  struct gc_arena gc = gc_new ();
+  CLEAR (*ctx);
+  if (kt->cipher && kt->cipher_length > 0)
+    {
+
+      ALLOC_OBJ(ctx->cipher, cipher_ctx_t);
+      cipher_ctx_init (ctx->cipher, key->cipher, kt->cipher_length,
+	  kt->cipher, enc);
+
+      msg (D_HANDSHAKE, "%s: Cipher '%s' initialized with %d bit key",
+          prefix,
+          cipher_kt_name(kt->cipher),
+          kt->cipher_length *8);
+
+      dmsg (D_SHOW_KEYS, "%s: CIPHER KEY: %s", prefix,
+          format_hex (key->cipher, kt->cipher_length, 0, &gc));
+      dmsg (D_CRYPTO_DEBUG, "%s: CIPHER block_size=%d iv_size=%d",
+          prefix,
+          cipher_kt_block_size(kt->cipher),
+          cipher_kt_iv_size(kt->cipher));
+    }
+  if (kt->digest && kt->hmac_length > 0)
+    {
+      ALLOC_OBJ(ctx->hmac, hmac_ctx_t);
+      hmac_ctx_init (ctx->hmac, key->hmac, kt->hmac_length, kt->digest);
+
+      msg (D_HANDSHAKE,
+      "%s: Using %d bit message hash '%s' for HMAC authentication",
+      prefix, md_kt_size(kt->digest) * 8, md_kt_name(kt->digest));
+
+      dmsg (D_SHOW_KEYS, "%s: HMAC KEY: %s", prefix,
+	  format_hex (key->hmac, kt->hmac_length, 0, &gc));
+
+      dmsg (D_CRYPTO_DEBUG, "%s: HMAC size=%d block_size=%d",
+	prefix,
+	md_kt_size(kt->digest),
+	hmac_ctx_size(ctx->hmac));
+
+    }
+  gc_free (&gc);
+}
+
+void
+free_key_ctx (struct key_ctx *ctx)
+{
+  if (ctx->cipher)
+    {
+      cipher_ctx_cleanup(ctx->cipher);
+      free(ctx->cipher);
+      ctx->cipher = NULL;
+    }
+  if (ctx->hmac)
+    {
+      hmac_ctx_cleanup(ctx->hmac);
+      free(ctx->hmac);
+      ctx->hmac = NULL;
+    }
+}
+
+void
+free_key_ctx_bi (struct key_ctx_bi *ctx)
+{
+  free_key_ctx(&ctx->encrypt);
+  free_key_ctx(&ctx->decrypt);
+}
+
+
+static bool
+key_is_zero (struct key *key, const struct key_type *kt)
+{
+  int i;
+  for (i = 0; i < kt->cipher_length; ++i)
+    if (key->cipher[i])
+      return false;
+  msg (D_CRYPT_ERRORS, "CRYPTO INFO: WARNING: zero key detected");
+  return true;
+}
+
+/*
+ * Make sure that cipher key is a valid key for current key_type.
+ */
+bool
+check_key (struct key *key, const struct key_type *kt)
+{
+  if (kt->cipher)
+    {
+      /*
+       * Check for zero key
+       */
+      if (key_is_zero(key, kt))
+	return false;
+
+      /*
+       * Check for weak or semi-weak DES keys.
+       */
+      {
+	const int ndc = key_des_num_cblocks (kt->cipher);
+	if (ndc)
+	  return key_des_check (key->cipher, kt->cipher_length, ndc);
+	else
+	  return true;
+      }
+    }
+  return true;
+}
+
+/*
+ * Make safe mutations to key to ensure it is valid,
+ * such as ensuring correct parity on DES keys.
+ *
+ * This routine cannot guarantee it will generate a good
+ * key.  You must always call check_key after this routine
+ * to make sure.
+ */ 
+void
+fixup_key (struct key *key, const struct key_type *kt)
+{
+  struct gc_arena gc = gc_new ();
+  if (kt->cipher)
+    {
+#ifdef ENABLE_DEBUG
+      const struct key orig = *key;
+#endif
+      const int ndc = key_des_num_cblocks (kt->cipher);
+
+      if (ndc)
+	key_des_fixup (key->cipher, kt->cipher_length, ndc);
+
+#ifdef ENABLE_DEBUG
+      if (check_debug_level (D_CRYPTO_DEBUG))
+	{
+	  if (memcmp (orig.cipher, key->cipher, kt->cipher_length))
+	    dmsg (D_CRYPTO_DEBUG, "CRYPTO INFO: fixup_key: before=%s after=%s",
+		 format_hex (orig.cipher, kt->cipher_length, 0, &gc),
+		 format_hex (key->cipher, kt->cipher_length, 0, &gc));
+	}
+#endif
+    }
+  gc_free (&gc);
+}
+
+void
+check_replay_iv_consistency (const struct key_type *kt, bool packet_id, bool use_iv)
+{
+  if (cfb_ofb_mode (kt) && !(packet_id && use_iv))
+    msg (M_FATAL, "--no-replay or --no-iv cannot be used with a CFB or OFB mode cipher");
+}
+
+bool
+cfb_ofb_mode (const struct key_type* kt)
+{
+  if (kt && kt->cipher) {
+      const unsigned int mode = cipher_kt_mode (kt->cipher);
+      return mode == OPENVPN_MODE_CFB || mode == OPENVPN_MODE_OFB;
+  }
+  return false;
+}
+
+/*
+ * Generate a random key.  If key_type is provided, make
+ * sure generated key is valid for key_type.
+ */
+void
+generate_key_random (struct key *key, const struct key_type *kt)
+{
+  int cipher_len = MAX_CIPHER_KEY_LENGTH;
+  int hmac_len = MAX_HMAC_KEY_LENGTH;
+
+  struct gc_arena gc = gc_new ();
+
+  do {
+    CLEAR (*key);
+    if (kt)
+      {
+	if (kt->cipher && kt->cipher_length > 0 && kt->cipher_length <= cipher_len)
+	  cipher_len = kt->cipher_length;
+
+	if (kt->digest && kt->hmac_length > 0 && kt->hmac_length <= hmac_len)
+	  hmac_len = kt->hmac_length;
+      }
+    if (!rand_bytes (key->cipher, cipher_len)
+	|| !rand_bytes (key->hmac, hmac_len))
+      msg (M_FATAL, "ERROR: Random number generator cannot obtain entropy for key generation");
+
+    dmsg (D_SHOW_KEY_SOURCE, "Cipher source entropy: %s", format_hex (key->cipher, cipher_len, 0, &gc));
+    dmsg (D_SHOW_KEY_SOURCE, "HMAC source entropy: %s", format_hex (key->hmac, hmac_len, 0, &gc));
+
+    if (kt)
+      fixup_key (key, kt);
+  } while (kt && !check_key (key, kt));
+
+  gc_free (&gc);
+}
+
+/*
+ * Print key material
+ */
+void
+key2_print (const struct key2* k,
+	    const struct key_type *kt,
+	    const char* prefix0,
+	    const char* prefix1)
+{
+  struct gc_arena gc = gc_new ();
+  ASSERT (k->n == 2);
+  dmsg (D_SHOW_KEY_SOURCE, "%s (cipher): %s",
+       prefix0,
+       format_hex (k->keys[0].cipher, kt->cipher_length, 0, &gc));
+  dmsg (D_SHOW_KEY_SOURCE, "%s (hmac): %s",
+       prefix0,
+       format_hex (k->keys[0].hmac, kt->hmac_length, 0, &gc));
+  dmsg (D_SHOW_KEY_SOURCE, "%s (cipher): %s",
+       prefix1,
+       format_hex (k->keys[1].cipher, kt->cipher_length, 0, &gc));
+  dmsg (D_SHOW_KEY_SOURCE, "%s (hmac): %s",
+       prefix1,
+       format_hex (k->keys[1].hmac, kt->hmac_length, 0, &gc));
+  gc_free (&gc);
+}
+
+void
+test_crypto (const struct crypto_options *co, struct frame* frame)
+{
+  int i, j;
+  struct gc_arena gc = gc_new ();
+  struct buffer src = alloc_buf_gc (TUN_MTU_SIZE (frame), &gc);
+  struct buffer work = alloc_buf_gc (BUF_SIZE (frame), &gc);
+  struct buffer encrypt_workspace = alloc_buf_gc (BUF_SIZE (frame), &gc);
+  struct buffer decrypt_workspace = alloc_buf_gc (BUF_SIZE (frame), &gc);
+  struct buffer buf = clear_buf();
+
+  /* init work */
+  ASSERT (buf_init (&work, FRAME_HEADROOM (frame)));
+
+  msg (M_INFO, "Entering " PACKAGE_NAME " crypto self-test mode.");
+  for (i = 1; i <= TUN_MTU_SIZE (frame); ++i)
+    {
+      update_time ();
+
+      msg (M_INFO, "TESTING ENCRYPT/DECRYPT of packet length=%d", i);
+
+      /*
+       * Load src with random data.
+       */
+      ASSERT (buf_init (&src, 0));
+      ASSERT (i <= src.capacity);
+      src.len = i;
+      ASSERT (rand_bytes (BPTR (&src), BLEN (&src)));
+
+      /* copy source to input buf */
+      buf = work;
+      memcpy (buf_write_alloc (&buf, BLEN (&src)), BPTR (&src), BLEN (&src));
+
+      /* encrypt */
+      openvpn_encrypt (&buf, encrypt_workspace, co, frame);
+
+      /* decrypt */
+      openvpn_decrypt (&buf, decrypt_workspace, co, frame);
+
+      /* compare */
+      if (buf.len != src.len)
+	msg (M_FATAL, "SELF TEST FAILED, src.len=%d buf.len=%d", src.len, buf.len);
+      for (j = 0; j < i; ++j)
+	{
+	  const uint8_t in = *(BPTR (&src) + j);
+	  const uint8_t out = *(BPTR (&buf) + j);
+	  if (in != out)
+	    msg (M_FATAL, "SELF TEST FAILED, pos=%d in=%d out=%d", j, in, out);
+	}
+    }
+  msg (M_INFO, PACKAGE_NAME " crypto self-test mode SUCCEEDED.");
+  gc_free (&gc);
+}
+
+#ifdef ENABLE_SSL
+
+void
+get_tls_handshake_key (const struct key_type *key_type,
+		       struct key_ctx_bi *ctx,
+		       const char *passphrase_file,
+		       const int key_direction,
+		       const unsigned int flags)
+{
+  if (passphrase_file && key_type->hmac_length)
+    {
+      struct key2 key2;
+      struct key_type kt = *key_type;
+      struct key_direction_state kds;
+
+      /* for control channel we are only authenticating, not encrypting */
+      kt.cipher_length = 0;
+      kt.cipher = NULL;
+
+      if (flags & GHK_INLINE)
+	{
+	  /* key was specified inline, key text is in passphrase_file */
+	  read_key_file (&key2, passphrase_file, RKF_INLINE|RKF_MUST_SUCCEED);
+
+	  /* succeeded? */
+	  if (key2.n == 2)
+	    msg (M_INFO, "Control Channel Authentication: tls-auth using INLINE static key file");
+	  else
+	    msg (M_FATAL, "INLINE tls-auth file lacks the requisite 2 keys");
+	}
+      else
+      {
+	/* first try to parse as an OpenVPN static key file */
+	read_key_file (&key2, passphrase_file, 0);
+
+	/* succeeded? */
+	if (key2.n == 2)
+	  {
+	    msg (M_INFO,
+		 "Control Channel Authentication: using '%s' as a " PACKAGE_NAME " static key file",
+		 passphrase_file);
+	  }
+	else
+	  {
+	    int hash_size;
+
+	    CLEAR (key2);
+
+	    /* failed, now try to get hash from a freeform file */
+	    hash_size = read_passphrase_hash (passphrase_file,
+					      kt.digest,
+					      key2.keys[0].hmac,
+					      MAX_HMAC_KEY_LENGTH);
+	    ASSERT (hash_size == kt.hmac_length);
+
+	    /* suceeded */
+	    key2.n = 1;
+
+	    msg (M_INFO,
+		 "Control Channel Authentication: using '%s' as a free-form passphrase file",
+		 passphrase_file);
+	  }
+      }
+      /* handle key direction */
+
+      key_direction_state_init (&kds, key_direction);
+      must_have_n_keys (passphrase_file, "tls-auth", &key2, kds.need_keys);
+
+      /* initialize hmac key in both directions */
+
+      init_key_ctx (&ctx->encrypt, &key2.keys[kds.out_key], &kt, OPENVPN_OP_ENCRYPT,
+		    "Outgoing Control Channel Authentication");
+      init_key_ctx (&ctx->decrypt, &key2.keys[kds.in_key], &kt, OPENVPN_OP_DECRYPT,
+		    "Incoming Control Channel Authentication");
+
+      CLEAR (key2);
+    }
+  else
+    {
+      CLEAR (*ctx);
+    }
+}
+#endif
+
+/* header and footer for static key file */
+static const char static_key_head[] = "-----BEGIN OpenVPN Static key V1-----";
+static const char static_key_foot[] = "-----END OpenVPN Static key V1-----";
+
+static const char printable_char_fmt[] =
+  "Non-Hex character ('%c') found at line %d in key file '%s' (%d/%d/%d bytes found/min/max)";
+
+static const char unprintable_char_fmt[] =
+  "Non-Hex, unprintable character (0x%02x) found at line %d in key file '%s' (%d/%d/%d bytes found/min/max)";
+
+/* read key from file */
+
+void
+read_key_file (struct key2 *key2, const char *file, const unsigned int flags)
+{
+  struct gc_arena gc = gc_new ();
+  struct buffer in;
+  int fd, size;
+  uint8_t hex_byte[3] = {0, 0, 0};
+  const char *error_filename = file;
+
+  /* parse info */
+  const unsigned char *cp;
+  int hb_index = 0;
+  int line_num = 1;
+  int line_index = 0;
+  int match = 0;
+
+  /* output */
+  uint8_t* out = (uint8_t*) &key2->keys;
+  const int keylen = sizeof (key2->keys);
+  int count = 0;
+
+  /* parse states */
+# define PARSE_INITIAL        0
+# define PARSE_HEAD           1
+# define PARSE_DATA           2
+# define PARSE_DATA_COMPLETE  3
+# define PARSE_FOOT           4
+# define PARSE_FINISHED       5
+  int state = PARSE_INITIAL;
+
+  /* constants */
+  const int hlen = strlen (static_key_head);
+  const int flen = strlen (static_key_foot);
+  const int onekeylen = sizeof (key2->keys[0]);
+
+  CLEAR (*key2);
+
+  /*
+   * Key can be provided as a filename in 'file' or if RKF_INLINE
+   * is set, the actual key data itself in ascii form.
+   */
+  if (flags & RKF_INLINE) /* 'file' is a string containing ascii representation of key */
+    {
+      size = strlen (file) + 1;
+      buf_set_read (&in, (const uint8_t *)file, size);
+      error_filename = INLINE_FILE_TAG;
+    }
+  else /* 'file' is a filename which refers to a file containing the ascii key */
+    {
+      in = alloc_buf_gc (2048, &gc);
+      fd = platform_open (file, O_RDONLY, 0);
+      if (fd == -1)
+	msg (M_ERR, "Cannot open file key file '%s'", file);
+      size = read (fd, in.data, in.capacity);
+      if (size < 0)
+	msg (M_FATAL, "Read error on key file ('%s')", file);
+      if (size == in.capacity)
+	msg (M_FATAL, "Key file ('%s') can be a maximum of %d bytes", file, (int)in.capacity);
+      close (fd);
+    }
+
+  cp = (unsigned char *)in.data;
+  while (size > 0)
+    {
+      const unsigned char c = *cp;
+
+#if 0
+      msg (M_INFO, "char='%c'[%d] s=%d ln=%d li=%d m=%d c=%d",
+	   c, (int)c, state, line_num, line_index, match, count);
+#endif
+
+      if (c == '\n')
+	{
+	  line_index = match = 0;
+	  ++line_num;	      
+	}
+      else
+	{
+	  /* first char of new line */
+	  if (!line_index)
+	    {
+	      /* first char of line after header line? */
+	      if (state == PARSE_HEAD)
+		state = PARSE_DATA;
+
+	      /* first char of footer */
+	      if ((state == PARSE_DATA || state == PARSE_DATA_COMPLETE) && c == '-')
+		state = PARSE_FOOT;
+	    }
+
+	  /* compare read chars with header line */
+	  if (state == PARSE_INITIAL)
+	    {
+	      if (line_index < hlen && c == static_key_head[line_index])
+		{
+		  if (++match == hlen)
+		    state = PARSE_HEAD;
+		}
+	    }
+
+	  /* compare read chars with footer line */
+	  if (state == PARSE_FOOT)
+	    {
+	      if (line_index < flen && c == static_key_foot[line_index])
+		{
+		  if (++match == flen)
+		    state = PARSE_FINISHED;
+		}
+	    }
+
+	  /* reading key */
+	  if (state == PARSE_DATA)
+	    {
+	      if (isxdigit(c))
+		{
+		  ASSERT (hb_index >= 0 && hb_index < 2);
+		  hex_byte[hb_index++] = c;
+		  if (hb_index == 2)
+		    {
+		      unsigned int u;
+		      ASSERT(sscanf((const char *)hex_byte, "%x", &u) == 1);
+		      *out++ = u;
+		      hb_index = 0;
+		      if (++count == keylen)
+			state = PARSE_DATA_COMPLETE;
+		    }
+		}
+	      else if (isspace(c))
+		;
+	      else
+		{
+		  msg (M_FATAL,
+		       (isprint (c) ? printable_char_fmt : unprintable_char_fmt),
+		       c, line_num, error_filename, count, onekeylen, keylen);
+		}
+	    }
+	  ++line_index;
+	}
+      ++cp;
+      --size;
+    }
+
+  /*
+   * Normally we will read either 1 or 2 keys from file.
+   */
+  key2->n = count / onekeylen;
+
+  ASSERT (key2->n >= 0 && key2->n <= (int) SIZE (key2->keys));
+
+  if (flags & RKF_MUST_SUCCEED)
+    {
+      if (!key2->n)
+	msg (M_FATAL, "Insufficient key material or header text not found in file '%s' (%d/%d/%d bytes found/min/max)",
+	     error_filename, count, onekeylen, keylen);
+
+      if (state != PARSE_FINISHED)
+	msg (M_FATAL, "Footer text not found in file '%s' (%d/%d/%d bytes found/min/max)",
+	     error_filename, count, onekeylen, keylen);
+    }
+
+  /* zero file read buffer if not an inline file */
+  if (!(flags & RKF_INLINE))
+    buf_clear (&in);
+
+  if (key2->n)
+    warn_if_group_others_accessible (error_filename);
+
+#if 0
+  /* DEBUGGING */
+  {
+    int i;
+    printf ("KEY READ, n=%d\n", key2->n);
+    for (i = 0; i < (int) SIZE (key2->keys); ++i)
+      {
+	/* format key as ascii */
+	const char *fmt = format_hex_ex ((const uint8_t*)&key2->keys[i],
+					 sizeof (key2->keys[i]),
+					 0,
+					 16,
+					 "\n",
+					 &gc);
+	printf ("[%d]\n%s\n\n", i, fmt);
+      }
+  }
+#endif
+
+  /* pop our garbage collection level */
+  gc_free (&gc);
+}
+
+int
+read_passphrase_hash (const char *passphrase_file,
+		      const md_kt_t *digest,
+		      uint8_t *output,
+		      int len)
+{
+  unsigned int outlen = 0;
+  md_ctx_t md;
+
+  ASSERT (len >= md_kt_size(digest));
+  memset (output, 0, len);
+
+  md_ctx_init(&md, digest);
+
+  /* read passphrase file */
+  {
+    const int min_passphrase_size = 8;
+    uint8_t buf[64];
+    int total_size = 0;
+    int fd = platform_open (passphrase_file, O_RDONLY, 0);
+
+    if (fd == -1)
+      msg (M_ERR, "Cannot open passphrase file: '%s'", passphrase_file);
+
+    for (;;)
+      {
+	int size = read (fd, buf, sizeof (buf));
+	if (size == 0)
+	  break;
+	if (size == -1)
+	  msg (M_ERR, "Read error on passphrase file: '%s'",
+	       passphrase_file);
+	md_ctx_update(&md, buf, size);
+	total_size += size;
+      }
+    close (fd);
+
+    warn_if_group_others_accessible (passphrase_file);
+
+    if (total_size < min_passphrase_size)
+      msg (M_FATAL,
+	   "Passphrase file '%s' is too small (must have at least %d characters)",
+	   passphrase_file, min_passphrase_size);
+  }
+  md_ctx_final(&md, output);
+  md_ctx_cleanup(&md);
+  return md_kt_size(digest);
+}
+
+/*
+ * Write key to file, return number of random bits
+ * written.
+ */
+int
+write_key_file (const int nkeys, const char *filename)
+{
+  struct gc_arena gc = gc_new ();
+
+  int fd, i;
+  int nbits = 0;
+
+  /* must be large enough to hold full key file */
+  struct buffer out = alloc_buf_gc (2048, &gc);
+  struct buffer nbits_head_text = alloc_buf_gc (128, &gc);
+
+  /* how to format the ascii file representation of key */
+  const int bytes_per_line = 16;
+
+  /* open key file */
+  fd = platform_open (filename, O_CREAT | O_TRUNC | O_WRONLY, S_IRUSR | S_IWUSR);
+
+  if (fd == -1)
+    msg (M_ERR, "Cannot open shared secret file '%s' for write", filename);
+
+  buf_printf (&out, "%s\n", static_key_head);
+
+  for (i = 0; i < nkeys; ++i)
+    {
+      struct key key;
+      char* fmt;
+
+      /* generate random bits */
+      generate_key_random (&key, NULL);
+
+      /* format key as ascii */
+      fmt = format_hex_ex ((const uint8_t*)&key,
+			   sizeof (key),
+			   0,
+			   bytes_per_line,
+			   "\n",
+			   &gc);
+
+      /* increment random bits counter */
+      nbits += sizeof (key) * 8;
+
+      /* write to holding buffer */
+      buf_printf (&out, "%s\n", fmt);
+
+      /* zero memory which held key component (will be freed by GC) */
+      memset (fmt, 0, strlen(fmt));
+      CLEAR (key);
+    }
+
+  buf_printf (&out, "%s\n", static_key_foot);
+
+  /* write number of bits */
+  buf_printf (&nbits_head_text, "#\n# %d bit OpenVPN static key\n#\n", nbits);
+  buf_write_string_file (&nbits_head_text, filename, fd);
+
+  /* write key file, now formatted in out, to file */
+  buf_write_string_file (&out, filename, fd);
+
+  if (close (fd))
+    msg (M_ERR, "Close error on shared secret file %s", filename);
+
+  /* zero memory which held file content (memory will be freed by GC) */
+  buf_clear (&out);
+
+  /* pop our garbage collection level */
+  gc_free (&gc);
+
+  return nbits;
+}
+
+void
+must_have_n_keys (const char *filename, const char *option, const struct key2 *key2, int n)
+{
+  if (key2->n < n)
+    {
+#ifdef ENABLE_SMALL
+      msg (M_FATAL, "Key file '%s' used in --%s contains insufficient key material [keys found=%d required=%d]", filename, option, key2->n, n);
+#else
+      msg (M_FATAL, "Key file '%s' used in --%s contains insufficient key material [keys found=%d required=%d] -- try generating a new key file with '" PACKAGE " --genkey --secret [file]', or use the existing key file in bidirectional mode by specifying --%s without a key direction parameter", filename, option, key2->n, n, option);
+#endif
+    }
+}
+
+int
+ascii2keydirection (int msglevel, const char *str)
+{
+  if (!str)
+    return KEY_DIRECTION_BIDIRECTIONAL;
+  else if (!strcmp (str, "0"))
+    return KEY_DIRECTION_NORMAL;
+  else if (!strcmp (str, "1"))
+    return KEY_DIRECTION_INVERSE;
+  else
+    {
+      msg (msglevel, "Unknown key direction '%s' -- must be '0' or '1'", str);
+      return -1;
+    }
+  return KEY_DIRECTION_BIDIRECTIONAL; /* NOTREACHED */
+}
+
+const char *
+keydirection2ascii (int kd, bool remote)
+{
+  if (kd == KEY_DIRECTION_BIDIRECTIONAL)
+    return NULL;
+  else if (kd == KEY_DIRECTION_NORMAL)
+    return remote ? "1" : "0";
+  else if (kd == KEY_DIRECTION_INVERSE)
+    return remote ? "0" : "1";
+  else
+    {
+      ASSERT (0);
+    }
+  return NULL; /* NOTREACHED */
+}
+
+void
+key_direction_state_init (struct key_direction_state *kds, int key_direction)
+{
+  CLEAR (*kds);
+  switch (key_direction)
+    {
+    case KEY_DIRECTION_NORMAL:
+      kds->out_key = 0;
+      kds->in_key = 1;
+      kds->need_keys = 2;
+      break;
+    case KEY_DIRECTION_INVERSE:
+      kds->out_key = 1;
+      kds->in_key = 0;
+      kds->need_keys = 2;
+      break;
+    case KEY_DIRECTION_BIDIRECTIONAL:
+      kds->out_key = 0;
+      kds->in_key = 0;
+      kds->need_keys = 1;
+      break;
+    default:
+      ASSERT (0);
+    }
+}
+
+void
+verify_fix_key2 (struct key2 *key2, const struct key_type *kt, const char *shared_secret_file)
+{
+  int i;
+
+  for (i = 0; i < key2->n; ++i)
+    {
+      /* Fix parity for DES keys and make sure not a weak key */
+      fixup_key (&key2->keys[i], kt);
+
+      /* This should be a very improbable failure */
+      if (!check_key (&key2->keys[i], kt))
+	msg (M_FATAL, "Key #%d in '%s' is bad.  Try making a new key with --genkey.",
+	     i+1, shared_secret_file);
+    }
+}
+
+/* given a key and key_type, write key to buffer */
+bool
+write_key (const struct key *key, const struct key_type *kt,
+	   struct buffer *buf)
+{
+  ASSERT (kt->cipher_length <= MAX_CIPHER_KEY_LENGTH
+	  && kt->hmac_length <= MAX_HMAC_KEY_LENGTH);
+
+  if (!buf_write (buf, &kt->cipher_length, 1))
+    return false;
+  if (!buf_write (buf, &kt->hmac_length, 1))
+    return false;
+  if (!buf_write (buf, key->cipher, kt->cipher_length))
+    return false;
+  if (!buf_write (buf, key->hmac, kt->hmac_length))
+    return false;
+
+  return true;
+}
+
+/*
+ * Given a key_type and buffer, read key from buffer.
+ * Return: 1 on success
+ *        -1 read failure
+ *         0 on key length mismatch 
+ */
+int
+read_key (struct key *key, const struct key_type *kt, struct buffer *buf)
+{
+  uint8_t cipher_length;
+  uint8_t hmac_length;
+
+  CLEAR (*key);
+  if (!buf_read (buf, &cipher_length, 1))
+    goto read_err;
+  if (!buf_read (buf, &hmac_length, 1))
+    goto read_err;
+
+  if (!buf_read (buf, key->cipher, cipher_length))
+    goto read_err;
+  if (!buf_read (buf, key->hmac, hmac_length))
+    goto read_err;
+
+  if (cipher_length != kt->cipher_length || hmac_length != kt->hmac_length)
+    goto key_len_err;
+
+  return 1;
+
+read_err:
+  msg (D_TLS_ERRORS, "TLS Error: error reading key from remote");
+  return -1;
+
+key_len_err:
+  msg (D_TLS_ERRORS,
+       "TLS Error: key length mismatch, local cipher/hmac %d/%d, remote cipher/hmac %d/%d",
+       kt->cipher_length, kt->hmac_length, cipher_length, hmac_length);
+  return 0;
+}
+
+/*
+ * Random number functions, used in cases where we want
+ * reasonably strong cryptographic random number generation
+ * without depleting our entropy pool.  Used for random
+ * IV values and a number of other miscellaneous tasks.
+ */
+
+static uint8_t *nonce_data = NULL; /* GLOBAL */
+static const md_kt_t *nonce_md = NULL; /* GLOBAL */
+static int nonce_secret_len = 0; /* GLOBAL */
+
+/* Reset the nonce value, also done periodically to refresh entropy */
+static void
+prng_reset_nonce ()
+{
+  const int size = md_kt_size (nonce_md) + nonce_secret_len;
+#if 1 /* Must be 1 for real usage */
+  if (!rand_bytes (nonce_data, size))
+    msg (M_FATAL, "ERROR: Random number generator cannot obtain entropy for PRNG");
+#else
+    /* Only for testing -- will cause a predictable PRNG sequence */
+    {
+      int i;
+      for (i = 0; i < size; ++i)
+	nonce_data[i] = (uint8_t) i;
+    }
+#endif
+}
+
+void
+prng_init (const char *md_name, const int nonce_secret_len_parm)
+{
+  prng_uninit ();
+  nonce_md = md_name ? md_kt_get (md_name) : NULL;
+  if (nonce_md)
+    {
+      ASSERT (nonce_secret_len_parm >= NONCE_SECRET_LEN_MIN && nonce_secret_len_parm <= NONCE_SECRET_LEN_MAX);
+      nonce_secret_len = nonce_secret_len_parm;
+      {
+	const int size = md_kt_size(nonce_md) + nonce_secret_len;
+	dmsg (D_CRYPTO_DEBUG, "PRNG init md=%s size=%d", md_kt_name(nonce_md), size);
+	nonce_data = (uint8_t*) malloc (size);
+	check_malloc_return (nonce_data);
+	prng_reset_nonce();
+      }
+    }
+}
+
+void
+prng_uninit (void)
+{
+  free (nonce_data);
+  nonce_data = NULL;
+  nonce_md = NULL;
+  nonce_secret_len = 0;
+}
+
+void
+prng_bytes (uint8_t *output, int len)
+{
+  static size_t processed = 0;
+
+  if (nonce_md)
+    {
+      const int md_size = md_kt_size (nonce_md);
+      while (len > 0)
+	{
+	  unsigned int outlen = 0;
+	  const int blen = min_int (len, md_size);
+	  md_full(nonce_md, nonce_data, md_size + nonce_secret_len, nonce_data);
+	  memcpy (output, nonce_data, blen);
+	  output += blen;
+	  len -= blen;
+
+	  /* Ensure that random data is reset regularly */
+	  processed += blen;
+	  if(processed > PRNG_NONCE_RESET_BYTES) {
+	    prng_reset_nonce();
+	    processed = 0;
+	  }
+	}
+    }
+  else
+    rand_bytes (output, len);
+}
+
+/* an analogue to the random() function, but use prng_bytes */
+long int
+get_random()
+{
+  long int l;
+  prng_bytes ((unsigned char *)&l, sizeof(l));
+  if (l < 0)
+    l = -l;
+  return l;
+}
+
+#ifndef ENABLE_SSL
+
+void
+init_ssl_lib (void)
+{
+  crypto_init_lib ();
+}
+
+void
+free_ssl_lib (void)
+{
+  crypto_uninit_lib ();
+  prng_uninit();
+}
+
+#endif /* ENABLE_SSL */
+
+/*
+ * md5 functions
+ */
+
+const char *
+md5sum (uint8_t *buf, int len, int n_print_chars, struct gc_arena *gc)
+{
+  uint8_t digest[MD5_DIGEST_LENGTH];
+  const md_kt_t *md5_kt = md_kt_get("MD5");
+
+  md_full(md5_kt, buf, len, digest);
+
+  return format_hex (digest, MD5_DIGEST_LENGTH, n_print_chars, gc);
+}
+
+void
+md5_state_init (struct md5_state *s)
+{
+  const md_kt_t *md5_kt = md_kt_get("MD5");
+
+  md_ctx_init(&s->ctx, md5_kt);
+}
+
+void
+md5_state_update (struct md5_state *s, void *data, size_t len)
+{
+  md_ctx_update(&s->ctx, data, len);
+}
+
+void
+md5_state_final (struct md5_state *s, struct md5_digest *out)
+{
+  md_ctx_final(&s->ctx, out->digest);
+  md_ctx_cleanup(&s->ctx);
+}
+
+void
+md5_digest_clear (struct md5_digest *digest)
+{
+  CLEAR (*digest);
+}
+
+bool
+md5_digest_defined (const struct md5_digest *digest)
+{
+  int i;
+  for (i = 0; i < MD5_DIGEST_LENGTH; ++i)
+    if (digest->digest[i])
+      return true;
+  return false;
+}
+
+bool
+md5_digest_equal (const struct md5_digest *d1, const struct md5_digest *d2)
+{
+  return memcmp(d1->digest, d2->digest, MD5_DIGEST_LENGTH) == 0;
+}
+
+#endif /* ENABLE_CRYPTO */