X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=src%2Futil%2Fcrypto_hkdf.c;h=c2b96778a6e1284161bdc06effc2313b4efc2c25;hb=72c8645af31896829b674b575c5375706f362a30;hp=6a87e496b9d04b872676ba68cea50e336728e64b;hpb=4b9b323560928f1a03459e22191a69bc7d777e7e;p=oweals%2Fgnunet.git

diff --git a/src/util/crypto_hkdf.c b/src/util/crypto_hkdf.c
index 6a87e496b..c2b96778a 100644
--- a/src/util/crypto_hkdf.c
+++ b/src/util/crypto_hkdf.c
@@ -24,16 +24,48 @@
  * @file src/util/crypto_hkdf.c
  * @brief Hash-based KDF as defined in RFC 5869
  * @see http://www.rfc-editor.org/rfc/rfc5869.txt
+ * @todo remove GNUNET references
  * @author Nils Durner
+ *
+ * The following list of people have reviewed this code and considered
+ * it correct on the date given (if you reviewed it, please
+ * have your name added to the list):
+ *
+ * - Christian Grothoff (08.10.2010)
+ * - Nathan Evans (08.10.2010)
+ * - Matthias Wachs (08.10.2010)
  */
 
-#include <gcrypt.h>
+#define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__)
+
+/**
+ * Set this to 0 if you compile this code outside of GNUnet.
+ */
+#define GNUNET_BUILD 1
+
+/**
+ * Enable debugging.
+ */
+#define DEBUG_HKDF 0
 
+
+
+#if GNUNET_BUILD
 #include "platform.h"
 #include "gnunet_crypto_lib.h"
+#else
+#define GNUNET_NO 0
+#define GNUNET_YES 1
+#define GNUNET_SYSERR -1
+#include <stdlib.h>
+#endif
+
+#include <gcrypt.h>
+
 
 /**
  * @brief Compute the HMAC
+ * @todo use chunked buffers
  * @param mac gcrypt MAC handle
  * @param key HMAC key
  * @param key_len length of key
@@ -41,14 +73,14 @@
  * @param buf_len length of buf
  * @return HMAC, freed by caller via gcry_md_close/_reset
  */
-static void *
-doHMAC (gcry_md_hd_t mac, const void *key, const size_t key_len,
-    const void *buf, const size_t buf_len)
+static const void *
+doHMAC (gcry_md_hd_t mac, const void *key, size_t key_len, const void *buf,
+        size_t buf_len)
 {
   gcry_md_setkey (mac, key, key_len);
   gcry_md_write (mac, buf, buf_len);
 
-  return (void *) gcry_md_read (mac, 0);
+  return (const void *) gcry_md_read (mac, 0);
 }
 
 /**
@@ -62,10 +94,10 @@ doHMAC (gcry_md_hd_t mac, const void *key, const size_t key_len,
  * @return GNUNET_YES on success
  */
 static int
-getPRK (gcry_md_hd_t mac, const void *xts, const unsigned long long xts_len,
-    const void *skm, const unsigned long long skm_len, void *prk)
+getPRK (gcry_md_hd_t mac, const void *xts, size_t xts_len, const void *skm,
+        size_t skm_len, void *prk)
 {
-  void *ret;
+  const void *ret;
 
   ret = doHMAC (mac, xts, xts_len, skm, skm_len);
   if (ret == NULL)
@@ -75,92 +107,122 @@ getPRK (gcry_md_hd_t mac, const void *xts, const unsigned long long xts_len,
   return GNUNET_YES;
 }
 
-static void dump(void *p, unsigned int l)
+
+#if DEBUG_HKDF
+static void
+dump (const char *src, const void *p, unsigned int l)
 {
   unsigned int i;
 
-  printf("\n");
+  printf ("\n%s: ", src);
   for (i = 0; i < l; i++)
-    {
-      printf("%2x", (int) ((unsigned char *) p)[i]);
-    }
-  printf("\n");
+  {
+    printf ("%2x", (int) ((const unsigned char *) p)[i]);
+  }
+  printf ("\n");
 }
+#endif
+
 
 /**
  * @brief Derive key
+ * @param result buffer for the derived key, allocated by caller
+ * @param out_len desired length of the derived key
  * @param xtr_algo hash algorithm for the extraction phase, GCRY_MD_...
  * @param prf_algo hash algorithm for the expansion phase, GCRY_MD_...
  * @param xts salt
  * @param xts_len length of xts
  * @param skm source key material
  * @param skm_len length of skm
- * @param ctx context info
- * @param ctx_len length of ctx
- * @param out_len desired length of the derived key
- * @param result buffer for the derived key, allocated by caller
+ * @param argp va_list of void * & size_t pairs for context chunks
  * @return GNUNET_YES on success
  */
 int
-GNUNET_CRYPTO_hkdf (int xtr_algo, int prf_algo, const void *xts,
-    const size_t xts_len, const void *skm, const size_t skm_len,
-    const void *ctx, const size_t ctx_len, const unsigned long long out_len,
-    void *result)
+GNUNET_CRYPTO_hkdf_v (void *result, size_t out_len, int xtr_algo, int prf_algo,
+                      const void *xts, size_t xts_len, const void *skm,
+                      size_t skm_len, va_list argp)
 {
-  void *prk, *hc, *plain;
-  unsigned long long plain_len;
+  const void *hc;
   unsigned long i, t, d;
-  unsigned int k, xtr_len;
+  unsigned int k = gcry_md_get_algo_dlen (prf_algo);
+  unsigned int xtr_len = gcry_md_get_algo_dlen (xtr_algo);
+  char prk[xtr_len];
   int ret;
   gcry_md_hd_t xtr, prf;
+  size_t ctx_len;
+  va_list args;
+
+  if (k == 0)
+    return GNUNET_SYSERR;
 
-  prk = plain = NULL;
-  xtr_len = gcry_md_get_algo_dlen (xtr_algo);
-  k = gcry_md_get_algo_dlen (prf_algo);
-  gcry_md_open(&xtr, xtr_algo, GCRY_MD_FLAG_HMAC);
-  gcry_md_open(&prf, prf_algo, GCRY_MD_FLAG_HMAC);
+  if (gcry_md_open (&xtr, xtr_algo, GCRY_MD_FLAG_HMAC) != GPG_ERR_NO_ERROR)
+    return GNUNET_SYSERR;
 
-  if (out_len > (2 ^ 32 * k) || !xtr_algo || !prf_algo)
+  if (gcry_md_open (&prf, prf_algo, GCRY_MD_FLAG_HMAC) != GPG_ERR_NO_ERROR)
+  {
+    gcry_md_close (xtr);
     return GNUNET_SYSERR;
+  }
+
+  va_copy (args, argp);
+
+  ctx_len = 0;
+  while (NULL != va_arg (args, void *))
+         ctx_len += va_arg (args, size_t);
 
-  prk = GNUNET_malloc (xtr_len);
+  va_end (args);
 
   memset (result, 0, out_len);
-  gcry_md_reset (xtr);
-  if (getPRK (xtr, xts, xts_len, skm, skm_len, prk)
-      != GNUNET_YES)
+  if (getPRK (xtr, xts, xts_len, skm, skm_len, prk) != GNUNET_YES)
     goto hkdf_error;
-dump(prk, xtr_len);
+#if DEBUG_HKDF
+  dump ("PRK", prk, xtr_len);
+#endif
 
   t = out_len / k;
   d = out_len % k;
 
   /* K(1) */
-  plain_len = k + ctx_len + 1;
-  plain = GNUNET_malloc (plain_len);
-  if (t > 0)
+  {
+    size_t plain_len = k + ctx_len + 1;
+    char plain[plain_len];
+    const void *ctx;
+    char *dst;
+
+    dst = plain + k;
+    va_copy (args, argp);
+    while ((ctx = va_arg (args, void *)))
     {
-      memcpy (plain, ctx, ctx_len);
-      memset (plain + ctx_len, 1, 1);
-      gcry_md_reset (prf);
-dump(plain, plain_len);
-      hc = doHMAC (prf, prk, xtr_len, plain, ctx_len + 1);
+      size_t len;
+
+      len = va_arg (args, size_t);
+      memcpy (dst, ctx, len);
+      dst += len;
+    }
+    va_end (args);
+
+    if (t > 0)
+    {
+      memset (plain + k + ctx_len, 1, 1);
+#if DEBUG_HKDF
+      dump ("K(1)", plain, plain_len);
+#endif
+      hc = doHMAC (prf, prk, xtr_len, &plain[k], ctx_len + 1);
       if (hc == NULL)
         goto hkdf_error;
       memcpy (result, hc, k);
       result += k;
     }
 
-  if (t > 1 || d > 0)
-    memcpy (plain + k, ctx, ctx_len);
-
-  /* K(i+1) */
-  for (i = 1; i < t; i++)
+    /* K(i+1) */
+    for (i = 1; i < t; i++)
     {
       memcpy (plain, result - k, k);
       memset (plain + k + ctx_len, i + 1, 1);
       gcry_md_reset (prf);
-dump(plain, plain_len);
+#if DEBUG_HKDF
+      dump ("K(i+1)", plain, plain_len);
+#endif
       hc = doHMAC (prf, prk, xtr_len, plain, plain_len);
       if (hc == NULL)
         goto hkdf_error;
@@ -168,29 +230,37 @@ dump(plain, plain_len);
       result += k;
     }
 
-  /* K(t):d */
-  if (d > 0)
+    /* K(t):d */
+    if (d > 0)
     {
       if (t > 0)
+      {
         memcpy (plain, result - k, k);
-      memset (plain + k + ctx_len, i + 1, 1);
+        i++;
+      }
+      memset (plain + k + ctx_len, i, 1);
       gcry_md_reset (prf);
-dump(plain, plain_len);
-      hc = doHMAC (prf, prk, xtr_len, plain, plain_len);
+#if DEBUG_HKDF
+      dump ("K(t):d", plain, plain_len);
+#endif
+      if (t > 0)
+        hc = doHMAC (prf, prk, xtr_len, plain, plain_len);
+      else
+        hc = doHMAC (prf, prk, xtr_len, plain + k, plain_len - k);
       if (hc == NULL)
         goto hkdf_error;
       memcpy (result, hc, d);
     }
-dump(result - k, out_len);
-
-  ret = GNUNET_YES;
-  goto hkdf_ok;
+#if DEBUG_HKDF
+    dump ("result", result - k, out_len);
+#endif
 
+    ret = GNUNET_YES;
+    goto hkdf_ok;
+  }
 hkdf_error:
   ret = GNUNET_SYSERR;
 hkdf_ok:
-  GNUNET_free (prk);
-  GNUNET_free_non_null (plain);
   gcry_md_close (prf);
   gcry_md_close (xtr);
 
@@ -198,4 +268,33 @@ hkdf_ok:
 }
 
 
+/**
+ * @brief Derive key
+ * @param result buffer for the derived key, allocated by caller
+ * @param out_len desired length of the derived key
+ * @param xtr_algo hash algorithm for the extraction phase, GCRY_MD_...
+ * @param prf_algo hash algorithm for the expansion phase, GCRY_MD_...
+ * @param xts salt
+ * @param xts_len length of xts
+ * @param skm source key material
+ * @param skm_len length of skm
+ * @return GNUNET_YES on success
+ */
+int
+GNUNET_CRYPTO_hkdf (void *result, size_t out_len, int xtr_algo, int prf_algo,
+                    const void *xts, size_t xts_len, const void *skm,
+                    size_t skm_len, ...)
+{
+  va_list argp;
+  int ret;
+
+  va_start (argp, skm_len);
+  ret =
+      GNUNET_CRYPTO_hkdf_v (result, out_len, xtr_algo, prf_algo, xts, xts_len,
+                            skm, skm_len, argp);
+  va_end (argp);
+
+  return ret;
+}
+
 /* end of crypto_hkdf.c */