# 
# add_file "hmac.cc"
# 
# add_file "hmac.hh"
# 
# patch "ChangeLog"
#  from [a7d78e5b4cb7e07bdf3aba7a92ea4fc609a03316]
#    to [5293c86ecc14f6f36a61630082f5cd634840d21f]
# 
# patch "hmac.cc"
#  from []
#    to [39bc2c1c84cb059b9d4095dd23daa369c33c4cbf]
# 
# patch "hmac.hh"
#  from []
#    to [1aca898a8a90b9054cd1b4c0e966b298854cc924]
# 
# patch "transforms.hh"
#  from [9fb4f54ab766397cc5a40885457b2ddbabbb300f]
#    to [10da66c1dec345841caf96a4c7bc2291b7d3ecb3]
# 
--- ChangeLog
+++ ChangeLog
@@ -1,5 +1,10 @@
 2005-06-26  Matt Johnston  <address@hidden>
 
+	* transforms.hh: remove extraneous #ifdef
+	* hmac.cc, hmac.hh: actually add them
+
+2005-06-26  Matt Johnston  <address@hidden>
+
 	* netcmd.cc (netcmd::read, netcmd::write): change to using a HMACs 
 	chained by including the previous HMAC in the input data, rather
 	than altering the key each time.
--- hmac.cc
+++ hmac.cc
@@ -0,0 +1,43 @@
+#include <string.h>
+
+#include "cryptopp/hmac.h"
+#include "cryptopp/sha.h"
+
+#include "sanity.hh"
+#include "hmac.hh"
+#include "vocab.hh"
+#include "constants.hh"
+
+chained_hmac::chained_hmac(netsync_session_key const & session_key) :
+  key(session_key)
+{
+  memset(chain_val, 0, sizeof(chain_val));
+}
+
+void
+chained_hmac::set_key(netsync_session_key const & session_key)
+{
+  key = session_key;
+}
+
+std::string
+chained_hmac::process(std::string const & str, size_t pos, size_t n)
+{
+  I(pos < str.size());
+  if (n == std::string::npos)
+    n = str.size() - pos;
+
+  I(pos + n <= str.size());
+
+  CryptoPP::HMAC<CryptoPP::SHA> 
+      hmac(reinterpret_cast<const byte *>(key().data()), 
+        constants::netsync_session_key_length_in_bytes);
+  hmac.Update(reinterpret_cast<const byte *>(chain_val), 
+              sizeof(chain_val));
+  hmac.Update(reinterpret_cast<const byte *>(str.data() + pos),
+              n);
+  hmac.Final(reinterpret_cast<byte *>(chain_val));
+  
+  std::string out(chain_val, sizeof(chain_val));
+  return out;
+}
--- hmac.hh
+++ hmac.hh
@@ -0,0 +1,28 @@
+#ifndef __HMAC_HH__
+#define __HMAC_HH__
+
+#include <string>
+
+#include "cryptopp/hmac.h"
+#include "cryptopp/sha.h"
+
+#include "vocab.hh"
+
+struct chained_hmac
+{
+  public:
+    chained_hmac(netsync_session_key const & session_key);
+    void set_key(netsync_session_key const & session_key);
+    std::string process(std::string const & str, size_t pos = 0, 
+        size_t n = std::string::npos);
+
+  private:
+    netsync_session_key key;
+    char chain_val[CryptoPP::SHA::DIGESTSIZE];
+};
+
+
+
+
+#endif // __HMAC_HH__
+
--- transforms.hh
+++ transforms.hh
@@ -78,7 +78,6 @@
 void encode_gzip(std::string const & in, gzip<T> & out)
 { out = xform<CryptoPP::Gzip>(in); }
 
-#endif
 // both at once (this is relatively common)
 
 template <typename T>