1 files changed, 106 insertions, 0 deletions
diff --git a/src/pk_pad/emsa2/emsa2.cpp b/src/pk_pad/emsa2/emsa2.cpp
new file mode 100644
index 000000000..24292d390
--- /dev/null
+++ b/src/pk_pad/emsa2/emsa2.cpp
@@ -0,0 +1,106 @@
+/*************************************************
+* EMSA2 Source File                              *
+* (C) 1999-2007 Jack Lloyd                       *
+*************************************************/
+
+#include <botan/emsa2.h>
+#include <botan/hash_id.h>
+#include <botan/lookup.h>
+
+namespace Botan {
+
+namespace {
+
+/*************************************************
+* EMSA2 Encode Operation                         *
+*************************************************/
+SecureVector<byte> emsa2_encoding(const MemoryRegion<byte>& msg,
+                                  u32bit output_bits,
+                                  const MemoryRegion<byte>& empty_hash,
+                                  byte hash_id)
+   {
+   const u32bit HASH_SIZE = empty_hash.size();
+
+   u32bit output_length = (output_bits + 1) / 8;
+
+   if(msg.size() != HASH_SIZE)
+      throw Encoding_Error("EMSA2::encoding_of: Bad input length");
+   if(output_length < HASH_SIZE + 4)
+      throw Encoding_Error("EMSA2::encoding_of: Output length is too small");
+
+   bool empty = true;
+   for(u32bit j = 0; j != HASH_SIZE; ++j)
+      if(empty_hash[j] != msg[j])
+         empty = false;
+
+   SecureVector<byte> output(output_length);
+
+   output[0] = (empty ? 0x4B : 0x6B);
+   output[output_length - 3 - HASH_SIZE] = 0xBA;
+   set_mem(output + 1, output_length - 4 - HASH_SIZE, 0xBB);
+   output.copy(output_length - (HASH_SIZE + 2), msg, msg.size());
+   output[output_length-2] = hash_id;
+   output[output_length-1] = 0xCC;
+
+   return output;
+   }
+
+}
+
+/*************************************************
+* EMSA2 Update Operation                         *
+*************************************************/
+void EMSA2::update(const byte input[], u32bit length)
+   {
+   hash->update(input, length);
+   }
+
+/*************************************************
+* Return the raw (unencoded) data                *
+*************************************************/
+SecureVector<byte> EMSA2::raw_data()
+   {
+   return hash->final();
+   }
+
+/*************************************************
+* EMSA2 Encode Operation                         *
+*************************************************/
+SecureVector<byte> EMSA2::encoding_of(const MemoryRegion<byte>& msg,
+                                      u32bit output_bits,
+                                      RandomNumberGenerator&)
+   {
+   return emsa2_encoding(msg, output_bits, empty_hash, hash_id);
+   }
+
+/*************************************************
+* EMSA2 Verify Operation                         *
+*************************************************/
+bool EMSA2::verify(const MemoryRegion<byte>& coded,
+                   const MemoryRegion<byte>& raw,
+                   u32bit key_bits) throw()
+   {
+   try
+      {
+      return (coded == emsa2_encoding(raw, key_bits,
+                                      empty_hash, hash_id));
+      }
+   catch(...)
+      {
+      return false;
+      }
+   }
+
+/*************************************************
+* EMSA2 Constructor                              *
+*************************************************/
+EMSA2::EMSA2(const std::string& hash_name)
+   {
+   hash_id = ieee1363_hash_id(hash_name);
+   if(hash_id == 0)
+      throw Encoding_Error("EMSA2 cannot be used with " + hash->name());
+   hash = get_hash(hash_name);
+   empty_hash = hash->final();
+   }
+
+}