1 files changed, 95 insertions, 0 deletions
diff --git a/src/pk_pad/eme1/eme1.cpp b/src/pk_pad/eme1/eme1.cpp
new file mode 100644
index 000000000..2ca10c166
--- /dev/null
+++ b/src/pk_pad/eme1/eme1.cpp
@@ -0,0 +1,95 @@
+/*************************************************
+* EME1 Source File                               *
+* (C) 1999-2007 Jack Lloyd                       *
+*************************************************/
+
+#include <botan/eme1.h>
+#include <botan/lookup.h>
+#include <memory>
+
+namespace Botan {
+
+/*************************************************
+* EME1 Pad Operation                             *
+*************************************************/
+SecureVector<byte> EME1::pad(const byte in[], u32bit in_length,
+                             u32bit key_length,
+                             RandomNumberGenerator& rng) const
+   {
+   key_length /= 8;
+
+   if(in_length > key_length - 2*HASH_LENGTH - 1)
+      throw Exception("EME1: Input is too large");
+
+   SecureVector<byte> out(key_length);
+
+   out.clear();
+
+   rng.randomize(out, HASH_LENGTH);
+
+   out.copy(HASH_LENGTH, Phash, Phash.size());
+   out[out.size() - in_length - 1] = 0x01;
+   out.copy(out.size() - in_length, in, in_length);
+   mgf->mask(out, HASH_LENGTH, out + HASH_LENGTH, out.size() - HASH_LENGTH);
+   mgf->mask(out + HASH_LENGTH, out.size() - HASH_LENGTH, out, HASH_LENGTH);
+
+   return out;
+   }
+
+/*************************************************
+* EME1 Unpad Operation                           *
+*************************************************/
+SecureVector<byte> EME1::unpad(const byte in[], u32bit in_length,
+                               u32bit key_length) const
+   {
+   key_length /= 8;
+   if(in_length > key_length)
+      throw Decoding_Error("Invalid EME1 encoding");
+
+   SecureVector<byte> tmp(key_length);
+   tmp.copy(key_length - in_length, in, in_length);
+
+   mgf->mask(tmp + HASH_LENGTH, tmp.size() - HASH_LENGTH, tmp, HASH_LENGTH);
+   mgf->mask(tmp, HASH_LENGTH, tmp + HASH_LENGTH, tmp.size() - HASH_LENGTH);
+
+   for(u32bit j = 0; j != Phash.size(); ++j)
+      if(tmp[j+HASH_LENGTH] != Phash[j])
+         throw Decoding_Error("Invalid EME1 encoding");
+
+   for(u32bit j = HASH_LENGTH + Phash.size(); j != tmp.size(); ++j)
+      {
+      if(tmp[j] && tmp[j] != 0x01)
+         throw Decoding_Error("Invalid EME1 encoding");
+      if(tmp[j] && tmp[j] == 0x01)
+         {
+         SecureVector<byte> retval(tmp + j + 1, tmp.size() - j - 1);
+         return retval;
+         }
+      }
+   throw Decoding_Error("Invalid EME1 encoding");
+   }
+
+/*************************************************
+* Return the max input size for a given key size *
+*************************************************/
+u32bit EME1::maximum_input_size(u32bit keybits) const
+   {
+   if(keybits / 8 > 2*HASH_LENGTH + 1)
+      return ((keybits / 8) - 2*HASH_LENGTH - 1);
+   else
+      return 0;
+   }
+
+/*************************************************
+* EME1 Constructor                               *
+*************************************************/
+EME1::EME1(const std::string& hash_name, const std::string& mgf_name,
+           const std::string& P) :
+   HASH_LENGTH(output_length_of(hash_name))
+   {
+   mgf = get_mgf(mgf_name + "(" + hash_name + ")");
+   std::auto_ptr<HashFunction> hash(get_hash(hash_name));
+   Phash = hash->process(P);
+   }
+
+}