3 files changed, 158 insertions, 0 deletions
diff --git a/lib/pk_pad/emsa1/emsa1.cpp b/lib/pk_pad/emsa1/emsa1.cpp
new file mode 100644
index 000000000..2358023f8
--- /dev/null
+++ b/lib/pk_pad/emsa1/emsa1.cpp
@@ -0,0 +1,105 @@
+/*
+* EMSA1
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/emsa1.h>
+
+namespace Botan {
+
+namespace {
+
+secure_vector<byte> emsa1_encoding(const secure_vector<byte>& msg,
+                                  size_t output_bits)
+   {
+   if(8*msg.size() <= output_bits)
+      return msg;
+
+   size_t shift = 8*msg.size() - output_bits;
+
+   size_t byte_shift = shift / 8, bit_shift = shift % 8;
+   secure_vector<byte> digest(msg.size() - byte_shift);
+
+   for(size_t j = 0; j != msg.size() - byte_shift; ++j)
+      digest[j] = msg[j];
+
+   if(bit_shift)
+      {
+      byte carry = 0;
+      for(size_t j = 0; j != digest.size(); ++j)
+         {
+         byte temp = digest[j];
+         digest[j] = (temp >> bit_shift) | carry;
+         carry = (temp << (8 - bit_shift));
+         }
+      }
+   return digest;
+   }
+
+}
+
+/*
+* EMSA1 Update Operation
+*/
+void EMSA1::update(const byte input[], size_t length)
+   {
+   hash->update(input, length);
+   }
+
+/*
+* Return the raw (unencoded) data
+*/
+secure_vector<byte> EMSA1::raw_data()
+   {
+   return hash->final();
+   }
+
+/*
+* EMSA1 Encode Operation
+*/
+secure_vector<byte> EMSA1::encoding_of(const secure_vector<byte>& msg,
+                                      size_t output_bits,
+                                      RandomNumberGenerator&)
+   {
+   if(msg.size() != hash->output_length())
+      throw Encoding_Error("EMSA1::encoding_of: Invalid size for input");
+   return emsa1_encoding(msg, output_bits);
+   }
+
+/*
+* EMSA1 Decode/Verify Operation
+*/
+bool EMSA1::verify(const secure_vector<byte>& coded,
+                   const secure_vector<byte>& raw, size_t key_bits)
+   {
+   try {
+      if(raw.size() != hash->output_length())
+         throw Encoding_Error("EMSA1::encoding_of: Invalid size for input");
+
+      secure_vector<byte> our_coding = emsa1_encoding(raw, key_bits);
+
+      if(our_coding == coded) return true;
+      if(our_coding.empty() || our_coding[0] != 0) return false;
+      if(our_coding.size() <= coded.size()) return false;
+
+      size_t offset = 0;
+      while(offset < our_coding.size() && our_coding[offset] == 0)
+         ++offset;
+      if(our_coding.size() - offset != coded.size())
+         return false;
+
+      for(size_t j = 0; j != coded.size(); ++j)
+         if(coded[j] != our_coding[j+offset])
+            return false;
+
+      return true;
+      }
+   catch(Invalid_Argument)
+      {
+      return false;
+      }
+   }
+
+}
diff --git a/lib/pk_pad/emsa1/emsa1.h b/lib/pk_pad/emsa1/emsa1.h
new file mode 100644
index 000000000..f84ca5ae7
--- /dev/null
+++ b/lib/pk_pad/emsa1/emsa1.h
@@ -0,0 +1,48 @@
+/*
+* EMSA1
+* (C) 1999-2007 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_EMSA1_H__
+#define BOTAN_EMSA1_H__
+
+#include <botan/emsa.h>
+#include <botan/hash.h>
+
+namespace Botan {
+
+/**
+* EMSA1 from IEEE 1363
+* Essentially, sign the hash directly
+*/
+class BOTAN_DLL EMSA1 : public EMSA
+   {
+   public:
+      /**
+      * @param h the hash object to use
+      */
+      EMSA1(HashFunction* h) : hash(h) {}
+      ~EMSA1() { delete hash; }
+   protected:
+      /**
+      * @return const pointer to the underlying hash
+      */
+      const HashFunction* hash_ptr() const { return hash; }
+   private:
+      void update(const byte[], size_t);
+      secure_vector<byte> raw_data();
+
+      secure_vector<byte> encoding_of(const secure_vector<byte>&, size_t,
+                                     RandomNumberGenerator& rng);
+
+      bool verify(const secure_vector<byte>&, const secure_vector<byte>&,
+                  size_t);
+
+      HashFunction* hash;
+   };
+
+}
+
+#endif
diff --git a/lib/pk_pad/emsa1/info.txt b/lib/pk_pad/emsa1/info.txt
new file mode 100644
index 000000000..83d9744e6
--- /dev/null
+++ b/lib/pk_pad/emsa1/info.txt
@@ -0,0 +1,5 @@
+define EMSA1 20131128
+
+<requires>
+hash
+</requires>