Add block cipher cascade

1 files changed, 98 insertions, 0 deletions

diff --git a/src/block/cascade/cascade.cpp b/src/block/cascade/cascade.cpp
new file mode 100644
index 000000000..f72ef7b76
--- /dev/null
+++ b/src/block/cascade/cascade.cpp
@@ -0,0 +1,98 @@
+/*
+* Block Cipher Cascade
+* (C) 2010 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#include <botan/cascade.h>
+
+namespace Botan {
+
+void Cascade_Cipher::encrypt_n(const byte in[], byte out[],
+                               u32bit blocks) const
+   {
+   u32bit c1_blocks = blocks * (BLOCK_SIZE / cipher1->BLOCK_SIZE);
+   u32bit c2_blocks = blocks * (BLOCK_SIZE / cipher2->BLOCK_SIZE);
+
+   cipher1->encrypt_n(in, out, c1_blocks);
+   cipher2->encrypt_n(out, out, c2_blocks);
+   }
+
+void Cascade_Cipher::decrypt_n(const byte in[], byte out[],
+                               u32bit blocks) const
+   {
+   u32bit c1_blocks = blocks * (BLOCK_SIZE / cipher1->BLOCK_SIZE);
+   u32bit c2_blocks = blocks * (BLOCK_SIZE / cipher2->BLOCK_SIZE);
+
+   cipher2->decrypt_n(in, out, c2_blocks);
+   cipher1->decrypt_n(out, out, c1_blocks);
+   }
+
+void Cascade_Cipher::key_schedule(const byte key[], u32bit)
+   {
+   const byte* key2 = key + cipher1->MAXIMUM_KEYLENGTH;
+
+   cipher1->set_key(key , cipher1->MAXIMUM_KEYLENGTH);
+   cipher2->set_key(key2, cipher2->MAXIMUM_KEYLENGTH);
+   }
+
+void Cascade_Cipher::clear()
+   {
+   cipher1->clear();
+   cipher2->clear();
+   }
+
+std::string Cascade_Cipher::name() const
+   {
+   return "Cascade(" + cipher1->name() + "," + cipher2->name() + ")";
+   }
+
+BlockCipher* Cascade_Cipher::clone() const
+   {
+   return new Cascade_Cipher(cipher1->clone(),
+                             cipher2->clone());
+   }
+
+namespace {
+
+u32bit euclids_algorithm(u32bit a, u32bit b)
+   {
+   while(b != 0) // gcd
+      {
+      u32bit t = b;
+      b = a % b;
+      a = t;
+      }
+
+   return a;
+   }
+
+u32bit block_size_for_cascade(u32bit bs, u32bit bs2)
+   {
+   if(bs == bs2)
+      return bs;
+
+   u32bit gcd = euclids_algorithm(bs, bs2);
+
+   return (bs * bs2) / gcd;
+   }
+
+}
+
+Cascade_Cipher::Cascade_Cipher(BlockCipher* c1, BlockCipher* c2) :
+   BlockCipher(block_size_for_cascade(c1->BLOCK_SIZE, c2->BLOCK_SIZE),
+               c1->MAXIMUM_KEYLENGTH + c2->MAXIMUM_KEYLENGTH),
+   cipher1(c1), cipher2(c2)
+   {
+   if(BLOCK_SIZE % c1->BLOCK_SIZE || BLOCK_SIZE % c2->BLOCK_SIZE)
+      throw Internal_Error("Failure in " + name() + " constructor");
+   }
+
+Cascade_Cipher::~Cascade_Cipher()
+   {
+   delete cipher1;
+   delete cipher2;
+   }
+
+}