1 files changed, 93 insertions, 0 deletions
diff --git a/src/sym_algo/sym_algo.h b/src/sym_algo/sym_algo.h
new file mode 100644
index 000000000..02343ed56
--- /dev/null
+++ b/src/sym_algo/sym_algo.h
@@ -0,0 +1,93 @@
+/**
+* Symmetric Algorithm Base Class
+* (C) 1999-2007 Jack Lloyd
+*/
+
+#ifndef BOTAN_SYMMETRIC_ALGORITHM_H__
+#define BOTAN_SYMMETRIC_ALGORITHM_H__
+
+#include <botan/types.h>
+#include <botan/exceptn.h>
+#include <botan/symkey.h>
+
+namespace Botan {
+
+/**
+* This class represents a symmetric algorithm object.
+*/
+class BOTAN_DLL SymmetricAlgorithm
+   {
+   public:
+
+      /**
+      * The maximum allowed key length.
+      */
+      const u32bit MAXIMUM_KEYLENGTH;
+
+      /**
+      * The minimal allowed key length.
+      */
+      const u32bit MINIMUM_KEYLENGTH;
+
+      /**
+      * A valid keylength is a multiple of this value.
+      */
+      const u32bit KEYLENGTH_MULTIPLE;
+
+      /**
+      * The name of the algorithm.
+      * @return the name of the algorithm
+      */
+      virtual std::string name() const = 0;
+
+      /**
+      * Set the symmetric key of this object.
+      * @param key the SymmetricKey to be set.
+      */
+      void set_key(const SymmetricKey& skey) throw(Invalid_Key_Length)
+         { set_key(skey.begin(), skey.length()); }
+
+      /**
+      * Set the symmetric key of this object.
+      * @param key the to be set as a byte array.
+      * @param the length of the byte array.
+      */
+      void set_key(const byte skey[], u32bit length) throw(Invalid_Key_Length)
+         {
+         if(!valid_keylength(length))
+            throw Invalid_Key_Length(name(), length);
+         key(skey, length);
+         }
+
+      /**
+      * Check whether a given key length is valid for this algorithm.
+      * @param length the key length to be checked.
+      * @return true if the key length is valid.
+      */
+      bool valid_keylength(u32bit length) const
+         {
+         return ((length >= MINIMUM_KEYLENGTH) &&
+                 (length <= MAXIMUM_KEYLENGTH) &&
+                 (length % KEYLENGTH_MULTIPLE == 0));
+         }
+
+      /**
+      * Construct a SymmetricAlgorithm.
+      * @param key_min the minimum allowed key length
+      * @param key_max the maximum allowed key length
+      * @param key_mod any valid key length must be a multiple of this value
+      */
+      SymmetricAlgorithm(u32bit key_min, u32bit key_max, u32bit key_mod) :
+         MAXIMUM_KEYLENGTH(key_max ? key_max : key_min),
+         MINIMUM_KEYLENGTH(key_min),
+         KEYLENGTH_MULTIPLE(key_mod)
+            {}
+
+      virtual ~SymmetricAlgorithm() {}
+   private:
+      virtual void key(const byte[], u32bit) = 0;
+   };
+
+}
+
+#endif