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/*
* Transformations of data
* (C) 2013 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#ifndef BOTAN_TRANSFORM_H__
#define BOTAN_TRANSFORM_H__
#include <botan/secmem.h>
#include <botan/key_spec.h>
#include <botan/exceptn.h>
#include <botan/symkey.h>
#include <string>
#include <vector>
namespace Botan {
/**
* Interface for general transformations on data
*/
class BOTAN_DLL Transformation
{
public:
/**
* Begin processing a message.
* @param nonce the per message nonce
*/
template<typename Alloc>
secure_vector<byte> start_vec(const std::vector<byte, Alloc>& nonce)
{
return start(&nonce[0], nonce.size());
}
/**
* Begin processing a message.
* @param nonce the per message nonce
* @param nonce_len length of nonce
*/
virtual secure_vector<byte> start(const byte nonce[], size_t nonce_len) = 0;
/**
* Process some data. Input must be in size update_granularity() byte blocks.
* @param blocks in/out paramter which will possibly be resized
* @param offset an offset into blocks to begin processing
*/
virtual void update(secure_vector<byte>& blocks, size_t offset = 0) = 0;
/**
* Complete processing of a message.
*
* @param final_block in/out parameter which must be at least
* minimum_final_size() bytes, and will be set to any final output
* @param offset an offset into final_block to begin processing
*/
virtual void finish(secure_vector<byte>& final_block, size_t offset = 0) = 0;
/**
* Returns the size of the output if this transform is used to process a
* message with input_length bytes. Will throw if unable to give a precise
* answer.
*/
virtual size_t output_length(size_t input_length) const = 0;
/**
* @return size of required blocks to update
*/
virtual size_t update_granularity() const = 0;
/**
* @return required minimium size to finalize() - may be any
* length larger than this.
*/
virtual size_t minimum_final_size() const = 0;
/**
* Return the default size for a nonce
*/
virtual size_t default_nonce_length() const = 0;
/**
* Return true iff nonce_len is a valid length for the nonce
*/
virtual bool valid_nonce_length(size_t nonce_len) const = 0;
/**
* Return some short name describing the provider of this tranformation.
* Useful in cases where multiple implementations are available (eg,
* different implementations of AES). Default "core" is used for the
* 'standard' implementation included in the library.
*/
virtual std::string provider() const { return "core"; }
virtual std::string name() const = 0;
virtual void clear() = 0;
virtual ~Transformation() {}
};
class BOTAN_DLL Keyed_Transform : public Transformation
{
public:
/**
* @return object describing limits on key size
*/
virtual Key_Length_Specification key_spec() const = 0;
/**
* 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(size_t length) const
{
return key_spec().valid_keylength(length);
}
template<typename Alloc>
void set_key(const std::vector<byte, Alloc>& key)
{
set_key(&key[0], key.size());
}
void set_key(const SymmetricKey& key)
{
set_key(key.begin(), key.length());
}
/**
* Set the symmetric key of this transform
* @param key contains the key material
* @param length in bytes of key param
*/
void set_key(const byte key[], size_t length)
{
if(!valid_keylength(length))
throw Invalid_Key_Length(name(), length);
key_schedule(key, length);
}
private:
virtual void key_schedule(const byte key[], size_t length) = 0;
};
}
#endif
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