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/*
* ECB/CBC Padding Methods
* (C) 1999-2008,2013 Jack Lloyd
* (C) 2016 René Korthaus, Rohde & Schwarz Cybersecurity
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_MODE_PADDING_H__
#define BOTAN_MODE_PADDING_H__
#include <botan/secmem.h>
#include <string>
namespace Botan {
/**
* Block Cipher Mode Padding Method
* This class is pretty limited, it cannot deal well with
* randomized padding methods, or any padding method that
* wants to add more than one block. For instance, it should
* be possible to define cipher text stealing mode as simply
* a padding mode for CBC, which happens to consume the last
* two block (and requires use of the block cipher).
*/
class BOTAN_DLL BlockCipherModePaddingMethod
{
public:
/**
* Add padding bytes to buffer.
* @param buffer data to pad
* @param final_block_bytes size of the final block in bytes
* @param block_size size of each block in bytes
*/
virtual void add_padding(secure_vector<byte>& buffer,
size_t final_block_bytes,
size_t block_size) const = 0;
/**
* Remove padding bytes from block
* @param block the last block
* @param size the size of the block in bytes
* @return number of padding bytes
*/
virtual size_t unpad(const byte block[],
size_t size) const = 0;
/**
* @param block_size of the cipher
* @return valid block size for this padding mode
*/
virtual bool valid_blocksize(size_t block_size) const = 0;
/**
* @return name of the mode
*/
virtual std::string name() const = 0;
/**
* virtual destructor
*/
virtual ~BlockCipherModePaddingMethod() {}
};
/**
* PKCS#7 Padding
*/
class BOTAN_DLL PKCS7_Padding final : public BlockCipherModePaddingMethod
{
public:
void add_padding(secure_vector<byte>& buffer,
size_t final_block_bytes,
size_t block_size) const override;
size_t unpad(const byte[], size_t) const override;
bool valid_blocksize(size_t bs) const override { return (bs > 0 && bs < 256); }
std::string name() const override { return "PKCS7"; }
};
/**
* ANSI X9.23 Padding
*/
class BOTAN_DLL ANSI_X923_Padding final : public BlockCipherModePaddingMethod
{
public:
void add_padding(secure_vector<byte>& buffer,
size_t final_block_bytes,
size_t block_size) const override;
size_t unpad(const byte[], size_t) const override;
bool valid_blocksize(size_t bs) const override { return (bs > 0 && bs < 256); }
std::string name() const override { return "X9.23"; }
};
/**
* One And Zeros Padding (ISO/IEC 7816-4)
*/
class BOTAN_DLL OneAndZeros_Padding final : public BlockCipherModePaddingMethod
{
public:
void add_padding(secure_vector<byte>& buffer,
size_t final_block_bytes,
size_t block_size) const override;
size_t unpad(const byte[], size_t) const override;
bool valid_blocksize(size_t bs) const override { return (bs > 0); }
std::string name() const override { return "OneAndZeros"; }
};
/**
* ESP Padding (RFC 4304)
*/
class BOTAN_DLL ESP_Padding final : public BlockCipherModePaddingMethod
{
public:
void add_padding(secure_vector<byte>& buffer,
size_t final_block_bytes,
size_t block_size) const override;
size_t unpad(const byte[], size_t) const override;
bool valid_blocksize(size_t bs) const override { return (bs > 0); }
std::string name() const override { return "ESP"; }
};
/**
* Null Padding
*/
class BOTAN_DLL Null_Padding final : public BlockCipherModePaddingMethod
{
public:
void add_padding(secure_vector<byte>&, size_t, size_t) const override {}
size_t unpad(const byte[], size_t size) const override { return size; }
bool valid_blocksize(size_t) const override { return true; }
std::string name() const override { return "NoPadding"; }
};
/**
* Get a block cipher padding mode by name (eg "NoPadding" or "PKCS7")
* @param algo_spec block cipher padding mode name
*/
BOTAN_DLL BlockCipherModePaddingMethod* get_bc_pad(const std::string& algo_spec);
}
#endif
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