Botan::Buffered_Filter Class Reference

#include <buf_filt.h>

Inheritance diagram for Botan::Buffered_Filter:

Public Member Functions
	Buffered_Filter (size_t block_size, size_t final_minimum)
void	end_msg ()
void	write (const byte in[], size_t length)
virtual	~Buffered_Filter ()

Protected Member Functions
void	buffer_reset ()
virtual void	buffered_block (const byte input[], size_t length)=0
size_t	buffered_block_size () const
virtual void	buffered_final (const byte input[], size_t length)=0
size_t	current_position () const

Detailed Description

Filter mixin that breaks input into blocks, useful for cipher modes

Definition at line 19 of file buf_filt.h.

Constructor & Destructor Documentation

Buffered_Filter()

Botan::Buffered_Filter::Buffered_Filter	(	size_t	block_size,
		size_t	final_minimum )

Initialize a Buffered_Filter

Parameters

block_size	the function buffered_block will be called with inputs which are a multiple of this size
final_minimum	the function buffered_final will be called with at least this many bytes.

Definition at line 18 of file buf_filt.cpp.

                                                   :
   main_block_mod(b), final_minimum(f)
   {
   if(main_block_mod == 0)
      throw std::invalid_argument("main_block_mod == 0");
 
   if(final_minimum > main_block_mod)
      throw std::invalid_argument("final_minimum > main_block_mod");
 
   buffer.resize(2 * main_block_mod);
   buffer_pos = 0;
   }

Referenced by Botan::CBC_Decryption::CBC_Decryption(), Botan::CBC_Decryption::CBC_Decryption(), Botan::CBC_Encryption::CBC_Encryption(), Botan::CBC_Encryption::CBC_Encryption(), Botan::ECB_Decryption::ECB_Decryption(), Botan::ECB_Decryption::ECB_Decryption(), Botan::ECB_Encryption::ECB_Encryption(), Botan::ECB_Encryption::ECB_Encryption(), Botan::XTS_Decryption::XTS_Decryption(), Botan::XTS_Decryption::XTS_Decryption(), Botan::XTS_Encryption::XTS_Encryption(), and Botan::XTS_Encryption::XTS_Encryption().

~Buffered_Filter()

virtual Botan::Buffered_Filter::~Buffered_Filter ( )

inlinevirtual

Definition at line 46 of file buf_filt.h.

{}

Member Function Documentation

buffer_reset()

void Botan::Buffered_Filter::buffer_reset ( )

inlineprotected

Reset the buffer position

Definition at line 77 of file buf_filt.h.

{ buffer_pos = 0; }

Referenced by Botan::CBC_Decryption::set_iv(), and Botan::CBC_Encryption::set_iv().

buffered_block()

virtual void Botan::Buffered_Filter::buffered_block ( const byte input[], size_t length )

protectedpure virtual

The block processor, implemented by subclasses

Parameters

input	some input bytes
length	the size of input, guaranteed to be a multiple of block_size

Referenced by end_msg(), and write().

buffered_block_size()

size_t Botan::Buffered_Filter::buffered_block_size ( ) const

inlineprotected

Returns

block size of inputs

Definition at line 67 of file buf_filt.h.

{ return main_block_mod; }

Referenced by Botan::CBC_Decryption::CBC_Decryption(), Botan::CBC_Decryption::CBC_Decryption(), Botan::ECB_Decryption::ECB_Decryption(), Botan::ECB_Decryption::ECB_Decryption(), Botan::ECB_Encryption::ECB_Encryption(), Botan::ECB_Encryption::ECB_Encryption(), Botan::XTS_Decryption::XTS_Decryption(), Botan::XTS_Decryption::XTS_Decryption(), Botan::XTS_Encryption::XTS_Encryption(), and Botan::XTS_Encryption::XTS_Encryption().

buffered_final()

virtual void Botan::Buffered_Filter::buffered_final ( const byte input[], size_t length )

protectedpure virtual

The final block, implemented by subclasses

Parameters

input	some input bytes
length	the size of input, guaranteed to be at least final_minimum bytes

Referenced by end_msg().

current_position()

size_t Botan::Buffered_Filter::current_position ( ) const

inlineprotected

Returns

current position in the buffer

Definition at line 72 of file buf_filt.h.

{ return buffer_pos; }

end_msg()

void Botan::Buffered_Filter::end_msg

(

)

Finish a message, emitting to buffered_block and buffered_final Will throw an exception if less than final_minimum bytes were written into the filter.

Definition at line 82 of file buf_filt.cpp.

   {
   if(buffer_pos < final_minimum)
      throw std::runtime_error("Buffered filter end_msg without enough input");
 
   size_t spare_blocks = (buffer_pos - final_minimum) / main_block_mod;
 
   if(spare_blocks)
      {
      size_t spare_bytes = main_block_mod * spare_blocks;
      buffered_block(&buffer[0], spare_bytes);
      buffered_final(&buffer[spare_bytes], buffer_pos - spare_bytes);
      }
   else
      {
      buffered_final(&buffer[0], buffer_pos);
      }
 
   buffer_pos = 0;
   }

References buffered_block(), and buffered_final().

write()

void Botan::Buffered_Filter::write	(	const byte	in[],
		size_t	length )

Write bytes into the buffered filter, which will them emit them in calls to buffered_block in the subclass

Parameters

in	the input bytes
length	of in in bytes

Definition at line 34 of file buf_filt.cpp.

   {
   if(!input_size)
      return;
 
   if(buffer_pos + input_size >= main_block_mod + final_minimum)
      {
      size_t to_copy = std::min<size_t>(buffer.size() - buffer_pos, input_size);
 
      copy_mem(&buffer[buffer_pos], input, to_copy);
      buffer_pos += to_copy;
 
      input += to_copy;
      input_size -= to_copy;
 
      size_t total_to_consume =
         round_down(std::min(buffer_pos,
                             buffer_pos + input_size - final_minimum),
                    main_block_mod);
 
      buffered_block(&buffer[0], total_to_consume);
 
      buffer_pos -= total_to_consume;
 
      copy_mem(&buffer[0], &buffer[total_to_consume], buffer_pos);
      }
 
   if(input_size >= final_minimum)
      {
      size_t full_blocks = (input_size - final_minimum) / main_block_mod;
      size_t to_copy = full_blocks * main_block_mod;
 
      if(to_copy)
         {
         buffered_block(input, to_copy);
 
         input += to_copy;
         input_size -= to_copy;
         }
      }
 
   copy_mem(&buffer[buffer_pos], input, input_size);
   buffer_pos += input_size;
   }

References buffered_block(), Botan::copy_mem(), and Botan::round_down().

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The documentation for this class was generated from the following files:

• src/filters/buf_filt.h
• src/filters/buf_filt.cpp