Botan::Null_Padding Class Reference

#include <mode_pad.h>

Inheritance diagram for Botan::Null_Padding:

Public Member Functions
void	add_padding (std::span< uint8_t >, size_t, size_t) const override
std::string	name () const override
size_t	output_length (size_t input_length, size_t) const override
size_t	remove_padding (std::span< const uint8_t > last_block) const override
size_t	unpad (std::span< const uint8_t > last_block) const
bool	valid_blocksize (size_t) const override

Static Public Member Functions
static std::unique_ptr< BlockCipherModePaddingMethod >	create (std::string_view algo_spec)

Detailed Description

Null Padding

Definition at line 162 of file mode_pad.h.

Member Function Documentation

add_padding()

void Botan::Null_Padding::add_padding ( std::span< uint8_t > buffer, size_t final_block_bytes, size_t block_size ) const

inlineoverridevirtual

Add padding bytes to buffer.

Parameters

buffer	data to pad, span must be large enough to hold the padding behind the final (partial) block
final_block_bytes	size of the final block in bytes
block_size	size of each block in bytes

Reimplemented from Botan::BlockCipherModePaddingMethod.

Definition at line 164 of file mode_pad.h.

                                                {
         // no padding
      }

create()

std::unique_ptr< BlockCipherModePaddingMethod > Botan::BlockCipherModePaddingMethod::create ( std::string_view algo_spec )

staticinherited

Get a block cipher padding mode by name (eg "NoPadding" or "PKCS7")

Parameters

algo_spec

block cipher padding mode name

Get a block cipher padding method by name

Definition at line 20 of file mode_pad.cpp.

                                                                                                         {
   if(algo_spec == "NoPadding") {
      return std::make_unique<Null_Padding>();
   }
 
   if(algo_spec == "PKCS7") {
      return std::make_unique<PKCS7_Padding>();
   }
 
   if(algo_spec == "OneAndZeros") {
      return std::make_unique<OneAndZeros_Padding>();
   }
 
   if(algo_spec == "X9.23") {
      return std::make_unique<ANSI_X923_Padding>();
   }
 
   if(algo_spec == "ESP") {
      return std::make_unique<ESP_Padding>();
   }
 
   return nullptr;
}

Referenced by Botan::Cipher_Mode::create().

name()

std::string Botan::Null_Padding::name ( ) const

inlineoverridevirtual

Returns

name of the mode

Implements Botan::BlockCipherModePaddingMethod.

Definition at line 176 of file mode_pad.h.

{ return "NoPadding"; }

output_length()

size_t Botan::Null_Padding::output_length ( size_t input_length, size_t block_size ) const

inlineoverridevirtual

Parameters

input_length	number of bytes to be padded
block_size	size of each block in bytes

Returns

the total number of output bytes (including the padding)

Reimplemented from Botan::BlockCipherModePaddingMethod.

Definition at line 174 of file mode_pad.h.

{ return input_length; }

remove_padding()

size_t Botan::Null_Padding::remove_padding ( std::span< const uint8_t > last_block ) const

inlineoverridevirtual

Removes the padding from last_block and returns the number of data bytes. If the padding is invalid, this returns the byte length of last_block.

Concrete implementations of this function must ensure not to leak the size or validity of the padding via side channels. The bytes of last_block are passed in with CT::poison applied to them.

Implements Botan::BlockCipherModePaddingMethod.

Definition at line 170 of file mode_pad.h.

{ return last_block.size(); }

unpad()

size_t Botan::BlockCipherModePaddingMethod::unpad ( std::span< const uint8_t > last_block ) const

inherited

Remove padding bytes from block

Parameters

last_block

the last block containing the padding

Returns

number of data bytes, or if the padding is invalid returns the byte length of last_block (i.e. the block size)

Definition at line 54 of file mode_pad.cpp.

                                                                                  {
   if(!valid_blocksize(last_block.size())) {
      return last_block.size();
   }
 
   auto poison = CT::scoped_poison(last_block);
   return CT::driveby_unpoison(remove_padding(last_block));
}

References Botan::CT::driveby_unpoison(), remove_padding(), Botan::CT::scoped_poison(), and valid_blocksize().

valid_blocksize()

bool Botan::Null_Padding::valid_blocksize ( size_t block_size ) const

inlineoverridevirtual

Parameters

block_size

of the cipher

Returns

valid block size for this padding mode

Implements Botan::BlockCipherModePaddingMethod.

Definition at line 172 of file mode_pad.h.

{ return true; }

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

• src/lib/modes/mode_pad/mode_pad.h