Botan::PKCS7_Padding Class Reference

#include <mode_pad.h>

Inheritance diagram for Botan::PKCS7_Padding:

Public Member Functions
std::string	name () const
void	pad (byte[], size_t, size_t) const
virtual size_t	pad_bytes (size_t block_size, size_t position) const
size_t	unpad (const byte[], size_t) const
bool	valid_blocksize (size_t) const

Detailed Description

PKCS#7 Padding

Definition at line 72 of file mode_pad.h.

Member Function Documentation

name()

std::string Botan::PKCS7_Padding::name ( ) const

inlinevirtual

Returns

name of the mode

Implements Botan::BlockCipherModePaddingMethod.

Definition at line 78 of file mode_pad.h.

{ return "PKCS7"; }

Referenced by unpad().

pad()

void Botan::PKCS7_Padding::pad ( byte block[], size_t size, size_t current_position ) const

virtual

Parameters

block	output buffer
size	of the block
current_position	in the last block

Implements Botan::BlockCipherModePaddingMethod.

Definition at line 25 of file mode_pad.cpp.

   {
   const size_t bytes_remaining = size - position;
   const byte pad_value = static_cast<byte>(bytes_remaining);
 
   BOTAN_ASSERT_EQUAL(pad_value, bytes_remaining,
                      "Overflow in PKCS7_Padding");
 
   for(size_t j = 0; j != size; ++j)
      block[j] = pad_value;
   }

References BOTAN_ASSERT_EQUAL.

pad_bytes()

size_t Botan::BlockCipherModePaddingMethod::pad_bytes ( size_t block_size, size_t position ) const

virtualinherited

Parameters

block_size	of the cipher
position	in the current block

Returns

number of padding bytes that will be appended

Reimplemented in Botan::Null_Padding.

Definition at line 17 of file mode_pad.cpp.

   {
   return (bs - pos);
   }

Referenced by unpad().

unpad()

size_t Botan::PKCS7_Padding::unpad ( const byte block[], size_t size ) const

virtual

Parameters

block	the last block
size	the of the block

Implements Botan::BlockCipherModePaddingMethod.

Definition at line 40 of file mode_pad.cpp.

   {
   size_t position = block[size-1];
   if(position > size)
      throw Decoding_Error(name());
   for(size_t j = size-position; j != size-1; ++j)
      if(block[j] != position)
         throw Decoding_Error(name());
   return (size-position);
   }

References Botan::Decoding_Error::Decoding_Error(), and name().

valid_blocksize()

bool Botan::PKCS7_Padding::valid_blocksize ( size_t block_size ) const

virtual

Parameters

block_size

of the cipher

Returns

valid block size for this padding mode

Implements Botan::BlockCipherModePaddingMethod.

Definition at line 54 of file mode_pad.cpp.

   {
   if(size > 0 && size < 256)
      return true;
   else
      return false;
   }

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

• src/filters/modes/mode_pad/mode_pad.h
• src/filters/modes/mode_pad/mode_pad.cpp