Botan  2.6.0
Crypto and TLS for C++11
Public Member Functions | List of all members
Botan::OneAndZeros_Padding Class Referencefinal

#include <mode_pad.h>

Inheritance diagram for Botan::OneAndZeros_Padding:
Botan::BlockCipherModePaddingMethod

Public Member Functions

void add_padding (secure_vector< uint8_t > &buffer, size_t final_block_bytes, size_t block_size) const override
 
std::string name () const override
 
size_t unpad (const uint8_t[], size_t) const override
 
bool valid_blocksize (size_t bs) const override
 

Detailed Description

One And Zeros Padding (ISO/IEC 9797-1, padding method 2)

Definition at line 102 of file mode_pad.h.

Member Function Documentation

◆ add_padding()

void Botan::OneAndZeros_Padding::add_padding ( secure_vector< uint8_t > &  buffer,
size_t  final_block_bytes,
size_t  block_size 
) const
overridevirtual

Add padding bytes to buffer.

Parameters
bufferdata to pad
final_block_bytessize of the final block in bytes
block_sizesize of each block in bytes

Implements Botan::BlockCipherModePaddingMethod.

Definition at line 119 of file mode_pad.cpp.

122  {
123  buffer.push_back(0x80);
124 
125  for(size_t i = last_byte_pos + 1; i % block_size; ++i)
126  buffer.push_back(0x00);
127  }

◆ name()

std::string Botan::OneAndZeros_Padding::name ( ) const
inlineoverridevirtual
Returns
name of the mode

Implements Botan::BlockCipherModePaddingMethod.

Definition at line 113 of file mode_pad.h.

113 { return "OneAndZeros"; }

◆ unpad()

size_t Botan::OneAndZeros_Padding::unpad ( const uint8_t  block[],
size_t  size 
) const
overridevirtual

Remove padding bytes from block

Parameters
blockthe last block
sizethe size of the block in bytes
Returns
number of padding bytes

Implements Botan::BlockCipherModePaddingMethod.

Definition at line 132 of file mode_pad.cpp.

References Botan::CT::conditional_copy_mem(), Botan::CT::poison(), and Botan::CT::unpoison().

133  {
134  CT::poison(block, size);
135  uint8_t bad_input = 0;
136  uint8_t seen_one = 0;
137  size_t pad_pos = size - 1;
138  size_t i = size;
139 
140  while(i)
141  {
142  seen_one |= CT::is_equal<uint8_t>(block[i-1],0x80);
143  pad_pos -= CT::select<uint8_t>(~seen_one, 1, 0);
144  bad_input |= ~CT::is_zero<uint8_t>(block[i-1]) & ~seen_one;
145  i--;
146  }
147  bad_input |= ~seen_one;
148 
149  CT::conditional_copy_mem(size_t(bad_input),&pad_pos,&size,&pad_pos,1);
150  CT::unpoison(block, size);
151  CT::unpoison(pad_pos);
152 
153  return pad_pos;
154  }
void conditional_copy_mem(T value, T *to, const T *from0, const T *from1, size_t elems)
Definition: ct_utils.h:142
void poison(const T *p, size_t n)
Definition: ct_utils.h:46
void unpoison(const T *p, size_t n)
Definition: ct_utils.h:57

◆ valid_blocksize()

bool Botan::OneAndZeros_Padding::valid_blocksize ( size_t  block_size) const
inlineoverridevirtual
Parameters
block_sizeof the cipher
Returns
valid block size for this padding mode

Implements Botan::BlockCipherModePaddingMethod.

Definition at line 111 of file mode_pad.h.

111 { return (bs > 0); }

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