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/*************************************************
* CBC Padding Methods Source File *
* (C) 1999-2008 The Botan Project *
*************************************************/
#include <botan/mode_pad.h>
#include <botan/util.h>
namespace Botan {
/*************************************************
* Default amount of padding *
*************************************************/
u32bit BlockCipherModePaddingMethod::pad_bytes(u32bit bs, u32bit pos) const
{
return (bs - pos);
}
/*************************************************
* Pad with PKCS #7 Method *
*************************************************/
void PKCS7_Padding::pad(byte block[], u32bit size, u32bit position) const
{
for(u32bit j = 0; j != size; ++j)
block[j] = (size-position);
}
/*************************************************
* Unpad with PKCS #7 Method *
*************************************************/
u32bit PKCS7_Padding::unpad(const byte block[], u32bit size) const
{
u32bit position = block[size-1];
if(position > size)
throw Decoding_Error(name());
for(u32bit j = size-position; j != size-1; ++j)
if(block[j] != position)
throw Decoding_Error(name());
return (size-position);
}
/*************************************************
* Query if the size is valid for this method *
*************************************************/
bool PKCS7_Padding::valid_blocksize(u32bit size) const
{
if(size > 0 && size < 256)
return true;
else
return false;
}
/*************************************************
* Pad with ANSI X9.23 Method *
*************************************************/
void ANSI_X923_Padding::pad(byte block[], u32bit size, u32bit position) const
{
for(u32bit j = 0; j != size-position; ++j)
block[j] = 0;
block[size-position-1] = (size-position);
}
/*************************************************
* Unpad with ANSI X9.23 Method *
*************************************************/
u32bit ANSI_X923_Padding::unpad(const byte block[], u32bit size) const
{
u32bit position = block[size-1];
if(position > size)
throw Decoding_Error(name());
for(u32bit j = size-position; j != size-1; ++j)
if(block[j] != 0)
throw Decoding_Error(name());
return (size-position);
}
/*************************************************
* Query if the size is valid for this method *
*************************************************/
bool ANSI_X923_Padding::valid_blocksize(u32bit size) const
{
if(size > 0 && size < 256)
return true;
else
return false;
}
/*************************************************
* Pad with One and Zeros Method *
*************************************************/
void OneAndZeros_Padding::pad(byte block[], u32bit size, u32bit) const
{
block[0] = 0x80;
for(u32bit j = 1; j != size; ++j)
block[j] = 0x00;
}
/*************************************************
* Unpad with One and Zeros Method *
*************************************************/
u32bit OneAndZeros_Padding::unpad(const byte block[], u32bit size) const
{
while(size)
{
if(block[size-1] == 0x80)
break;
if(block[size-1] != 0x00)
throw Decoding_Error(name());
size--;
}
if(!size)
throw Decoding_Error(name());
return (size-1);
}
/*************************************************
* Query if the size is valid for this method *
*************************************************/
bool OneAndZeros_Padding::valid_blocksize(u32bit size) const
{
if(size) return true;
else return false;
}
}
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