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/*
* MGF1
* (C) 1999-2007 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/mgf1.h>
#include <botan/loadstor.h>
#include <botan/exceptn.h>
#include <botan/xor_buf.h>
#include <algorithm>
#include <memory>
namespace Botan {
/*
* MGF1 Mask Generation Function
*/
void MGF1::mask(const byte in[], u32bit in_len, byte out[],
u32bit out_len) const
{
u32bit counter = 0;
while(out_len)
{
hash->update(in, in_len);
for(u32bit j = 0; j != 4; ++j)
hash->update(get_byte(j, counter));
SecureVector<byte> buffer = hash->final();
u32bit xored = std::min(buffer.size(), out_len);
xor_buf(out, buffer.begin(), xored);
out += xored;
out_len -= xored;
++counter;
}
}
/*
* MGF1 Constructor
*/
MGF1::MGF1(HashFunction* h) : hash(h)
{
if(!hash)
throw Invalid_Argument("MGF1 given null hash object");
}
/*
* MGF1 Destructor
*/
MGF1::~MGF1()
{
delete hash;
}
}
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