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/**
* XMSS Common Ops
* Operations shared by XMSS signature generation and verification operations.
* (C) 2016 Matthias Gierlings
*
* Botan is released under the Simplified BSD License (see license.txt)
**/
#include <botan/xmss_common_ops.h>
namespace Botan {
void
XMSS_Common_Ops::randomize_tree_hash(secure_vector<byte>& result,
const secure_vector<byte>& left,
const secure_vector<byte>& right,
XMSS_Address& adrs,
const secure_vector<byte>& seed)
{
adrs.set_key_mask_mode(XMSS_Address::Key_Mask::Key_Mode);
secure_vector<byte> key { m_hash.prf(seed, adrs.bytes()) };
adrs.set_key_mask_mode(XMSS_Address::Key_Mask::Mask_MSB_Mode);
secure_vector<byte> bitmask_l { m_hash.prf(seed, adrs.bytes()) };
adrs.set_key_mask_mode(XMSS_Address::Key_Mask::Mask_LSB_Mode);
secure_vector<byte> bitmask_r { m_hash.prf(seed, adrs.bytes()) };
BOTAN_ASSERT(bitmask_l.size() == left.size() &&
bitmask_r.size() == right.size(),
"Bitmask size doesn't match node size.");
secure_vector<byte> concat_xor(m_xmss_params.element_size() * 2);
for(size_t i = 0; i < left.size(); i++)
{
concat_xor[i] = left[i] ^ bitmask_l[i];
concat_xor[i + left.size()] = right[i] ^ bitmask_r[i];
}
m_hash.h(result, key, concat_xor);
}
void
XMSS_Common_Ops::create_l_tree(secure_vector<byte>& result,
wots_keysig_t pk,
XMSS_Address& adrs,
const secure_vector<byte>& seed)
{
size_t l = m_xmss_params.len();
adrs.set_tree_height(0);
while(l > 1)
{
for(size_t i = 0; i < l >> 1; i++)
{
adrs.set_tree_index(i);
randomize_tree_hash(pk[i], pk[2 * i], pk[2 * i + 1], adrs, seed);
}
if(l & 0x01)
{
pk[l >> 1] = pk[l - 1];
}
l = (l >> 1) + (l & 0x01);
adrs.set_tree_height(adrs.get_tree_height() + 1);
}
result = pk[0];
}
}
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