Botan::XMSS_Common_Ops Class Reference

#include <xmss_common_ops.h>

Static Public Member Functions
static void	create_l_tree (secure_vector< uint8_t > &result, wots_keysig_t pk, XMSS_Address &adrs, const secure_vector< uint8_t > &seed, XMSS_Hash &hash, const XMSS_Parameters &params)
static void	randomize_tree_hash (secure_vector< uint8_t > &result, const secure_vector< uint8_t > &left, const secure_vector< uint8_t > &right, XMSS_Address &adrs, const secure_vector< uint8_t > &seed, XMSS_Hash &hash, const XMSS_Parameters &params)

Detailed Description

Operations shared by XMSS signature generation and verification operations.

Definition at line 25 of file xmss_common_ops.h.

Member Function Documentation

create_l_tree()

void Botan::XMSS_Common_Ops::create_l_tree ( secure_vector< uint8_t > & result, wots_keysig_t pk, XMSS_Address & adrs, const secure_vector< uint8_t > & seed, XMSS_Hash & hash, const XMSS_Parameters & params )

static

Algorithm 8: "ltree" Create an L-tree used to compute the leaves of the binary hash tree. Takes a WOTS+ public key and compresses it to a single n-byte value.

This overload is used in multithreaded scenarios, where it is required to provide seperate instances of XMSS_Hash to each thread.

Parameters

[out]	result	Public key compressed to a single n-byte value pk[0].
[in]	pk	Winternitz One Time Signatures+ public key.
[in]	adrs	Address encoding the address of the L-Tree
[in]	seed	The seed generated during the public key generation.
[in]	hash	Instance of XMSS_Hash, that may only be used by the thread executing create_l_tree.
[in]	params	parameters

Definition at line 46 of file xmss_common_ops.cpp.

                                                                   {
   size_t l = params.len();
   adrs.set_tree_height(0);
 
   while(l > 1) {
      for(size_t i = 0; i < l >> 1; i++) {
         adrs.set_tree_index(static_cast<uint32_t>(i));
         randomize_tree_hash(pk[i], pk[2 * i], pk[2 * i + 1], adrs, seed, hash, params);
      }
      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];
}

References Botan::XMSS_Address::get_tree_height(), Botan::XMSS_Parameters::len(), randomize_tree_hash(), Botan::XMSS_Address::set_tree_height(), and Botan::XMSS_Address::set_tree_index().

randomize_tree_hash()

void Botan::XMSS_Common_Ops::randomize_tree_hash ( secure_vector< uint8_t > & result, const secure_vector< uint8_t > & left, const secure_vector< uint8_t > & right, XMSS_Address & adrs, const secure_vector< uint8_t > & seed, XMSS_Hash & hash, const XMSS_Parameters & params )

static

Algorithm 7: "RAND_HASH"

Generates a randomized hash.

This overload is used in multithreaded scenarios, where it is required to provide seperate instances of XMSS_Hash to each thread.

Parameters

[out]	result	The resulting randomized hash.
[in]	left	Left half of the hash function input.
[in]	right	Right half of the hash function input.
[in]	adrs	Adress of the hash function call.
[in]	seed	The seed for G.
[in]	hash	Instance of XMSS_Hash, that may only by the thread executing generate_public_key.
[in]	params	parameters

Definition at line 15 of file xmss_common_ops.cpp.

                                                                         {
   adrs.set_key_mask_mode(XMSS_Address::Key_Mask::Key_Mode);
   secure_vector<uint8_t> key;
   hash.prf(key, seed, adrs.bytes());
 
   adrs.set_key_mask_mode(XMSS_Address::Key_Mask::Mask_MSB_Mode);
   secure_vector<uint8_t> bitmask_l;
   hash.prf(bitmask_l, seed, adrs.bytes());
 
   adrs.set_key_mask_mode(XMSS_Address::Key_Mask::Mask_LSB_Mode);
   secure_vector<uint8_t> bitmask_r;
   hash.prf(bitmask_r, seed, adrs.bytes());
 
   BOTAN_ASSERT(bitmask_l.size() == left.size() && bitmask_r.size() == right.size(),
                "Bitmask size doesn't match node size.");
 
   secure_vector<uint8_t> concat_xor(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];
   }
 
   hash.h(result, key, concat_xor);
}

References BOTAN_ASSERT, Botan::XMSS_Address::bytes(), Botan::XMSS_Parameters::element_size(), Botan::XMSS_Hash::h(), Botan::XMSS_Address::Key_Mode, Botan::XMSS_Address::Mask_LSB_Mode, Botan::XMSS_Address::Mask_MSB_Mode, Botan::XMSS_Hash::prf(), and Botan::XMSS_Address::set_key_mask_mode().

Referenced by create_l_tree().

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

• src/lib/pubkey/xmss/xmss_common_ops.h
• src/lib/pubkey/xmss/xmss_common_ops.cpp