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added K-anonymity helper functions

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This commit is contained in:
Some Random Crypto Guy
2024-06-18 23:47:00 +01:00
parent f41c20ee7c
commit 6404d34e33
2 changed files with 82 additions and 9 deletions
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src/cryptonote_basic/cryptonote_basic_impl.h
+35 -9
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@@ -39,15 +39,6 @@ namespace cryptonote {
/************************************************************************/
/* */
/************************************************************************/
template<class t_array>
struct array_hasher: std::unary_function<t_array&, std::size_t>
{
std::size_t operator()(const t_array& val) const
{
return boost::hash_range(&val.data[0], &val.data[sizeof(val.data)]);
}
};
#pragma pack(push, 1)
struct public_address_outer_blob
@@ -121,6 +112,41 @@ namespace cryptonote {
bool operator ==(const cryptonote::transaction& a, const cryptonote::transaction& b);
bool operator ==(const cryptonote::block& a, const cryptonote::block& b);
/************************************************************************/
/* K-anonymity helper functions */
/************************************************************************/
/**
* @brief Compares two hashes up to `nbits` bits in reverse byte order ("LMDB key order")
*
* The comparison essentially goes from the 31th, 30th, 29th, ..., 0th byte and compares the MSBs
* to the LSBs in each byte, up to `nbits` bits. If we use up `nbits` bits before finding a
* difference in the bits between the two hashes, we return 0. If we encounter a zero bit in `ha`
* where `hb` has a one in that bit place, then we reutrn -1. If the converse scenario happens,
* we return a 1. When `nbits` == 256 (there are 256 bits in `crypto::hash`), calling this is
* functionally identical to `BlockchainLMDB::compare_hash32`.
*
* @param ha left hash
* @param hb right hash
* @param nbits the number of bits to consider, a higher value means a finer comparison
* @return int 0 if ha == hb, -1 if ha < hb, 1 if ha > hb
*/
int compare_hash32_reversed_nbits(const crypto::hash& ha, const crypto::hash& hb, unsigned int nbits);
/**
* @brief Make a template which matches `h` in LMDB order up to `nbits` bits, safe for k-anonymous fetching
*
* To be more technical, this function creates a hash which satifies the following property:
* For all `H_prime` s.t. `0 == compare_hash32_reversed_nbits(real_hash, H_prime, nbits)`,
* `1 > compare_hash32_reversed_nbits(real_hash, H_prime, 256)`.
* In other words, we return the "least" hash nbit-equal to `real_hash`.
*
* @param nbits The number of "MSB" bits to include in the template
* @param real_hash The original hash which contains more information than we want to disclose
* @return crypto::hash hash template that contains `nbits` bits matching real_hash and no more
*/
crypto::hash make_hash32_loose_template(unsigned int nbits, const crypto::hash& real_hash);
}
bool parse_hash256(const std::string &str_hash, crypto::hash& hash);