Merge #19935: Move SaltedHashers to separate file and add some new ones

281fd1a4a032cded7f9ea9857e3e99fc793c714b Replace KeyIDHasher with SaltedSipHasher (Andrew Chow)
210b693db66e7c5b618014b5a287aee15af00045 Add generic SaltedSipHasher (Andrew Chow)
95e61c1cf2a91d041c8025306ba36f0ea2806894 Move Hashers to util/hasher.{cpp/h} (Andrew Chow)

Pull request description:

  There are existing `SaltedOutPointHasher` and `SaltedTxidHasher` classes used for `std::unordered_map` and `std::unordered_set` that could be useful in other places in the codebase. So we these to their own `saltedhash.{cpp/h}` file. An existing `KeyIDHasher` is moved there too. Additionally, `ScriptIDHasher`, `SaltedPubkeyHasher`, and `SaltedScriptHasher` are added so that they can be used in future work.

  `KeyIDHasher` and `ScriptIDHasher` are not salted so that equality comparisons of maps and sets keyed by `CKeyID` and `CScriptID` will actually work.

  Split from #19602 (and a few other PRs/branches I have).

ACKs for top commit:
  laanwj:
    Code review ACK 281fd1a4a032cded7f9ea9857e3e99fc793c714b
  jonatack:
    ACK 281fd1a4a032cded7f9ea9857e3e99fc793c714b, code review, debug build and ran bitcoind after rebasing to master @ dff0f6f753ea
  fjahr:
    utACK 281fd1a4a032cded7f9ea9857e3e99fc793c714b

Tree-SHA512: bb03b231ccf3c9ecefc997b8da9c3770af4819f9be5b0a72997a103864e84046a2ac39b8eadf0dc9247bdccd53f86f433642e3a098882e6748341a9e7736271b

1 files changed, 1 insertions, 21 deletions

diff --git a/src/script/sigcache.h b/src/script/sigcache.h
index 512f61f2bf..bf0ba38c2d 100644
--- a/src/script/sigcache.h
+++ b/src/script/sigcache.h
@@ -8,6 +8,7 @@
 
 #include <script/interpreter.h>
 #include <span.h>
+#include <util/hasher.h>
 
 #include <vector>
 
@@ -20,27 +21,6 @@ static const int64_t MAX_MAX_SIG_CACHE_SIZE = 16384;
 
 class CPubKey;
 
-/**
- * We're hashing a nonce into the entries themselves, so we don't need extra
- * blinding in the set hash computation.
- *
- * This may exhibit platform endian dependent behavior but because these are
- * nonced hashes (random) and this state is only ever used locally it is safe.
- * All that matters is local consistency.
- */
-class SignatureCacheHasher
-{
-public:
-    template <uint8_t hash_select>
-    uint32_t operator()(const uint256& key) const
-    {
-        static_assert(hash_select <8, "SignatureCacheHasher only has 8 hashes available.");
-        uint32_t u;
-        std::memcpy(&u, key.begin()+4*hash_select, 4);
-        return u;
-    }
-};
-
 class CachingTransactionSignatureChecker : public TransactionSignatureChecker
 {
 private: