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203 lines (171 loc) · 8.4 KB
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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2022 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <script/sigcache.h>
#include <crypto/sha256.h>
#include <logging.h>
#include <pubkey.h>
#include <random.h>
#include <script/interpreter.h>
#include <span.h>
#include <uint256.h>
#include <mutex>
#include <shared_mutex>
#include <vector>
SignatureCache::SignatureCache(const size_t max_size_bytes)
{
uint256 nonce = GetRandHash();
// We want the nonce to be 64 bytes long to force the hasher to process
// this chunk, which makes later hash computations more efficient. We
// just write our 32-byte entropy, and then pad with 'E' for ECDSA and
// 'S' for Schnorr (followed by 0 bytes).
static constexpr unsigned char PADDING_ECDSA[32] = {'E'};
static constexpr unsigned char PADDING_SCHNORR[32] = {'S'};
static constexpr unsigned char PADDING_RANGE_PROOF[32] = {'r'};
static constexpr unsigned char PADDING_SURJECTION_PROOF[32] = {'s'};
m_salted_hasher_ecdsa.Write(nonce.begin(), 32);
m_salted_hasher_ecdsa.Write(PADDING_ECDSA, 32);
m_salted_hasher_schnorr.Write(nonce.begin(), 32);
m_salted_hasher_schnorr.Write(PADDING_SCHNORR, 32);
m_salted_hasher_range_proof.Write(nonce.begin(), 32);
m_salted_hasher_range_proof.Write(PADDING_RANGE_PROOF, 32);
m_salted_hasher_surjection_proof.Write(nonce.begin(), 32);
m_salted_hasher_surjection_proof.Write(PADDING_SURJECTION_PROOF, 32);
const auto [num_elems, approx_size_bytes] = setValid.setup_bytes(max_size_bytes);
LogPrintf("Using %zu MiB out of %zu MiB requested for signature cache, able to store %zu elements\n",
approx_size_bytes >> 20, max_size_bytes >> 20, num_elems);
}
void SignatureCache::ComputeEntryECDSA(uint256& entry, const uint256& hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubkey) const
{
CSHA256 hasher = m_salted_hasher_ecdsa;
hasher.Write(hash.begin(), 32).Write(pubkey.data(), pubkey.size()).Write(vchSig.data(), vchSig.size()).Finalize(entry.begin());
}
void SignatureCache::ComputeEntrySchnorr(uint256& entry, const uint256& hash, Span<const unsigned char> sig, const XOnlyPubKey& pubkey) const
{
CSHA256 hasher = m_salted_hasher_schnorr;
hasher.Write(hash.begin(), 32).Write(pubkey.data(), pubkey.size()).Write(sig.data(), sig.size()).Finalize(entry.begin());
}
// ELEMENTS:
void SignatureCache::ComputeEntryRangeProof(uint256& entry, const std::vector<unsigned char>& proof, const std::vector<unsigned char>& commitment) const {
CSHA256 hasher = m_salted_hasher_range_proof;
hasher.Write(proof.data(), proof.size()).Write(commitment.data(), commitment.size()).Finalize(entry.begin());
}
void SignatureCache::ComputeEntrySurjectionProof(uint256& entry, const uint256 &hash, const std::vector<unsigned char>& proof, const std::vector<unsigned char>& commitment) const {
CSHA256 hasher = m_salted_hasher_surjection_proof;
hasher.Write(hash.begin(), 32).Write(proof.data(), proof.size()).Write(commitment.data(), commitment.size()).Finalize(entry.begin());
}
bool SignatureCache::Get(const uint256& entry, const bool erase)
{
std::shared_lock<std::shared_mutex> lock(cs_sigcache);
return setValid.contains(entry, erase);
}
void SignatureCache::Set(const uint256& entry)
{
std::unique_lock<std::shared_mutex> lock(cs_sigcache);
setValid.insert(entry);
}
bool CachingTransactionSignatureChecker::VerifyECDSASignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const
{
uint256 entry;
m_signature_cache.ComputeEntryECDSA(entry, sighash, vchSig, pubkey);
if (m_signature_cache.Get(entry, !store))
return true;
if (!TransactionSignatureChecker::VerifyECDSASignature(vchSig, pubkey, sighash))
return false;
if (store)
m_signature_cache.Set(entry);
return true;
}
bool CachingTransactionSignatureChecker::VerifySchnorrSignature(Span<const unsigned char> sig, const XOnlyPubKey& pubkey, const uint256& sighash) const
{
uint256 entry;
m_signature_cache.ComputeEntrySchnorr(entry, sighash, sig, pubkey);
if (m_signature_cache.Get(entry, !store)) return true;
if (!TransactionSignatureChecker::VerifySchnorrSignature(sig, pubkey, sighash)) return false;
if (store) m_signature_cache.Set(entry);
return true;
}
// TODO: de-globalise
// ELEMENTS CACHES
namespace {
static SignatureCache rangeProofCache;
static SignatureCache surjectionProofCache;
}
// To be called once in AppInit2/TestingSetup to initialize the rangeproof cache
bool InitRangeproofCache(size_t max_size_bytes)
{
auto setup_results = rangeProofCache.setup_bytes(max_size_bytes);
if (!setup_results) return false;
const auto [num_elems, approx_size_bytes] = *setup_results;
LogPrintf("Using %zu MiB out of %zu Mib requested for rangeproof cache, able to store %zu elements\n",
approx_size_bytes >> 20, max_size_bytes >> 20, num_elems);
return true;
}
// To be called once in AppInit2/TestingSetup to initialize the surjectionrproof cache
bool InitSurjectionproofCache(size_t max_size_bytes)
{
auto setup_results = surjectionProofCache.setup_bytes(max_size_bytes);
if (!setup_results) return false;
const auto [num_elems, approx_size_bytes] = *setup_results;
LogPrintf("Using %zu MiB out of %zu Mib requested for surjectionproof cache, able to store %zu elements\n",
approx_size_bytes >> 20, max_size_bytes >> 20, num_elems);
return true;
}
bool CachingRangeProofChecker::VerifyRangeProof(const std::vector<unsigned char>& vchRangeProof, const std::vector<unsigned char>& vchValueCommitment, const std::vector<unsigned char>& vchAssetCommitment, const CScript& scriptPubKey, const secp256k1_context* secp256k1_ctx_verify_amounts) const
{
uint256 entry;
rangeProofCache.ComputeEntryRangeProof(entry, vchRangeProof, vchValueCommitment);
if (rangeProofCache.Get(entry, !store)) {
return true;
}
if (vchRangeProof.size() == 0) {
return false;
}
uint64_t min_value, max_value;
secp256k1_pedersen_commitment commit;
if (secp256k1_pedersen_commitment_parse(secp256k1_ctx_verify_amounts, &commit, &vchValueCommitment[0]) != 1)
return false;
secp256k1_generator tag;
if (secp256k1_generator_parse(secp256k1_ctx_verify_amounts, &tag, &vchAssetCommitment[0]) != 1)
return false;
if (!secp256k1_rangeproof_verify(secp256k1_ctx_verify_amounts, &min_value, &max_value, &commit, vchRangeProof.data(), vchRangeProof.size(), scriptPubKey.size() ? &scriptPubKey.front() : nullptr, scriptPubKey.size(), &tag)) {
return false;
}
// An rangeproof is not valid if the output is spendable but the minimum number
// is 0. This is to prevent people passing 0-value tokens around, or conjuring
// reissuance tokens from nothing then attempting to reissue an asset.
// ie reissuance doesn't require revealing value of reissuance output
// Issuances proofs are always "unspendable" as they commit to an empty script.
if (min_value == 0 && !scriptPubKey.IsUnspendable()) {
return false;
}
if (store) {
rangeProofCache.Set(entry);
}
return true;
}
bool CachingSurjectionProofChecker::VerifySurjectionProof(secp256k1_surjectionproof& proof, std::vector<secp256k1_generator>& vTags, secp256k1_generator& gen, const secp256k1_context* secp256k1_ctx_verify_amounts, const uint256& wtxid) const
{
// Serialize proof
std::vector<unsigned char> vchproof;
size_t proof_len = secp256k1_surjectionproof_serialized_size(secp256k1_ctx_verify_amounts, &proof);
vchproof.resize(proof_len);
assert(secp256k1_surjectionproof_serialize(secp256k1_ctx_verify_amounts, vchproof.data(), &proof_len, &proof) == 1);
// wtxid commits to all data including surj targets
// we need to specify the proof and output asset point to be unique
uint256 entry;
surjectionProofCache.ComputeEntrySurjectionProof(entry, wtxid, vchproof, std::vector<unsigned char>(std::begin(gen.data), std::end(gen.data)));
if (surjectionProofCache.Get(entry, !store)) {
return true;
}
if (secp256k1_surjectionproof_verify(secp256k1_ctx_verify_amounts, &proof, vTags.data(), vTags.size(), &gen) != 1) {
return false;
}
if (store) {
surjectionProofCache.Set(entry);
}
return true;
}
// END ELEMENTS
//