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fuzz: add ConstructPubKeyBytes function

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Today, this code only has one spot where it needs well-formed pubkeys,
but future PRs will want to reuse this code.

Add a function which creates a well-formed byte array that can be turned
into a pubkey. It is not required that the pubkey is valid, just that it
can be recognized as a compressed or uncompressed pubkey.

Note: while the main intent of this commit is to wrap the existing
logic into a function, it also switches to `PickValueFromArray` so that
we are only choosing one of 0x04, 0x06, or 0x07. The previous code,
`ConsumeIntegralInRange` would have also picked 0x05, which is not
definied in the context of compressed vs uncompressed keys.

See https://bitcoin.stackexchange.com/questions/57855/c-secp256k1-what-do-prefixes-0x06-and-0x07-in-an-uncompressed-public-key-signif
for more details.
This commit is contained in:
josibake 2023-08-29 09:19:41 +02:00
parent ab42b2ebdb
commit 1580e3be83
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GPG key ID: 8ADCB558C4F33D65
1 changed files with 16 additions and 7 deletions
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23
src/test/fuzz/util.cpp
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@ -14,6 +14,19 @@
#include <memory>
std::vector<uint8_t> ConstructPubKeyBytes(FuzzedDataProvider& fuzzed_data_provider, Span<const uint8_t> byte_data, const bool compressed) noexcept
{
uint8_t pk_type;
if (compressed) {
pk_type = fuzzed_data_provider.PickValueInArray({0x02, 0x03});
} else {
pk_type = fuzzed_data_provider.PickValueInArray({0x04, 0x06, 0x07});
}
std::vector<uint8_t> pk_data{byte_data.begin(), byte_data.begin() + (compressed ? CPubKey::COMPRESSED_SIZE : CPubKey::SIZE)};
pk_data[0] = pk_type;
return pk_data;
}
CAmount ConsumeMoney(FuzzedDataProvider& fuzzed_data_provider, const std::optional<CAmount>& max) noexcept
{
return fuzzed_data_provider.ConsumeIntegralInRange<CAmount>(0, max.value_or(MAX_MONEY));
@ -103,16 +116,12 @@ CScript ConsumeScript(FuzzedDataProvider& fuzzed_data_provider, const bool maybe
// navigate the highly structured multisig format.
r_script << fuzzed_data_provider.ConsumeIntegralInRange<int64_t>(0, 22);
int num_data{fuzzed_data_provider.ConsumeIntegralInRange(1, 22)};
std::vector<uint8_t> pubkey_comp{buffer.begin(), buffer.begin() + CPubKey::COMPRESSED_SIZE};
pubkey_comp.front() = fuzzed_data_provider.ConsumeIntegralInRange(2, 3); // Set first byte for GetLen() to pass
std::vector<uint8_t> pubkey_uncomp{buffer.begin(), buffer.begin() + CPubKey::SIZE};
pubkey_uncomp.front() = fuzzed_data_provider.ConsumeIntegralInRange(4, 7); // Set first byte for GetLen() to pass
while (num_data--) {
auto& pubkey{fuzzed_data_provider.ConsumeBool() ? pubkey_uncomp : pubkey_comp};
auto pubkey_bytes{ConstructPubKeyBytes(fuzzed_data_provider, buffer, fuzzed_data_provider.ConsumeBool())};
if (fuzzed_data_provider.ConsumeBool()) {
pubkey.back() = num_data; // Make each pubkey different
pubkey_bytes.back() = num_data; // Make each pubkey different
}
r_script << pubkey;
r_script << pubkey_bytes;
}
r_script << fuzzed_data_provider.ConsumeIntegralInRange<int64_t>(0, 22);
},