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key: don't allocate secure mem for null (invalid) key

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Instead of storing the key material as an std::vector (with secure allocator),
use a secure_unique_ptr to a 32-byte array, and use nullptr for invalid keys.
This means a smaller CKey type, and no secure/dynamic memory usage for invalid
keys.
This commit is contained in:
Pieter Wuille
2023-09-18 12:10:19 -04:00
parent d9841a7ac6
commit 6ef405ddb1
2 changed files with 60 additions and 39 deletions
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37
src/key.cpp
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@@ -159,21 +159,21 @@ bool CKey::Check(const unsigned char *vch) {
}
void CKey::MakeNewKey(bool fCompressedIn) {
MakeKeyData();
do {
GetStrongRandBytes(keydata);
} while (!Check(keydata.data()));
fValid = true;
GetStrongRandBytes(*keydata);
} while (!Check(keydata->data()));
fCompressed = fCompressedIn;
}
bool CKey::Negate()
{
assert(fValid);
return secp256k1_ec_seckey_negate(secp256k1_context_sign, keydata.data());
assert(keydata);
return secp256k1_ec_seckey_negate(secp256k1_context_sign, keydata->data());
}
CPrivKey CKey::GetPrivKey() const {
assert(fValid);
assert(keydata);
CPrivKey seckey;
int ret;
size_t seckeylen;
@@ -186,7 +186,7 @@ CPrivKey CKey::GetPrivKey() const {
}
CPubKey CKey::GetPubKey() const {
assert(fValid);
assert(keydata);
secp256k1_pubkey pubkey;
size_t clen = CPubKey::SIZE;
CPubKey result;
@@ -212,7 +212,7 @@ bool SigHasLowR(const secp256k1_ecdsa_signature* sig)
}
bool CKey::Sign(const uint256 &hash, std::vector<unsigned char>& vchSig, bool grind, uint32_t test_case) const {
if (!fValid)
if (!keydata)
return false;
vchSig.resize(CPubKey::SIGNATURE_SIZE);
size_t nSigLen = CPubKey::SIGNATURE_SIZE;
@@ -253,7 +253,7 @@ bool CKey::VerifyPubKey(const CPubKey& pubkey) const {
}
bool CKey::SignCompact(const uint256 &hash, std::vector<unsigned char>& vchSig) const {
if (!fValid)
if (!keydata)
return false;
vchSig.resize(CPubKey::COMPACT_SIGNATURE_SIZE);
int rec = -1;
@@ -301,10 +301,12 @@ bool CKey::SignSchnorr(const uint256& hash, Span<unsigned char> sig, const uint2
}
bool CKey::Load(const CPrivKey &seckey, const CPubKey &vchPubKey, bool fSkipCheck=false) {
if (!ec_seckey_import_der(secp256k1_context_sign, (unsigned char*)begin(), seckey.data(), seckey.size()))
MakeKeyData();
if (!ec_seckey_import_der(secp256k1_context_sign, (unsigned char*)begin(), seckey.data(), seckey.size())) {
ClearKeyData();
return false;
}
fCompressed = vchPubKey.IsCompressed();
fValid = true;
if (fSkipCheck)
return true;
@@ -325,22 +327,21 @@ bool CKey::Derive(CKey& keyChild, ChainCode &ccChild, unsigned int nChild, const
BIP32Hash(cc, nChild, 0, begin(), vout.data());
}
memcpy(ccChild.begin(), vout.data()+32, 32);
memcpy((unsigned char*)keyChild.begin(), begin(), 32);
keyChild.Set(begin(), begin() + 32, true);
bool ret = secp256k1_ec_seckey_tweak_add(secp256k1_context_sign, (unsigned char*)keyChild.begin(), vout.data());
keyChild.fCompressed = true;
keyChild.fValid = ret;
if (!ret) keyChild.ClearKeyData();
return ret;
}
EllSwiftPubKey CKey::EllSwiftCreate(Span<const std::byte> ent32) const
{
assert(fValid);
assert(keydata);
assert(ent32.size() == 32);
std::array<std::byte, EllSwiftPubKey::size()> encoded_pubkey;
auto success = secp256k1_ellswift_create(secp256k1_context_sign,
UCharCast(encoded_pubkey.data()),
keydata.data(),
keydata->data(),
UCharCast(ent32.data()));
// Should always succeed for valid keys (asserted above).
@@ -350,7 +351,7 @@ EllSwiftPubKey CKey::EllSwiftCreate(Span<const std::byte> ent32) const
ECDHSecret CKey::ComputeBIP324ECDHSecret(const EllSwiftPubKey& their_ellswift, const EllSwiftPubKey& our_ellswift, bool initiating) const
{
assert(fValid);
assert(keydata);
ECDHSecret output;
// BIP324 uses the initiator as party A, and the responder as party B. Remap the inputs
@@ -359,7 +360,7 @@ ECDHSecret CKey::ComputeBIP324ECDHSecret(const EllSwiftPubKey& their_ellswift, c
UCharCast(output.data()),
UCharCast(initiating ? our_ellswift.data() : their_ellswift.data()),
UCharCast(initiating ? their_ellswift.data() : our_ellswift.data()),
keydata.data(),
keydata->data(),
initiating ? 0 : 1,
secp256k1_ellswift_xdh_hash_function_bip324,
nullptr);