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Add private key derivation functions to descriptors

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This commit is contained in:
MeshCollider 2018-12-19 15:54:40 +13:00
parent 03858b23fe
commit a4d1bd1a29
2 changed files with 48 additions and 8 deletions
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48
src/script/descriptor.cpp
View file

@ -164,6 +164,9 @@ struct PubkeyProvider
/** Get the descriptor string form including private data (if available in arg). */
virtual bool ToPrivateString(const SigningProvider& arg, std::string& out) const = 0;
/** Derive a private key, if private data is available in arg. */
virtual bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const = 0;
};
class OriginPubkeyProvider final : public PubkeyProvider
@ -195,6 +198,10 @@ public:
ret = "[" + OriginString() + "]" + std::move(sub);
return true;
}
bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const override
{
return m_provider->GetPrivKey(pos, arg, key);
}
};
/** An object representing a parsed constant public key in a descriptor. */
@ -222,6 +229,10 @@ public:
ret = EncodeSecret(key);
return true;
}
bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const override
{
return arg.GetKey(m_pubkey.GetID(), key);
}
};
enum class DeriveType {
@ -266,14 +277,9 @@ public:
{
if (key) {
if (IsHardened()) {
CExtKey extkey;
if (!GetExtKey(arg, extkey)) return false;
for (auto entry : m_path) {
extkey.Derive(extkey, entry);
}
if (m_derive == DeriveType::UNHARDENED) extkey.Derive(extkey, pos);
if (m_derive == DeriveType::HARDENED) extkey.Derive(extkey, pos | 0x80000000UL);
*key = extkey.Neuter().pubkey;
CKey priv_key;
if (!GetPrivKey(pos, arg, priv_key)) return false;
*key = priv_key.GetPubKey();
} else {
// TODO: optimize by caching
CExtPubKey extkey = m_extkey;
@ -312,6 +318,18 @@ public:
}
return true;
}
bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const override
{
CExtKey extkey;
if (!GetExtKey(arg, extkey)) return false;
for (auto entry : m_path) {
extkey.Derive(extkey, entry);
}
if (m_derive == DeriveType::UNHARDENED) extkey.Derive(extkey, pos);
if (m_derive == DeriveType::HARDENED) extkey.Derive(extkey, pos | 0x80000000UL);
key = extkey.key;
return true;
}
};
/** Base class for all Descriptor implementations. */
@ -462,6 +480,20 @@ public:
Span<const unsigned char> span = MakeSpan(cache);
return ExpandHelper(pos, DUMMY_SIGNING_PROVIDER, &span, output_scripts, out, nullptr) && span.size() == 0;
}
void ExpandPrivate(int pos, const SigningProvider& provider, FlatSigningProvider& out) const final
{
for (const auto& p : m_pubkey_args) {
CKey key;
if (!p->GetPrivKey(pos, provider, key)) continue;
out.keys.emplace(key.GetPubKey().GetID(), key);
}
if (m_script_arg) {
FlatSigningProvider subprovider;
m_script_arg->ExpandPrivate(pos, provider, subprovider);
out = Merge(out, subprovider);
}
}
};
/** Construct a vector with one element, which is moved into it. */

8
src/script/descriptor.h
View file

@ -60,6 +60,14 @@ struct Descriptor {
* out: scripts and public keys necessary for solving the expanded scriptPubKeys will be put here (may be equal to provider).
*/
virtual bool ExpandFromCache(int pos, const std::vector<unsigned char>& cache, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const = 0;
/** Expand the private key for a descriptor at a specified position, if possible.
*
* pos: the position at which to expand the descriptor. If IsRange() is false, this is ignored.
* provider: the provider to query for the private keys.
* out: any private keys available for the specified pos will be placed here.
*/
virtual void ExpandPrivate(int pos, const SigningProvider& provider, FlatSigningProvider& out) const = 0;
};
/** Parse a descriptor string. Included private keys are put in out.