Add support for encrypting spending keys

src/gtest/test_keystore.cpp

@@ -1,6 +1,8 @@
 #include <gtest/gtest.h>
 
 #include "keystore.h"
+#include "random.h"
+#include "wallet/crypter.h"
 #include "zcash/Address.hpp"
 
 TEST(keystore_tests, store_and_retrieve_spending_key) {
@@ -41,3 +43,58 @@ TEST(keystore_tests, store_and_retrieve_note_decryptor) {
     EXPECT_TRUE(keyStore.GetNoteDecryptor(addr, decOut));
     EXPECT_EQ(ZCNoteDecryption(sk.viewing_key()), decOut);
 }
+
+class TestCCryptoKeyStore : public CCryptoKeyStore
+{
+public:
+    bool EncryptKeys(CKeyingMaterial& vMasterKeyIn) { return CCryptoKeyStore::EncryptKeys(vMasterKeyIn); }
+    bool Unlock(const CKeyingMaterial& vMasterKeyIn) { return CCryptoKeyStore::Unlock(vMasterKeyIn); }
+};
+
+TEST(keystore_tests, store_and_retrieve_spending_key_in_encrypted_store) {
+    TestCCryptoKeyStore keyStore;
+    uint256 r {GetRandHash()};
+    CKeyingMaterial vMasterKey (r.begin(), r.end());
+    libzcash::SpendingKey keyOut;
+    std::set<libzcash::PaymentAddress> addrs;
+
+    // 1) Test adding a key to an unencrypted key store, then encrypting it
+    auto sk = libzcash::SpendingKey::random();
+    auto addr = sk.address();
+    keyStore.AddSpendingKey(sk);
+    ASSERT_TRUE(keyStore.HaveSpendingKey(addr));
+    ASSERT_TRUE(keyStore.GetSpendingKey(addr, keyOut));
+    ASSERT_EQ(sk, keyOut);
+
+    ASSERT_TRUE(keyStore.EncryptKeys(vMasterKey));
+    ASSERT_TRUE(keyStore.HaveSpendingKey(addr));
+    ASSERT_FALSE(keyStore.GetSpendingKey(addr, keyOut));
+
+    ASSERT_TRUE(keyStore.Unlock(vMasterKey));
+    ASSERT_TRUE(keyStore.GetSpendingKey(addr, keyOut));
+    ASSERT_EQ(sk, keyOut);
+
+    keyStore.GetPaymentAddresses(addrs);
+    ASSERT_EQ(1, addrs.size());
+    ASSERT_EQ(1, addrs.count(addr));
+
+    // 2) Test adding a spending key to an already-encrypted key store
+    auto sk2 = libzcash::SpendingKey::random();
+    auto addr2 = sk2.address();
+    keyStore.AddSpendingKey(sk2);
+    ASSERT_TRUE(keyStore.HaveSpendingKey(addr2));
+    ASSERT_TRUE(keyStore.GetSpendingKey(addr2, keyOut));
+    ASSERT_EQ(sk2, keyOut);
+
+    ASSERT_TRUE(keyStore.Lock());
+    ASSERT_TRUE(keyStore.HaveSpendingKey(addr2));
+    ASSERT_FALSE(keyStore.GetSpendingKey(addr2, keyOut));
+
+    ASSERT_TRUE(keyStore.Unlock(vMasterKey));
+    ASSERT_TRUE(keyStore.GetSpendingKey(addr2, keyOut));
+    ASSERT_EQ(sk2, keyOut);
+
+    keyStore.GetPaymentAddresses(addrs);
+    ASSERT_EQ(2, addrs.size());
+    ASSERT_EQ(1, addrs.count(addr2));
+}

src/keystore.h

@@ -172,5 +172,6 @@ public:
 
 typedef std::vector<unsigned char, secure_allocator<unsigned char> > CKeyingMaterial;
 typedef std::map<CKeyID, std::pair<CPubKey, std::vector<unsigned char> > > CryptedKeyMap;
+typedef std::map<libzcash::PaymentAddress, std::vector<unsigned char> > CryptedSpendingKeyMap;
 
 #endif // BITCOIN_KEYSTORE_H

src/wallet/crypter.cpp

@@ -6,6 +6,7 @@
 
 #include "script/script.h"
 #include "script/standard.h"
+#include "streams.h"
 #include "util.h"
 
 #include <string>
@@ -135,12 +136,31 @@ static bool DecryptKey(const CKeyingMaterial& vMasterKey, const std::vector<unsi
     return key.VerifyPubKey(vchPubKey);
 }
 
+static bool DecryptSpendingKey(const CKeyingMaterial& vMasterKey,
+                               const std::vector<unsigned char>& vchCryptedSecret,
+                               const libzcash::PaymentAddress& address,
+                               libzcash::SpendingKey& sk)
+{
+    CKeyingMaterial vchSecret;
+    if(!DecryptSecret(vMasterKey, vchCryptedSecret, address.GetHash(), vchSecret))
+        return false;
+
+    if (vchSecret.size() != 32)
+        return false;
+
+    // TODO does this undo the benefits of using CKeyingMaterial?
+    std::vector<unsigned char> serialized(vchSecret.begin(), vchSecret.end());
+    CDataStream ss(serialized, SER_NETWORK, PROTOCOL_VERSION);
+    ss >> sk;
+    return sk.address() == address;
+}
+
 bool CCryptoKeyStore::SetCrypted()
 {
     LOCK(cs_KeyStore);
     if (fUseCrypto)
         return true;
-    if (!mapKeys.empty())
+    if (!(mapKeys.empty() && mapSpendingKeys.empty()))
         return false;
     fUseCrypto = true;
     return true;
@@ -184,6 +204,21 @@ bool CCryptoKeyStore::Unlock(const CKeyingMaterial& vMasterKeyIn)
             if (fDecryptionThoroughlyChecked)
                 break;
         }
+        CryptedSpendingKeyMap::const_iterator skmi = mapCryptedSpendingKeys.begin();
+        for (; skmi != mapCryptedSpendingKeys.end(); ++skmi)
+        {
+            const libzcash::PaymentAddress &address = (*skmi).first;
+            const std::vector<unsigned char> &vchCryptedSecret = (*skmi).second;
+            libzcash::SpendingKey sk;
+            if (!DecryptSpendingKey(vMasterKeyIn, vchCryptedSecret, address, sk))
+            {
+                keyFail = true;
+                break;
+            }
+            keyPass = true;
+            if (fDecryptionThoroughlyChecked)
+                break;
+        }
         if (keyPass && keyFail)
         {
             LogPrintf("The wallet is probably corrupted: Some keys decrypt but not all.\n");
@@ -267,6 +302,59 @@ bool CCryptoKeyStore::GetPubKey(const CKeyID &address, CPubKey& vchPubKeyOut) co
     return false;
 }
 
+bool CCryptoKeyStore::AddSpendingKey(const libzcash::SpendingKey &sk)
+{
+    {
+        LOCK(cs_KeyStore);
+        if (!IsCrypted())
+            return CBasicKeyStore::AddSpendingKey(sk);
+
+        if (IsLocked())
+            return false;
+
+        std::vector<unsigned char> vchCryptedSecret;
+        CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
+        ss << sk;
+        CKeyingMaterial vchSecret(ss.begin(), ss.end());
+        auto address = sk.address();
+        if (!EncryptSecret(vMasterKey, vchSecret, address.GetHash(), vchCryptedSecret))
+            return false;
+
+        if (!AddCryptedSpendingKey(address, vchCryptedSecret))
+            return false;
+    }
+    return true;
+}
+
+bool CCryptoKeyStore::AddCryptedSpendingKey(const libzcash::PaymentAddress &address, const std::vector<unsigned char> &vchCryptedSecret)
+{
+    {
+        LOCK(cs_KeyStore);
+        if (!SetCrypted())
+            return false;
+
+        mapCryptedSpendingKeys[address] = vchCryptedSecret;
+    }
+    return true;
+}
+
+bool CCryptoKeyStore::GetSpendingKey(const libzcash::PaymentAddress &address, libzcash::SpendingKey &skOut) const
+{
+    {
+        LOCK(cs_KeyStore);
+        if (!IsCrypted())
+            return CBasicKeyStore::GetSpendingKey(address, skOut);
+
+        CryptedSpendingKeyMap::const_iterator mi = mapCryptedSpendingKeys.find(address);
+        if (mi != mapCryptedSpendingKeys.end())
+        {
+            const std::vector<unsigned char> &vchCryptedSecret = (*mi).second;
+            return DecryptSpendingKey(vMasterKey, vchCryptedSecret, address, skOut);
+        }
+    }
+    return false;
+}
+
 bool CCryptoKeyStore::EncryptKeys(CKeyingMaterial& vMasterKeyIn)
 {
     {
@@ -287,6 +375,20 @@ bool CCryptoKeyStore::EncryptKeys(CKeyingMaterial& vMasterKeyIn)
                 return false;
         }
         mapKeys.clear();
+        BOOST_FOREACH(SpendingKeyMap::value_type& mSpendingKey, mapSpendingKeys)
+        {
+            const libzcash::SpendingKey &sk = mSpendingKey.second;
+            CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
+            ss << sk;
+            CKeyingMaterial vchSecret(ss.begin(), ss.end());
+            libzcash::PaymentAddress address = sk.address();
+            std::vector<unsigned char> vchCryptedSecret;
+            if (!EncryptSecret(vMasterKeyIn, vchSecret, address.GetHash(), vchCryptedSecret))
+                return false;
+            if (!AddCryptedSpendingKey(address, vchCryptedSecret))
+                return false;
+        }
+        mapSpendingKeys.clear();
     }
     return true;
 }

src/wallet/crypter.h

@@ -8,6 +8,7 @@
 #include "keystore.h"
 #include "serialize.h"
 #include "support/allocators/secure.h"
+#include "zcash/Address.hpp"
 
 class uint256;
 
@@ -114,10 +115,11 @@ class CCryptoKeyStore : public CBasicKeyStore
 {
 private:
     CryptedKeyMap mapCryptedKeys;
+    CryptedSpendingKeyMap mapCryptedSpendingKeys;
 
     CKeyingMaterial vMasterKey;
 
-    //! if fUseCrypto is true, mapKeys must be empty
+    //! if fUseCrypto is true, mapKeys and mapSpendingKeys must be empty
     //! if fUseCrypto is false, vMasterKey must be empty
     bool fUseCrypto;
 
@@ -185,6 +187,34 @@ public:
             mi++;
         }
     }
+    virtual bool AddCryptedSpendingKey(const libzcash::PaymentAddress &address, const std::vector<unsigned char> &vchCryptedSecret);
+    bool AddSpendingKey(const libzcash::SpendingKey &sk);
+    bool HaveSpendingKey(const libzcash::PaymentAddress &address) const
+    {
+        {
+            LOCK(cs_KeyStore);
+            if (!IsCrypted())
+                return CBasicKeyStore::HaveSpendingKey(address);
+            return mapCryptedSpendingKeys.count(address) > 0;
+        }
+        return false;
+    }
+    bool GetSpendingKey(const libzcash::PaymentAddress &address, libzcash::SpendingKey &skOut) const;
+    void GetPaymentAddresses(std::set<libzcash::PaymentAddress> &setAddress) const
+    {
+        if (!IsCrypted())
+        {
+            CBasicKeyStore::GetPaymentAddresses(setAddress);
+            return;
+        }
+        setAddress.clear();
+        CryptedSpendingKeyMap::const_iterator mi = mapCryptedSpendingKeys.begin();
+        while (mi != mapCryptedSpendingKeys.end())
+        {
+            setAddress.insert((*mi).first);
+            mi++;
+        }
+    }
 
     /**
      * Wallet status (encrypted, locked) changed.

src/zcash/Address.cpp

@@ -1,9 +1,17 @@
 #include "Address.hpp"
 #include "NoteEncryption.hpp"
+#include "hash.h"
 #include "prf.h"
+#include "streams.h"
 
 namespace libzcash {
 
+uint256 PaymentAddress::GetHash() const {
+    CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
+    ss << *this;
+    return Hash(ss.begin(), ss.end());
+}
+
 uint256 ViewingKey::pk_enc() {
     return ZCNoteEncryption::generate_pubkey(*this);
 }

src/zcash/Address.hpp

@@ -23,6 +23,9 @@ public:
         READWRITE(pk_enc);
     }
 
+    //! Get the 256-bit SHA256d hash of this payment address.
+    uint256 GetHash() const;
+
     friend inline bool operator==(const PaymentAddress& a, const PaymentAddress& b) {
         return a.a_pk == b.a_pk && a.pk_enc == b.pk_enc;
     }