wallet: encrypt atomically under the SQLite backend

EncryptWallet() had only a Berkeley DB path: it rebuilt a wallet.dat temp
file and swapped it in. Under -walletbackend=sqlite that was wrong -- it
would leave the live wallet.sqlite unencrypted and write a divergent
wallet.dat instead. Add a SQLite persistence branch that rebuilds a fresh
wallet.sqlite in one transaction (public records copied from the live
store, encrypted key material serialized byte-for-byte the way the BDB
path writes it), checkpoints it, and swaps it in with a .before-encrypt
backup, mirroring the BDB rename dance. A fresh file rather than an
in-place rewrite keeps the change atomic and leaves no plaintext key in a
freed page.

CmdEncryptWallet skips PurgeDbEnvironmentLogs under SQLite (no Berkeley DB
environment behind the wallet) and reports the backend it used.

New wallet-sqlite-encrypt self-test drives the real command path in child
processes: export a wallet to SQLite, encrypt it through
-walletbackend=sqlite, and prove it comes out encrypted, unlockable with
the right passphrase, refusing the wrong one, with its recovery phrase
intact and the original wallet.dat left untouched.

4 files changed, 410 insertions, 5 deletions

diff --git a/src/db.cpp b/src/db.cpp
index 771a4ba..86f6dd7 100644
--- a/src/db.cpp
+++ b/src/db.cpp
@@ -1974,9 +1974,9 @@ static bool CopyPublicWalletRecordsTo(CWalletRewriteDB& dbTo,
     return ScanWalletRecords(visitor, strErrorRet);
 }
 
-static string WalletEncryptBackupPath()
+static string WalletEncryptBackupPathFor(const char* pszBaseName)
 {
-    string strBase = GetAppDir() + "/wallet.dat.before-encrypt.";
+    string strBase = GetAppDir() + "/" + pszBaseName + ".before-encrypt.";
     string strPath = strBase + i64tostr(GetTime()) + ".bak";
     for (int i = 1; FileExists(strPath.c_str()); i++)
         strPath = strBase + i64tostr(GetTime()) + "." + itostr(i) + ".bak";
@@ -2006,6 +2006,192 @@ static void SecureClearBytes(vector<unsigned char>& vch)
     vch.clear();
 }
 
+// The SQLite counterpart of CWalletPublicRecordCopyVisitor: same skip list,
+// same byte-for-byte copy, but the destination is a CWalletDBSQLite record
+// store rather than a Berkeley DB file.
+class CWalletPublicRecordCopyToSQLiteVisitor : public CWalletRecordVisitor
+{
+public:
+    CWalletDBSQLite& dbTo;
+    int& nCopied;
+
+    CWalletPublicRecordCopyToSQLiteVisitor(CWalletDBSQLite& dbToIn, int& nCopiedIn)
+        : dbTo(dbToIn), nCopied(nCopiedIn) { }
+
+    bool VisitWalletRecord(const CDataStream& ssKey,
+                           const CDataStream& ssValue,
+                           string& strErrorRet)
+    {
+        string strType;
+        try
+        {
+            CDataStream ssType = ssKey;
+            ssType >> strType;
+        }
+        catch (...)
+        {
+            strErrorRet = "SQLite wallet has a record whose key type cannot be read";
+            return false;
+        }
+
+        if (IsWalletEncryptionPrivateRecord(strType))
+            return true;
+
+        vector<unsigned char> vchKey(ssKey.begin(), ssKey.end());
+        vector<unsigned char> vchValue(ssValue.begin(), ssValue.end());
+        bool fOk = dbTo.WriteRecord(vchKey, vchValue, strErrorRet, true);
+        if (!vchKey.empty())
+            memset(&vchKey[0], 0, vchKey.size());
+        if (!vchValue.empty())
+            memset(&vchValue[0], 0, vchValue.size());
+        if (!fOk)
+        {
+            strErrorRet = strprintf("could not copy wallet record '%s': %s",
+                                    strType.c_str(), strErrorRet.c_str());
+            return false;
+        }
+        nCopied++;
+        return true;
+    }
+};
+
+// Persist an encrypted wallet under the SQLite backend. Everything the caller
+// computed -- the master key, the re-encrypted private keys, the fresh crypted
+// key pool, the encrypted HD seed -- lands in a brand new wallet.sqlite built
+// in one transaction, which is then swapped in for the plaintext original.
+//
+// A fresh file rather than an in-place rewrite for two reasons: it keeps the
+// whole change atomic (a crash before the rename leaves the old wallet whole),
+// and it guarantees no plaintext key survives in a freed page the way an
+// in-place DELETE would leave behind until a VACUUM.
+static bool EncryptWalletPersistSQLite(
+    const vector<pair<vector<unsigned char>, vector<unsigned char> > >& vCryptedKeys,
+    const vector<pair<vector<unsigned char>, vector<unsigned char> > >& vNewPoolKeys,
+    const vector<pair<int64, vector<unsigned char> > >& vNewPool,
+    const CWalletMasterKey& kMasterKey,
+    const vector<unsigned char>& vchCryptedHDMasterNew,
+    const vector<unsigned char>& vchCryptedHDChainCodeNew,
+    unsigned int nHDNextNew,
+    int& nCopiedRet,
+    string& strBackupRet,
+    string& strErrorRet)
+{
+    nCopiedRet = 0;
+    if (!pWalletSQLiteRuntime)
+    {
+        strErrorRet = "SQLite wallet backend is not active";
+        return false;
+    }
+
+    string strWalletPath = GetAppDir() + "/wallet.sqlite";
+    string strTempPath = GetAppDir() + "/" +
+        strprintf("wallet.sqlite.encrypting.%lld", GetTime());
+    remove(strTempPath.c_str());
+    remove((strTempPath + "-wal").c_str());
+    remove((strTempPath + "-shm").c_str());
+
+    {
+        CWalletDBSQLite dbTmp;
+        if (!dbTmp.Open(strTempPath, strErrorRet))
+        {
+            remove(strTempPath.c_str());
+            return false;
+        }
+        if (!dbTmp.BeginTransaction(strErrorRet))
+        {
+            dbTmp.Close();
+            remove(strTempPath.c_str());
+            return false;
+        }
+
+        // The public records come from the live SQLite store -- under this
+        // backend ScanWalletRecords() has no Berkeley DB behind it to read.
+        CWalletPublicRecordCopyToSQLiteVisitor visitor(dbTmp, nCopiedRet);
+        bool fOk = pWalletSQLiteRuntime->ScanRecords(visitor, strErrorRet);
+
+        // Encrypted metadata, serialized byte-for-byte the way the Berkeley DB
+        // path (CWalletRewriteDB) writes it, so a wallet encrypted under either
+        // backend is the same set of records. ckey uses INSERT-only to match
+        // WriteCryptedKey; the rest overwrite.
+        fOk = fOk &&
+            dbTmp.WriteTypedRecord(string("walletminversion"),
+                                   (int)WALLET_FORMAT_ENCRYPTED, strErrorRet, true) &&
+            dbTmp.WriteTypedRecord(make_pair(string("mkey"),
+                                       (unsigned int)(nWalletMasterKeyMaxID + 1)),
+                                   kMasterKey, strErrorRet, true);
+        for (size_t i = 0; fOk && i < vCryptedKeys.size(); i++)
+            fOk = dbTmp.WriteTypedRecord(make_pair(string("ckey"), vCryptedKeys[i].first),
+                                         vCryptedKeys[i].second, strErrorRet, false);
+        for (size_t i = 0; fOk && i < vNewPoolKeys.size(); i++)
+            fOk = dbTmp.WriteTypedRecord(make_pair(string("ckey"), vNewPoolKeys[i].first),
+                                         vNewPoolKeys[i].second, strErrorRet, false);
+        if (fOk && !vchCryptedHDMasterNew.empty())
+            fOk = dbTmp.WriteTypedRecord(string("cryptedhdmaster"),
+                                         vchCryptedHDMasterNew, strErrorRet, true) &&
+                  dbTmp.WriteTypedRecord(string("cryptedhdchaincode"),
+                                         vchCryptedHDChainCodeNew, strErrorRet, true);
+        if (fOk)
+            fOk = dbTmp.WriteTypedRecord(string("hdnext"), nHDNextNew, strErrorRet, true);
+        for (size_t i = 0; fOk && i < vNewPool.size(); i++)
+            fOk = dbTmp.WriteTypedRecord(make_pair(string("pool"), vNewPool[i].first),
+                                         vNewPool[i].second, strErrorRet, true);
+
+        if (!fOk)
+        {
+            string strIgnore;
+            dbTmp.RollbackTransaction(strIgnore);
+            dbTmp.Close();
+            remove(strTempPath.c_str());
+            remove((strTempPath + "-wal").c_str());
+            remove((strTempPath + "-shm").c_str());
+            return false;
+        }
+
+        if (!dbTmp.CommitTransaction(strErrorRet))
+        {
+            dbTmp.Close();
+            remove(strTempPath.c_str());
+            remove((strTempPath + "-wal").c_str());
+            remove((strTempPath + "-shm").c_str());
+            return false;
+        }
+        string strCheckpointError;
+        dbTmp.Checkpoint(strCheckpointError);
+        dbTmp.Close();
+    }
+
+    // The rebuilt wallet is committed and self-contained. Close the live handle
+    // so the file can be swapped: Windows will not rename a file that still has
+    // an open handle, and the node exits right after this.
+    WalletSQLiteRuntimeClose();
+
+    string strBackupPath = WalletEncryptBackupPathFor("wallet.sqlite");
+    if (rename(strWalletPath.c_str(), strBackupPath.c_str()) != 0)
+    {
+        strErrorRet = strprintf("could not move the original SQLite wallet to %s",
+                                strBackupPath.c_str());
+        remove(strTempPath.c_str());
+        return false;
+    }
+    // The moved-aside wallet owns any leftover write-ahead log or shared-memory
+    // sidecar; drop stale ones so they cannot shadow the new wallet.
+    remove((strWalletPath + "-wal").c_str());
+    remove((strWalletPath + "-shm").c_str());
+
+    if (rename(strTempPath.c_str(), strWalletPath.c_str()) != 0)
+    {
+        rename(strBackupPath.c_str(), strWalletPath.c_str());
+        strErrorRet = "could not install the encrypted SQLite wallet; the original was restored";
+        remove(strTempPath.c_str());
+        return false;
+    }
+    remove((strTempPath + "-wal").c_str());
+    remove((strTempPath + "-shm").c_str());
+
+    strBackupRet = strBackupPath;
+    return true;
+}
+
 bool EncryptWallet(const string& strPassphrase, string& strBackupRet, string& strErrorRet)
 {
     strBackupRet.clear();
@@ -2144,6 +2330,24 @@ bool EncryptWallet(const string& strPassphrase, string& strBackupRet, string& st
         vNewPool.push_back(make_pair((int64)i + 1, vchPubKey));
     }
 
+    // Every ciphertext is computed; nothing has touched the store yet. Under
+    // the SQLite backend, persist by rebuilding wallet.sqlite in one atomic
+    // transaction and swapping it in. The Berkeley DB path below is unchanged.
+    if (WalletSQLiteRuntimeActive())
+    {
+        int nCopiedSQLite = 0;
+        if (!EncryptWalletPersistSQLite(vCryptedKeys, vNewPoolKeys, vNewPool,
+                                        kMasterKey, vchCryptedHDMasterNew,
+                                        vchCryptedHDChainCodeNew, nHDNextNew,
+                                        nCopiedSQLite, strBackupRet, strErrorRet))
+            return false;
+        printf("EncryptWallet() : copied %d public record(s), encrypted %u key(s), "
+               "rebuilt %d key-pool entry(s) [SQLite]\n",
+               nCopiedSQLite, (unsigned int)(vCryptedKeys.size() + vNewPoolKeys.size()),
+               (int)vNewPool.size());
+        return true;
+    }
+
     string strTempFile = strprintf("wallet.encrypting.%lld.dat", GetTime());
     string strTempPath = GetAppDir() + "/" + strTempFile;
     remove(strTempPath.c_str());
@@ -2211,7 +2415,7 @@ bool EncryptWallet(const string& strPassphrase, string& strBackupRet, string& st
     DBFlush(true);
 
     string strWalletPath = GetAppDir() + "/wallet.dat";
-    string strBackupPath = WalletEncryptBackupPath();
+    string strBackupPath = WalletEncryptBackupPathFor("wallet.dat");
     if (rename(strWalletPath.c_str(), strBackupPath.c_str()) != 0)
     {
         strErrorRet = strprintf("could not move the original wallet to %s", strBackupPath.c_str());
diff --git a/src/makefile.mingw b/src/makefile.mingw
index 14e6b32..1cb47fb 100644
--- a/src/makefile.mingw
+++ b/src/makefile.mingw
@@ -112,6 +112,7 @@ tests: test_bip32.exe bitflash.exe
         ./bitflash.exe -selftest=wallet-sqlite-migration
         ./bitflash.exe -selftest=wallet-crypto
         ./bitflash.exe -selftest=wallet-encrypt
+        ./bitflash.exe -selftest=wallet-sqlite-encrypt
         ./bitflash.exe -selftest=net-message
         ./bitflash.exe -selftest=consensus-limits
         ./bitflash.exe -selftest=pool-stratum
diff --git a/src/selftest.cpp b/src/selftest.cpp
index 098eed6..fc10947 100644
--- a/src/selftest.cpp
+++ b/src/selftest.cpp
@@ -2252,6 +2252,191 @@ static int RunWalletEncryptSelfTest()
     return nFail == 0 ? 0 : 1;
 }
 
+// Encrypting a wallet while it runs on the SQLite backend. Unlike the Berkeley
+// DB encrypt test above, this drives the real command-line path end to end in
+// child processes: build a Berkeley DB wallet, export it to SQLite, then run
+// -walletbackend=sqlite -encryptwallet and prove the SQLite wallet came out
+// encrypted, unlockable, and with wallet.dat left untouched.
+static int RunWalletSQLiteEncryptSelfTest()
+{
+    fflush(stdout);
+    printf("wallet-sqlite-encrypt self-test\n");
+
+    std::string tmp;
+    std::string cwd;
+    if (!MakeTempDir(tmp))
+    {
+        printf("  FAIL could not create a temporary data directory\n");
+        return 1;
+    }
+    if (!GetCurrentDir(cwd) || !SetCurrentDir(tmp))
+    {
+        printf("  FAIL could not move into the temporary data directory\n");
+        RemoveTree(tmp);
+        return 1;
+    }
+
+    int nFail = 0;
+    strSetDataDir = tmp;
+    printf("  temp datadir: %s\n", tmp.c_str());
+
+    try
+    {
+        // Build a normal Berkeley DB wallet with a recovery phrase, a key pool,
+        // and a couple of public records, then release it. Everything after this
+        // runs the real command-line paths in child processes.
+        if (!LoadWallet())
+            throw std::runtime_error("LoadWallet failed");
+
+        string strError;
+        const string strMnemonic =
+            "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about";
+        nFail += Check(SetHDSeedFromMnemonic(strMnemonic, strError),
+                       "a phrase can be installed before encryption") ? 0 : 1;
+        TopUpKeyPool();
+
+        vector<unsigned char> vchDefaultPubKey = keyUser.GetPubKey();
+        CKey publicLabelKey;
+        publicLabelKey.MakeNewKey();
+        string strPublicLabelAddress = PubKeyToAddress(publicLabelKey.GetPubKey());
+        nFail += Check(CWalletDB().WriteName(strPublicLabelAddress, "rewrite-public-name") &&
+                       CWalletDB().WriteSetting("rewrite-public-setting", (int64)424242),
+                       "public wallet records can be written before encryption") ? 0 : 1;
+
+        CPrivKey vchDefaultPrivKey;
+        nFail += Check(GetWalletPrivKey(vchDefaultPubKey, vchDefaultPrivKey, strError),
+                       "the default private key is readable before encryption") ? 0 : 1;
+        vector<unsigned char> vchDefaultPrivBytes(vchDefaultPrivKey.begin(), vchDefaultPrivKey.end());
+        vector<unsigned char> vchPlainHDMaster = vchHDMaster;
+        vector<unsigned char> vchPlainHDChainCode = vchHDChainCode;
+
+        // Release wallet.dat so a child process can read it for the export.
+        DBFlush(true);
+
+#ifdef _WIN32
+        string strExe = cwd + "\\bitflash.exe";
+#else
+        string strExe = cwd + "/bitflash-node";
+#endif
+        string strSQLitePath = tmp + "/wallet.sqlite";
+        string strWalletDatPath = tmp + "/wallet.dat";
+        string strRightPassFile = tmp + "/right-pass.txt";
+        string strWrongPassFile = tmp + "/wrong-pass.txt";
+        nFail += Check(WriteTextFile(strRightPassFile, "btf-test-passphrase\n") &&
+                       WriteTextFile(strWrongPassFile, "wrong-passphrase\n"),
+                       "passphrase files can be written for restarted commands") ? 0 : 1;
+
+        // Step 1: export the Berkeley DB wallet to SQLite.
+        vector<string> vExportArgs;
+        vExportArgs.push_back("-datadir=" + tmp);
+        vExportArgs.push_back("-walletsqliteexport=" + strSQLitePath);
+        vExportArgs.push_back("-nogui");
+        int nExportRet = RunBitflashChild(strExe, vExportArgs);
+        nFail += Check(nExportRet == 0 && FileExists(strSQLitePath.c_str()),
+                       "the wallet exports to a SQLite file") ? 0 : 1;
+        nFail += Check(FileContainsBytes(strSQLitePath, vchDefaultPrivBytes),
+                       "the exported SQLite wallet holds the plaintext key before encryption") ? 0 : 1;
+
+        // Step 2: encrypt through the real SQLite backend command path.
+        string strEncryptOut = tmp + "/sqlite-encrypt-out.txt";
+        vector<string> vEncryptArgs;
+        vEncryptArgs.push_back("-datadir=" + tmp);
+        vEncryptArgs.push_back("-walletbackend=sqlite");
+        vEncryptArgs.push_back("-encryptwallet=@" + strRightPassFile);
+        vEncryptArgs.push_back("-nogui");
+        int nEncryptRet = RunBitflashChild(strExe, vEncryptArgs, NULL, &strEncryptOut);
+        nFail += Check(nEncryptRet == 0,
+                       "the SQLite wallet can be encrypted through -walletbackend=sqlite") ? 0 : 1;
+        nFail += Check(FileContainsText(strEncryptOut, "Wallet backend: SQLite"),
+                       "encryption took the SQLite persistence path") ? 0 : 1;
+        nFail += Check(FileContainsText(strEncryptOut, "wallet.sqlite.before-encrypt"),
+                       "the plaintext SQLite wallet is preserved as an explicit backup") ? 0 : 1;
+
+        // The encrypted SQLite wallet must no longer hold the plaintext secrets.
+        nFail += Check(!FileContainsBytes(strSQLitePath, vchDefaultPrivBytes),
+                       "the encrypted SQLite wallet no longer contains the default private key bytes") ? 0 : 1;
+        nFail += Check(!FileContainsBytes(strSQLitePath, vchPlainHDMaster),
+                       "the encrypted SQLite wallet no longer contains the HD master key bytes") ? 0 : 1;
+        nFail += Check(!FileContainsBytes(strSQLitePath, vchPlainHDChainCode),
+                       "the encrypted SQLite wallet no longer contains the HD chain-code bytes") ? 0 : 1;
+
+        // The Berkeley DB wallet.dat is a separate file: the SQLite encrypt path
+        // must never touch it, so its plaintext key is still exactly there.
+        nFail += Check(FileContainsBytes(strWalletDatPath, vchDefaultPrivBytes),
+                       "the original Berkeley DB wallet.dat is left untouched by the SQLite encrypt") ? 0 : 1;
+
+        // Step 3: a locked encrypted SQLite wallet reports that phrase coverage
+        // needs an unlock, exactly as the Berkeley DB path does (exit code 2).
+        string strLockedAudit = tmp + "/locked-recovery-audit.txt";
+        vector<string> vLockedArgs;
+        vLockedArgs.push_back("-datadir=" + tmp);
+        vLockedArgs.push_back("-walletbackend=sqlite");
+        vLockedArgs.push_back("-recoveryaudit");
+        vLockedArgs.push_back("-nogui");
+        int nLockedRet = RunBitflashChild(strExe, vLockedArgs, NULL, &strLockedAudit);
+        nFail += Check(nLockedRet == 2 &&
+                       FileContainsText(strLockedAudit, "recovery phrase: encrypted, unlock wallet to audit"),
+                       "a locked encrypted SQLite wallet reports that phrase coverage needs unlock") ? 0 : 1;
+
+        // The wrong passphrase is rejected and reveals nothing.
+        string strWrongDump = tmp + "/wrong-dump.txt";
+        vector<string> vWrongArgs;
+        vWrongArgs.push_back("-datadir=" + tmp);
+        vWrongArgs.push_back("-walletbackend=sqlite");
+        vWrongArgs.push_back("-walletpassphrase=@" + strWrongPassFile);
+        vWrongArgs.push_back("-dumpwallet=" + strWrongDump);
+        vWrongArgs.push_back("-nogui");
+        int nWrongRet = RunBitflashChild(strExe, vWrongArgs);
+        nFail += Check(nWrongRet != 0 && !FileExists(strWrongDump.c_str()),
+                       "a restarted SQLite wallet rejects the wrong passphrase") ? 0 : 1;
+
+        // The right passphrase unlocks and can dump the original key.
+        string strRightDump = tmp + "/right-dump.txt";
+        vector<string> vRightArgs;
+        vRightArgs.push_back("-datadir=" + tmp);
+        vRightArgs.push_back("-walletbackend=sqlite");
+        vRightArgs.push_back("-walletpassphrase=@" + strRightPassFile);
+        vRightArgs.push_back("-dumpwallet=" + strRightDump);
+        vRightArgs.push_back("-nogui");
+        int nRightRet = RunBitflashChild(strExe, vRightArgs);
+        nFail += Check(nRightRet == 0 && FileExists(strRightDump.c_str()),
+                       "a restarted SQLite wallet unlocks with the right passphrase") ? 0 : 1;
+        nFail += Check(FileContainsText(strRightDump, HexStrLocal(vchDefaultPrivBytes)),
+                       "the unlocked SQLite wallet decrypts and dumps the original key") ? 0 : 1;
+
+        // The recovery phrase survives the encryption.
+        string strAudit = tmp + "/recovery-audit.txt";
+        vector<string> vAuditArgs;
+        vAuditArgs.push_back("-datadir=" + tmp);
+        vAuditArgs.push_back("-walletbackend=sqlite");
+        vAuditArgs.push_back("-walletpassphrase=@" + strRightPassFile);
+        vAuditArgs.push_back("-recoveryaudit");
+        vAuditArgs.push_back("-nogui");
+        int nAuditRet = RunBitflashChild(strExe, vAuditArgs, NULL, &strAudit);
+        nFail += Check(nAuditRet == 0 &&
+                       FileContainsText(strAudit, "recovery phrase: present"),
+                       "the encrypted SQLite wallet still has its recovery phrase") ? 0 : 1;
+    }
+    catch (const std::exception& e)
+    {
+        printf("  FAIL exception: %s\n", e.what());
+        nFail++;
+    }
+    catch (...)
+    {
+        printf("  FAIL unknown exception\n");
+        nFail++;
+    }
+
+    DBFlush(true);
+    SetCurrentDir(cwd);
+    RemoveTree(tmp);
+    printf("%s (%d failure%s)\n", nFail == 0 ? "ALL TESTS PASSED" : "TESTS FAILED",
+           nFail, nFail == 1 ? "" : "s");
+    fflush(stdout);
+    return nFail == 0 ? 0 : 1;
+}
+
 static int RunWalletPortabilitySelfTest()
 {
     fflush(stdout);
@@ -2981,6 +3166,8 @@ int RunSelfTest(const std::string& name)
         return RunWalletCryptoSelfTest();
     if (name == "wallet-encrypt")
         return RunWalletEncryptSelfTest();
+    if (name == "wallet-sqlite-encrypt")
+        return RunWalletSQLiteEncryptSelfTest();
     if (name == "wallet-portability")
         return RunWalletPortabilitySelfTest();
     if (name == "net-message")
@@ -2997,6 +3184,6 @@ int RunSelfTest(const std::string& name)
         return RunManagedTorSelfTest();
 
     printf("Unknown self-test '%s'\n", name.c_str());
-    printf("Known self-tests: wallet-keypool, wallet-hd, wallet-format, wallet-storage-sanity, db-env-reopen, wallet-sqlite, wallet-sqlite-migration, wallet-crypto, wallet-encrypt, wallet-portability, net-message, consensus-limits, pool-stratum, parse-money, socks5-proxy, managed-tor\n");
+    printf("Known self-tests: wallet-keypool, wallet-hd, wallet-format, wallet-storage-sanity, db-env-reopen, wallet-sqlite, wallet-sqlite-migration, wallet-crypto, wallet-encrypt, wallet-sqlite-encrypt, wallet-portability, net-message, consensus-limits, pool-stratum, parse-money, socks5-proxy, managed-tor\n");
     return 1;
 }
diff --git a/src/walletcmd.cpp b/src/walletcmd.cpp
index 4dda8dd..374b2cc 100644
--- a/src/walletcmd.cpp
+++ b/src/walletcmd.cpp
@@ -1365,6 +1365,11 @@ int CmdEncryptWallet(const std::string& strPassphrase)
 {
     AttachTerminal();
 
+    // Capture the backend now: under SQLite, EncryptWallet() closes the runtime
+    // store to swap the file, so WalletSQLiteRuntimeActive() reads false by the
+    // time we would decide whether to purge Berkeley DB logs below.
+    bool fSQLiteBackend = WalletSQLiteRuntimeActive();
+
     string strBackup;
     string strError;
     if (!EncryptWallet(strPassphrase, strBackup, strError))
@@ -1375,6 +1380,8 @@ int CmdEncryptWallet(const std::string& strPassphrase)
     }
 
     printf("Wallet encrypted.\n");
+    if (fSQLiteBackend)
+        printf("Wallet backend: SQLite (wallet.sqlite).\n");
     printf("The old unencrypted wallet was moved to:\n");
     printf("  %s\n", strBackup.c_str());
     printf("That backup still contains private keys in plain text. Move it offline or\n");
@@ -1387,7 +1394,13 @@ int CmdEncryptWallet(const std::string& strPassphrase)
     // them. Closing the environment and dropping the logs is the last step of
     // encrypting, not an optimisation -- our own backup advice is to copy the
     // whole directory, and following it otherwise carries the keys along.
-    PurgeDbEnvironmentLogs();
+    //
+    // The SQLite backend has no Berkeley DB environment behind the wallet, and
+    // EncryptWallet() already closed and swapped the SQLite store; there is
+    // nothing to purge, and calling into the environment here would only open
+    // one needlessly.
+    if (!fSQLiteBackend)
+        PurgeDbEnvironmentLogs();
     return 0;
 }