Add SQLite3 encryption codec, contributed by Olivier de Gaalon. Uses

Twofish in XTS mode for encryption by default, but is easily tweakable.

1 files changed, 261 insertions, 0 deletions

diff --git a/src/wrap/sqlite/codecext.cpp b/src/wrap/sqlite/codecext.cpp
new file mode 100644
index 000000000..e542df975
--- /dev/null
+++ b/src/wrap/sqlite/codecext.cpp
@@ -0,0 +1,261 @@
+/*
+ * SQLite3 encryption extention codec
+ * (C) 2010 Olivier de Gaalon
+ *
+ * Distributed under the terms of the Botan license
+ */
+
+#ifndef SQLITE_OMIT_DISKIO
+#ifdef SQLITE_HAS_CODEC
+
+#include "codec.h"
+#include "sqlite3.h"
+
+// Required to implement, called from pragma.c, guessing that "see" is related to the
+// "SQLite Encryption Extension" (the semi-official, for-pay, encryption codec)
+extern "C"
+void sqlite3_activate_see(const char *info) { }
+
+// Free the encryption codec, called from pager.c (address passed in sqlite3PagerSetCodec)
+extern "C"
+void sqlite3PagerFreeCodec(void *pCodec)
+{
+    if (pCodec)
+        delete (Codec*) pCodec;
+}
+
+// Report the page size to the codec, called from pager.c (address passed in sqlite3PagerSetCodec)
+extern "C"
+void sqlite3CodecSizeChange(void *pCodec, int pageSize, int nReserve)
+{
+    Codec* codec = (Codec*) pCodec;
+    codec->SetPageSize(pageSize);
+}
+
+// Encrypt/Decrypt functionality, called by pager.c
+extern "C"
+void* sqlite3Codec(void* pCodec, void* data, Pgno nPageNum, int nMode)
+{
+    if (pCodec == NULL) //Db not encrypted
+        return data;
+
+    Codec* codec = (Codec*) pCodec;
+
+    try
+    {
+        switch(nMode)
+        {
+        case 0: // Undo a "case 7" journal file encryption
+        case 2: // Reload a page
+        case 3: // Load a page
+                if (codec->HasReadKey())
+                    codec->Decrypt(nPageNum, (unsigned char*) data);
+            break;
+        case 6: // Encrypt a page for the main database file
+            if (codec->HasWriteKey())
+                data = codec->Encrypt(nPageNum, (unsigned char*) data, true);
+            break;
+        case 7: // Encrypt a page for the journal file
+        /*
+        *Under normal circumstances, the readkey is the same as the writekey.  However,
+        *when the database is being rekeyed, the readkey is not the same as the writekey.
+        *(The writekey is the "destination key" for the rekey operation and the readkey
+        *is the key the db is currently encrypted with)
+        *Therefore, for case 7, when the rollback is being written, always encrypt using
+        *the database's readkey, which is guaranteed to be the same key that was used to
+        *read and write the original data.
+        */
+            if (codec->HasReadKey())
+                data = codec->Encrypt(nPageNum, (unsigned char*) data, false);
+            break;
+        }
+    }
+    catch(Botan::Exception e)
+    {
+        sqlite3Error((sqlite3*)codec->GetDB(), SQLITE_ERROR, "Botan Error: %s", e.what());
+    }
+
+    return data;
+}
+
+//These functions are defined in pager.c
+extern "C" void* sqlite3PagerGetCodec(Pager *pPager);
+extern "C" void sqlite3PagerSetCodec(
+    Pager *pPager,
+    void *(*xCodec)(void*,void*,Pgno,int),
+    void (*xCodecSizeChng)(void*,int,int),
+    void (*xCodecFree)(void*),
+    void *pCodec
+);
+
+
+extern "C"
+int sqlite3CodecAttach(sqlite3* db, int nDb, const void* zKey, int nKey)
+{
+    try {
+        if (zKey == NULL || nKey <= 0)
+        {
+            // No key specified, could mean either use the main db's encryption or no encryption
+            if (nDb != 0 && nKey < 0)
+            {
+                //Is an attached database, therefore use the key of main database, if main database is encrypted
+                Codec* mainCodec = (Codec*) sqlite3PagerGetCodec(sqlite3BtreePager(db->aDb[0].pBt));
+                if (mainCodec != NULL)
+                {
+                    Codec* codec = new Codec(*mainCodec, db);
+                    sqlite3PagerSetCodec(sqlite3BtreePager(db->aDb[nDb].pBt),
+                                        sqlite3Codec,
+                                        sqlite3CodecSizeChange,
+                                        sqlite3PagerFreeCodec, codec);
+                }
+            }
+        }
+        else
+        {
+            // Key specified, setup encryption key for database
+            Codec* codec = new Codec(db);
+            codec->GenerateWriteKey((const char*) zKey, nKey);
+            codec->SetReadIsWrite();
+            sqlite3PagerSetCodec(sqlite3BtreePager(db->aDb[nDb].pBt),
+                                sqlite3Codec,
+                                sqlite3CodecSizeChange,
+                                sqlite3PagerFreeCodec, codec);
+        }
+    }
+    catch(Botan::Exception e) {
+        sqlite3Error(db, SQLITE_ERROR, "Botan Error: %s", e.what());
+        return SQLITE_ERROR;
+    }
+    return SQLITE_OK;
+}
+
+extern "C"
+void sqlite3CodecGetKey(sqlite3* db, int nDb, void** zKey, int* nKey)
+{
+    // The unencrypted password is not stored for security reasons
+    // therefore always return NULL
+    *zKey = NULL;
+    *nKey = -1;
+}
+
+extern "C"
+int sqlite3_key(sqlite3 *db, const void *zKey, int nKey)
+{
+    // The key is only set for the main database, not the temp database
+    return sqlite3CodecAttach(db, 0, zKey, nKey);
+}
+
+extern "C"
+int sqlite3_rekey(sqlite3 *db, const void *zKey, int nKey)
+{
+    // Changes the encryption key for an existing database.
+    int rc = SQLITE_ERROR;
+    Btree* pbt = db->aDb[0].pBt;
+    Pager* pPager = sqlite3BtreePager(pbt);
+    Codec* codec = (Codec*) sqlite3PagerGetCodec(pPager);
+
+    if ((zKey == NULL || nKey == 0) && codec == NULL)
+    {
+        // Database not encrypted and key not specified. Do nothing
+        return SQLITE_OK;
+    }
+
+    if (codec == NULL)
+    {
+        // Database not encrypted, but key specified. Encrypt database
+        try {
+            codec = new Codec(db);
+            codec->GenerateWriteKey((const char*) zKey, nKey);
+        } catch (Botan::Exception e) {
+            sqlite3Error(db, SQLITE_ERROR, "Botan Error %s", e.what());
+            return SQLITE_ERROR;
+        }
+        sqlite3PagerSetCodec(pPager, sqlite3Codec, sqlite3CodecSizeChange, sqlite3PagerFreeCodec, codec);
+    }
+    else if (zKey == NULL || nKey == 0)
+    {
+        // Database encrypted, but key not specified. Decrypt database
+        // Keep read key, drop write key
+        codec->DropWriteKey();
+    }
+    else
+    {
+        // Database encrypted and key specified. Re-encrypt database with new key
+        // Keep read key, change write key to new key
+        try {
+            codec->GenerateWriteKey((const char*) zKey, nKey);
+        } catch (Botan::Exception e) {
+            sqlite3Error(db, SQLITE_ERROR, "Botan Error %s", e.what());
+            return SQLITE_ERROR;
+        }
+    }
+
+    // Start transaction
+    rc = sqlite3BtreeBeginTrans(pbt, 1);
+    if (rc == SQLITE_OK)
+    {
+        // Rewrite all pages using the new encryption key (if specified)
+        int nPageCount = -1;
+        int rc = sqlite3PagerPagecount(pPager, &nPageCount);
+        Pgno nPage = (Pgno) nPageCount;
+        int pageSize = sqlite3BtreeGetPageSize(pbt);
+        //Can't use SQLite3 macro here since pager is forward declared...sigh
+        Pgno nSkip = CODEC_PAGER_MJ_PGNO(pageSize);
+        DbPage *pPage;
+
+        for (Pgno n = 1; rc == SQLITE_OK && n <= nPage; n++)
+        {
+            if (n == nSkip)
+                continue;
+
+            rc = sqlite3PagerGet(pPager, n, &pPage);
+
+            if (!rc)
+            {
+                rc = sqlite3PagerWrite(pPage);
+                sqlite3PagerUnref(pPage);
+            }
+            else
+                sqlite3Error(db, SQLITE_ERROR, "%s", "Error while rekeying database page. Transaction Canceled.");
+        }
+    }
+    else
+        sqlite3Error(db, SQLITE_ERROR, "%s", "Error beginning rekey transaction. Make sure that the current encryption key is correct.");
+
+    if (rc == SQLITE_OK)
+    {
+        // All good, commit
+        rc = sqlite3BtreeCommit(pbt);
+
+        if (rc == SQLITE_OK)
+        {
+            //Database rekeyed and committed successfully, update read key
+            if (codec->HasWriteKey())
+                codec->SetReadIsWrite();
+            else //No write key == no longer encrypted
+                sqlite3PagerSetCodec(pPager, NULL, NULL, NULL, NULL); 
+        }
+        else
+        {
+            //FIXME: can't trigger this, not sure if rollback is needed, reference implementation didn't rollback
+            sqlite3Error(db, SQLITE_ERROR, "%s", "Could not commit rekey transaction.");
+        }
+    }
+    else
+    {
+        // Rollback, rekey failed
+        sqlite3BtreeRollback(pbt);
+
+        // go back to read key
+        if (codec->HasReadKey())
+            codec->SetWriteIsRead();
+        else //Database wasn't encrypted to start with
+            sqlite3PagerSetCodec(pPager, NULL, NULL, NULL, NULL); 
+    }
+
+    return rc;
+}
+
+#endif // SQLITE_HAS_CODEC
+
+#endif // SQLITE_OMIT_DISKIO