// Changes the encryption key for an existing database.
int sqlite3_rekey(sqlite3 *db, const unsigned char *pKey, int nKeySize)
{
Btree *pbt = db->aDb[0].pBt;
Pager *p = sqlite3BtreePager(pbt);
LPCRYPTBLOCK pBlock = (LPCRYPTBLOCK)sqlite3pager_get_codecarg(p);
HCRYPTKEY hKey = DeriveKey(pKey, nKeySize);
int rc = SQLITE_ERROR;
if (hKey == MAXDWORD)
{
sqlite3Error(db, rc, SQLITECRYPTERROR_PROVIDER);
return rc;
}
if (!pBlock && !hKey) return SQLITE_OK; // Wasn't encrypted to begin with
// To rekey a database, we change the writekey for the pager. The readkey remains
// the same
if (!pBlock) // Encrypt an unencrypted database
{
pBlock = CreateCryptBlock(hKey, p, -1, NULL);
if (!pBlock)
return SQLITE_NOMEM;
pBlock->hReadKey = 0; // Original database is not encrypted
sqlite3PagerSetCodec(sqlite3BtreePager(pbt), sqlite3Codec, sqlite3CodecSizeChange, sqlite3CodecFree, pBlock);
//db->aDb[0].pAux = pBlock;
//db->aDb[0].xFreeAux = DestroyCryptBlock;
}
else // Change the writekey for an already-encrypted database
{
pBlock->hWriteKey = hKey;
}
// Start a transaction
rc = sqlite3BtreeBeginTrans(pbt, 1);
if (!rc)
{
// Rewrite all the pages in the database using the new encryption key
Pgno nPage;
Pgno nSkip = PAGER_MJ_PGNO(p);
DbPage *pPage;
Pgno n;
rc = sqlite3PagerPagecount(p, &nPage);
for(n = 1; rc == SQLITE_OK && n <= nPage; n ++)
{
if (n == nSkip) continue;
rc = sqlite3PagerGet(p, n, &pPage);
if(!rc)
{
rc = sqlite3PagerWrite(pPage);
sqlite3PagerUnref(pPage);
}
}
}
// If we succeeded, try and commit the transaction
if (!rc)
{
rc = sqlite3BtreeCommit(pbt);
}
// If we failed, rollback
if (rc)
{
sqlite3BtreeRollback(pbt);
}
// If we succeeded, destroy any previous read key this database used
// and make the readkey equal to the writekey
if (!rc)
{
if (pBlock->hReadKey)
{
CryptDestroyKey(pBlock->hReadKey);
}
pBlock->hReadKey = pBlock->hWriteKey;
}
// We failed. Destroy the new writekey (if there was one) and revert it back to
// the original readkey
else
{
if (pBlock->hWriteKey)
{
CryptDestroyKey(pBlock->hWriteKey);
}
pBlock->hWriteKey = pBlock->hReadKey;
}
// If the readkey and writekey are both empty, there's no need for a codec on this
// pager anymore. Destroy the crypt block and remove the codec from the pager.
if (!pBlock->hReadKey && !pBlock->hWriteKey)
{
sqlite3PagerSetCodec(p, NULL, NULL, NULL, NULL);
}
return rc;
}
int sqlite3_rekey(sqlite3 *db, const void *zKey, int nKey)
{
BOTANSQLITE_TRACE("sqlite3_rekey");
// Changes the encryption key for an existing database.
int rc = SQLITE_ERROR;
Btree *pbt = db->aDb[0].pBt;
Pager *pPager = sqlite3BtreePager(pbt);
void *pCodec = sqlite3PagerGetCodec(pPager);
if ((!zKey || nKey <= 0) && !pCodec)
{
// Database not encrypted and key not specified. Do nothing
return SQLITE_OK;
}
if (!pCodec)
{
// Database not encrypted, but key specified. Encrypt database
pCodec = InitializeNewCodec(db);
assert(nKey >= 0);
SetWriteKey(pCodec, (const char*) zKey, (size_t) nKey);
if (HandleError(pCodec))
{
DeleteCodec(pCodec);
return SQLITE_ERROR;
}
sqlite3PagerSetCodec(pPager, Codec, CodecSizeChange, PagerFreeCodec, pCodec);
}
else if (!zKey || nKey <= 0)
{
// Database encrypted, but key not specified. Decrypt database
// Keep read key, drop write key
DropWriteKey(pCodec);
}
else
{
// Database encrypted and key specified. Re-encrypt database with new key
// Keep read key, change write key to new key
assert(nKey >= 0);
SetWriteKey(pCodec, (const char*) zKey, (size_t) nKey);
if (HandleError(pCodec)) 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;
sqlite3PagerPagecount(pPager, &nPageCount);
Pgno nPage = (Pgno) nPageCount;
Pgno nSkip = PAGER_MJ_PGNO(pPager);
DbPage *pPage;
Pgno n;
for (n = 1; rc == SQLITE_OK && n <= nPage; n++)
{
if (n == nSkip) continue;
rc = sqlite3PagerGet(pPager, n, &pPage, 0);
if (rc == SQLITE_OK)
{
rc = sqlite3PagerWrite(pPage);
sqlite3PagerUnref(pPage);
}
else
{
sqlite3ErrorWithMsg(db, SQLITE_ERROR, "%s", "Error while rekeying database page. Transaction Canceled.");
}
}
}
else
{
sqlite3ErrorWithMsg(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 (HasWriteKey(pCodec))
{
SetReadIsWrite(pCodec);
}
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
sqlite3ErrorWithMsg(db, SQLITE_ERROR, "%s", "Could not commit rekey transaction.");
}
}
else
{
// Rollback, rekey failed
sqlite3BtreeRollback(pbt, SQLITE_ERROR, 0);
// go back to read key
if (HasReadKey(pCodec))
{
SetWriteIsRead(pCodec);
}
else //Database wasn't encrypted to start with
{
sqlite3PagerSetCodec(pPager, NULL, NULL, NULL, NULL);
}
}
return rc;
}
int sqlite3pager_is_mj_pgno(Pager *pPager, Pgno pgno) {
return (PAGER_MJ_PGNO(pPager) == pgno) ? 1 : 0;
}
