SQLite加密

发布时间：2020-12-12 23:55:50 所属栏目：百科来源：网络整理

导读：SQLiteCrypt API SQLiteCrypt is very easy to use. SQLiteCrypt is based on SQLite with all API functions remain unchanged. All encryption/ decryption routines are performed transparently. SQLiteCrypt uses three PRAGMA statements to work with

SQLiteCrypt API

SQLiteCrypt is very easy to use. SQLiteCrypt is based on SQLite with all API functions remain unchanged. All encryption/ decryption routines are performed transparently. SQLiteCrypt uses three PRAGMA statements to work with encrypted database:

PRAGMA key = 'the passphrase'// passphrase

PRAGMA rekey = 'new passphrase'// change passphrase

PRAGMA lic = 'the license key'//the software key

The first PRAGMA statement is used to create/ access encrypted database. The second one will re-write database with new passphrase. The third one used to identify legal copy of SQLiteCrypt software.

Remark: Do not userekey in middle of a transaction. This method decrypt whole database using old passphrase,then encrypt using new passphrase. You can continue to use SQLite API functions,no need of closing and re-opening database. This is time-consuming operation.

Example 1: Create/ open encrypted SQLite database

sqlite3_open_v2("data.db",&db,SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE,NULL);

sqlite3_stmt* stm;
const char*pzTail;

intres;

res = sqlite3_prepare(db,"PRAGMA key = 'ac23';",-1,&stm,&pzTail);//ac23 is database passphrase
res = sqlite3_step(stm);

res = sqlite3_prepare(db,"PRAGMA lic = '77523-009-0000007-72328';",&pzTail);//software license key
res = sqlite3_step(stm);

//now you have all access to data.db

Example 2: Decrypt SQLite database (remove encryption,so any other SQLite application can open it)

sqlite3_open_v2("data.db",NULL);

sqlite3_stmt* stm;
const char*pzTail;

intres;

res = sqlite3_prepare(db,&pzTail);//ac23 is current passphrase
res = sqlite3_step(stm);

res = sqlite3_prepare(db,&pzTail);//software license key
res = sqlite3_step(stm);

//now you have all access to encrypted data.db

res = sqlite3_prepare(db,"PRAGMA rekey = '';",&pzTail);// new empty passphrase
res = sqlite3_step(stm);

//now data.db is NOT encrypted

Example 3: Change encryption key on-the-fly

sqlite3_open_v2("data.db",NULL);

sqlite3_stmt* stm;
const char* pzTail;

intres;

res = sqlite3_prepare(db,"PRAGMA rekey = 'abc123';",&pzTail);//abc123 is new passphrase
res = sqlite3_step(stm);

//now data.db re-written using new passphrase

Example 4: Encrypt SQLite database (add encryption to regular SQLite database)

sqlite3_open_v2("data.db",&pzTail);//software license key
res = sqlite3_step(stm);

//now you have all access to regular data.db

res = sqlite3_prepare(db,&pzTail);// encrypt database using abc123 passphrase
res = sqlite3_step(stm);

//now data.db is encrypted

Example 5: Using SQLiteCrypt command line tool

Opening encrypted db without passphrase:

D:&;sqlite.exe data.db
SQLite version 3.7.15.2 2013-01-09 11:53:05
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> select * from _MapPropertyA;
Error: file is encrypted or is not a database

Querry on an encrypted database

D:&;sqlite.exe data.db SQLite version 3.7.15.2 2013-01-09 11:53:05 Enter ".help" for instructions Enter SQL statements terminated with a ";" sqlite> PRAGMA key = 'ac23'; sqlite> PRAGMA lic = '77523-009-0000007-72328'; sqlite> select * from _MapPropertyA; 3.0|8.0 3.0|8.0

（编辑：李大同）

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