6.7 KiB
SQLCipher
SQLCipher is an SQLite extension that provides transparent 256-bit AES encryption of database files. Pages are encrypted before being written to disk and are decrypted when read back. Due to the small footprint and great performance it’s ideal for protecting embedded application databases and is well suited for mobile development.
The official SQLCipher software site is http://sqlcipher.net
SQLCipher was initially developed by Stephen Lombardo at Zetetic LLC (sjlombardo@zetetic.net) as the encrypted database layer for Strip, an iPhone data vault and password manager (http://getstrip.com).
Features
- Fast performance with as little as 5-15% overhead for encryption on many operations
- 100% of data in the database file is encrypted
- Good security practices (CBC mode, key derivation)
- Zero-configuration and application level cryptography
- Algorithms provided by the peer reviewed OpenSSL crypto library.
- Configurable crypto providers
Compiling
Building SQLCipher is almost the same as compiling a regular version of SQLite with two small exceptions:
- You must define SQLITE_HAS_CODEC and SQLITE_TEMP_STORE=2 when building sqlcipher
- You need to link against a OpenSSL's libcrypto
Example Static linking (replace /opt/local/lib with the path to libcrypto.a)
$ ./configure --enable-tempstore=yes CFLAGS="-DSQLITE_HAS_CODEC" \
LDFLAGS="/opt/local/lib/libcrypto.a"
$ make
Example Dynamic linking
$ ./configure --enable-tempstore=yes CFLAGS="-DSQLITE_HAS_CODEC" \
LDFLAGS="-lcrypto"
$ make
Encrypting a database
To specify an encryption passphrase for the database via the SQL interface you use a pragma. The passphrase you enter is passed through PBKDF2 key derivation to obtain the encryption key for the database
PRAGMA key = 'passphrase';
Alternately, you can specify an exact byte sequence using a blob literal. If you use this method it is your responsibility to ensure that the data you provide a 64 character hex string, which will be converted directly to 32 bytes (256 bits) of key data without key derivation.
PRAGMA key = "x'2DD29CA851E7B56E4697B0E1F08507293D761A05CE4D1B628663F411A8086D99'";
To encrypt a database programatically you can use the sqlite3_key function. The data provided in pKey is converted to an encryption key according to the same rules as PRAGMA key.
int sqlite3_key(sqlite3 *db, const void *pKey, int nKey);
PRAGMA key or sqlite3_key should be called as the first operation when a database is open.
Changing a database key
To change the encryption passphrase for an existing database you may use the rekey pragma after you've supplied the correct database password;
PRAGMA key = 'passphrase'; -- start with the existing database passphrase
PRAGMA rekey = 'new-passphrase'; -- rekey will reencrypt with the new passphrase
The hexrekey pragma may be used to rekey to a specific binary value
PRAGMA rekey = "x'2DD29CA851E7B56E4697B0E1F08507293D761A05CE4D1B628663F411A8086D99'";
This can be accomplished programtically by using sqlite3_rekey;
sqlite3_rekey(sqlite3 *db, const void *pKey, int nKey)
Support
The primary avenue for support and discussions is the SQLCipher users mailing list:
http://groups.google.com/group/sqlcipher
Issues or support questions on using SQLCipher should be entered into the GitHub Issue tracker:
https://github.com/sqlcipher/sqlcipher/issues
Please DO NOT post issues, support questions, or other problems to blog posts about SQLCipher as we do not monitor them frequently.
If you are using SQLCipher in your own software please let us know at support@zetetic.net!
License
Copyright (c) 2008, ZETETIC LLC All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. * Neither the name of the ZETETIC LLC nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY ZETETIC LLC ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL ZETETIC LLC BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
End SQLCipher
This directory contains source code to
SQLite: An Embeddable SQL Database Engine
To compile the project, first create a directory in which to place the build products. It is recommended, but not required, that the build directory be separate from the source directory. Cd into the build directory and then from the build directory run the configure script found at the root of the source tree. Then run "make".
For example:
tar xzf sqlite.tar.gz ;# Unpack the source tree into "sqlite"
mkdir bld ;# Build will occur in a sibling directory
cd bld ;# Change to the build directory
../sqlite/configure ;# Run the configure script
make ;# Run the makefile.
make install ;# (Optional) Install the build products
The configure script uses autoconf 2.61 and libtool. If the configure script does not work out for you, there is a generic makefile named "Makefile.linux-gcc" in the top directory of the source tree that you can copy and edit to suit your needs. Comments on the generic makefile show what changes are needed.
The linux binaries on the website are created using the generic makefile, not the configure script. The windows binaries on the website are created using MinGW32 configured as a cross-compiler running under Linux. For details, see the ./publish.sh script at the top-level of the source tree. The developers do not use teh configure script.
SQLite does not require TCL to run, but a TCL installation is required by the makefiles. SQLite contains a lot of generated code and TCL is used to do much of that code generation. The makefile also requires AWK.
Contacts: