SQLCipher is a standalone fork of SQLite that adds 256 bit AES encryption of database files and other security features.
SQLCipher is a standalone fork of the SQLite database library that adds 256 bit AES encryption of database files and other security features like:
SQLCipher is based on SQLite and stable upstream release features are periodically integrated. While SQLCipher is maintained as a separate version of the source tree, the project minimizes alterations to core SQLite code whenever possible.
SQLCipher is maintained by Zetetic, LLC, and additional information and documentation is available on the official SQLCipher site.
SQLCipher maintains database format compatibility within the same major version number so an application on any platform can open databases created by any other application provided the major version of SQLCipher is the same between them. However, major version updates (e.g. from 3.x to 4.x) often include changes to default settings. This means that newer major versions of SQLCipher will not open databases created by older versions without using special settings. For example, SQLCipher 4 introduces many new performance and security enhancements. The new default algorithms, increased KDF iterations, and larger page size mean that SQLCipher 4 will not open databases created by SQLCipher 1.x, 2.x, or 3.x by default. Instead, an application would either need to migrate the older databases to use the new format or enable a special backwards-compatibility mode. The available options are described in SQLCipher’s upgrade documentation.
SQLCipher is also compatible with standard SQLite databases. When a key is not provided, SQLCipher will behave just like the standard SQLite library. It is also possible to convert from a plaintext database (standard SQLite) to an encrypted SQLCipher database using ATTACH and the sqlcipher_export() convenience function.
The SQLCipher team welcomes contributions to the core library. All contributions including pull requests and patches should be based on the prerelease branch, and must be accompanied by a contributor agreement. We strongly encourage discussion of the proposed change prior to development and submission.
Building SQLCipher is similar to compiling a regular version of SQLite from source, with a couple of small exceptions:
SQLITE_HAS_CODEC and either SQLITE_TEMP_STORE=2 or SQLITE_TEMP_STORE=3The following examples demonstrate linking against OpenSSL, which is a readily available provider on most Unix-like systems.
Example 1. Static linking (replace /opt/local/lib with the path to libcrypto.a). Note in this
example, --enable-tempstore=yes is setting SQLITE_TEMP_STORE=2 for the build.
$ ./configure --enable-tempstore=yes CFLAGS="-DSQLITE_HAS_CODEC" \
LDFLAGS="/opt/local/lib/libcrypto.a"
$ make
Example 2. Dynamic linking
$ ./configure --enable-tempstore=yes CFLAGS="-DSQLITE_HAS_CODEC" \
LDFLAGS="-lcrypto"
$ make
The full SQLite test suite will not complete successfully when using SQLCipher. In some cases encryption interferes with low-level tests that require access to database file data or features which are unsupported by SQLCipher. Those tests that are intended to support encryption are intended for non-SQLCipher implementations. In addition, because SQLite tests are not always isolated, if one test fails it can trigger a domino effect with other failures in later steps.
As a result, the SQLCipher package includes it’s own independent tests that exercise and verify the core functionality of the SQLCipher extensions. This test suite is intended to provide an abbreviated verification of SQLCipher’s internal logic; it does not perform an exhaustive test of the SQLite database system as a whole or verify functionality on specific platforms. Because SQLCipher is based on stable upstream builds of SQLite, it is considered a basic assumption that the core SQLite library code is operating properly (the SQLite core is almost untouched in SQLCipher). Thus, the additional SQLCipher-specific test provide the requisite verification that the library is operating as expected with SQLCipher’s security features enabled.
To run SQLCipher specific tests, configure as described here and run the following to execute the tests and receive a report of the results:
$ ./configure --enable-tempstore=yes --enable-fts5 CFLAGS="-DSQLITE_HAS_CODEC -DSQLCIPHER_TEST" \
LDFLAGS="-lcrypto"
$ make testfixture
$ ./testfixture test/sqlcipher.test
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 is 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 programmatically 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.
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 hex rekey pragma may be used to rekey to a specific binary value
PRAGMA rekey = "x'2DD29CA851E7B56E4697B0E1F08507293D761A05CE4D1B628663F411A8086D99'";
This can be accomplished programmatically by using sqlite3_rekey;
sqlite3_rekey(sqlite3 *db, const void *pKey, int nKey)
The primary source for complete documentation (design, API, platforms, usage) is the SQLCipher website:
https://www.zetetic.net/sqlcipher/documentation
The primary avenue for support and discussions is the SQLCipher discuss site:
https://discuss.zetetic.net/c/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
[email protected]!
Copyright © 2020, ZETETIC LLC
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This repository contains the complete source code for the
SQLite database engine. Some test scripts
are also included. However, many other test scripts
and most of the documentation are managed separately.
SQLite sources are managed using
Fossil, a distributed version control system
that was specifically designed and written to support SQLite development.
The Fossil repository contains the urtext.
If you are reading this on GitHub or some other Git repository or service,
then you are looking at a mirror. The names of check-ins and
other artifacts in a Git mirror are different from the official
names for those objects. The official names for check-ins are
found in a footer on the check-in comment for authorized mirrors.
The official check-in name can also be seen in the manifest.uuid file
in the root of the tree. Always use the official name, not the
Git-name, when communicating about an SQLite check-in.
If you pulled your SQLite source code from a secondary source and want to
verify its integrity, there are hints on how to do that in the
Verifying Code Authenticity section below.
The preferred way to ask questions or make comments about SQLite or to
report bugs against SQLite is to visit the
SQLite Forum at https://sqlite.org/forum/.
Anonymous postings are permitted.
If you think you have found a bug that has security implications and
you do not want to report it on the public forum, you can send a private
email to drh at sqlite dot org.
The SQLite source code is in the public domain. See
https://sqlite.org/copyright.html for details.
Because SQLite is in the public domain, we do not normally accept pull
requests, because if we did take a pull request, the changes in that
pull request might carry a copyright and the SQLite source code would
then no longer be fully in the public domain.
If you do not want to use Fossil, you can download tarballs or ZIP
archives or SQLite archives as follows:
Latest trunk check-in as
Tarball,
ZIP-archive, or
SQLite-archive.
Latest release as
Tarball,
ZIP-archive, or
SQLite-archive.
For other check-ins, substitute an appropriate branch name or
tag or hash prefix in place of “release” in the URLs of the previous
bullet. Or browse the timeline
to locate the check-in desired, click on its information page link,
then click on the “Tarball” or “ZIP Archive” links on the information
page.
If you do want to use Fossil to check out the source tree,
first install Fossil version 2.0 or later.
(Source tarballs and precompiled binaries available
here. Fossil is
a stand-alone program. To install, simply download or build the single
executable file and put that file someplace on your $PATH.)
Then run commands like this:
mkdir -p ~/sqlite ~/Fossils
cd ~/sqlite
fossil clone https://www.sqlite.org/src ~/Fossils/sqlite.fossil
fossil open ~/Fossils/sqlite.fossil
After setting up a repository using the steps above, you can always
update to the latest version using:
fossil update trunk ;# latest trunk check-in
fossil update release ;# latest official release
Or type “fossil ui” to get a web-based user interface.
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 ;# Builds the "sqlite3" command-line tool
make sqlite3.c ;# Build the "amalgamation" source file
make devtest ;# Run some tests (requires Tcl)
See the makefile for additional targets.
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.
On Windows, all applicable build products can be compiled with MSVC.
You will also need a working installation of TCL.
See the compile-for-windows.md document for
additional information about how to install MSVC and TCL and configure your
build environment.
If you want to run tests, you need to let SQLite know the location of your
TCL library, using a command like this:
set TCLDIR=c:\Tcl
SQLite uses “tclsh.exe” as part of the build process, and so that utility
program will need to be somewhere on your %PATH%. The finished SQLite library
does not contain any TCL code, but it does use TCL to help with the build process
and to run tests.
Build using Makefile.msc. Example:
nmake /f Makefile.msc
nmake /f Makefile.msc sqlite3.c
nmake /f Makefile.msc devtest
nmake /f Makefile.msc releasetest
There are many other makefile targets. See comments in Makefile.msc for
details.
Most of the core source files are in the src/ subdirectory. The
src/ folder also contains files used to build the “testfixture” test
harness. The names of the source files used by “testfixture” all begin
with “test”.
The src/ also contains the “shell.c” file
which is the main program for the “sqlite3.exe”
command-line shell and
the “tclsqlite.c” file which implements the
Tcl bindings for SQLite.
(Historical note: SQLite began as a Tcl
extension and only later escaped to the wild as an independent library.)
Test scripts and programs are found in the test/ subdirectory.
Additional test code is found in other source repositories.
See How SQLite Is Tested for
additional information.
The ext/ subdirectory contains code for extensions. The
Full-text search engine is in ext/fts3. The R-Tree engine is in
ext/rtree. The ext/misc subdirectory contains a number of
smaller, single-file extensions, such as a REGEXP operator.
The tool/ subdirectory contains various scripts and programs used
for building generated source code files or for testing or for generating
accessory programs such as “sqlite3_analyzer(.exe)”.
Several of the C-language source files used by SQLite are generated from
other sources rather than being typed in manually by a programmer. This
section will summarize those automatically-generated files. To create all
of the automatically-generated files, simply run “make target_source”.
The “target_source” make target will create a subdirectory “tsrc/” and
fill it with all the source files needed to build SQLite, both
manually-edited files and automatically-generated files.
The SQLite interface is defined by the sqlite3.h header file, which is
generated from src/sqlite.h.in, ./manifest.uuid, and ./VERSION. The
Tcl script at tool/mksqlite3h.tcl does the conversion.
The manifest.uuid file contains the SHA3 hash of the particular check-in
and is used to generate the SQLITE_SOURCE_ID macro. The VERSION file
contains the current SQLite version number. The sqlite3.h header is really
just a copy of src/sqlite.h.in with the source-id and version number inserted
at just the right spots. Note that comment text in the sqlite3.h file is
used to generate much of the SQLite API documentation. The Tcl scripts
used to generate that documentation are in a separate source repository.
The SQL language parser is parse.c which is generated from a grammar in
the src/parse.y file. The conversion of “parse.y” into “parse.c” is done
by the lemon LALR(1) parser generator. The source code
for lemon is at tool/lemon.c. Lemon uses the tool/lempar.c file as a
template for generating its parser.
Lemon also generates the parse.h header file, at the same time it
generates parse.c.
The opcodes.h header file contains macros that define the numbers
corresponding to opcodes in the “VDBE” virtual machine. The opcodes.h
file is generated by scanning the src/vdbe.c source file. The
Tcl script at ./mkopcodeh.tcl does this scan and generates opcodes.h.
A second Tcl script, ./mkopcodec.tcl, then scans opcodes.h to generate
the opcodes.c source file, which contains a reverse mapping from
opcode-number to opcode-name that is used for EXPLAIN output.
The keywordhash.h header file contains the definition of a hash table
that maps SQL language keywords (ex: “CREATE”, “SELECT”, “INDEX”, etc.) into
the numeric codes used by the parse.c parser. The keywordhash.h file is
generated by a C-language program at tool mkkeywordhash.c.
The pragma.h header file contains various definitions used to parse
and implement the PRAGMA statements. The header is generated by a
script tool/mkpragmatab.tcl. If you want to add a new PRAGMA, edit
the tool/mkpragmatab.tcl file to insert the information needed by the
parser for your new PRAGMA, then run the script to regenerate the
pragma.h header file.
All of the individual C source code and header files (both manually-edited
and automatically-generated) can be combined into a single big source file
sqlite3.c called “the amalgamation”. The amalgamation is the recommended
way of using SQLite in a larger application. Combining all individual
source code files into a single big source code file allows the C compiler
to perform more cross-procedure analysis and generate better code. SQLite
runs about 5% faster when compiled from the amalgamation versus when compiled
from individual source files.
The amalgamation is generated from the tool/mksqlite3c.tcl Tcl script.
First, all of the individual source files must be gathered into the tsrc/
subdirectory (using the equivalent of “make target_source”) then the
tool/mksqlite3c.tcl script is run to copy them all together in just the
right order while resolving internal “#include” references.
The amalgamation source file is more than 200K lines long. Some symbolic
debuggers (most notably MSVC) are unable to deal with files longer than 64K
lines. To work around this, a separate Tcl script, tool/split-sqlite3c.tcl,
can be run on the amalgamation to break it up into a single small C file
called sqlite3-all.c that does #include on about seven other files
named sqlite3-1.c, sqlite3-2.c, …, sqlite3-7.c. In this way,
all of the source code is contained within a single translation unit so
that the compiler can do extra cross-procedure optimization, but no
individual source file exceeds 32K lines in length.
SQLite is modular in design.
See the architectural description
for details. Other documents that are useful in
(helping to understand how SQLite works include the
file format description,
the virtual machine that runs
prepared statements, the description of
how transactions work, and
the overview of the query planner.
Years of effort have gone into optimizing SQLite, both
for small size and high performance. And optimizations tend to result in
complex code. So there is a lot of complexity in the current SQLite
implementation. It will not be the easiest library in the world to hack.
Key files:
sqlite.h.in - This file defines the public interface to the SQLite
library. Readers will need to be familiar with this interface before
trying to understand how the library works internally.
sqliteInt.h - this header file defines many of the data objects
used internally by SQLite. In addition to “sqliteInt.h”, some
subsystems have their own header files.
parse.y - This file describes the LALR(1) grammar that SQLite uses
to parse SQL statements, and the actions that are taken at each step
in the parsing process.
vdbe.c - This file implements the virtual machine that runs
prepared statements. There are various helper files whose names
begin with “vdbe”. The VDBE has access to the vdbeInt.h header file
which defines internal data objects. The rest of SQLite interacts
with the VDBE through an interface defined by vdbe.h.
where.c - This file (together with its helper files named
by “where*.c”) analyzes the WHERE clause and generates
virtual machine code to run queries efficiently. This file is
sometimes called the “query optimizer”. It has its own private
header file, whereInt.h, that defines data objects used internally.
btree.c - This file contains the implementation of the B-Tree
storage engine used by SQLite. The interface to the rest of the system
is defined by “btree.h”. The “btreeInt.h” header defines objects
used internally by btree.c and not published to the rest of the system.
pager.c - This file contains the “pager” implementation, the
module that implements transactions. The “pager.h” header file
defines the interface between pager.c and the rest of the system.
os_unix.c and os_win.c - These two files implement the interface
between SQLite and the underlying operating system using the run-time
pluggable VFS interface.
shell.c.in - This file is not part of the core SQLite library. This
is the file that, when linked against sqlite3.a, generates the
“sqlite3.exe” command-line shell. The “shell.c.in” file is transformed
into “shell.c” as part of the build process.
tclsqlite.c - This file implements the Tcl bindings for SQLite. It
is not part of the core SQLite library. But as most of the tests in this
repository are written in Tcl, the Tcl language bindings are important.
test*.c - Files in the src/ folder that begin with “test” go into
building the “testfixture.exe” program. The testfixture.exe program is
an enhanced Tcl shell. The testfixture.exe program runs scripts in the
test/ folder to validate the core SQLite code. The testfixture program
(and some other test programs too) is built and run when you type
“make test”.
There are many other source files. Each has a succinct header comment that
describes its purpose and role within the larger system.
The manifest file at the root directory of the source tree
contains either a SHA3-256 hash or a SHA1 hash
for every source file in the repository.
The name of the version of the entire source tree is just the
SHA3-256 hash of the manifest file itself, possibly with the
last line of that file omitted if the last line begins with
“# Remove this line”.
The manifest.uuid file should contain the SHA3-256 hash of the
manifest file. If all of the above hash comparisons are correct, then
you can be confident that your source tree is authentic and unadulterated.
Details on the format for the manifest files are available
on the Fossil website.
The process of checking source code authenticity is automated by the
makefile:
make verify-source
Or on windows:
nmake /f Makefile.msc verify-source
Using the makefile to verify source integrity is good for detecting
accidental changes to the source tree, but malicious changes could be
hidden by also modifying the makefiles.
The main SQLite website is https://sqlite.org/
with geographically distributed backups at
https://www2.sqlite.org/ and
https://www3.sqlite.org/.