sqlite-hashes

Implement SQLite hashing functions with aggregation support, including MD5, SHA1, SHA224, SHA256, SHA384, SHA512, FNV-1a, xxHash. Functions are available as a loadable extension, or as a Rust library.

See also SQLite-compressions extension for gzip, brotli, and bsdiff support.

Usage

This SQLite extension adds hashing functions like sha256(...), sha256_hex(...), sha256_concat and sha256_concat_hex for multiple hashing algorithms. The sha256 and sha256_concat function returns a blob value, while the *_hex return a HEX string similar to SQLite's own hex() function.

Functions support any number of arguments, e.g. sha256('foo', 'bar', 'baz'), hashing them in order as if they were concatenated. Functions can hash text and blob values, but will raise an error on other types like integers and floating point numbers. All NULL values are ignored. When calling the built-in SQLite's hex(NULL), the result is an empty string, so sha256_hex(NULL) will return an empty string as well to be consistent.

The *_concat functions support aggregate to compute combined hash over a set of values like a column in a table, e.g. sha256_concat and sha256_concat_hex. Just like scalar functions, multiple arguments are also supported, so you can compute a hash over a set of columns, e.g. sha256_concat(col1, col2, col3).

Note: The window functionality is not supported in the loadable extension, only when used as as a Rust crate. PRs welcome.

Extension

To use as an extension, load the libsqlite_hashes.so shared library into SQLite.

$ sqlite3
sqlite> .load ./libsqlite_hashes
sqlite> SELECT md5_hex('Hello world!');
86FB269D190D2C85F6E0468CECA42A20

Rust library

To use as a Rust library, add sqlite-hashes to your Cargo.toml dependencies. Then, register the needed functions with register_hash_functions(&db). This will register all available functions, or you can use register_md5_functions(&db) or register_sha256_functions(&db) to register just the needed ones (you may also disable the default features to reduce compile time and binary size).

use sqlite_hashes::{register_hash_functions, rusqlite::Connection};

// Connect to SQLite DB and register needed hashing functions
let db = Connection::open_in_memory().unwrap();
// can also use hash-specific ones like register_sha256_functions(&db)  
register_hash_functions( & db).unwrap();

// Hash 'password' using SHA-256, and dump resulting BLOB as a HEX string
let sql = "SELECT hex(sha256('password'));";
let hash: String = db.query_row_and_then( & sql, [], | r| r.get(0)).unwrap();
assert_eq!(hash, "5E884898DA28047151D0E56F8DC6292773603D0D6AABBDD62A11EF721D1542D8");

// Same as above, but use sha256_hex() function to dump the result as a HEX string directly
let sql = "SELECT sha256_hex('password');";
let hash: String = db.query_row_and_then( & sql, [], | r| r.get(0)).unwrap();
assert_eq!(hash, "5E884898DA28047151D0E56F8DC6292773603D0D6AABBDD62A11EF721D1542D8");

// Hash 'pass' (as text) and 'word' (as blob) using SHA-256, and dump it as a HEX string
// The result is the same as the above 'password' example.
let sql = "SELECT sha256_hex(cast('pass' as text), cast('word' as blob));";
let hash: String = db.query_row_and_then( & sql, [], | r| r.get(0)).unwrap();
assert_eq!(hash, "5E884898DA28047151D0E56F8DC6292773603D0D6AABBDD62A11EF721D1542D8");

Aggregate and Window Functions

When aggregate or window feature is enabled (default), there are functions to compute combined hash over a set of values like a column in a table, e.g. sha256_concat and sha256_concat_hex. Just like scalar functions, multiple arguments are also supported, so you can compute a hash over a set of columns, e.g. sha256_concat(col1, col2, col3). Note that the window functionality is not supported in the loadable extension.

IMPORTANT NOTE: ORDERING

SQLite does NOT guarantee the order of rows when executing aggregate functions. A query SELECT sha256_concat(v) FROM tbl ORDER BY v; will NOT concatenate values in sorted order, but will use some internal storage order instead.

SQLite v3.44.0(2023-11-01) added support for the ORDER BY clause inside the aggregate function call, e.g. SELECT sha256_concat(v ORDER BY v) FROM tbl;. Make sure to use that to guarantee consistent results.

For older SQLite versions, one common workaround was to use a subquery, e.g. SELECT group_concat(v) FROM (SELECT v FROM tbl ORDER BY v);. This is NOT guaranteed to work in future versions of SQLite. See discussion for more details.

Another way for older SQLite to guarantee the ordering is to use a window function.

SELECT sha256_concat_hex(v)
       OVER (ORDER BY v ROWS
           BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING)
FROM tbl
LIMIT 1;

The hashing window functions will only work if the starting point of the window is not moving (UNBOUNDED PRECEDING). To force a non-NULL value, use COALESCE:

SELECT coalesce(
               (SELECT sha256_concat_hex(v)
                       OVER (ORDER BY v ROWS
                           BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING)
                FROM tbl
                LIMIT 1),
               sha256_hex('')
       );

Note that window functions are only available in SQLite 3.25 and later, so a bundled SQLite version must be used, at least for now.

use sqlite_hashes::{register_hash_functions, rusqlite::Connection};

let db = Connection::open_in_memory().unwrap();
register_hash_functions( & db).unwrap();

// Pre-populate the DB with some data. Note that the b values are not alphabetical.
db.execute_batch("
    CREATE TABLE tbl(id INTEGER PRIMARY KEY, v TEXT);
    INSERT INTO tbl VALUES (1, 'bbb'), (2, 'ccc'), (3, 'aaa');
  ").unwrap();

let sql = "SELECT sha256_concat_hex(v) OVER (
    ORDER BY v ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING)
    FROM tbl LIMIT 1;";
let hash: String = db.query_row_and_then( & sql, [], | r| r.get(0)).unwrap();
assert_eq!(hash, "FB84A45F6DF7D1D17036F939F1CFEB87339FF5DBDF411222F3762DD76779A287");

// The above window aggregation example is equivalent to this scalar hash:
let sql = "SELECT sha256_hex('aaabbbccc');";
let hash: String = db.query_row_and_then( & sql, [], | r| r.get(0)).unwrap();
assert_eq!(hash, "FB84A45F6DF7D1D17036F939F1CFEB87339FF5DBDF411222F3762DD76779A287");

Using with SQLx

To use with SQLx, you need to get the raw handle from the SqliteConnection and pass it to the registration function.

use rusqlite::Connection;
use sqlite_hashes::register_hash_functions;
use sqlx::sqlite::SqliteConnection;

async fn register_functions(sqlx_conn: &mut SqliteConnection) {
    // SAFETY: No query must be performed on `sqlx_conn` until `handle_lock` is dropped.
    let mut handle_lock = sqlx_conn.lock_handle().await.unwrap();
    let handle = handle_lock.as_raw_handle().as_ptr();

    // SAFETY: this is safe as long as handle_lock is valid.
    let rusqlite_conn = unsafe { Connection::from_handle(handle) }.unwrap();

    // Registration is attached to the connection, not to rusqlite_conn,
    // so it will be available for the entire lifetime of the `sqlx_conn`.
    // Registration will be automatically dropped when SqliteConnection is dropped.
    register_hash_functions(&rusqlite_conn).unwrap();
}

Crate features

By default, this crate will compile with all features. You can enable just the ones you need to reduce compile time and binary size.

[dependencies]
sqlite-hashes = { version = "0.7", default-features = false, features = ["hex", "window", "sha256"] }

• trace - enable tracing support, logging all function calls and their arguments
• hex - enable hex string functions like *_hex() and *_concat_hex() (if aggregate is enabled)
• aggregate - enable aggregate functions like *_concat() and *_concat_hex() (if hex is enabled)
• window - enable window functions support (implies aggregate)
• md5 - enable MD5 hash support
• sha1 - enable SHA1 hash support
• sha224 - enable SHA224 hash support
• sha256 - enable SHA256 hash support
• sha384 - enable SHA384 hash support
• sha512 - enable SHA512 hash support
• fnv - enable FNV-1a hash support
• xxhash - enable xxh32, xxh64, xxh3_64, xxh3_128 hash support

The loadable_extension feature should only be used when building a .so / .dylib / .dll extension file that can be loaded directly into sqlite3 executable.

Development

• You must install sqlite3 and libsqlite3-dev, e.g. sudo apt install -y libsqlite3-dev sqlite3 on Ubuntu/Mint.
• This project is easier to develop with just, a modern alternative to make. Install it with cargo install just.
• To get a list of available commands, run just.
• To run tests, use just test.
• On git push, it will run a few validations, including cargo fmt, cargo clippy, and cargo test. Use git push --no-verify to skip these checks.

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT) at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.