citadeldb 0.11.0

Citadel: encrypted-first embedded database engine that outperforms unencrypted SQLite
Documentation

Every page is encrypted and authenticated before it hits disk. The database file is always opaque. Wins all 38 head-to-head benchmarks against unencrypted SQLite at equal cache budgets.

Features

  • Encrypted at rest - AES-256-CTR + HMAC-SHA256 per page, verified before decryption
  • SQL - JOINs, subqueries, CTEs (recursive), UNION/INTERSECT/EXCEPT, window functions, views, aggregates, indexes, constraints, generated columns (STORED + VIRTUAL), ALTER TABLE, UPSERT (ON CONFLICT), RETURNING (with OLD/NEW), prepared statements
  • ACID - Copy-on-Write B+ tree, shadow paging, no WAL. Snapshot isolation with concurrent readers
  • P2P sync - Merkle-based table diffing over Noise-encrypted channels with PSK auth
  • CLI - SQL shell with tab completion, syntax highlighting, dot-commands (.backup, .verify, .rekey, .sync, .dump, ...)
  • 3-tier key hierarchy - Passphrase -> Argon2id -> Master Key -> AES-KW -> REK -> HKDF -> DEK + MAC
  • FIPS 140-3 - PBKDF2-HMAC-SHA256 + AES-256-CTR when compliance requires it
  • Audit log - HMAC-SHA256 chained, tamper-evident
  • Hot backup - Consistent snapshots via MVCC, no write blocking
  • Overflow pages - Large values handled transparently, no size limits
  • Cross-platform - Windows, Linux, macOS. C FFI (37 functions), WebAssembly bindings
  • 3,100+ tests - Unit, integration, torture tests across 10 crates

Benchmarks

Single-threaded on 100K rows, schema (id INTEGER PK, name TEXT, age INTEGER). Ratio = SQLite / Citadel time.

Benchmark              Citadel        SQLite         Ratio
----------------------------------------------------------
correlated_in          5.92 ms        1.87 s         315.5x
count                  146 ns         21.4 us        146.6x
correlated_scalar      292 us         17.96 ms       61.5x
point                  772 ns         12.4 us        16.0x
group_by               1.27 ms        9.89 ms        7.81x
cte                    1.16 ms        5.85 ms        5.03x
view_point             2.78 us        12.4 us        4.44x
upsert_returning       55.5 us        166 us         2.99x
insert_returning       57.6 us        165 us         2.86x
window_agg             31.7 ms        74.0 ms        2.34x
filter                 769 us         1.76 ms        2.29x
view_filter            768 us         1.74 ms        2.26x
savepoint_create       316 ns         687 ns         2.17x
sort                   1.22 ms        2.58 ms        2.11x
upsert_counter         25.0 us        52.8 us        2.11x
window_rank            60.2 ms        121 ms         2.01x
delete_returning       86.5 us        161 us         1.86x
upsert_dedup           18.7 us        31.7 us        1.70x
update                 18.2 us        28.4 us        1.56x
insert_select          720 us         1.12 ms        1.55x
delete                 43.5 us        66.5 us        1.53x
correlated_exists      4.32 ms        6.50 ms        1.50x
savepoint_nested       216 us         303 us         1.41x
savepoint_rollback     1.52 ms        2.10 ms        1.39x
distinct               2.67 ms        3.63 ms        1.36x
insert                 36.9 us        49.9 us        1.35x
update_returning       110 us         144 us         1.31x
scan                   6.35 ms        7.70 ms        1.21x
union                  119 us         140 us         1.18x
insert_gen_stored      47.6 us        55.7 us        1.17x
insert_gen_virtual     44.9 us        52.4 us        1.17x
sum                    1.60 ms        1.85 ms        1.16x
update_gen_propagate   38.2 us        44.3 us        1.16x
upsert_all_new         44.1 us        49.3 us        1.12x
select_gen_virtual     15.5 us        17.5 us        1.12x
recursive_cte          104 us         117 us         1.12x
upsert_mixed           51.5 us        56.2 us        1.09x
join                   91.4 us        93.8 us        1.025x

Native DATE / TIMESTAMP (Citadel only, SQLite has no native type)

Benchmark          Citadel
-------------------------------
date_sort          1.32 ms
date_range_scan    1.75 ms
date_arith         1.76 ms
date_groupby       9.12 ms
date_extract       12.68 ms

H2H benchmarks (sorted by ratio, highest first):

  • correlated_in - SELECT COUNT(*) FROM t WHERE id IN (SELECT id FROM ref_table WHERE ref_table.val = t.age)
  • count - SELECT COUNT(*) FROM t
  • correlated_scalar - SELECT a.id, (SELECT COUNT(*) FROM b WHERE b.a_id = a.id) FROM a
  • point - SELECT * FROM t WHERE id = 50000
  • group_by - SELECT age, COUNT(*) FROM t GROUP BY age
  • cte - WITH filtered AS (SELECT ... WHERE age < 50) SELECT age, COUNT(*) FROM filtered GROUP BY age
  • view_point - SELECT * FROM v WHERE id = 50000
  • upsert_returning - INSERT ... ON CONFLICT (id) DO UPDATE SET c = c + 1 RETURNING c
  • insert_returning - INSERT INTO t (id, val) VALUES (...) RETURNING id, val
  • window_agg - SUM(age) OVER (ORDER BY id ROWS 50 PRECEDING)
  • filter - SELECT * FROM t WHERE age = 42
  • view_filter - SELECT * FROM v WHERE age = 42
  • savepoint_create - BEGIN; SAVEPOINT sp; RELEASE sp; COMMIT
  • sort - SELECT * FROM t ORDER BY age LIMIT 10
  • upsert_counter - INSERT ... ON CONFLICT (id) DO UPDATE SET c = c + 1
  • window_rank - ROW_NUMBER() OVER (PARTITION BY age ORDER BY id)
  • delete_returning - DELETE ... WHERE id = ? RETURNING id, val
  • upsert_dedup - INSERT ... ON CONFLICT (id) DO NOTHING
  • update - UPDATE t SET age = age + 1 WHERE id BETWEEN 10000 AND 10099
  • insert_select - INSERT INTO sink SELECT id, val FROM a
  • delete - DELETE FROM t WHERE id = ?
  • correlated_exists - SELECT COUNT(*) FROM t WHERE EXISTS (SELECT 1 FROM ref_table WHERE ref_table.id = t.id)
  • savepoint_nested - BEGIN; SAVEPOINT sp1; ... ; RELEASE/ROLLBACK TO sp1; COMMIT
  • savepoint_rollback - BEGIN; INSERT 1K rows; SAVEPOINT sp; INSERT 10K rows; ROLLBACK TO sp; COMMIT
  • distinct - SELECT DISTINCT age FROM t
  • insert - INSERT INTO t (id, val) VALUES (?, ?)
  • update_returning - UPDATE t SET c = c + ? WHERE id = ? RETURNING c
  • scan - SELECT * FROM t
  • union - SELECT id, val FROM a UNION ALL SELECT id, data FROM b
  • insert_gen_stored - INSERT INTO t (id, a, b) VALUES (?, ?, ?)
  • insert_gen_virtual - INSERT INTO t (id, a, b) VALUES (?, ?, ?)
  • sum - SELECT SUM(age) FROM t
  • update_gen_propagate - UPDATE t SET a = a + ? WHERE id = ?
  • upsert_all_new - INSERT ... ON CONFLICT (id) DO NOTHING
  • select_gen_virtual - SELECT id, s FROM t WHERE s > ?
  • recursive_cte - WITH RECURSIVE seq(x) AS (SELECT 1 UNION ALL SELECT x+1 FROM seq WHERE x < 1000) SELECT SUM(x) FROM seq
  • upsert_mixed - INSERT ... ON CONFLICT (id) DO UPDATE SET c = c + 1
  • join - SELECT a.id, b.data FROM a INNER JOIN b ON a.id = b.a_id

Date benchmarks (Citadel-only, sorted by duration):

  • date_sort - SELECT id FROM events ORDER BY ts LIMIT 100
  • date_range_scan - SELECT COUNT(*) FROM events WHERE d BETWEEN DATE '2024-02-01' AND DATE '2024-03-31'
  • date_arith - SELECT COUNT(*) FROM events WHERE ts + INTERVAL '1 day' > TIMESTAMP '2024-06-01 00:00:00'
  • date_groupby - SELECT DATE_TRUNC('month', ts), COUNT(*) FROM events GROUP BY 1
  • date_extract - SELECT AVG(EXTRACT(HOUR FROM ts)) FROM events

SQLite config: journal_mode=OFF, synchronous=OFF, cache_size=8192 (~32 MB). Citadel config: SyncMode::Off, cache_size=4096 (~32 MB). Both run with durability disabled to measure pure engine overhead, not disk I/O.

Reproduce with cargo bench -p citadeldb-sql --bench h2h_bench

Quick Start

Library

use citadel::DatabaseBuilder;
use citadel_sql::Connection;

let db = DatabaseBuilder::new("my.db")
    .passphrase(b"secret")
    .create()?;

let mut conn = Connection::open(&db)?;
conn.execute("CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT NOT NULL);")?;
conn.execute("INSERT INTO users (id, name) VALUES (1, 'Alice');")?;
let result = conn.query("SELECT * FROM users;")?;

// Key-value API
let mut wtx = db.begin_write()?;
wtx.insert(b"key", b"value")?;
wtx.commit()?;

let mut rtx = db.begin_read();
assert_eq!(rtx.get(b"key")?.unwrap(), b"value");

// Named tables
let mut wtx = db.begin_write()?;
wtx.create_table(b"sessions")?;
wtx.table_insert(b"sessions", b"token-abc", b"user-42")?;
wtx.commit()?;

// In-memory (no file I/O - useful for testing and WASM)
let mem_db = DatabaseBuilder::new("")
    .passphrase(b"secret")
    .create_in_memory()?;

CLI

citadel --create my.db


citadel> CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT NOT NULL);
citadel> INSERT INTO users (id, name) VALUES (1, 'Alice'), (2, 'Bob');
citadel> SELECT * FROM users;
+----+-------+

| id | name  |
+----+-------+

|  1 | Alice |
|  2 | Bob   |
+----+-------+


citadel> .backup mydb.bak

citadel> .verify

citadel> .stats

citadel> .audit verify

citadel> .rekey

citadel> .compact clean.db

citadel> .dump users


# P2P sync

citadel> .keygen

citadel> .listen 4248 <KEY>              # Terminal A

citadel> .sync 127.0.0.1:4248 <KEY>      # Terminal B

SQL

Statements - CREATE/DROP TABLE, ALTER TABLE (ADD/DROP/RENAME COLUMN, RENAME TABLE), CREATE/DROP INDEX, CREATE/DROP VIEW, INSERT (VALUES, SELECT, ON CONFLICT DO NOTHING/DO UPDATE, ON CONSTRAINT), SELECT, UPDATE, DELETE, RETURNING (with OLD/NEW), BEGIN/COMMIT/ROLLBACK, SAVEPOINT/RELEASE/ROLLBACK TO, SET TIME ZONE, EXPLAIN

Constraints - PRIMARY KEY, NOT NULL, UNIQUE, DEFAULT, CHECK (column + table level), FOREIGN KEY (RESTRICT/NO ACTION), GENERATED ALWAYS AS (...) STORED|VIRTUAL

Types - INTEGER, REAL, TEXT, BLOB, BOOLEAN, DATE, TIME, TIMESTAMP (WITH TIME ZONE), INTERVAL

Clauses - JOINs (INNER, LEFT, RIGHT, CROSS), subqueries (scalar, IN, EXISTS, correlated), CTEs (WITH / WITH RECURSIVE), UNION/INTERSECT/EXCEPT [ALL], CASE, BETWEEN, LIKE, DISTINCT, GROUP BY/HAVING, ORDER BY, LIMIT/OFFSET

Window functions - ROW_NUMBER, RANK, DENSE_RANK, NTILE, LAG, LEAD, FIRST_VALUE, LAST_VALUE, SUM/COUNT/AVG/MIN/MAX OVER with PARTITION BY, ORDER BY, ROWS/RANGE frames

Views - CREATE/DROP VIEW, OR REPLACE, IF NOT EXISTS/IF EXISTS, column aliases, nested views

Functions - COUNT, SUM, AVG, MIN, MAX, LENGTH, UPPER, LOWER, SUBSTR/SUBSTRING, TRIM/LTRIM/RTRIM, REPLACE, INSTR, CONCAT, HEX, ABS, ROUND, CEIL/CEILING, FLOOR, SIGN, SQRT, RANDOM, COALESCE, NULLIF, CAST, TYPEOF, IIF

Date/Time Functions - NOW, CURRENT_TIMESTAMP, CURRENT_DATE, CURRENT_TIME, LOCALTIMESTAMP, LOCALTIME, CLOCK_TIMESTAMP, EXTRACT, DATE_PART, DATE_TRUNC, DATE_BIN, AGE, MAKE_DATE, MAKE_TIME, MAKE_TIMESTAMP, MAKE_INTERVAL, JUSTIFY_DAYS, JUSTIFY_HOURS, JUSTIFY_INTERVAL, ISFINITE, DATE, TIME, DATETIME, STRFTIME, JULIANDAY, UNIXEPOCH, TIMEDIFF, AT TIME ZONE. Supports INTERVAL '1 year 2 months', DATE '2024-01-15', TIMESTAMP '2024-01-15 12:30:00Z', infinity/-infinity sentinels, BC dates, full IANA zone parsing (jiff), PG-normalized INTERVAL comparison.

Prepared statements - $1, $2, ... positional parameters with LRU statement cache

Multi-statement scripts - Connection::execute_script(sql) runs ;-separated statements in one call, returning per-statement outcomes with partial-success preserved. WASM: db.run(sql) returns [{type, ...}, ...].

UPSERT - INSERT ... ON CONFLICT (cols) DO NOTHING / DO UPDATE SET col = excluded.col ... WHERE ... and ON CONFLICT ON CONSTRAINT idx_name. excluded.* refers to the proposed row; bare col refers to the existing row. Single-descent storage primitive: on the canonical DO UPDATE SET counter = counter + 1 pattern, Citadel is ~2× faster than SQLite.

Security

No plaintext on disk. Every page is encrypted before writing and authenticated before reading.

Separate key file. Encryption keys live in {dbname}.citadel-keys, not inside the database. The passphrase derives a master key in memory via Argon2id (or PBKDF2 in FIPS mode) and never touches disk.

Key backup. Export an encrypted key backup with a separate recovery passphrase. Restore access without re-encrypting the entire database.

Instant rekey. Changing the passphrase re-wraps the root encryption key. No page re-encryption - instant regardless of database size.

Encrypted sync. Noise protocol (NNpsk0_25519_ChaChaPoly_BLAKE2s) with a 256-bit pre-shared key. Ephemeral Curve25519 keys per session for forward secrecy.

Architecture

+-------------+---------------+---------------+
| citadel-cli | citadel-ffi   | citadel-wasm  |  CLI, C FFI, WebAssembly
+-------------+---------------+---------------+
|                 citadel-sql                  |  SQL parser, planner, executor
+---------------------------------------------+
|                  citadel                     |  Database API, builder, sync
+--------------+--------------+---------------+
|  citadel-txn | citadel-sync | citadel-crypto|  Transactions, replication, keys
+--------------+--------------+---------------+
|citadel-buffer|         citadel-page         |  Buffer pool (SIEVE), page codec
+--------------+------------------------------+
|              citadel-io                      |  File I/O, fsync, io_uring
+---------------------------------------------+
|              citadel-core                    |  Types, errors, constants
+---------------------------------------------+

Page Layout (8,208 bytes)

+----------+--------------------+----------+
|  IV 16B  |  Ciphertext 8160B  |  MAC 32B |
+----------+--------------------+----------+

Fresh random IV per page. HMAC verified before decryption.

Commit Protocol

Shadow paging with a god byte - one byte selects the active commit slot. Atomic commits without WAL:

  1. Write dirty pages to new locations (CoW)
  2. Compute Merkle hashes bottom-up
  3. Update the inactive commit slot
  4. Flip the god byte

Language Bindings

C / C++

Static or dynamic library with auto-generated citadel.h (cbindgen). All 37 functions are panic-safe.

#include "citadel.h"

CitadelDb *db = NULL;
citadel_create("my.db", "secret", 6, &db);

CitadelWriteTxn *wtx = NULL;
citadel_write_begin(db, &wtx);
citadel_write_put(wtx, (const uint8_t*)"key", 3, (const uint8_t*)"val", 3);
citadel_write_commit(wtx);

CitadelSqlConn *conn = NULL;
citadel_sql_open(db, &conn);
CitadelSqlResult *result = NULL;
citadel_sql_execute(conn, "SELECT * FROM users;", &result);

citadel_close(db);

WebAssembly

import { CitadelDb } from "@citadeldb/wasm";

const db = new CitadelDb("secret");
db.execute("CREATE TABLE t (id INTEGER PRIMARY KEY, name TEXT);");
db.execute("INSERT INTO t (id, name) VALUES (1, 'Alice');");

const result = db.query("SELECT * FROM t;");
// { columns: ["id", "name"], rows: [[1, "Alice"]] }

db.put(new Uint8Array([1, 2, 3]), new Uint8Array([4, 5, 6]));

Build: wasm-pack build crates/citadel-wasm --target web

Building

Rust 1.75+.

git clone https://github.com/yp3y5akh0v/citadel.git

cd citadel

cargo build --release

Feature Flags

Flag Description
audit-log HMAC-chained tamper-evident audit log (default: on)
fips FIPS 140-3: PBKDF2 + AES-256-CTR only
io-uring Linux io_uring async I/O

License

MIT OR Apache-2.0