Function timelock 

pub fn timelock(
    cadence: Option<TimeLockCadence>,
    time: Option<TimeLockTime>,
    precision: Option<TimePrecision>,
    format: Option<TimeFormat>,
    salts: Option<TimeLockSalts>,
    kdf: Option<KdfParams>,
    params: Option<TimeLockParams>,
) -> Result<TimeLockKey, TimeLockError>

Derive a 32-byte time-locked key — unified sync entry point.

Encryption path (params = None)

Set params to None and supply all of cadence, time, precision, format, salts, and kdf as Some(...). Requires the enc-timelock-keygen-input feature. After calling, use pack with the same arguments to produce a TimeLockParams header for the ciphertext.

Decryption path (params = Some(p))

Set params to Some(header) where header is the TimeLockParams read from the ciphertext. All other arguments are ignored and may be None. Requires the enc-timelock-keygen-now feature.

Errors

• TimeLockError::ForbiddenAction if the required feature is not active, or if the _at path is taken but any required Option argument is None.
• TimeLockError::Argon2 / TimeLockError::Scrypt on KDF failure.
• TimeLockError::ClockUnavailable if the OS clock is unusable (_now path).

Example

let salts = TimeLockSalts::generate();
let kdf   = KdfPreset::BalancedMac.params();

// Encryption side — lock to every Tuesday at 18:00
let enc_key = timelock(
    Some(TimeLockCadence::DayOfWeek(Weekday::Tuesday)),
    Some(TimeLockTime::new(18, 0).unwrap()),
    Some(TimePrecision::Hour),
    Some(TimeFormat::Hour24),
    Some(salts.clone()),
    Some(kdf),
    None,
).unwrap();

// Pack settings + salts + kdf into header; store in ciphertext.
let header = pack(TimePrecision::Hour, TimeFormat::Hour24,
                  &TimeLockCadence::DayOfWeek(Weekday::Tuesday), salts, kdf);

// Decryption side — call on a Tuesday at 18:xx:
let dec_key = timelock(
    None, None, None, None, None, None,
    Some(header),
).unwrap();
// enc_key.as_bytes() == dec_key.as_bytes() when called at the right time

Examples found in repository

examples/timelock_round_trip.rs (lines 39-47)

fn main() {
    // ── Encryption side ───────────────────────────────────────────────────────
    // Generate fresh salts.  Salts are NOT secret — store them in plaintext
    // alongside the ciphertext so the decryption side can reproduce the key.
    let salts = TimeLockSalts::generate();

    // Use a deliberately fast preset so the example finishes quickly.
    // In production use KdfPreset::Balanced or stronger.
    let kdf = KdfPreset::Balanced.params();

    // Lock to any Tuesday at 18:00 (hour-precision window = the full 18:00–18:59 block).
    let cadence   = TimeLockCadence::DayOfWeek(Weekday::Tuesday);
    let lock_time = TimeLockTime::new(18, 0).unwrap();

    println!("Deriving encryption key (this may take a few seconds)…");
    let enc_key = timelock(
        Some(cadence.clone()),
        Some(lock_time),
        Some(TimePrecision::Hour),
        Some(TimeFormat::Hour24),
        Some(salts.clone()),
        Some(kdf),
        None,   // params = None → _at (encryption) path
    )
    .expect("encryption-side key derivation failed");

    println!("enc_key[:8] = {:02x?}", &enc_key.as_bytes()[..8]);

    // Pack every setting — including salts and KDF params — into a compact header.
    // This header goes into the ciphertext in plaintext; nothing here is secret.
    let header = pack(
        TimePrecision::Hour,
        TimeFormat::Hour24,
        &cadence,
        salts,
        kdf,
    );

    // ── Decryption side ───────────────────────────────────────────────────────
    // Load `header` from the ciphertext and call timelock() at the matching
    // time slot with params = Some(header).
    println!("Deriving decryption key from system clock…");
    let dec_key = timelock(
        None, None, None, None, None, None,
        Some(header),   // params = Some → _now (decryption) path
    )
    .expect("decryption-side key derivation failed");

    println!("dec_key[:8] = {:02x?}", &dec_key.as_bytes()[..8]);

    // ── Verdict ───────────────────────────────────────────────────────────────
    if enc_key.as_bytes() == dec_key.as_bytes() {
        println!("\nKeys match ✓  — running on a Tuesday at 18:xx");
    } else {
        println!("\nKeys differ — not running on a Tuesday at 18:xx (expected outside that window)");
    }
}