Crate hacspec_lib

Expand description

The hacspec standard library

Data types

The standard library provides two main data types.

Sequences

Sequences Seq arrays with a fixed length set at runtime. They replace Rust vectors, which are not allowed in hacspec.

See the seq module documentation for more details.

use hacspec_lib::*;
let x = Seq::<U128>::from_public_slice(&[5, 2, 7, 8, 9]);
let x = Seq::<u128>::from_native_slice(&[5, 2, 7, 8, 9]);
let y = ByteSeq::from_hex("0388dace60b6a392f328c2b971b2fe78");

Arrays

Arrays have a fixed length that is known at compile time. They replace the Rust arrays, which are not allowed in hacspec.

See the arrays module documentation for more details.

To define a new array type with name State, holding 16 u32 run

use hacspec_lib::*;
array!(State, 16, u32, type_for_indexes: StateIdx);

The type_for_indexes defines the index type for this array as StateIdx. Such an array can now be used similarly to regular Rust arrays.

use hacspec_lib::*;
array!(State, 16, u32, type_for_indexes: StateIdx);
fn modify_state(mut state: State) -> State {
    state[1] = state[1] + state[2];
    state
}

Numeric Types

The standard library provides two main numeric types.

Math Integers

Integers with a fixed upper bound on the byte length. See the math integer module documentation for more details.

The following example defines and uses the type LargeSecretInteger that can hold unsigned integers up to 2^233-1.

use hacspec_lib::*;
unsigned_integer!(LargeSecretInteger, 233);
let a = LargeSecretInteger::from_literal(1);
let b = LargeSecretInteger::from_literal(2);
let c = a + b;
let result = std::panic::catch_unwind(|| {
    // This panics because comparing secret math integers is currently not support.
    assert!(c.equal(LargeSecretInteger::from_literal(3)));
});
assert!(result.is_err());
let _max = LargeSecretInteger::from_hex("1ffffffffffffffffffffffffffffffffffffffffffffffffffffffffff");

Secret Integers

All numeric types can be public or secret. By default they are secret types. Public types are prefixed with public_.

Secret Machine Integers

The regular machine integers Rust provides are considered public integers. This standard library defines secret variants for all public machine integers defined as follows.

Unsigned secret integers: U8, U16, U32, U64, U128

Signed secret integers: I8, I16, I32, I64, I128

See the secret integers for details.