[−][src]Trait ff::PrimeField
This represents an element of a prime field.
Associated Types
type Repr: Default + AsRef<[u8]> + AsMut<[u8]> + From<Self> + for<'r> From<&'r Self>
The prime field can be converted back and forth into this binary representation.
type ReprBits: BitView + Send + Sync
The backing store for a bit representation of a prime field element.
Associated Constants
const NUM_BITS: u32
How many bits are needed to represent an element of this field.
const CAPACITY: u32
How many bits of information can be reliably stored in the field element.
This is usually Self::NUM_BITS - 1
.
const S: u32
An integer s
satisfying the equation 2^s * t = modulus - 1
with t
odd.
This is the number of leading zero bits in the little-endian bit representation of
modulus - 1
.
Required methods
fn from_repr(_: Self::Repr) -> Option<Self>
Attempts to convert a byte representation of a field element into an element of this prime field, failing if the input is not canonical (is not smaller than the field's modulus).
The byte representation is interpreted with the same endianness as elements
returned by PrimeField::to_repr
.
fn to_repr(&self) -> Self::Repr
Converts an element of the prime field into the standard byte representation for this field.
The endianness of the byte representation is implementation-specific. Generic encodings of field elements should be treated as opaque.
fn to_le_bits(&self) -> BitArray<Lsb0, Self::ReprBits>
Converts an element of the prime field into a little-endian sequence of bits.
fn is_odd(&self) -> bool
Returns true iff this element is odd.
fn char_le_bits() -> BitArray<Lsb0, Self::ReprBits>
Returns the bits of the field characteristic (the modulus) in little-endian order.
fn multiplicative_generator() -> Self
Returns a fixed multiplicative generator of modulus - 1
order. This element must
also be a quadratic nonresidue.
It can be calculated using SageMath as GF(modulus).primitive_element()
.
Implementations of this method MUST ensure that this is the generator used to
derive Self::root_of_unity
.
fn root_of_unity() -> Self
Returns the 2^s
root of unity.
It can be calculated by exponentiating Self::multiplicative_generator
by t
,
where t = (modulus - 1) >> Self::S
.
Provided methods
fn from_str(s: &str) -> Option<Self>
Interpret a string of numbers as a (congruent) prime field element. Does not accept unnecessary leading zeroes or a blank string.
fn is_even(&self) -> bool
Returns true iff this element is even.