secp256k1-internal 0.4.0 (latest)

Field element module. * * Field elements can be represented in several ways, but code accessing * it (and implementations) need to take certain properties into account: * - Each field element can be normalized or not. * - Each field element has a magnitude, which represents how far away * its representation is away from normalization. Normalized elements * always have a magnitude of 1, but a magnitude of 1 doesn't imply * normality.

type t

module Storage : sig ... end

val const : 
  ?d7:int32 ->
  ?d6:int32 ->
  ?d5:int32 ->
  ?d4:int32 ->
  ?d3:int32 ->
  ?d2:int32 ->
  ?d1:int32 ->
  ?d0:int32 ->
  unit ->
  t

Unpacks a constant into a overlapping multi-limbed FE element.

val normalize : t -> unit

Normalize a field element.

val normalize_weak : t -> unit

Weakly normalize a field element: reduce it magnitude to 1, but don't fully normalize.

val normalize_var : t -> unit

Normalize a field element, without constant-time guarantee.

val normalizes_to_zero : t -> bool

Verify whether a field element represents zero i.e. would normalize to a zero value. The field implementation may optionally normalize the input, but this should not be relied upon.

val normalizes_to_zero_var : t -> bool

Verify whether a field element represents zero i.e. would normalize to a zero value. The field implementation may optionally normalize the input, but this should not be relied upon.

val set_int : t -> int -> unit

Set a field element equal to a small integer. Resulting field element is normalized.

val clear : t -> unit

Sets a field element equal to zero, initializing all fields.

val is_zero : t -> bool

Verify whether a field element is zero. Requires the input to be normalized.

val is_odd : t -> bool

Check the "oddness" of a field element. Requires the input to be normalized.

val equal : t -> t -> bool

Compare two field elements. Requires magnitude-1 inputs.

val equal_var : t -> t -> bool

Same as secp256k1_fe_equal, but may be variable time.

val cmp_var : t -> t -> int

Compare two field elements. Requires both inputs to be normalized.

val compare : t -> t -> int

Alias to cmp_var.

val set_b32 : t -> Cstruct.t -> bool

Set a field element equal to 32-byte big endian value. If successful, the resulting field element is normalized.

val get_b32 : Cstruct.t -> t -> unit

Convert a field element to a 32-byte big endian value. Requires the input to be normalized.

val negate : t -> t -> int -> unit

Set a field element equal to the additive inverse of another. Takes a maximum magnitude of the input as an argument. The magnitude of the output is one higher.

val mul_int : t -> int -> unit

Multiplies the passed field element with a small integer constant. Multiplies the magnitude by that small integer.

val add : t -> t -> unit

Adds a field element to another. The result has the sum of the inputs' magnitudes as magnitude.

val mul : t -> t -> t -> unit

Sets a field element to be the product of two others. Requires the inputs' magnitudes to be at most 8. The output magnitude is 1 (but not guaranteed to be normalized).

val sqrt : t -> t -> int

If a has a square root, it is computed in r and 1 is returned. If a does not have a square root, the root of its negation is computed and 0 is returned. The input's magnitude can be at most 8. The output magnitude is 1 (but not guaranteed to be normalized). The result in r will always be a square itself.

val inv : t -> t -> unit

Sets a field element to be the (modular) inverse of another. Requires the input's magnitude to be at most 8. The output magnitude is 1 (but not guaranteed to be normalized).

val inv_var : t -> t -> unit

Potentially faster version of secp256k1_fe_inv, without constant-time guarantee.

val to_storage : Storage.t -> t -> unit

Convert a field element to the storage type.

val from_storage : t -> Storage.t -> unit

Convert a field element back from the storage type.

val cmov : t -> t -> bool -> unit

If flag is true, set *r equal to *a; otherwise leave it. Constant-time.

package secp256k1-internal