make hash2curve module

Signed-off-by: Michael Lodder <redmike7@gmail.com>

elliptic-curve/Cargo.toml

@@ -29,7 +29,7 @@ zeroize = { version = "1", default-features = false }
 
 # optional dependencies
 base64ct = { version = "1", optional = true, default-features = false }
-digest_traits = { version = "0.9", optional = true, default-features = false, package = "digest" }
+digest = { version = "0.9", optional = true, default-features = false }
 ff = { version = "0.11", optional = true, default-features = false }
 group = { version = "0.11", optional = true, default-features = false }
 hex-literal = { version = "0.3", optional = true }
@@ -47,7 +47,7 @@ alloc = ["der/alloc", "sec1/alloc", "zeroize/alloc"] # todo: use weak activation
 arithmetic = ["ff", "group"]
 bits = ["arithmetic", "ff/bits"]
 dev = ["arithmetic", "hex-literal", "pem", "pkcs8"]
-digest = ["digest_traits", "ff", "group"]
+hash2curve = ["digest", "ff", "group"]
 ecdh = ["arithmetic"]
 hazmat = []
 jwk = ["alloc", "base64ct/alloc", "serde", "serde_json", "zeroize/alloc"]

elliptic-curve/src/hash2curve.rs

@@ -0,0 +1,14 @@
+/// Traits for handling hash to curve
+mod group_digest;
+/// Traits for mapping an isogeny to another curve
+/// <https://datatracker.ietf.org/doc/draft-irtf-cfrg-hash-to-curve>
+mod isogeny;
+/// Traits for mapping field elements to points on the curve
+mod map2curve;
+/// Optimized simplified Shallue-van de Woestijne-Ulas methods
+mod osswu;
+
+pub use group_digest::*;
+pub use isogeny::*;
+pub use map2curve::*;
+pub use osswu::*;

elliptic-curve/src/group_digest.rs → elliptic-curve/src/hash2curve/group_digest.rs

@@ -1,5 +1,5 @@
+use super::MapToCurve;
 use crate::hash2field::{hash_to_field, ExpandMsg, FromOkm};
-use crate::map2curve::MapToCurve;
 use group::cofactor::CofactorGroup;
 
 /// Adds hashing arbitrary byte sequences to a valid group element

elliptic-curve/src/hash2field/expand_msg.rs

@@ -1,4 +1,4 @@
-use digest_traits::{Digest, ExtendableOutputDirty, Update, XofReader};
+use digest::{Digest, ExtendableOutputDirty, Update, XofReader};
 use generic_array::{ArrayLength, GenericArray};
 
 /// Salt when the DST is too long

elliptic-curve/src/hash2field/expand_msg_xmd.rs

@@ -1,13 +1,17 @@
 use super::{Domain, ExpandMsg};
-use digest_traits::{
-    generic_array::{typenum::Unsigned, GenericArray},
+use digest::{
+    generic_array::{
+        typenum::{IsLess, Unsigned, U256},
+        GenericArray,
+    },
     BlockInput, Digest,
 };
 
 /// Placeholder type for implementing expand_message_xmd based on a hash function
 pub struct ExpandMsgXmd<HashT>
 where
     HashT: Digest + BlockInput,
+    HashT::OutputSize: IsLess<U256>,
 {
     b_0: GenericArray<u8, HashT::OutputSize>,
     b_vals: GenericArray<u8, HashT::OutputSize>,
@@ -20,6 +24,7 @@ where
 impl<HashT> ExpandMsgXmd<HashT>
 where
     HashT: Digest + BlockInput,
+    HashT::OutputSize: IsLess<U256>,
 {
     fn next(&mut self) -> bool {
         if self.index < self.ell {
@@ -49,6 +54,7 @@ where
 impl<HashT> ExpandMsg for ExpandMsgXmd<HashT>
 where
     HashT: Digest + BlockInput,
+    HashT::OutputSize: IsLess<U256>,
 {
     fn expand_message(msg: &[u8], dst: &'static [u8], len_in_bytes: usize) -> Self {
         let b_in_bytes = HashT::OutputSize::to_usize();

elliptic-curve/src/hash2field/expand_msg_xof.rs

@@ -1,6 +1,6 @@
 use super::ExpandMsg;
 use crate::hash2field::Domain;
-use digest_traits::{ExtendableOutput, ExtendableOutputDirty, Update, XofReader};
+use digest::{ExtendableOutput, ExtendableOutputDirty, Update, XofReader};
 use generic_array::typenum::U32;
 
 /// Placeholder type for implementing expand_message_xof based on an extendable output function

elliptic-curve/src/lib.rs

@@ -94,33 +94,15 @@ pub mod ecdh;
 #[cfg(feature = "jwk")]
 mod jwk;
 
-/// Optimized simplified Shallue-van de Woestijne-Ulas methods
-#[cfg(feature = "digest")]
-#[cfg_attr(docsrs, doc(cfg(feature = "digest")))]
-pub mod osswu;
-
-/// Traits for computing hash to field as described in
-/// <https://datatracker.ietf.org/doc/draft-irtf-cfrg-hash-to-curve>
-#[cfg(feature = "digest")]
-#[cfg_attr(docsrs, doc(cfg(feature = "digest")))]
+/// Traits for hashing to field elements
+#[cfg(feature = "hash2curve")]
+#[cfg_attr(docsrs, doc(cfg(feature = "hash2curve")))]
 pub mod hash2field;
 
-/// Traits for mapping an isogeny to another curve
-/// <https://datatracker.ietf.org/doc/draft-irtf-cfrg-hash-to-curve>
-#[cfg(feature = "digest")]
-#[cfg_attr(docsrs, doc(cfg(feature = "digest")))]
-pub mod isogeny;
-
-/// Traits for computing hash to curve as described in
-/// <https://datatracker.ietf.org/doc/draft-irtf-cfrg-hash-to-curve>
-#[cfg(feature = "digest")]
-#[cfg_attr(docsrs, doc(cfg(feature = "digest")))]
-pub mod group_digest;
-
-/// Traits for mapping field elements to points on the curve
-#[cfg(feature = "digest")]
-#[cfg_attr(docsrs, doc(cfg(feature = "digest")))]
-pub mod map2curve;
+/// Traits for hashing byte sequences to curve points
+#[cfg(feature = "hash2curve")]
+#[cfg_attr(docsrs, doc(cfg(feature = "hash2curve")))]
+pub mod hash2curve;
 
 pub use crate::{
     error::{Error, Result},

elliptic-curve/src/ops.rs

@@ -9,7 +9,7 @@ use subtle::CtOption;
 use group::Group;
 
 #[cfg(feature = "digest")]
-use digest_traits::{BlockInput, Digest, FixedOutput, Reset, Update};
+use digest::{BlockInput, Digest, FixedOutput, Reset, Update};
 
 /// Perform an inversion on a field element (i.e. base field element or scalar)
 pub trait Invert {