Make rfc-6979 nonce optional

Cargo.toml

@@ -14,7 +14,7 @@ ark-serialize = { version = "0.4.2", default-features = false }
 rand_core = { version = "0.6.4", default-features = false, optional = true }
 rand_chacha = { version = "0.3.1", default-features = false }
 zeroize = { version = "1.7.0", default-features = false }
-hmac = {version = "0.12.1", default-features = false }
+hmac = {version = "0.12.1", default-features = false, optional = true }
 digest = { version = "0.10.7", default-features = false }
 # Curves
 ark-secp256r1 = { version = "0.4.0", default-features = false, optional = true }
@@ -48,7 +48,10 @@ curves = [
   "ed25519",
   "bandersnatch",
 ]
-secp256r1 = [ "ark-secp256r1" ]
+secp256r1 = [
+  "ark-secp256r1",
+  "rfc-6979",
+]
 ed25519 = [ "ark-ed25519" ]
 bandersnatch = [ "ark-ed-on-bls12-381-bandersnatch" ]
 parallel = [
@@ -63,3 +66,4 @@ ring = [
   "ark-bls12-381/curve",
   "merlin",
 ]
+rfc-6979 = [ "hmac" ]

src/utils.rs

@@ -1,6 +1,7 @@
 use crate::{AffinePoint, ScalarField, Suite};
+
 use ark_ff::PrimeField;
-use digest::{core_api::BlockSizeUser, Digest};
+use digest::Digest;
 
 #[cfg(not(feature = "std"))]
 use ark_std::vec::Vec;
@@ -34,8 +35,9 @@ pub(crate) fn hash<H: Digest>(data: &[u8]) -> digest::Output<H> {
 }
 
 /// Generic HMAC wrapper.
+#[cfg(feature = "rfc-6979")]
 #[inline(always)]
-pub(crate) fn hmac<H: Digest + BlockSizeUser>(sk: &[u8], data: &[u8]) -> Vec<u8> {
+pub(crate) fn hmac<H: Digest + digest::core_api::BlockSizeUser>(sk: &[u8], data: &[u8]) -> Vec<u8> {
     use hmac::{Mac, SimpleHmac};
     SimpleHmac::<H>::new_from_slice(sk)
         .expect("HMAC can take key of any size")
@@ -128,9 +130,10 @@ pub fn nonce_rfc_8032<S: Suite>(sk: &ScalarField<S>, input: &AffinePoint<S>) ->
 ///
 /// The algorithm generate the nonce value in a deterministic
 /// pseudorandom fashion.
+#[cfg(feature = "rfc-6979")]
 pub fn nonce_rfc_6979<S: Suite>(sk: &ScalarField<S>, input: &AffinePoint<S>) -> ScalarField<S>
 where
-    S::Hasher: BlockSizeUser,
+    S::Hasher: digest::core_api::BlockSizeUser,
 {
     let raw = encode_point::<S>(input);
     let h1 = hash::<S::Hasher>(&raw);