Maybe I should try compiling my code before showing other cryptographers?

lol

Cargo.toml

@@ -24,8 +24,9 @@ features = ["nightly", "batch"]
 [dependencies]
 clear_on_drop = { version = "0.2" }
 curve25519-dalek = { version = "2.0.0-alpha.1", default-features = false }
-merlin = { version = "1", default-features = false, optional = true }
+merlin = { version = "1", default-features = false, optional = true, git = "https://github.com/isislovecruft/merlin", branch = "develop" }
 rand = { version = "0.7", default-features = false, optional = true }
+rand_core = { version = "0.5", default-features = false, optional = true }
 serde = { version = "1.0", optional = true }
 sha2 = { version = "0.8", default-features = false }
 
@@ -49,7 +50,7 @@ alloc = ["curve25519-dalek/alloc", "rand/alloc"]
 nightly = ["curve25519-dalek/nightly", "clear_on_drop/nightly", "rand/nightly"]
 batch = ["merlin", "rand"]
 # This feature enables deterministic batch verification.
-batch_deterministic = ["merlin", "rand"]
+batch_deterministic = ["merlin", "rand", "rand_core"]
 asm = ["sha2/asm"]
 # This features turns off stricter checking for scalar malleability in signatures
 legacy_compatibility = []
@@ -57,4 +58,4 @@ u64_backend = ["curve25519-dalek/u64_backend"]
 u32_backend = ["curve25519-dalek/u32_backend"]
 # Deprecated curve25519-dalek feature, use "simd_backend" instead:
 avx2_backend = ["curve25519-dalek/avx2_backend"]
-simd_backend = ["curve25519-dalek/simd_backend"]
+simd_backend = ["curve25519-dalek/simd_backend"]

src/batch.rs

@@ -26,10 +26,11 @@ pub use curve25519_dalek::digest::Digest;
 
 use merlin::Transcript;
 
+use rand::Rng;
 #[cfg(all(feature = "batch", not(feature = "batch_deterministic")))]
-use rand::{Rng, thread_rng};
+use rand::thread_rng;
 #[cfg(all(not(feature = "batch"), feature = "batch_deterministic"))]
-use rand::{CryptoRng, RngCore};
+use rand_core;
 
 use sha2::Sha512;
 
@@ -58,7 +59,7 @@ impl BatchTranscript for Transcript {
     fn append_message_lengths(&mut self, message_lengths: &Vec<usize>) {
         for (i, len) in message_lengths.iter().enumerate() {
             self.append_u64(b"", i as u64);
-            self.append_u64(b"mlen", len as u64);
+            self.append_u64(b"mlen", *len as u64);
         }
     }
 }
@@ -79,7 +80,15 @@ impl rand_core::RngCore for ZeroRng {
         rand_core::impls::next_u64_via_fill(self)
     }
 
-    fn fill_bytes(&mut self, dest: &mut [u8]) { }
+    /// A no-op function which leaves the destination bytes for randomness unchanged.
+    ///
+    /// In this case, the internal merlin code is initialising the destination
+    /// by doing `[0u8; …]`, which means that when we call
+    /// `merlin::TranscriptRngBuilder.finalize()`, rather than rekeying the
+    /// STROBE state based on external randomness, we're doing an
+    /// `ENC_{state}(00000000000000000000000000000000)` operation, which is
+    /// identical to the STROBE `MAC` operation.
+    fn fill_bytes(&mut self, _dest: &mut [u8]) { }
 
     fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), rand_core::Error> {
         self.fill_bytes(dest);
@@ -92,7 +101,7 @@ impl rand_core::CryptoRng for ZeroRng {}
 
 #[cfg(all(not(feature = "batch"), feature = "batch_deterministic"))]
 fn zero_rng() -> ZeroRng {
-    ZeroRng
+    ZeroRng {}
 }
 
 /// Verify a batch of `signatures` on `messages` with their respective `public_keys`.
@@ -170,7 +179,7 @@ pub fn verify_batch(
     // This provides synthethic randomness in the default configuration, and
     // purely deterministic in the case of compiling with the
     // "batch_deterministic" feature.
-    let transcript: Transcript = Transcript::new(b"ed25519 batch verification");
+    let mut transcript: Transcript = Transcript::new(b"ed25519 batch verification");
 
     transcript.append_hrams(&hrams);
     transcript.append_message_lengths(&message_lengths);

src/lib.rs

@@ -249,7 +249,7 @@ extern crate rand;
 extern crate serde;
 extern crate sha2;
 
-#[cfg(all(feature = "batch", any(feature = "std", feature = "alloc")))]
+#[cfg(all(any(feature = "batch", feature = "batch_deterministic"), any(feature = "std", feature = "alloc")))]
 mod batch;
 mod constants;
 mod ed25519;
@@ -260,3 +260,5 @@ mod signature;
 
 // Export everything public in ed25519.
 pub use crate::ed25519::*;
+#[cfg(all(any(feature = "batch", feature = "batch_deterministic"), any(feature = "std", feature = "alloc")))]
+pub use crate::batch::*;