diff --git a/.travis.yml b/.travis.yml
index 7a99953..dc3f978 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -17,7 +17,7 @@ matrix:
     - rust: nightly
       env: TEST_COMMAND=test FEATURES=--features="serde"
     - rust: nightly
-      env: TEST_COMMAND=build FEATURES=--no-default-features
+      env: TEST_COMMAND=build FEATURES="--no-default-features --features=u32_backend"
     - rust: nightly
       env: TEST_COMMAND=test FEATURES=--features="nightly"
     - rust: nightly
diff --git a/Cargo.toml b/Cargo.toml
index 55d6173..f0ee015 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,7 +16,7 @@ exclude = [ ".gitignore", "TESTVECTORS", "res/*" ]
 travis-ci = { repository = "dalek-cryptography/ed25519-dalek", branch = "master"}
 
 [dependencies.curve25519-dalek]
-version = "0.16"
+version = "0.17"
 default-features = false
 
 [dependencies.subtle]
@@ -25,7 +25,7 @@ default-features = false
 
 [dependencies.rand]
 optional = true
-version = "0.4"
+version = "0.5.0-pre.2"
 
 [dependencies.digest]
 version = "^0.7"
@@ -52,9 +52,12 @@ sha2 = "^0.7"
 bincode = "^0.9"
 
 [features]
-default = ["std"]
+default = ["std", "u64_backend"]
 std = ["rand", "subtle/std", "curve25519-dalek/std", "failure/std"]
 bench = []
 nightly = ["curve25519-dalek/nightly", "subtle/nightly"]
 asm = ["sha2/asm"]
 yolocrypto = ["curve25519-dalek/yolocrypto"]
+u64_backend = ["curve25519-dalek/u64_backend"]
+u32_backend = ["curve25519-dalek/u32_backend"]
+avx2_backend = ["curve25519-dalek/avx2_backend"]
diff --git a/src/ed25519.rs b/src/ed25519.rs
index e7a656c..1803aa1 100644
--- a/src/ed25519.rs
+++ b/src/ed25519.rs
@@ -12,6 +12,8 @@
 
 use core::fmt::{Debug};
 
+#[cfg(feature = "std")]
+use rand::CryptoRng;
 #[cfg(feature = "std")]
 use rand::Rng;
 
@@ -310,7 +312,9 @@ impl SecretKey {
     /// from `rand::OsRng::new()` (in the `rand` crate).
     ///
     #[cfg(feature = "std")]
-    pub fn generate(csprng: &mut Rng) -> SecretKey {
+    pub fn generate<T>(csprng: &mut T) -> SecretKey
+        where T: CryptoRng + Rng,
+    {
         let mut sk: SecretKey = SecretKey([0u8; 32]);
 
         csprng.fill_bytes(&mut sk.0);
@@ -723,8 +727,6 @@ impl PublicKey {
     pub fn verify<D>(&self, message: &[u8], signature: &Signature) -> bool
             where D: Digest<OutputSize = U64> + Default
     {
-        use curve25519_dalek::edwards::vartime;
-
         let mut h: D = D::default();
         let mut a: EdwardsPoint;
         let ao:  Option<EdwardsPoint>;
@@ -746,7 +748,8 @@ impl PublicKey {
         digest.copy_from_slice(h.fixed_result().as_slice());
 
         let digest_reduced: Scalar = Scalar::from_bytes_mod_order_wide(&digest);
-        let r: EdwardsPoint = vartime::double_scalar_mul_basepoint(&digest_reduced, &a, &signature.s);
+        let r: EdwardsPoint = EdwardsPoint::vartime_double_scalar_mul_basepoint(&digest_reduced,
+                                                                                &a, &signature.s);
 
         (signature.r.as_bytes()).ct_eq(r.compress().as_bytes()).unwrap_u8() == 1
     }
@@ -856,7 +859,7 @@ impl Keypair {
     /// use ed25519_dalek::Signature;
     ///
     /// let mut cspring: OsRng = OsRng::new().unwrap();
-    /// let keypair: Keypair = Keypair::generate::<Sha512>(&mut cspring);
+    /// let keypair: Keypair = Keypair::generate::<Sha512, OsRng>(&mut cspring);
     ///
     /// # }
     /// ```
@@ -872,8 +875,10 @@ impl Keypair {
     /// which is available with `use sha2::Sha512` as in the example above.
     /// Other suitable hash functions include Keccak-512 and Blake2b-512.
     #[cfg(feature = "std")]
-    pub fn generate<D>(csprng: &mut Rng) -> Keypair
-            where D: Digest<OutputSize = U64> + Default {
+    pub fn generate<D, R>(csprng: &mut R) -> Keypair
+        where D: Digest<OutputSize = U64> + Default,
+              R: CryptoRng + Rng,
+    {
         let sk: SecretKey = SecretKey::generate(csprng);
         let pk: PublicKey = PublicKey::from_secret::<D>(&sk);
 
@@ -981,7 +986,7 @@ mod test {
 
         // from_bytes() fails if vx²-u=0 and vx²+u=0
         loop {
-            keypair = Keypair::generate::<Sha512>(&mut cspring);
+            keypair = Keypair::generate::<Sha512, OsRng>(&mut cspring);
             x = keypair.public.decompress();
 
             if x.is_some() {
@@ -1005,7 +1010,7 @@ mod test {
         let bad:  &[u8] = "wrong message".as_bytes();
 
         cspring  = OsRng::new().unwrap();
-        keypair  = Keypair::generate::<Sha512>(&mut cspring);
+        keypair  = Keypair::generate::<Sha512, OsRng>(&mut cspring);
         good_sig = keypair.sign::<Sha512>(&good);
         bad_sig  = keypair.sign::<Sha512>(&bad);
 
diff --git a/src/lib.rs b/src/lib.rs
index a9a34e4..99011e2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -32,7 +32,7 @@
 //! use ed25519_dalek::Signature;
 //!
 //! let mut cspring: OsRng = OsRng::new().unwrap();
-//! let keypair: Keypair = Keypair::generate::<Sha512>(&mut cspring);
+//! let keypair: Keypair = Keypair::generate::<Sha512, OsRng>(&mut cspring);
 //! # }
 //! ```
 //!
@@ -49,7 +49,7 @@
 //! # use ed25519_dalek::Keypair;
 //! # use ed25519_dalek::Signature;
 //! # let mut cspring: OsRng = OsRng::new().unwrap();
-//! # let keypair: Keypair = Keypair::generate::<Sha512>(&mut cspring);
+//! # let keypair: Keypair = Keypair::generate::<Sha512, OsRng>(&mut cspring);
 //! let message: &[u8] = "This is a test of the tsunami alert system.".as_bytes();
 //! let signature: Signature = keypair.sign::<Sha512>(message);
 //! # }
@@ -69,7 +69,7 @@
 //! # use ed25519_dalek::Keypair;
 //! # use ed25519_dalek::Signature;
 //! # let mut cspring: OsRng = OsRng::new().unwrap();
-//! # let keypair: Keypair = Keypair::generate::<Sha512>(&mut cspring);
+//! # let keypair: Keypair = Keypair::generate::<Sha512, OsRng>(&mut cspring);
 //! # let message: &[u8] = "This is a test of the tsunami alert system.".as_bytes();
 //! # let signature: Signature = keypair.sign::<Sha512>(message);
 //! let verified: bool = keypair.verify::<Sha512>(message, &signature);
@@ -93,7 +93,7 @@
 //! # use ed25519_dalek::Signature;
 //! use ed25519_dalek::PublicKey;
 //! # let mut cspring: OsRng = OsRng::new().unwrap();
-//! # let keypair: Keypair = Keypair::generate::<Sha512>(&mut cspring);
+//! # let keypair: Keypair = Keypair::generate::<Sha512, OsRng>(&mut cspring);
 //! # let message: &[u8] = "This is a test of the tsunami alert system.".as_bytes();
 //! # let signature: Signature = keypair.sign::<Sha512>(message);
 //!
@@ -122,7 +122,7 @@
 //! # use ed25519_dalek::{Keypair, Signature, PublicKey};
 //! use ed25519_dalek::{PUBLIC_KEY_LENGTH, SECRET_KEY_LENGTH, KEYPAIR_LENGTH, SIGNATURE_LENGTH};
 //! # let mut cspring: OsRng = OsRng::new().unwrap();
-//! # let keypair: Keypair = Keypair::generate::<Sha512>(&mut cspring);
+//! # let keypair: Keypair = Keypair::generate::<Sha512, OsRng>(&mut cspring);
 //! # let message: &[u8] = "This is a test of the tsunami alert system.".as_bytes();
 //! # let signature: Signature = keypair.sign::<Sha512>(message);
 //! # let public_key: PublicKey = keypair.public;
@@ -147,7 +147,7 @@
 //! # use ed25519_dalek::{PUBLIC_KEY_LENGTH, SECRET_KEY_LENGTH, KEYPAIR_LENGTH, SIGNATURE_LENGTH};
 //! # fn do_test() -> Result<(SecretKey, PublicKey, Keypair, Signature), DecodingError> {
 //! # let mut cspring: OsRng = OsRng::new().unwrap();
-//! # let keypair_orig: Keypair = Keypair::generate::<Sha512>(&mut cspring);
+//! # let keypair_orig: Keypair = Keypair::generate::<Sha512, OsRng>(&mut cspring);
 //! # let message: &[u8] = "This is a test of the tsunami alert system.".as_bytes();
 //! # let signature_orig: Signature = keypair_orig.sign::<Sha512>(message);
 //! # let public_key_bytes: [u8; PUBLIC_KEY_LENGTH] = keypair_orig.public.to_bytes();