diff --git a/Cargo.toml b/Cargo.toml
index 382e8bc..3522e69 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,11 +18,15 @@ wasm-bindgen = { version = "0.2.87", optional = true }
 
 [dependencies.rand]
 version = "0.8.5"
+default-features = false
 features = ["getrandom"]
+optional = true
 
 [dev-dependencies]
+rand = "0.8.5"
 pqc_core = {version = "0.3.0", features = ["load"]}
 
+
 [target.'cfg(bench)'.dev-dependencies.criterion]
 criterion = "0.4.0"
 
@@ -46,8 +50,10 @@ aes = []
 # message that is being signed.
 random_signing = []
 
-# For compiling to wasm targets 
-wasm = ["wasm-bindgen", "getrandom/js"]
+# For compiling to wasm targets
+wasm = ["wasm-bindgen", "getrandom/js", "rand"]
+
+std = []
 
 [lib]
 crate-type = ["cdylib", "rlib"]
\ No newline at end of file
diff --git a/README.md b/README.md
index fdb0246..80e8507 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@ A rust implementation of the Dilithium, a KEM standardised by the NIST Post-Quan
 
 See the [**features**](#features) section for different options regarding security levels and modes of operation. The default security setting is Dilithium3.
 
-It is recommended to use Dilithium in a hybrid system alongside a traditional signature algorithm such as ed25519. 
+It is recommended to use Dilithium in a hybrid system alongside a traditional signature algorithm such as ed25519.
 
 **Minimum Supported Rust Version: 1.50.0**
 
@@ -23,25 +23,27 @@ It is recommended to use Dilithium in a hybrid system alongside a traditional si
 
 ```shell
 cargo add pqc_dilithium
-``` 
+```
 
-## Usage 
+## Usage
 
 ```rust
 use pqc_dilithium::*;
+use rand_core::OsRng;
 ```
 
 ### Key Generation
 ```rust
-let keys = Keypair::generate();
+use rand_core::
+let keys = Keypair::generate(&mut OsRng);
 assert!(keys.public.len() == PUBLICKEYBYTES);
 assert!(keys.expose_secret().len() == SECRETKEYBYTES);
 ```
 
-### Signing 
+### Signing
 ```rust
 let msg = "Hello".as_bytes();
-let sig = keys.sign(&msg);
+let sig = keys.sign(&msg, &mut OsRng);
 assert!(sig.len() == SIGNBYTES);
 ```
 
@@ -55,7 +57,7 @@ assert!(sig_verify.is_ok());
 
 ## AES mode
 
-Dilithium-AES, that uses AES-256 in counter mode instead of SHAKE to 
+Dilithium-AES, that uses AES-256 in counter mode instead of SHAKE to
 expand the matrix and the masking vectors, and to sample the secret polynomials.
 This offers hardware speedups on certain platforms.
 
@@ -87,7 +89,7 @@ By default this library uses Dilithium3
 
 ---
 
-## Testing 
+## Testing
 
 To run the known answer tests, you'll need to enable the `dilithium_kat` in `RUSTFLAGS` eg.
 
@@ -120,16 +122,16 @@ For example, using [wasm-pack](https://rustwasm.github.io/wasm-pack/installer/):
 wasm-pack build -- --features wasm
 ```
 
-Which will export the wasm, javascript and  typescript files into `./pkg/`. 
+Which will export the wasm, javascript and  typescript files into `./pkg/`.
 
-To compile a different variant into a separate folder: 
+To compile a different variant into a separate folder:
 ```shell
-wasm-pack build --out-dir pkg_mode5/ -- --features "wasm mode5" 
+wasm-pack build --out-dir pkg_mode5/ -- --features "wasm mode5"
 ```
 
 There is also a basic html demo in the [www](./www/readme.md) folder.
- 
-From the www folder run: 
+
+From the www folder run:
 
 ```shell
 npm install
@@ -140,11 +142,11 @@ npm run start
 
 ## Alternatives
 
-The PQClean project has rust bindings for their C post quantum libraries. 
+The PQClean project has rust bindings for their C post quantum libraries.
 
 https://github.com/rustpq/pqcrypto/tree/main/pqcrypto-dilithium
 
---- 
+---
 
 ## About
 
@@ -152,7 +154,7 @@ Dilithium is a digital signature scheme that is strongly secure under chosen mes
 
 The official website: https://pq-crystals.org/dilithium/
 
-Authors of the Dilithium Algorithm: 
+Authors of the Dilithium Algorithm:
 
 * Roberto Avanzi, ARM Limited (DE)
 * Joppe Bos, NXP Semiconductors (BE)
diff --git a/benches/api.rs b/benches/api.rs
index b7ccfbb..599857d 100644
--- a/benches/api.rs
+++ b/benches/api.rs
@@ -1,20 +1,21 @@
 use criterion::{black_box, criterion_group, criterion_main, Criterion};
 use pqc_dilithium::*;
+use rand_core::OsRng;
 
 fn sign_small_msg(c: &mut Criterion) {
-  let keys = Keypair::generate();
+  let keys = Keypair::generate(&mut OsRng).unwrap();
   let msg = "Hello".as_bytes();
   c.bench_function("Sign Small Message", |b| {
-    b.iter(|| keys.sign(black_box(msg)))
+    b.iter(|| keys.sign(&black_box(msg), &mut OsRng).unwrap())
   });
 }
 
 fn verify_small_msg(c: &mut Criterion) {
-  let keys = Keypair::generate();
+  let keys = Keypair::generate(&mut OsRng).unwrap();
   let msg = "Hello".as_bytes();
-  let sig = keys.sign(msg);
+  let sig = keys.sign(msg, &mut OsRng).unwrap();
   c.bench_function("Verify Small Message", |b| {
-    b.iter(|| verify(black_box(sig), black_box(msg), black_box(&keys.public)))
+    b.iter(|| verify(black_box(&sig), black_box(msg), black_box(&keys.public)))
   });
 }
 
diff --git a/src/api.rs b/src/api.rs
index 3a29494..92bf99f 100644
--- a/src/api.rs
+++ b/src/api.rs
@@ -1,5 +1,7 @@
+use crate::error::*;
 use crate::params::{PUBLICKEYBYTES, SECRETKEYBYTES, SIGNBYTES};
 use crate::sign::*;
+use rand_core::{CryptoRng, RngCore};
 
 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
 pub struct Keypair {
@@ -14,16 +16,12 @@ impl std::fmt::Debug for Keypair {
   }
 }
 
-pub enum SignError {
-  Input,
-  Verify,
-}
-
 impl Keypair {
   /// Explicitly expose secret key
   /// ```
   /// # use pqc_dilithium::*;
-  /// let keys = Keypair::generate();
+  /// use rand_core::OsRng;
+  /// let keys = Keypair::generate(&mut OsRng).expect("couldn't obtain random bytes");
   /// let secret_key = keys.expose_secret();
   /// assert!(secret_key.len() == SECRETKEYBYTES);
   /// ```
@@ -36,15 +34,19 @@ impl Keypair {
   /// Example:
   /// ```
   /// # use pqc_dilithium::*;
-  /// let keys = Keypair::generate();
+  /// # use rand_core::OsRng;
+  /// let keys = Keypair::generate(&mut OsRng).expect("couldn't obtain random bytes");
   /// assert!(keys.public.len() == PUBLICKEYBYTES);
   /// assert!(keys.expose_secret().len() == SECRETKEYBYTES);
   /// ```
-  pub fn generate() -> Keypair {
+  pub fn generate<R>(rng: &mut R) -> Result<Keypair, DilithiumError>
+  where
+    R: RngCore + CryptoRng,
+  {
     let mut public = [0u8; PUBLICKEYBYTES];
     let mut secret = [0u8; SECRETKEYBYTES];
-    crypto_sign_keypair(&mut public, &mut secret, None);
-    Keypair { public, secret }
+    crypto_sign_keypair(&mut public, &mut secret, rng, None)?;
+    Ok(Keypair { public, secret })
   }
 
   /// Generates a signature for the given message using a keypair
@@ -52,15 +54,23 @@ impl Keypair {
   /// Example:
   /// ```
   /// # use pqc_dilithium::*;
-  /// # let keys = Keypair::generate();
+  /// # use rand_core::OsRng;
+  /// # let keys = Keypair::generate(&mut OsRng).unwrap();
   /// let msg = "Hello".as_bytes();
-  /// let sig = keys.sign(&msg);
+  /// let sig = keys.sign(&msg, &mut OsRng).expect("couldn't obtain random bytes");
   /// assert!(sig.len() == SIGNBYTES);
-  /// ```  
-  pub fn sign(&self, msg: &[u8]) -> [u8; SIGNBYTES] {
+  /// ```
+  pub fn sign<R>(
+    &self,
+    msg: &[u8],
+    rng: &mut R,
+  ) -> Result<[u8; SIGNBYTES], DilithiumError>
+  where
+    R: RngCore + CryptoRng,
+  {
     let mut sig = [0u8; SIGNBYTES];
-    crypto_sign_signature(&mut sig, msg, &self.secret);
-    sig
+    crypto_sign_signature(&mut sig, msg, &self.secret, rng)?;
+    Ok(sig)
   }
 }
 
@@ -69,18 +79,19 @@ impl Keypair {
 /// Example:
 /// ```
 /// # use pqc_dilithium::*;
-/// # let keys = Keypair::generate();
+/// # use rand_core::OsRng;
+/// # let keys = Keypair::generate(&mut OsRng).unwrap();
 /// # let msg = [0u8; 32];
-/// # let sig = keys.sign(&msg);
+/// # let sig = keys.sign(&msg, &mut OsRng).unwrap();
 /// let sig_verify = verify(&sig, &msg, &keys.public);
 /// assert!(sig_verify.is_ok());
 pub fn verify(
   sig: &[u8],
   msg: &[u8],
   public_key: &[u8],
-) -> Result<(), SignError> {
+) -> Result<(), DilithiumError> {
   if sig.len() != SIGNBYTES {
-    return Err(SignError::Input);
+    return Err(DilithiumError::Input);
   }
   crypto_sign_verify(&sig, &msg, public_key)
 }
diff --git a/src/error.rs b/src/error.rs
new file mode 100644
index 0000000..b334172
--- /dev/null
+++ b/src/error.rs
@@ -0,0 +1,9 @@
+#[derive(Debug, PartialEq)]
+pub enum DilithiumError {
+  Input,
+  Verify,
+  RandomBytesGeneration,
+}
+
+#[cfg(feature = "std")]
+impl std::error::Error for DilithiumError {}
diff --git a/src/lib.rs b/src/lib.rs
index 33a1226..4ea0e69 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,14 +1,15 @@
 #[cfg(feature = "aes")]
 mod aes256ctr;
 mod api;
+mod error;
 mod fips202;
 mod ntt;
 mod packing;
 mod params;
 mod poly;
 mod polyvec;
-mod randombytes;
 mod reduce;
+mod rng;
 mod rounding;
 mod sign;
 mod symmetric;
diff --git a/src/packing.rs b/src/packing.rs
index 561ffbf..77d2c4e 100644
--- a/src/packing.rs
+++ b/src/packing.rs
@@ -1,4 +1,4 @@
-use crate::{params::*, poly::*, polyvec::*, SignError};
+use crate::{error::DilithiumError, params::*, poly::*, polyvec::*};
 
 /// Bit-pack public key pk = (rho, t1).
 pub fn pack_pk(pk: &mut [u8], rho: &[u8], t1: &Polyveck) {
@@ -123,7 +123,7 @@ pub fn unpack_sig(
   z: &mut Polyvecl,
   h: &mut Polyveck,
   sig: &[u8],
-) -> Result<(), SignError> {
+) -> Result<(), DilithiumError> {
   let mut idx = 0usize;
 
   c[..SEEDBYTES].copy_from_slice(&sig[..SEEDBYTES]);
@@ -138,12 +138,12 @@ pub fn unpack_sig(
   let mut k = 0usize;
   for i in 0..K {
     if sig[idx + OMEGA + i] < k as u8 || sig[idx + OMEGA + i] > OMEGA_U8 {
-      return Err(SignError::Input);
+      return Err(DilithiumError::Input);
     }
     for j in k..sig[idx + OMEGA + i] as usize {
       // Coefficients are ordered for strong unforgeability
       if j > k && sig[idx + j as usize] <= sig[idx + j as usize - 1] {
-        return Err(SignError::Input);
+        return Err(DilithiumError::Input);
       }
       h.vec[i].coeffs[sig[idx + j] as usize] = 1;
     }
@@ -153,7 +153,7 @@ pub fn unpack_sig(
   // Extra indices are zero for strong unforgeability
   for j in k..OMEGA {
     if sig[idx + j as usize] > 0 {
-      return Err(SignError::Input);
+      return Err(DilithiumError::Input);
     }
   }
 
diff --git a/src/randombytes.rs b/src/randombytes.rs
deleted file mode 100644
index b67a2fc..0000000
--- a/src/randombytes.rs
+++ /dev/null
@@ -1,5 +0,0 @@
-use rand::prelude::*;
-
-pub fn randombytes(x: &mut [u8], len: usize) {
-  thread_rng().fill_bytes(&mut x[..len])
-}
diff --git a/src/rng.rs b/src/rng.rs
new file mode 100644
index 0000000..249fee6
--- /dev/null
+++ b/src/rng.rs
@@ -0,0 +1,16 @@
+use crate::error::DilithiumError;
+use rand_core::*;
+
+pub fn randombytes<R>(
+  x: &mut [u8],
+  len: usize,
+  rng: &mut R,
+) -> Result<(), DilithiumError>
+where
+  R: RngCore + CryptoRng,
+{
+  match rng.try_fill_bytes(&mut x[..len]) {
+    Ok(_) => Ok(()),
+    Err(_) => Err(DilithiumError::RandomBytesGeneration),
+  }
+}
diff --git a/src/sign.rs b/src/sign.rs
index 6067211..0a54ace 100644
--- a/src/sign.rs
+++ b/src/sign.rs
@@ -1,17 +1,22 @@
 use crate::{
-  fips202::*, packing::*, params::*, poly::*, polyvec::*, randombytes::*,
-  SignError,
+  error::DilithiumError, fips202::*, packing::*, params::*, poly::*,
+  polyvec::*, rng::*,
 };
+use rand_core::{CryptoRng, RngCore};
 
-pub fn crypto_sign_keypair(
+pub fn crypto_sign_keypair<R>(
   pk: &mut [u8],
   sk: &mut [u8],
+  rng: &mut R,
   seed: Option<&[u8]>,
-) -> u8 {
+) -> Result<(), DilithiumError>
+where
+  R: RngCore + CryptoRng,
+{
   let mut init_seed = [0u8; SEEDBYTES];
   match seed {
     Some(x) => init_seed.copy_from_slice(x),
-    None => randombytes(&mut init_seed, SEEDBYTES),
+    None => randombytes(&mut init_seed, SEEDBYTES, rng)?,
   };
   let mut seedbuf = [0u8; 2 * SEEDBYTES + CRHBYTES];
   let mut tr = [0u8; SEEDBYTES];
@@ -61,10 +66,18 @@ pub fn crypto_sign_keypair(
   shake256(&mut tr, SEEDBYTES, pk, PUBLICKEYBYTES);
   pack_sk(sk, &rho, &tr, &key, &t0, &s1, &s2);
 
-  return 0;
+  Ok(())
 }
 
-pub fn crypto_sign_signature(sig: &mut [u8], m: &[u8], sk: &[u8]) {
+pub fn crypto_sign_signature<R>(
+  sig: &mut [u8],
+  m: &[u8],
+  sk: &[u8],
+  rng: &mut R,
+) -> Result<(), DilithiumError>
+where
+  R: RngCore + CryptoRng,
+{
   // `key` and `mu` are concatenated
   let mut keymu = [0u8; SEEDBYTES + CRHBYTES];
 
@@ -97,7 +110,7 @@ pub fn crypto_sign_signature(sig: &mut [u8], m: &[u8], sk: &[u8]) {
   shake256_squeeze(&mut keymu[SEEDBYTES..], CRHBYTES, &mut state);
 
   if RANDOMIZED_SIGNING {
-    randombytes(&mut rhoprime, CRHBYTES);
+    randombytes(&mut rhoprime, CRHBYTES, rng)?;
   } else {
     shake256(&mut rhoprime, CRHBYTES, &keymu, SEEDBYTES + CRHBYTES);
   }
@@ -168,7 +181,7 @@ pub fn crypto_sign_signature(sig: &mut [u8], m: &[u8], sk: &[u8]) {
 
     // Write signature
     pack_sig(sig, None, &z, &h);
-    return;
+    return Ok(());
   }
 }
 
@@ -176,7 +189,7 @@ pub fn crypto_sign_verify(
   sig: &[u8],
   m: &[u8],
   pk: &[u8],
-) -> Result<(), SignError> {
+) -> Result<(), DilithiumError> {
   let mut buf = [0u8; K * POLYW1_PACKEDBYTES];
   let mut rho = [0u8; SEEDBYTES];
   let mut mu = [0u8; CRHBYTES];
@@ -192,7 +205,7 @@ pub fn crypto_sign_verify(
   let mut state = KeccakState::default(); // shake256_init()
 
   if sig.len() != SIGNBYTES {
-    return Err(SignError::Input);
+    return Err(DilithiumError::Input);
   }
 
   unpack_pk(&mut rho, &mut t1, pk);
@@ -200,7 +213,7 @@ pub fn crypto_sign_verify(
     return Err(e);
   }
   if polyvecl_chknorm(&z, (GAMMA1 - BETA) as i32) > 0 {
-    return Err(SignError::Input);
+    return Err(DilithiumError::Input);
   }
 
   // Compute CRH(CRH(rho, t1), msg)
@@ -240,7 +253,7 @@ pub fn crypto_sign_verify(
   shake256_squeeze(&mut c2, SEEDBYTES, &mut state);
   // Doesn't require constant time equality check
   if c != c2 {
-    Err(SignError::Verify)
+    Err(DilithiumError::Verify)
   } else {
     Ok(())
   }
diff --git a/src/wasm.rs b/src/wasm.rs
index 123e49b..3cc5c04 100644
--- a/src/wasm.rs
+++ b/src/wasm.rs
@@ -12,16 +12,21 @@ pub struct Keys {
 }
 
 #[wasm_bindgen]
-pub fn keypair() -> Keys {
-  Keys {
-    keypair: api::Keypair::generate(),
+pub fn keypair() -> Result<Keys, JsError> {
+  let mut rng = rand::rngs::OsRng {};
+  match api::Keypair::generate(&mut rng) {
+    Ok(keypair) => Ok(Keys { keypair }),
+    Err(error::DilithiumError::RandomBytesGeneration) => {
+      Err(JsError::new("Error trying to fill random bytes"))
+    }
+    _ => Err(JsError::new("The keypair could not be generated")),
   }
 }
 
 #[wasm_bindgen]
 impl Keys {
   #[wasm_bindgen(constructor)]
-  pub fn new() -> Keys {
+  pub fn new() -> Result<Keys, JsError> {
     keypair()
   }
 
@@ -36,8 +41,12 @@ impl Keys {
   }
 
   #[wasm_bindgen]
-  pub fn sign(&self, msg: Box<[u8]>) -> Box<[u8]> {
-    Box::new(self.keypair.sign(&msg))
+  pub fn sign(&self, msg: Box<[u8]>) -> Result<Box<[u8]>, JsValue> {
+    let mut rng = rand::rngs::OsRng {};
+    match self.keypair.sign(&msg, &mut rng) {
+      Ok(signature) => Ok(Box::new(signature)),
+      Err(_) => Err(JsValue::null()),
+    }
   }
 }
 
diff --git a/tests/integration.rs b/tests/integration.rs
index cd0dfd9..d9958be 100644
--- a/tests/integration.rs
+++ b/tests/integration.rs
@@ -2,17 +2,19 @@ use pqc_dilithium::*;
 
 #[test]
 fn sign_then_verify_valid() {
+  let mut rng = rand::thread_rng();
   let msg = b"Hello";
-  let keys = Keypair::generate();
-  let signature = keys.sign(msg);
+  let keys = Keypair::generate(&mut rng).unwrap();
+  let signature = keys.sign(msg, &mut rng).unwrap();
   assert!(verify(&signature, msg, &keys.public).is_ok())
 }
 
 #[test]
 fn sign_then_verify_invalid() {
+  let mut rng = rand::thread_rng();
   let msg = b"Hello";
-  let keys = Keypair::generate();
-  let mut signature = keys.sign(msg);
+  let keys = Keypair::generate(&mut rng).unwrap();
+  let mut signature = keys.sign(msg, &mut rng).unwrap();
   signature[..4].copy_from_slice(&[255u8; 4]);
   assert!(verify(&signature, msg, &keys.public).is_err())
 }
diff --git a/tests/kat.rs b/tests/kat.rs
index 5300946..897193c 100644
--- a/tests/kat.rs
+++ b/tests/kat.rs
@@ -2,6 +2,7 @@
 
 use pqc_core::load::*;
 use pqc_dilithium::*;
+use rand_core::OsRng;
 use std::path::PathBuf;
 
 const MODE: u8 = if cfg!(feature = "mode2") {
@@ -25,7 +26,8 @@ fn keypair() {
     let sk = kat.sk.clone();
     let mut pk2 = [0u8; PUBLICKEYBYTES];
     let mut sk2 = [0u8; SECRETKEYBYTES];
-    crypto_sign_keypair(&mut pk2, &mut sk2, Some(&bufvec[i]));
+    crypto_sign_keypair(&mut pk2, &mut sk2, &mut OsRng, Some(&bufvec[i]))
+      .unwrap();
     assert_eq!(pk, pk2);
     assert_eq!(sk, sk2);
   }
@@ -41,7 +43,7 @@ pub fn sign() {
     let msg = kat.msg.clone();
     let sk = kat.sk.clone();
     let mut sig = vec![0u8; SIGNBYTES];
-    crypto_sign_signature(&mut sig, &msg, &sk);
+    crypto_sign_signature(&mut sig, &msg, &sk, &mut OsRng).unwrap();
     assert_eq!(sm[..SIGNBYTES], sig);
   }
 }
diff --git a/tests/wasm.js b/tests/wasm.js
index 34ba6c1..a1e4544 100644
--- a/tests/wasm.js
+++ b/tests/wasm.js
@@ -2,7 +2,7 @@
 
 // Uses CommonJS modules
 // Package needs to be built for node:
-// wasm-pack build --target nodejs -- features wasm
+// wasm-pack build --target nodejs -- --features wasm
 const dilithium = require("../pkg/pqc_dilithium");
 const assert = require("assert");