Update dependencies and refactor RNG usage to StdRng

Cargo.toml

@@ -8,15 +8,15 @@ license = "MIT OR Apache-2.0"
 readme = "README.md"
 
 [dependencies]
-num-bigint-dig = { version = "0.8", features = [
+num-bigint-dig = { version = "0.9.1", features = [
     "zeroize",
     "prime",
     "rand",
     "u64_digit",
 ] }
 num-traits = "0.2"
 num-integer = "0.1"
-rand = "0.8"
+rand = "0.9.3"
 zeroize = { version = "1.8", features = ["derive"] }
 thiserror = "2"
 # Constant-time modular arithmetic for the decryption hot path (SECURITY-2).

src/key.rs

@@ -4,7 +4,8 @@
 use num_bigint_dig::{BigUint, ModInverse, RandBigInt};
 use num_integer::Integer;
 use num_traits::{One, Zero};
-use rand::rngs::OsRng;
+use rand::rngs::StdRng;
+use rand::SeedableRng;
 use zeroize::{Zeroize, ZeroizeOnDrop};
 
 use crate::util::l_function;
@@ -214,7 +215,7 @@ impl KeyPair {
             });
         }
 
-        let mut rng = OsRng;
+        let mut rng = StdRng::from_os_rng();
         let p_bits = bit_length / 3;
         let q_bits = bit_length - (2 * p_bits);
 

src/okuchi.rs

@@ -4,7 +4,8 @@
 use num_bigint_dig::{BigUint, RandBigInt};
 use num_integer::Integer;
 use num_traits::{One, Zero};
-use rand::rngs::OsRng;
+use rand::rngs::StdRng;
+use rand::SeedableRng;
 
 use crate::ciphertext::Ciphertext;
 use crate::error::{Error, Result};
@@ -52,7 +53,7 @@ impl Okuchi {
             return Err(Error::PlaintextTooLarge);
         }
 
-        let mut rng = OsRng;
+        let mut rng = StdRng::from_os_rng();
 
         // OU requires gcd(r, n) = 1. With n = p²q the failure probability is
         // ≈ 1/p + 1/q. This is negligible but the protocol is undefined otherwise.

src/util.rs

@@ -9,7 +9,8 @@ use crypto_bigint::modular::{BoxedMontyForm, BoxedMontyParams};
 use crypto_bigint::{BoxedUint, Odd};
 use num_bigint_dig::{BigUint, RandPrime};
 use num_traits::One;
-use rand::rngs::OsRng;
+use rand::rngs::StdRng;
+use rand::SeedableRng;
 
 use crate::{Error, Result};
 
@@ -98,6 +99,6 @@ pub fn generate_prime(bits: usize) -> Result<BigUint> {
             "prime bit length must be >= 2".into(),
         ));
     }
-    let mut rng = OsRng;
+    let mut rng = StdRng::from_os_rng();
     Ok(rng.gen_prime(bits)) // gen_prime uses Miller-Rabin internally
 }