Replaces Rng256 with new Rng API (#612)

* Replaces the Rng256 with RngCore from rand_core

The old trait was designed with our software crypto in mind. We should
use a more standard API going forward.

- Removes libraries/rng256/
- Ports libraries/crypto/ to rand_core
- Moves the used RNG trait to api/

* Use StdRng directy in TestEnv

libraries/opensk/fuzz/fuzz_helper/Cargo.toml

@@ -9,6 +9,5 @@ edition = "2018"
 arrayref = "0.3.6"
 opensk = { path = "../..", features = ["fuzz"] }
 crypto = { path = "../../../crypto", features = ['std'] }
-rng256 = { path = "../../../rng256", features = ['std'] }
 sk-cbor = { path = "../../../cbor" }
 arbitrary = { version = "0.4.7", features = ["derive"] }

libraries/opensk/fuzz/fuzz_helper/src/lib.rs

@@ -137,7 +137,7 @@ pub fn process_ctap_any_type(data: &[u8]) -> arbitrary::Result<()> {
     let mut unstructured = Unstructured::new(data);
 
     let mut env = TestEnv::default();
-    env.rng().seed_from_u64(u64::arbitrary(&mut unstructured)?);
+    env.seed_rng_from_u64(u64::arbitrary(&mut unstructured)?);
 
     let data = unstructured.take_rest();
     // Initialize ctap state and hid and get the allocated cid.
@@ -184,7 +184,7 @@ pub fn process_ctap_specific_type(data: &[u8], input_type: InputType) -> arbitra
     let mut unstructured = Unstructured::new(data);
 
     let mut env = TestEnv::default();
-    env.rng().seed_from_u64(u64::arbitrary(&mut unstructured)?);
+    env.seed_rng_from_u64(u64::arbitrary(&mut unstructured)?);
 
     let data = unstructured.take_rest();
     if !is_type(data, input_type) {
@@ -218,7 +218,7 @@ pub fn process_ctap_structured(data: &[u8], input_type: InputType) -> FuzzResult
     let unstructured = &mut Unstructured::new(data);
 
     let mut env = TestEnv::default();
-    env.rng().seed_from_u64(u64::arbitrary(unstructured)?);
+    env.seed_rng_from_u64(u64::arbitrary(unstructured)?);
     setup_customization(unstructured, env.customization_mut())?;
 
     let mut state = CtapState::new(&mut env);
@@ -255,7 +255,7 @@ pub fn split_assemble_hid_packets(data: &[u8]) -> arbitrary::Result<()> {
     let mut unstructured = Unstructured::new(data);
 
     let mut env = TestEnv::default();
-    env.rng().seed_from_u64(u64::arbitrary(&mut unstructured)?);
+    env.seed_rng_from_u64(u64::arbitrary(&mut unstructured)?);
 
     let data = unstructured.take_rest();
     let message = raw_to_message(data);