Replaces Rng256 with new Rng API (google#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

Cargo.toml

@@ -17,18 +17,17 @@ lang_items = { path = "third_party/lang-items" }
 opensk = { path = "libraries/opensk" }
 sk-cbor = { path = "libraries/cbor" }
 crypto = { path = "libraries/crypto" }
-rng256 = { path = "libraries/rng256" }
 persistent_store = { path = "libraries/persistent_store" }
 byteorder = { version = "1", default-features = false }
 arrayref = "0.3.6"
-rand = { version = "0.8.4", optional = true }
+rand_core = "0.6.4"
 ed25519-compact = { version = "1", default-features = false, optional = true }
 
 [features]
 debug_allocations = ["lang_items/debug_allocations"]
 debug_ctap = ["libtock_drivers/debug_ctap", "opensk/debug_ctap"]
 panic_console = ["lang_items/panic_console"]
-std = ["crypto/std", "lang_items/std", "persistent_store/std", "rng256/std", "rand", "opensk/std"]
+std = ["crypto/std", "lang_items/std", "persistent_store/std", "opensk/std"]
 verbose = ["debug_ctap", "libtock_drivers/verbose_usb"]
 with_ctap1 = ["crypto/with_ctap1", "opensk/with_ctap1"]
 with_nfc = ["libtock_drivers/with_nfc"]

examples/crypto_bench.rs

@@ -21,7 +21,7 @@ use alloc::format;
 use alloc::vec::Vec;
 use core::fmt::Write;
 use crypto::{aes256, cbc, ecdsa, sha256, Hash256};
-use ctap2::env::tock::TockRng256;
+use ctap2::env::tock::TockRng;
 use libtock_drivers::console::Console;
 use libtock_drivers::result::FlexUnwrap;
 use libtock_drivers::timer;
@@ -36,7 +36,7 @@ fn main() {
     let mut with_callback = timer::with_callback(|_, _| {});
     let timer = with_callback.init().flex_unwrap();
 
-    let mut rng = TockRng256 {};
+    let mut rng = TockRng {};
 
     writeln!(console, "****************************************").unwrap();
     writeln!(

libraries/crypto/Cargo.toml

@@ -10,7 +10,6 @@ license = "Apache-2.0"
 edition = "2018"
 
 [dependencies]
-rng256 = { path = "../rng256" }
 arrayref = "0.3.6"
 subtle = { version = "2.2.3", default-features = false, features = ["nightly"] }
 byteorder = { version = "1", default-features = false }
@@ -20,7 +19,8 @@ untrusted = { version = "0.7.0", optional = true }
 serde = { version = "1.0", optional = true, features = ["derive"] }
 serde_json = { version = "=1.0.69", optional = true }
 regex = { version = "1", optional = true }
+rand_core = "0.6.4"
 
 [features]
-std = ["hex", "ring", "rng256/std", "untrusted", "serde", "serde_json", "regex"]
+std = ["hex", "ring", "untrusted", "serde", "serde_json", "regex", "rand_core/getrandom"]
 with_ctap1 = []