Update nitrokey crate to 0.4.0

This change finally updates the version of the nitrokey crate that we
consume to 0.4.0. Along with that we update rand_core, one of its
dependencies, to 0.5.1. Further more we add cfg-if in version 0.1.10 and
getrandom in version 0.1.13, both of which are now new (non-development)
dependencies.

Import subrepo nitrokey/:nitrokey at e81057037e9b4f370b64c0a030a725bc6bdfb870
Import subrepo cfg-if/:cfg-if at 4484a6faf816ff8058088ad857b0c6bb2f4b02b2
Import subrepo getrandom/:getrandom at d661aa7e1b8cc80b47dabe3d2135b3b47d2858af
Import subrepo rand/:rand at d877ed528248b52d947e0484364a4e1ae59ca502

1 files changed, 119 insertions, 0 deletions

diff --git a/rand/rand_jitter/README.md b/rand/rand_jitter/README.md
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+# rand_jitter
+[![Build Status](https://travis-ci.org/rust-random/rand.svg?branch=master)](https://travis-ci.org/rust-random/rand)
+[![Build Status](https://ci.appveyor.com/api/projects/status/github/rust-random/rand?svg=true)](https://ci.appveyor.com/project/rust-random/rand)
+[![Latest version](https://img.shields.io/crates/v/rand_jitter.svg)](https://crates.io/crates/rand_jitter)
+[![Book](https://img.shields.io/badge/book-master-yellow.svg)](https://rust-random.github.io/book/)
+[![API](https://img.shields.io/badge/api-master-yellow.svg)](https://rust-random.github.io/rand/rand_jitter)
+[![API](https://docs.rs/rand_jitter/badge.svg)](https://docs.rs/rand_jitter)
+[![Minimum rustc version](https://img.shields.io/badge/rustc-1.32+-lightgray.svg)](https://github.com/rust-random/rand#rust-version-requirements)
+
+Non-physical true random number generator based on timing jitter.
+
+Note that this RNG is not suited for use cases where cryptographic security is
+required (also see [this
+discussion](https://github.com/rust-random/rand/issues/699)).
+
+This crate depends on [rand_core](https://crates.io/crates/rand_core) and is
+part of the [Rand project](https://github.com/rust-random/rand).
+
+This crate aims to support all of Rust's `std` platforms with a system-provided
+entropy source. Unlike other Rand crates, this crate does not support `no_std`
+(handling this gracefully is a current discussion topic).
+
+Links:
+
+-   [API documentation (master)](https://rust-random.github.io/rand/rand_jitter)
+-   [API documentation (docs.rs)](https://docs.rs/rand_jitter)
+-   [Changelog](https://github.com/rust-random/rand/blob/master/rand_jitter/CHANGELOG.md)
+
+## Features
+
+This crate has optional `std` support which is *disabled by default*;
+this feature is required to provide the `JitterRng::new` function;
+without `std` support a timer must be supplied via `JitterRng::new_with_timer`.
+
+## Quality testing
+
+`JitterRng::new()` has build-in, but limited, quality testing, however
+before using `JitterRng` on untested hardware, or after changes that could
+effect how the code is optimized (such as a new LLVM version), it is
+recommend to run the much more stringent
+[NIST SP 800-90B Entropy Estimation Suite](https://github.com/usnistgov/SP800-90B_EntropyAssessment).
+
+Use the following code using `timer_stats` to collect the data:
+
+```rust,no_run
+use rand_jitter::JitterRng;
+
+use std::error::Error;
+use std::fs::File;
+use std::io::Write;
+
+fn get_nstime() -> u64 {
+    use std::time::{SystemTime, UNIX_EPOCH};
+
+    let dur = SystemTime::now().duration_since(UNIX_EPOCH).unwrap();
+    // The correct way to calculate the current time is
+    // `dur.as_secs() * 1_000_000_000 + dur.subsec_nanos() as u64`
+    // But this is faster, and the difference in terms of entropy is
+    // negligible (log2(10^9) == 29.9).
+    dur.as_secs() << 30 | dur.subsec_nanos() as u64
+}
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let mut rng = JitterRng::new_with_timer(get_nstime);
+
+    // 1_000_000 results are required for the
+    // NIST SP 800-90B Entropy Estimation Suite
+    const ROUNDS: usize = 1_000_000;
+    let mut deltas_variable: Vec<u8> = Vec::with_capacity(ROUNDS);
+    let mut deltas_minimal: Vec<u8> = Vec::with_capacity(ROUNDS);
+
+    for _ in 0..ROUNDS {
+        deltas_variable.push(rng.timer_stats(true) as u8);
+        deltas_minimal.push(rng.timer_stats(false) as u8);
+    }
+
+    // Write out after the statistics collection loop, to not disturb the
+    // test results.
+    File::create("jitter_rng_var.bin")?.write(&deltas_variable)?;
+    File::create("jitter_rng_min.bin")?.write(&deltas_minimal)?;
+    Ok(())
+}
+```
+
+This will produce two files: `jitter_rng_var.bin` and `jitter_rng_min.bin`.
+Run the Entropy Estimation Suite in three configurations, as outlined below.
+Every run has two steps. One step to produce an estimation, another to
+validate the estimation.
+
+1. Estimate the expected amount of entropy that is at least available with
+   each round of the entropy collector. This number should be greater than
+   the amount estimated with `64 / test_timer()`.
+   ```sh
+   python noniid_main.py -v jitter_rng_var.bin 8
+   restart.py -v jitter_rng_var.bin 8 <min-entropy>
+   ```
+2. Estimate the expected amount of entropy that is available in the last 4
+   bits of the timer delta after running noice sources. Note that a value of
+   `3.70` is the minimum estimated entropy for true randomness.
+   ```sh
+   python noniid_main.py -v -u 4 jitter_rng_var.bin 4
+   restart.py -v -u 4 jitter_rng_var.bin 4 <min-entropy>
+   ```
+3. Estimate the expected amount of entropy that is available to the entropy
+   collector if both noise sources only run their minimal number of times.
+   This measures the absolute worst-case, and gives a lower bound for the
+   available entropy.
+   ```sh
+   python noniid_main.py -v -u 4 jitter_rng_min.bin 4
+   restart.py -v -u 4 jitter_rng_min.bin 4 <min-entropy>
+   ```
+
+## License
+
+`rand_jitter` is distributed under the terms of both the MIT license and the
+Apache License (Version 2.0).
+
+See [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT), and
+[COPYRIGHT](COPYRIGHT) for details.