Update nitrokey crate to 0.2.3

This change updates the nitrokey crate to version 0.2.3. This version
bumps the rand crate used to 0.6.1, which in turn requires an additional
set of dependencies.

Import subrepo nitrokey/:nitrokey at b3e2adc5bb1300441ca74cc7672617c042f3ea31
Import subrepo rand/:rand at 73613ff903512e9503e41cc8ba9eae76269dc598
Import subrepo rustc_version/:rustc_version at 0294f2ba2018bf7be672abd53db351ce5055fa02
Import subrepo semver-parser/:semver-parser at 750da9b11a04125231b1fb293866ca036845acee
Import subrepo semver/:semver at 5eb6db94fa03f4d5c64a625a56188f496be47598

1 files changed, 102 insertions, 0 deletions

diff --git a/rand/src/distributions/unit_circle.rs b/rand/src/distributions/unit_circle.rs
new file mode 100644
index 0000000..abb36dc
--- /dev/null
+++ b/rand/src/distributions/unit_circle.rs
@@ -0,0 +1,102 @@
+// Copyright 2018 Developers of the Rand project.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use Rng;
+use distributions::{Distribution, Uniform};
+
+/// Samples uniformly from the edge of the unit circle in two dimensions.
+///
+/// Implemented via a method by von Neumann[^1].
+///
+///
+/// # Example
+///
+/// ```
+/// use rand::distributions::{UnitCircle, Distribution};
+///
+/// let circle = UnitCircle::new();
+/// let v = circle.sample(&mut rand::thread_rng());
+/// println!("{:?} is from the unit circle.", v)
+/// ```
+///
+/// [^1]: von Neumann, J. (1951) [*Various Techniques Used in Connection with
+///       Random Digits.*](https://mcnp.lanl.gov/pdf_files/nbs_vonneumann.pdf)
+///       NBS Appl. Math. Ser., No. 12. Washington, DC: U.S. Government Printing
+///       Office, pp. 36-38.
+#[derive(Clone, Copy, Debug)]
+pub struct UnitCircle {
+    uniform: Uniform<f64>,
+}
+
+impl UnitCircle {
+    /// Construct a new `UnitCircle` distribution.
+    #[inline]
+    pub fn new() -> UnitCircle {
+        UnitCircle { uniform: Uniform::new(-1., 1.) }
+    }
+}
+
+impl Distribution<[f64; 2]> for UnitCircle {
+    #[inline]
+    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> [f64; 2] {
+        let mut x1;
+        let mut x2;
+        let mut sum;
+        loop {
+            x1 = self.uniform.sample(rng);
+            x2 = self.uniform.sample(rng);
+            sum = x1*x1 + x2*x2;
+            if sum < 1. {
+                break;
+            }
+        }
+        let diff = x1*x1 - x2*x2;
+        [diff / sum, 2.*x1*x2 / sum]
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use distributions::Distribution;
+    use super::UnitCircle;
+
+    /// Assert that two numbers are almost equal to each other.
+    ///
+    /// On panic, this macro will print the values of the expressions with their
+    /// debug representations.
+    macro_rules! assert_almost_eq {
+        ($a:expr, $b:expr, $prec:expr) => (
+            let diff = ($a - $b).abs();
+            if diff > $prec {
+                panic!(format!(
+                    "assertion failed: `abs(left - right) = {:.1e} < {:e}`, \
+                     (left: `{}`, right: `{}`)",
+                    diff, $prec, $a, $b));
+            }
+        );
+    }
+
+    #[test]
+    fn norm() {
+        let mut rng = ::test::rng(1);
+        let dist = UnitCircle::new();
+        for _ in 0..1000 {
+            let x = dist.sample(&mut rng);
+            assert_almost_eq!(x[0]*x[0] + x[1]*x[1], 1., 1e-15);
+        }
+    }
+
+    #[test]
+    fn value_stability() {
+        let mut rng = ::test::rng(2);
+        let dist = UnitCircle::new();
+        assert_eq!(dist.sample(&mut rng), [-0.8032118336637037, 0.5956935036263119]);
+        assert_eq!(dist.sample(&mut rng), [-0.4742919588505423, -0.880367615130018]);
+        assert_eq!(dist.sample(&mut rng), [0.9297328981467168, 0.368234623716601]);
+    }
+}