Add examples/fastpkbdf2_bench.

This allows for performance comparisons between *ring* and other
implementations. I think the benchmark is too noisy. Unfortunately,
|cargo bench| doesn't work well for measuring this because
|cargo bench| insists on doing a huge number of iterations, which means
that each run takes too long in a edit-compile-measure cycle.

Cargo.toml

@@ -16,6 +16,7 @@ libc = "0.1"
 
 # TODO: [dev-dependencies]
 rustc-serialize = "0.3.15"
+time = "0.1.32"
 
 [profile.release]
 opt-level = 3

examples/fastpbkdf2_bench.rs

@@ -0,0 +1,56 @@
+// Copyright 2015 Brian Smith.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND AND THE AUTHORS DISCLAIM ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
+// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+// Derived from the CC0-licensed implementation by Joseph Birr-Pixton at
+// https://github.com/ctz/rust-fastpbkdf2/blob/master/pbkdf2-bench/src/main.rs
+// commit b000c72c7b3beb0bee761bebcf07ac3f0875d1ad. This version only measures
+// *ring*.
+
+extern crate ring;
+extern crate time;
+
+use ring::pbkdf2;
+use time::SteadyTime;
+
+const ITERATIONS: usize = 1 << 20;
+const PASSWORD: &'static [u8] = b"password";
+const SALT: &'static [u8] = b"salt";
+
+fn bench<F>(name: &'static str, f: F) where F: FnOnce() {
+  let start = SteadyTime::now();
+  f();
+  let duration = SteadyTime::now() - start;
+  println!("{} = {}ms", name, duration.num_milliseconds());
+}
+
+fn ring_sha1() {
+  let mut out = [0u8; 20];
+  pbkdf2::derive(&pbkdf2::HMAC_SHA1, ITERATIONS, PASSWORD, SALT, &mut out);
+}
+
+fn ring_sha256() {
+  let mut out = [0u8; 32];
+  pbkdf2::derive(&pbkdf2::HMAC_SHA256, ITERATIONS, PASSWORD, SALT, &mut out);
+}
+
+fn ring_sha512() {
+  let mut out = [0u8; 64];
+  pbkdf2::derive(&pbkdf2::HMAC_SHA512, ITERATIONS, PASSWORD, SALT, &mut out);
+}
+
+fn main() {
+  bench("ring-sha1", ring_sha1);
+  bench("ring-sha256", ring_sha256);
+  bench("ring-sha512", ring_sha512);
+}