Fix issue rust-lang-nursery#573 - hmac example (rust-lang-nursery#574)

* Update hmac example for ring v. ^0.16.9

* Update hmac example for ring v. ^0.16.9

* Update hmac example for ring v. ^0.16.9

* Update to ring 0.16.11 in Cargo.toml

* Update to SHA256 - sect. 4.1 explicit threads

* Update all to SHA256, including comments

Cargo.toml

@@ -40,7 +40,7 @@ rand = "0.6"
 rayon = "1.0"
 regex = "1.0"
 reqwest = "0.9"
-ring = "0.13.0-alpha"
+ring = "0.16.11"
 rusqlite = { version = "0.16", features = ["chrono"] }
 same-file = "1.0"
 select = "0.4"

src/concurrency/thread/threadpool-walk.md

@@ -1,12 +1,12 @@
-## Calculate SHA1 sum of iso files concurrently
+## Calculate SHA256 sum of iso files concurrently
 
 [![threadpool-badge]][threadpool] [![num_cpus-badge]][num_cpus] [![walkdir-badge]][walkdir] [![ring-badge]][ring] [![cat-concurrency-badge]][cat-concurrency][![cat-filesystem-badge]][cat-filesystem]
 
-This example calculates the SHA1 for every file with iso extension in the
+This example calculates the SHA256 for every file with iso extension in the
 current directory. A threadpool generates threads equal to the number of cores
 present in the system found with [`num_cpus::get`].  [`Walkdir::new`] iterates
 the current directory and calls [`execute`] to perform the operations of reading
-and computing SHA1 hash.
+and computing SHA256 hash.
 
 ```rust,no_run
 extern crate walkdir;
@@ -20,7 +20,7 @@ use std::io::{BufReader, Read, Error};
 use std::path::Path;
 use threadpool::ThreadPool;
 use std::sync::mpsc::channel;
-use ring::digest::{Context, Digest, SHA1};
+use ring::digest::{Context, Digest, SHA256};
 
 # // Verify the iso extension
 # fn is_iso(entry: &Path) -> bool {
@@ -32,7 +32,7 @@ use ring::digest::{Context, Digest, SHA1};
 
 fn compute_digest<P: AsRef<Path>>(filepath: P) -> Result<(Digest, P), Error> {
     let mut buf_reader = BufReader::new(File::open(&filepath)?);
-    let mut context = Context::new(&SHA1);
+    let mut context = Context::new(&SHA256);
     let mut buffer = [0; 1024];
 
     loop {

src/cryptography/hashing/hmac.md

@@ -7,19 +7,19 @@ Uses [`ring::hmac`] to creates a [`hmac::Signature`] of a string then verifies t
 ```rust
 extern crate ring;
 
-use ring::{digest, hmac, rand};
+use ring::{hmac, rand};
 use ring::rand::SecureRandom;
 use ring::error::Unspecified;
 
 fn main() -> Result<(), Unspecified> {
     let mut key_value = [0u8; 48];
     let rng = rand::SystemRandom::new();
     rng.fill(&mut key_value)?;
-    let key = hmac::SigningKey::new(&digest::SHA256, &key_value);
+    let key = hmac::Key::new(hmac::HMAC_SHA256, &key_value);
 
     let message = "Legitimate and important message.";
     let signature = hmac::sign(&key, message.as_bytes());
-    hmac::verify_with_own_key(&key, message.as_bytes(), signature.as_ref())?;
+    hmac::verify(&key, message.as_bytes(), signature.as_ref())?;
 
     Ok(())
 }