Finish challenge 28 by implementing sha-1

src/set4.rs

@@ -1,4 +1,6 @@
-use crate::{bytes::Bytes, cbc, ctr, parser, utils};
+#![allow(arithmetic_overflow)]
+
+use crate::{bytes::Bytes, cbc, ctr, parser, sha1, utils};
 
 pub fn challenge25() {
     let cipher = utils::read_base64("data/25.txt");
@@ -138,5 +140,50 @@ pub fn challenge27() {
 }
 
 pub fn challenge28() {
-    println!("[xxxx] Challenge 28: TBD");
+    let i1 = Bytes(vec![b'a'; 64]);
+    let e1 = Bytes::from_hex("0098ba824b5c16427bd7a1122a5a442a25ec644d");
+    let o1 = sha1::hash(&i1);
+    assert_eq!(e1, o1);
+
+    let i2 = Bytes(vec![b'a'; 128]);
+    let e2 = Bytes::from_hex("ad5b3fdbcb526778c2839d2f151ea753995e26a0");
+    let o2 = sha1::hash(&i2);
+    assert_eq!(e2, o2);
+
+    let i3 = Bytes(vec![b'a'; 3]);
+    let e3 = Bytes::from_hex("7e240de74fb1ed08fa08d38063f6a6a91462a815");
+    let o3 = sha1::hash(&i3);
+    assert_eq!(e3, o3);
+
+    let i4 = Bytes(vec![]);
+    let e4 = Bytes::from_hex("da39a3ee5e6b4b0d3255bfef95601890afd80709");
+    let o4 = sha1::hash(&i4);
+    assert_eq!(e4, o4);
+
+    fn authenticate(message: &Bytes, key: &Bytes) -> Bytes {
+        // Write a function to authenticate a message under a secret key by using a
+        // secret-prefix MAC, which is simply:
+        // SHA1(key || message)
+        let mut c = vec![];
+        c.append(&mut key.0.to_vec());
+        c.append(&mut message.0.to_vec());
+        // how to concatenate better: https://stackoverflow.com/a/56490417
+        sha1::hash(&Bytes(c))
+    }
+
+    // Verify that you cannot tamper with the message without breaking the MAC
+    // you've produced, and that you can't produce a new MAC without knowing the
+    // secret key.
+    let mut message = Bytes::from_utf8("love, love, love");
+    let key = Bytes::from_utf8("kisses!");
+    let auth = authenticate(&message, &key);
+    message.flip_bit(2, 3);
+    let auth_tempered = authenticate(&message, &key);
+    assert!(auth != auth_tempered);
+
+    println!("[okay] Challenge 28: implemented SHA-1");
+}
+
+pub fn challenge29() {
+    println!("[xxxx] Challenge 29: TBD");
 }