From b4210c80d347e3d3d7aafe17349e7bf54448994f Mon Sep 17 00:00:00 2001
From: Jesse Luehrs <doy@tozt.net>
Date: Sat, 18 Apr 2015 02:19:02 -0400
Subject: problem 27

---
 tests/set4.rs | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

(limited to 'tests')

diff --git a/tests/set4.rs b/tests/set4.rs
index 35c3edf..013ef38 100644
--- a/tests/set4.rs
+++ b/tests/set4.rs
@@ -86,3 +86,49 @@ fn problem_26 () {
     let ciphertext = matasano::crack_ctr_bitflipping(&encode);
     assert!(verify(&ciphertext[..]));
 }
+
+#[test]
+fn problem_27 () {
+    let key = util::random_aes_128_key();
+    let iv = key;
+    let prefix = "comment1=cooking%20MCs;userdata=";
+    let suffix = ";comment2=%20like%20a%20pound%20of%20bacon";
+    let admin = ";admin=true;";
+
+    let escape = |input: &str| {
+        input.replace("%", "%25").replace(";", "%3B").replace("=", "%3D")
+    };
+
+    let encode = |input: &str| -> Vec<u8> {
+        let plaintext: Vec<u8> = prefix
+            .as_bytes()
+            .iter()
+            .chain(escape(input).as_bytes().iter())
+            .chain(suffix.as_bytes().iter())
+            .map(|x| *x)
+            .collect();
+        return matasano::encrypt_aes_128_cbc(&plaintext[..], &key[..], &iv[..]);
+    };
+
+    let verify = |ciphertext: &[u8]| -> Result<bool, Vec<u8>> {
+        let plaintext = matasano::decrypt_aes_128_cbc(ciphertext, &key[..], &iv[..]).unwrap();
+        if plaintext.iter().any(|&c| c < 32 || c > 126) {
+            return Err(plaintext);
+        }
+        else {
+            println!("{}", ::std::str::from_utf8(&plaintext[..]).unwrap());
+            return Ok(
+                (0..(plaintext.len() - admin.len())).any(|i| {
+                    plaintext
+                        .iter()
+                        .skip(i)
+                        .zip(admin.as_bytes().iter())
+                        .all(|(&c1, &c2)| c1 == c2)
+                })
+            );
+        }
+    };
+
+    let ciphertext = matasano::crack_cbc_iv_key(&encode, &verify);
+    assert!(verify(&ciphertext[..]).unwrap());
+}
-- 
cgit v1.2.3-54-g00ecf