diff --git a/src/crypto.rs b/src/crypto.rs
index 3632c82..69389ec 100644
--- a/src/crypto.rs
+++ b/src/crypto.rs
@@ -58,7 +58,7 @@ impl Aes {
         Some(data.clone())
     }
 
-    pub fn ecb(&self, mut data: Vec<u8>, mode: Mode) -> Option<Vec<u8>> {
+    pub fn ecb(&self, data: Vec<u8>, mode: Mode) -> Option<Vec<u8>> {
         if (!self.pad) && (data.len() % Self::BLOCK_SIZE != 0) {
             return None;
         }
diff --git a/src/main.rs b/src/main.rs
index c1402a8..7638b03 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -168,8 +168,8 @@ fn q11() {
         let key: Vec<u8> = rng.sample_iter(&dist).take(16).collect();
         let iv: Vec<u8> = rng.sample_iter(&dist).take(16).collect();
         let aes = crypto::Aes::new(&key, true).unwrap();
-        let mut start: Vec<u8> = rng.sample_iter(&dist).take(rng.gen_range(5,11)).collect();
-        let mut end: Vec<u8> = rng.sample_iter(&dist).take(rng.gen_range(5,11)).collect();
+        let mut start: Vec<u8> = rng.sample_iter(&dist).take(rng.gen_range(5, 11)).collect();
+        let mut end: Vec<u8> = rng.sample_iter(&dist).take(rng.gen_range(5, 11)).collect();
 
         start.append(&mut data);
         start.append(&mut end);
@@ -180,21 +180,21 @@ fn q11() {
         }
     };
 
-    let oracle = |data: &Vec<u8>| -> bool {
-        data[16..32] == data[32..48]
-    };
+    let oracle = |data: &Vec<u8>| -> bool { data[16..32] == data[32..48] };
 
     for i in 0..128 {
-        let data = [0u8;64];
+        let data = [0u8; 64];
         let (ecb, data) = black_box(data.to_vec());
         assert!(ecb == oracle(&data));
     }
 }
 
-fn q12()
-{
+fn q12() {
     println!("Running q12");
-    let key: Vec<u8> = rand::thread_rng().sample_iter(rand::distributions::Standard).take(16).collect();
+    let key: Vec<u8> = rand::thread_rng()
+        .sample_iter(rand::distributions::Standard)
+        .take(16)
+        .collect();
     let plaintext: Vec<u8> = Bytes::from_base64("Um9sbGluJyBpbiBteSA1LjAKV2l0aCBteSByYWctdG9wIGRvd24gc28gbXkgaGFpciBjYW4gYmxvdwpUaGUgZ2lybGllcyBvbiBzdGFuZGJ5IHdhdmluZyBqdXN0IHRvIHNheSBoaQpEaWQgeW91IHN0b3A/IE5vLCBJIGp1c3QgZHJvdmUgYnkK").into();
     let aes = crate::crypto::Aes::new(&key, true).unwrap();
 
@@ -204,7 +204,10 @@ fn q12()
     };
 
     let starting_size = blackbox(Vec::new()).len();
-    let (first_increment, next_size) = (0..).map(|x:usize| (x, blackbox(std::iter::repeat(0u8).take(x).collect()).len())).find(|(_,x)| *x != starting_size).unwrap();
+    let (first_increment, next_size) = (0..)
+        .map(|x: usize| (x, blackbox(std::iter::repeat(0u8).take(x).collect()).len()))
+        .find(|(_, x)| *x != starting_size)
+        .unwrap();
     let block_size = next_size - starting_size;
     println!("  Block size is {}", block_size);
     assert!(block_size == 16);
@@ -220,15 +223,23 @@ fn q12()
     let mut known: Vec<u8> = Vec::with_capacity(data_length);
     println!("  Data length: {}", data_length);
 
-    for _ in 0..data_length
-    {
-        let nulls: Vec<u8> = std::iter::repeat(0u8).take(starting_size - known.len() - 1).collect();
+    for _ in 0..data_length {
+        let nulls: Vec<u8> = std::iter::repeat(0u8)
+            .take(starting_size - known.len() - 1)
+            .collect();
         let target_block = &blackbox(nulls.clone())[0..starting_size];
         let mut found = false;
         'byteiter: for b in 0u8..=255u8 {
-            let this_block = &blackbox(nulls.iter().chain(known.iter()).chain(std::iter::once(&b)).cloned().take(starting_size).collect())[0..starting_size];
-            if this_block == target_block
-            {
+            let this_block = &blackbox(
+                nulls
+                    .iter()
+                    .chain(known.iter())
+                    .chain(std::iter::once(&b))
+                    .cloned()
+                    .take(starting_size)
+                    .collect(),
+            )[0..starting_size];
+            if this_block == target_block {
                 known.push(b);
                 found = true;
                 break 'byteiter;
@@ -239,10 +250,12 @@ fn q12()
     // println!("  {}", String::from_utf8(known).unwrap().replace("\n", "\n  "));
 }
 
-fn q13()
-{
+fn q13() {
     println!("Running q13");
-    let key: Vec<u8> = rand::thread_rng().sample_iter(rand::distributions::Standard).take(16).collect();
+    let key: Vec<u8> = rand::thread_rng()
+        .sample_iter(rand::distributions::Standard)
+        .take(16)
+        .collect();
 
     let parse = |x: &str| -> std::collections::HashMap<String, String> {
         let mut out = std::collections::HashMap::new();
@@ -251,12 +264,15 @@ fn q13()
             if elements.len() == 2 {
                 out.insert(elements[0].to_owned(), elements[1].to_owned());
             }
-        };
+        }
         out
     };
 
     let profile_for = |mail: &str| -> String {
-        format!("email={}&uid=10&role=user", mail.replace("&","").replace("=",""))
+        format!(
+            "email={}&uid=10&role=user",
+            mail.replace("&", "").replace("=", "")
+        )
     };
 
     let encrypt = |profile: &str| -> Vec<u8> {
@@ -278,13 +294,128 @@ fn q13()
     let mail2 = " ".repeat(16 - "email=".len());
     let mail2 = mail2 + "admin";
     let padding_char = (16 - "admin".len()) as u8;
-    let mail2 = mail2 + &String::from_utf8(vec![padding_char]).unwrap().repeat(padding_char as usize);
+    let mail2 = mail2
+        + &String::from_utf8(vec![padding_char])
+            .unwrap()
+            .repeat(padding_char as usize);
     let part2: &[u8] = &encrypt(&profile_for(&mail2))[16..32];
     let whole: Vec<u8> = part1.iter().chain(part2.iter()).cloned().collect();
 
     assert!(is_admin(whole));
 }
 
+fn q14() {
+    println!("Running q14");
+    let key: Vec<u8> = rand::thread_rng()
+        .sample_iter(rand::distributions::Standard)
+        .take(16)
+        .collect();
+    let plaintext: Vec<u8> = Bytes::from_base64("Um9sbGluJyBpbiBteSA1LjAKV2l0aCBteSByYWctdG9wIGRvd24gc28gbXkgaGFpciBjYW4gYmxvdwpUaGUgZ2lybGllcyBvbiBzdGFuZGJ5IHdhdmluZyBqdXN0IHRvIHNheSBoaQpEaWQgeW91IHN0b3A/IE5vLCBJIGp1c3QgZHJvdmUgYnkK").into();
+    let aes = crate::crypto::Aes::new(&key, true).unwrap();
+    let prefix: Vec<u8> = rand::thread_rng()
+        .sample_iter(rand::distributions::Standard)
+        .take(rand::thread_rng().gen_range(5, 11))
+        .collect();
+
+    let blackbox = |mut attacker_data: Vec<u8>| -> Vec<u8> {
+        let mut data: Vec<u8> = prefix.clone();
+        data.append(&mut attacker_data);
+        data.append(&mut plaintext.clone());
+        let rv = aes.ecb(data, Mode::Encrypt).unwrap();
+        rv
+    };
+
+    let starting_size = blackbox(Vec::new()).len();
+    let (first_increment, next_size) = (0..)
+        .map(|x: usize| (x, blackbox(std::iter::repeat(0u8).take(x).collect()).len()))
+        .find(|(_, x)| *x != starting_size)
+        .unwrap();
+    println!("  First size increment at {}", first_increment);
+
+    let block_size = next_size - starting_size;
+    println!("  Block size is {}", block_size);
+    assert!(block_size == 16);
+
+    let long_block = blackbox(std::iter::repeat(0u8).take(1280).collect());
+    let using_ecb = long_block[480..496] == long_block[496..512];
+    println!("  Using ECB: {}", using_ecb);
+    assert!(using_ecb);
+
+    let all_zero_ciphertext = blackbox(std::iter::repeat(0u8).take(block_size).collect());
+    let first_different_block = |x: usize| -> usize {
+        let data: Vec<u8> = std::iter::repeat(0u8)
+            .take(x)
+            .chain(std::iter::once(1u8))
+            .chain(std::iter::repeat(0u8).take(block_size - 1 - x))
+            .collect();
+        let data: Vec<u8> = blackbox(data);
+        data.chunks_exact(block_size)
+            .zip(all_zero_ciphertext.chunks_exact(block_size))
+            .enumerate()
+            .find(|(_, (a, b))| a != b)
+            .unwrap()
+            .0
+    };
+    let start_block = first_different_block(0);
+    let mut prefix_size = start_block * block_size + block_size - 1;
+    for i in 2..block_size {
+        let diff_block = first_different_block(i);
+        if diff_block == start_block {
+            prefix_size = start_block * block_size + block_size - 1 - i;
+        }
+    }
+    println!("  Prefix length is {}", prefix_size);
+    assert!(prefix_size == prefix.len());
+
+    let data_length = starting_size - first_increment - prefix_size;
+    let mut known: Vec<u8> = Vec::with_capacity(data_length);
+    println!("  Data length: {}", data_length);
+    assert!(data_length == plaintext.len());
+
+    let prefix_total = (prefix_size + block_size - 1) / block_size * block_size;
+    let prefix_nulls = prefix_total - prefix_size;
+    let starting_size = (prefix_total + data_length + block_size - 1) / block_size * block_size;
+
+    for _ in 0..data_length {
+        let nulls: Vec<u8> = std::iter::repeat(0u8)
+            .take(starting_size - prefix_size - known.len() - 1)
+            .collect();
+        let target_block = &blackbox(nulls.clone())[prefix_total..starting_size];
+        let mut found = false;
+        'byteiter: for b in 0u8..=255u8 {
+            let this_block = &blackbox(
+                nulls
+                    .iter()
+                    .chain(known.iter())
+                    .chain(std::iter::once(&b))
+                    .cloned()
+                    .take(starting_size)
+                    .collect(),
+            )[prefix_total..starting_size];
+            if this_block == target_block {
+                known.push(b);
+                found = true;
+                break 'byteiter;
+            }
+        }
+        assert!(found);
+    }
+    assert!(known == plaintext);
+}
+
+fn q15() {
+    println!("Running q15");
+    let input = b"ICE ICE BABY\x05\x05\x05\x05";
+    let output = Bytes::from(&input[..]);
+    let output = output.unpad();
+    assert!(output == None);
+
+    let input = b"ICE ICE BABY\x04\x04\x04\x04";
+    let output = Bytes::from(&input[..]);
+    let output = output.unpad().unwrap();
+    assert!(output.to_string().unwrap() == "ICE ICE BABY");
+}
+
 fn main() {
     q01();
     q02();
@@ -299,4 +430,6 @@ fn main() {
     q11();
     q12();
     q13();
+    q14();
+    q15();
 }