First half of set 2

Cargo.lock

@@ -61,6 +61,7 @@ dependencies = [
  "aes",
  "base64",
  "hex",
+ "rand",
 ]
 
 [[package]]
@@ -73,6 +74,17 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "getrandom"
+version = "0.2.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c85e1d9ab2eadba7e5040d4e09cbd6d072b76a557ad64e797c2cb9d4da21d7e4"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
 [[package]]
 name = "hex"
 version = "0.4.3"
@@ -94,6 +106,42 @@ version = "0.2.142"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6a987beff54b60ffa6d51982e1aa1146bc42f19bd26be28b0586f252fccf5317"
 
+[[package]]
+name = "ppv-lite86"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
 [[package]]
 name = "typenum"
 version = "1.16.0"
@@ -105,3 +153,9 @@ name = "version_check"
 version = "0.9.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
+
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"

Cargo.toml

@@ -9,3 +9,4 @@ edition = "2021"
 aes = "0.8.2"
 hex = "0.4"
 base64 = "0.21.0"
+rand = "0.8.5"

examples/set1_7/main.rs

@@ -1,15 +1,13 @@
 #![feature(array_chunks)]
-use cryptopals::{prelude::*, bvec64, friendly::aes128};
+use cryptopals::{prelude::*, bvec64, friendly::{aes128, ecb_decrypt, ecb_encrypt}};
 
 fn main() {
     let key = *b"YELLOW SUBMARINE";
 
     let input = bvec64!("input.txt");
-    let mut output = Vec::new();
-    for chunk in input.array_chunks::<16>() {
-        output.extend(aes128::decrypt(key, *chunk));
-    }
+    let output = ecb_decrypt(&input, |block| aes128::decrypt(key, block));
 
     dbg!(output.to_text().unwrap());
+    assert_eq!(input, ecb_encrypt(&output, |block| aes128::encrypt(key, block)));
     println!("pass")
 }

examples/set1_8/main.rs

@@ -1,17 +1,13 @@
 use cryptopals::bvecs;
+use cryptopals::friendly::likely_ecb;
 use cryptopals::prelude::*;
 
 fn main() {
     let inputs = bvecs!("inputs.txt");
 
     for input in inputs {
-        'seek: for ix_0 in (0..input.len()).step_by(16) {
-            for ix_1 in (ix_0+16..input.len()).step_by(16) {
-                if input[ix_0..ix_0+16]==input[ix_1..ix_1+16] {
-                    println!("possible ECB: {}", input.to_hex());
-                    break 'seek
-                }
-            }
+        if likely_ecb(&input) {
+            println!("possible ECB: {}", input.to_hex());
         }
     }
 }

examples/set2_10/input.txt

@@ -0,0 +1,64 @@
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examples/set2_10/main.rs

@@ -0,0 +1,14 @@
+#![feature(array_chunks)]
+use cryptopals::{prelude::ByteBased, friendly::{aes128, cbc_decrypt, cbc_encrypt}, bvec64};
+
+fn main() {
+    let input = bvec64!("input.txt");
+    let key = *b"YELLOW SUBMARINE";
+    let output = cbc_decrypt([0; 16], &input, |block| aes128::decrypt(key, block));
+
+    let input2 = cbc_encrypt([0; 16], &output, |block| aes128::encrypt(key, block));
+
+    dbg!(output.to_text().unwrap());
+    assert_eq!(input, input2);
+    println!("pass")
+}

examples/set2_11/main.rs

@@ -0,0 +1,13 @@
+use cryptopals::{set2_adversary::Set2Adversary, prelude::ByteBased, friendly::likely_ecb};
+
+fn main() {
+    let adversary = Set2Adversary::gen();
+
+    // blackbox detector
+    for _ in 0..100 {
+        let output = adversary.oracle_11(&[b'A'; 64]);
+
+        println!("output: {}", output.to_hex());
+        println!("likely ECB: {}", likely_ecb(&output));
+    }
+}

examples/set2_12/main.rs

@@ -0,0 +1,91 @@
+use cryptopals::{set2_adversary::Set2Adversary, friendly::likely_ecb, prelude::ByteBased};
+
+fn main() {
+    let adversary = Set2Adversary::gen();
+
+    // first of all, find the block size
+    let block_size = {
+        let mut inp = vec![];
+        let l1 = adversary.oracle_12(&inp).len();
+        loop {
+            inp.push(b'A');
+            let l2 = adversary.oracle_12(&inp).len();
+            if l2 > l1 {
+                break l2 - l1;
+            }
+        }
+    };
+
+    assert_eq!(block_size, 16);
+
+    // make sure we're in ECB mode
+    assert!(likely_ecb(&adversary.oracle_12(&[b'A'; 64])));
+
+    let message_len = adversary.oracle_12(&[]).len();
+
+    let mut known_message: Vec<u8> = vec![];
+
+    // sample questions for 'ABCD EFGH' and block size 4
+    // question   dictionary pattern
+    // 000        000[A-Z]
+    // 00         00A[A-Z]
+    // 0          0AB[A-Z]
+    //            ABC[A-Z]
+    // 000        BCD[A-Z]
+    // 00         CDE[A-Z]
+    // 0          DEF[A-Z]
+    //            EFG[A-Z]
+
+    'inspect: while known_message.len() < message_len {
+        let interest_ix = known_message.len();
+
+        let interest_block_ix= interest_ix / block_size;
+        let interest_block_byte_ix = interest_ix % block_size;
+        let interest_shiftr1_padding = (block_size - interest_block_byte_ix - 1) % block_size; // padding it takes to put the character of interest at the end of a block
+
+        // build shiftr
+        let mut shiftr_block = vec![];
+        for _ in 0..interest_shiftr1_padding { shiftr_block.push(0)}
+
+        // build question
+        // this is the beginning of the dictionary pattern (minus the range at the end)
+        // if we're at the beginning of the string, use a zero as we know this
+        // comes from our shiftr block
+        // otherwise, use a character from the end of the string
+        let mut question_block = vec![];
+        for i in 0..block_size-1 {
+            let source_char_ix = known_message.len() as i64 - block_size as i64 + i as i64 + 1;
+            if source_char_ix < 0 { question_block.push(0); }
+            else { question_block.push(known_message[source_char_ix as usize]); }
+        }
+
+        // build dictionary
+        let mut dictionary: Vec<Vec<u8>> = vec![];
+        for possible_byte in u8::MIN..=u8::MAX {
+            let mut dict_block = question_block.clone();
+            dict_block.push(possible_byte);
+
+            let mut oracle_result = adversary.oracle_12(&dict_block);
+            dictionary.push(oracle_result.drain(0..block_size).collect())
+        }
+
+        // now shift the input. we know the position of the block containing the byte of interest
+        let mut tea_leaves: Vec<u8> = adversary.oracle_12(&shiftr_block);
+        let output_len = tea_leaves.len();
+        let block_of_interest: Vec<u8> = tea_leaves.drain(interest_block_ix * block_size..interest_block_ix * block_size + block_size).collect();
+
+        for possible_byte in u8::MIN..=u8::MAX {
+            if dictionary[possible_byte as usize] == block_of_interest {
+                if (possible_byte as usize) < block_size && (interest_ix + possible_byte as usize + shiftr_block.len() == output_len) {
+                    break 'inspect  // we hit padding
+                }
+                known_message.push(possible_byte);
+                continue 'inspect
+            }
+        }
+
+        panic!("we failed to break on padding");
+    }
+
+    println!("{}", known_message.to_text().unwrap())
+}

examples/set2_9/main.rs

@@ -0,0 +1,13 @@
+use cryptopals::friendly::pad_pkcs7;
+
+fn main() {
+    assert_eq!(
+        pad_pkcs7(b"YELLOW SUBMARINE".to_vec(), 20),
+        b"YELLOW SUBMARINE\x04\x04\x04\x04"
+    );
+    assert_eq!(
+        pad_pkcs7(b"".to_vec(), 8),
+        b"\x08\x08\x08\x08\x08\x08\x08\x08"
+    );
+    println!("pass!")
+}

src/friendly.rs

@@ -1,3 +1,74 @@
+use crate::prelude::ByteBased;
+
+pub fn pad_pkcs7(mut text: Vec<u8>, block_size: usize) -> Vec<u8> {
+    assert!(block_size < 256);
+    let overhang = text.len() % block_size;
+    let padding = (block_size - overhang) as u8;
+
+    for _ in 0..padding { text.push(padding) }
+    text
+}
+
+pub fn ecb_encrypt<const N: usize>(
+    plaintext: &[u8], 
+    encrypt_block: impl Fn([u8; N]) -> [u8; N]
+) -> Vec<u8> {
+    assert!(plaintext.len() % N == 0);
+
+    let mut ciphertext = vec![];
+
+    for plaintext_block in plaintext.array_chunks::<N>() {
+        ciphertext.extend(encrypt_block(*plaintext_block))
+    }
+
+    ciphertext
+}
+
+pub fn ecb_decrypt<const N: usize>(
+    ciphertext: &[u8],
+    decrypt_block: impl Fn([u8; N]) -> [u8; N]
+) -> Vec<u8> {
+    // wow! ecb is great
+    ecb_encrypt(ciphertext, decrypt_block)
+}
+
+pub fn cbc_encrypt<const N: usize>(
+    iv: [u8; N], 
+    plaintext: &[u8], 
+    encrypt_block: impl Fn([u8; N]) -> [u8; N]
+) -> Vec<u8> {
+    assert!(plaintext.len() % N == 0);
+
+    let mut ciphertext = vec![];
+
+    let mut xor_value = iv;
+    for plaintext_block in plaintext.array_chunks::<N>() {
+        let ciphertext_block = encrypt_block(plaintext_block.xor_with(&xor_value).unwrap());
+        ciphertext.extend(ciphertext_block);
+        xor_value = ciphertext_block;
+    };
+    return ciphertext
+}
+
+pub fn cbc_decrypt<const N: usize>(
+    iv: [u8; N], 
+    ciphertext: &[u8], 
+    decrypt_block: impl Fn([u8; N]) -> [u8; N]
+) -> Vec<u8> {
+    assert!(ciphertext.len() % N == 0);
+
+    let mut plaintext = vec![];
+
+    let mut xor_value = iv;
+    for ciphertext_block in ciphertext.array_chunks::<N>() {
+        let plaintext_block = decrypt_block(*ciphertext_block).xor_with(&xor_value).unwrap();
+        plaintext.extend(plaintext_block);
+        xor_value = *ciphertext_block;
+    };
+
+    plaintext
+}
+
 pub mod aes128 {
     use aes::cipher::{generic_array::GenericArray, KeyInit, BlockEncrypt, BlockDecrypt};
 
@@ -19,3 +90,17 @@ pub mod aes128 {
         <[u8; 16]>::from(block)
     }
 }
+
+pub fn likely_ecb(input: &[u8]) -> bool {
+    assert!(input.len() % 16 == 0);
+
+    // from set1_8
+    for ix_0 in (0..input.len()).step_by(16) {
+        for ix_1 in (ix_0+16..input.len()).step_by(16) {
+            if input[ix_0..ix_0+16]==input[ix_1..ix_1+16] {
+                return true
+            }
+        }
+    }
+    false
+}

src/lib.rs

@@ -2,3 +2,4 @@
 pub mod friendly;
 pub mod english;
 pub mod prelude;
+pub mod set2_adversary;

src/set2_adversary/mod.rs

@@ -0,0 +1,62 @@
+use rand::Rng;
+
+use crate::{friendly::{pad_pkcs7, cbc_encrypt, aes128, ecb_encrypt, ecb_decrypt}, bvec64};
+use crate::prelude::*;
+
+pub struct Set2Adversary {
+    key: [u8; 16],
+    secret_12: Vec<u8>
+}
+
+impl Set2Adversary {
+    pub fn gen() -> Self {
+        let mut key: [u8; 16] = [0; 16];
+        rand::thread_rng().fill(&mut key);
+
+        let secret_12 = bvec64!("nopeeking_12.txt");
+
+        Set2Adversary { key, secret_12 }
+    }
+
+    pub fn oracle_11(&self, input: &[u8]) -> Vec<u8> {
+        // introduced in challenge 11
+        let mut full_input: Vec<u8> = vec![];
+        let mut rng = rand::thread_rng();
+        let count_before = rng.gen_range(5..10);
+        let count_after = rng.gen_range(5..10);
+
+        for _ in 0..count_before {
+            full_input.push(rng.gen())
+        }
+        full_input.extend(input);
+        for _ in 0..count_after {
+            full_input.push(rng.gen())
+        }
+
+        full_input = pad_pkcs7(full_input, 16);
+
+        if rng.gen() {
+            // ecb
+            ecb_encrypt(&full_input, |block| aes128::encrypt(self.key, block))
+        } else {
+            // cbc
+            let mut iv = [0; 16];
+            rng.fill(&mut iv);
+            let message = cbc_encrypt(iv, &full_input, |block| aes128::encrypt(self.key, block));
+
+            let mut all_ciphertext = vec![];
+            all_ciphertext.extend(iv);
+            all_ciphertext.extend(message);
+            all_ciphertext
+        }
+    }
+
+    pub fn oracle_12(&self, attacker_prefix: &[u8]) -> Vec<u8> {
+        let mut full_input = vec![];
+        full_input.extend(attacker_prefix);
+        full_input.extend(&self.secret_12);
+        full_input = pad_pkcs7(full_input, 16);
+
+        ecb_encrypt(&full_input, |block| aes128::encrypt(self.key, block))
+    }
+}

src/set2_adversary/nopeeking_12.txt

@@ -0,0 +1,4 @@
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+aGFpciBjYW4gYmxvdwpUaGUgZ2lybGllcyBvbiBzdGFuZGJ5IHdhdmluZyBq
+dXN0IHRvIHNheSBoaQpEaWQgeW91IHN0b3A/IE5vLCBJIGp1c3QgZHJvdmUg
+YnkK