Begining of the machine oracle (work in progress..)

[crypto_lab1.git] / src / crypto.rs

diff --git a/src/crypto.rs b/src/crypto.rs
index 35c7b48..d9fe182 100644 (file)
--- a/src/crypto.rs
+++ b/src/crypto.rs
@@ -5,9 +5,11 @@ use openssl::crypto::hash::SHA256;
 use openssl::crypto::hmac::HMAC;
 use openssl::crypto::symm;
 
+// These aren't the keys you're looking for.
 static KEY_A: &'static [u8] = [125, 31, 131, 118, 143, 180, 252, 53, 211, 217, 79, 240, 128, 91, 252, 87, 104, 236, 145, 198, 163, 203, 161, 12, 53, 56, 218, 40, 221, 95, 171, 140];
 static KEY_C: &'static [u8] = [75, 226, 88, 31, 223, 216, 182, 216, 178, 58, 59, 193, 245, 80, 254, 128, 125, 246, 246, 224, 194, 190, 123, 123, 10, 131, 217, 183, 112, 157, 166, 102];
 
+/// Only returns the first ten bytes.
 pub fn compute_mac(data: &[u8]) -> [u8, ..10] {
    let mut hmac = HMAC(SHA256, KEY_A);
    hmac.update(data);
@@ -16,11 +18,12 @@ pub fn compute_mac(data: &[u8]) -> [u8, ..10] {
    result
 }
 
+/// Encrypt may fail if the provided data size isn't a multiple of 16.
 pub fn encrypt(plaindata: &[u8], iv: &[u8]) -> Option<Vec<u8>> {
    let c = symm::Crypter::new(symm::AES_256_CBC);
    c.init(symm::Encrypt, KEY_C, iv.to_vec());
    c.pad(false); // Padding disabled!
-   let mut r = c.update(plaindata);
+   let r = c.update(plaindata);
    let rest = c.finalize();
    if rest.is_empty() {
       Some(r)
@@ -29,11 +32,12 @@ pub fn encrypt(plaindata: &[u8], iv: &[u8]) -> Option<Vec<u8>> {
    }
 }
 
+/// Decrypt may fail if the provided data size isn't a multiple of 16.
 pub fn decrypt(cypherdata: &[u8], iv: &[u8]) -> Option<Vec<u8>> {
    let c = symm::Crypter::new(symm::AES_256_CBC);
    c.init(symm::Decrypt, KEY_C, iv.to_vec());
    c.pad(false); // Padding disabled!
-   let mut r = c.update(cypherdata);
+   let r = c.update(cypherdata);
    let rest = c.finalize();
    if rest.is_empty() {
       Some(r)