Start with challenge 44 by parsing text file

src/main.rs

@@ -4,6 +4,7 @@
 #![allow(clippy::items_after_statements)]
 #![allow(clippy::many_single_char_names)]
 #![allow(clippy::module_name_repetitions)]
+#![feature(string_remove_matches)]
 mod bytes;
 mod bytes_base64;
 mod cbc;
@@ -70,7 +71,7 @@ fn main() {
         set5::challenge40().unwrap_or_else(|| println!("[fail] challenge 40"));
         set6::challenge41().unwrap_or_else(|| println!("[fail] challenge 41"));
         set6::challenge42().unwrap_or_else(|| println!("[fail] challenge 42"));
+        set6::challenge43().unwrap_or_else(|| println!("[fail] challenge 43"));
     }
-    set6::challenge43().unwrap_or_else(|| println!("[fail] challenge 43"));
     set6::challenge44().unwrap_or_else(|| println!("[fail] challenge 44"));
 }

src/set6.rs

@@ -117,12 +117,11 @@ pub mod challenge43 {
             BigNum::from_hex_str("d2d0714f014a9784047eaeccf956520045c45265")?
         );
 
-        // They provide s and r as decimal integers and not hex strings. I
-        // converted the decimals to hex. I took me a couple of hours to figure
-        // that out.
+        // They provide s and r as decimal integers and not hex strings. Took me a while
+        // to notice that.
         let mut sig = dsa::DsaSig {
-            r: BigNum::from_hex_str("60019cacdc56eedf8e080984bfa898c8c5c419a8")?,
-            s: BigNum::from_hex_str("961f2062efc3c68db965a90c924cf76580ec1bbc")?,
+            r: BigNum::from_dec_str("548099063082341131477253921760299949438196259240")?,
+            s: BigNum::from_dec_str("857042759984254168557880549501802188789837994940")?,
             k: BigNum::from_u32(0)?,
         };
         let msg_h = dsa::h(&msg)?;
@@ -173,6 +172,30 @@ pub fn challenge43() -> Option<()> {
     Some(())
 }
 
+pub mod challenge44 {
+    use std::io::{BufReader, BufRead};
+    use crate::bytes::Bytes;
+    use openssl::bn::BigNum;
+    use crate::dsa;
+
+    pub fn read_dsa_signed_messages() {
+        let file = std::fs::File::open("data/44.txt").unwrap();
+        let mut lines: Vec<String> = BufReader::new(file).lines().map(|l| l.unwrap()).collect();
+        // each message cosists of four lines: msg, s, r, m (sha1 hash of msg)
+        for line in lines.chunks_mut(4) {
+            line[0].remove_matches("msg: ");
+            line[1].remove_matches("s: ");
+            line[2].remove_matches("r: ");
+            line[3].remove_matches("m: ");
+            let msg = Bytes::from_utf8(&line[0]);
+            let m = BigNum::from_hex_str(&line[3]).unwrap();
+            assert_eq!(dsa::h(&msg).unwrap(), m, "Message hash from data/44.txt does not match");
+        }
+    }
+
+}
+
+
 pub fn challenge44() -> Option<()> {
     println!("[xxxx] Challenge 44: DSA nonce recovery from repeated nonce");
     let msg = Bytes::from_utf8("hello, world!");
@@ -181,5 +204,6 @@ pub fn challenge44() -> Option<()> {
     let sig = keys.sign(&params, &msg).ok()?;
     let result = keys.verify(&params, &msg, &sig).ok()?;
     assert!(result, "verify failed unexpectedly");
+    challenge44::read_dsa_signed_messages();
     None
 }