1.2: Finish implementation of fixed XOR

src/xor.rs

@@ -1,8 +1,15 @@
-pub fn fixed(a: &str, b: &str) -> Result<String, String> {
-    let a_decoded = a.chars().map(|c| c.to_digit(16).unwrap() as u16);
-    let b_decoded = b.chars().map(|c| c.to_digit(16).unwrap() as u16);
-    let xor = a_decoded.zip(b_decoded).map(|(a, b)| a ^ b as char);
-    String::from_iter(xor)
+use hex::{AsHexBytes, HexDigest};
+
+#[derive(Debug)]
+pub enum FixedXORError {
+    Bad,
+}
+
+pub fn fixed(a: &str, b: &str) -> Result<String, FixedXORError> {
+    let a_decoded = a.hex_bytes().valid();
+    let b_decoded = b.hex_bytes().valid();
+    let xor: Vec<u8> = a_decoded.zip(b_decoded).map(|(x, y)| x ^ y).collect();
+    Ok(xor.hex_digest())
 }
 
 #[cfg(test)]
@@ -15,6 +22,6 @@ mod tests {
         let b = "686974207468652062756c6c277320657965";
         let ex_output = "746865206b696420646f6e277420706c6179";
         let output = fixed(a, b);
-        assert_eq!(output, ex_output);
+        assert_eq!(output.unwrap(), ex_output);
     }
 }