feat: parse pgp cert works

src/fido.rs

@@ -94,9 +94,9 @@ impl U2fV2Challenge {
     pub fn new_random<S>(app_id: S) -> Self where S: Into<String> {
         let mut rng = rand::thread_rng();
         let mut rand_bytes = [0_u8; 32];
-        for i in 0..32 {
+        for c in &mut rand_bytes {
             let b: u8 = rng.gen();
-            rand_bytes[i] = b;
+            *c = b;
         }
 
         let challenge = base64::encode_config(&rand_bytes, URL_SAFE_NO_PAD);
@@ -143,11 +143,11 @@ pub fn to_pem(bs: &[u8], sub: &str, w: usize) -> String {
     s.push_str(&format!("-----BEGIN {}-----", sub));
     let b64 = base64::encode(bs).chars().collect::<Vec<char>>();
     let mut b64 = b64.as_slice();
-    while b64.len() > 0 {
+    while !b64.is_empty() {
         s.push('\n');
         if b64.len() >= w {
-            for i in 0..w {
-                s.push(b64[i]);
+            for c in b64.iter().take(w) {
+                s.push(*c);
             }
             b64 = &b64[w..];
         } else {