Provides a debug instance for an RSA public key... (#1421)

* Provides a debug instance for an RSA public key...

that is a bit easier on the eyes than the raw Vec<u8>

* Move to_hex into the fmt method

PR feedback

* Remove to_hex altogether

core/src/identity/rsa.rs

@@ -26,7 +26,7 @@ use super::error::*;
 use ring::rand::SystemRandom;
 use ring::signature::{self, RsaKeyPair, RSA_PKCS1_SHA256, RSA_PKCS1_2048_8192_SHA256};
 use ring::signature::KeyPair;
-use std::sync::Arc;
+use std::{fmt::{self, Write}, sync::Arc};
 use zeroize::Zeroize;
 
 /// An RSA keypair.
@@ -62,7 +62,7 @@ impl Keypair {
 }
 
 /// An RSA public key.
-#[derive(Clone, PartialEq, Eq, Debug)]
+#[derive(Clone, PartialEq, Eq)]
 pub struct PublicKey(Vec<u8>);
 
 impl PublicKey {
@@ -107,6 +107,21 @@ impl PublicKey {
     }
 }
 
+impl fmt::Debug for PublicKey {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let bytes = &self.0;
+        let mut hex = String::with_capacity(bytes.len() * 2);
+
+        for byte in bytes {
+            write!(hex, "{:02x}", byte).expect("Can't fail on writing to string");
+        }
+
+        f.debug_struct("PublicKey")
+            .field("pkcs1", &hex)
+            .finish()
+    }
+}
+
 //////////////////////////////////////////////////////////////////////////////
 // DER encoding / decoding of public keys
 //