openpgp: Add methods for hexadecimal representation with spaces.

  - These are explicitly intended for manual comparison of key ids and
    fingerprints.

  - See #422.

1 files changed, 25 insertions, 0 deletions

diff --git a/openpgp/src/keyid.rs b/openpgp/src/keyid.rs
index cfa7ea6d..4e40b914 100644
--- a/openpgp/src/keyid.rs
+++ b/openpgp/src/keyid.rs
@@ -305,6 +305,31 @@ impl KeyID {
         format!("{:X}", self)
     }
 
+    /// Converts this `KeyID` to its hexadecimal representation with
+    /// spaces.
+    ///
+    /// This representation is always uppercase and with spaces
+    /// grouping the hexadecimal digits into groups of four.  It is
+    /// suitable for manual comparison of Key IDs.
+    ///
+    /// Note: The spaces will hinder other kind of use cases.  For
+    /// example, it is harder to select the whole Key ID for copying,
+    /// and it has to be quoted when used as a command line argument.
+    /// Only use this form for displaying a Key ID with the intent of
+    /// manual comparisons.
+    ///
+    /// ```rust
+    /// # fn main() -> sequoia_openpgp::Result<()> {
+    /// # use sequoia_openpgp as openpgp;
+    /// let keyid: openpgp::KeyID = "fb3751f1587daef1".parse()?;
+    ///
+    /// assert_eq!("FB37 51F1 587D AEF1", keyid.to_spaced_hex());
+    /// # Ok(()) }
+    /// ```
+    pub fn to_spaced_hex(&self) -> String {
+        self.convert_to_string(true)
+    }
+
     /// Parses the hexadecimal representation of an OpenPGP `KeyID`.
     ///
     /// This function is the reverse of `to_hex`. It also accepts