Add keypair & update pubkey

Keypair & FullKeypair match structs in damus ios

Signed-off-by: kernelkind <kernelkind@gmail.com>
Signed-off-by: William Casarin <jb55@jb55.com>

enostr/src/keypair.rs

@@ -0,0 +1,73 @@
+use crate::Pubkey;
+use crate::SecretKey;
+
+#[derive(Debug, Eq, PartialEq)]
+pub struct Keypair {
+    pub pubkey: Pubkey,
+    pub secret_key: Option<SecretKey>,
+}
+
+impl Keypair {
+    pub fn new(secret_key: SecretKey) -> Self {
+        let cloned_secret_key = secret_key.clone();
+        let nostr_keys = nostr::Keys::new(secret_key);
+        Keypair {
+            pubkey: Pubkey::new(&nostr_keys.public_key().to_bytes()),
+            secret_key: Some(cloned_secret_key),
+        }
+    }
+
+    pub fn only_pubkey(pubkey: Pubkey) -> Self {
+        Keypair {
+            pubkey,
+            secret_key: None,
+        }
+    }
+
+    pub fn to_full(self) -> Option<FullKeypair> {
+        if let Some(secret_key) = self.secret_key {
+            Some(FullKeypair {
+                pubkey: self.pubkey,
+                secret_key,
+            })
+        } else {
+            None
+        }
+    }
+}
+
+#[derive(Debug, Eq, PartialEq)]
+pub struct FullKeypair {
+    pub pubkey: Pubkey,
+    pub secret_key: SecretKey,
+}
+
+impl FullKeypair {
+    pub fn new(pubkey: Pubkey, secret_key: SecretKey) -> Self {
+        FullKeypair { pubkey, secret_key }
+    }
+}
+
+impl std::fmt::Display for Keypair {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "Keypair:\n\tpublic: {}\n\tsecret: {}",
+            self.pubkey,
+            match self.secret_key {
+                Some(_) => "Some(<hidden>)",
+                None => "None",
+            }
+        )
+    }
+}
+
+impl std::fmt::Display for FullKeypair {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "Keypair:\n\tpublic: {}\n\tsecret: {}",
+            self.pubkey, "<hidden>"
+        )
+    }
+}