fix persisting keys

internal/model.go

@@ -190,15 +190,39 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			if m.state == 0 {
 				pass := m.input.Value()
 				if len(pass) > 0 {
+					// REGISTERING USER FLOW
 					if m.identityKey != nil {
 						ciphertext, nonce, salt, err := encryptUserKey(m.identityKey.PrivateKey, pass)
 						if err != nil {
 							m.err = err
 							return m, nil
 						}
+						// Store encrypted private key
+						if err := storeUserEncryptedKey(m.username, ciphertext, salt, nonce); err != nil {
+							m.err = err
+							return m, nil
+						}
 						m.encryptedPrivKey = ciphertext
 						m.privKeyNonce = nonce
 						m.privKeySalt = salt
+					} else {
+						// LOGGING IN USER FLOW
+						encKey, salt, nonce, err := getUserEncryptedKey(m.username)
+						if err != nil {
+							m.err = fmt.Errorf("failed to load keys: %v", err)
+							return m, nil
+						}
+						privKey, err := decryptUserKey(encKey, nonce, salt, pass)
+						if err != nil {
+							m.err = fmt.Errorf("incorrect passphrase")
+							return m, nil
+						}
+						// Reconstruct IdentityKeyPair
+						pubKey, _ := getMemberIdentityKey(m.username)
+						m.identityKey = &IdentityKeyPair{
+							PrivateKey: privKey,
+							PublicKey:  pubKey,
+						}
 					}
 
 					m.passphrase = pass