fix: Login secret text transmission (#29659)

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Co-authored-by: Joel <iamjoel007@gmail.com>
Co-authored-by: -LAN- <laipz8200@outlook.com>

api/libs/encryption.py

@@ -0,0 +1,66 @@
+"""
+Field Encoding/Decoding Utilities
+
+Provides Base64 decoding for sensitive fields (password, verification code)
+received from the frontend.
+
+Note: This uses Base64 encoding for obfuscation, not cryptographic encryption.
+Real security relies on HTTPS for transport layer encryption.
+"""
+
+import base64
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+class FieldEncryption:
+    """Handle decoding of sensitive fields during transmission"""
+
+    @classmethod
+    def decrypt_field(cls, encoded_text: str) -> str | None:
+        """
+        Decode Base64 encoded field from frontend.
+
+        Args:
+            encoded_text: Base64 encoded text from frontend
+
+        Returns:
+            Decoded plaintext, or None if decoding fails
+        """
+        try:
+            # Decode base64
+            decoded_bytes = base64.b64decode(encoded_text)
+            decoded_text = decoded_bytes.decode("utf-8")
+            logger.debug("Field decoding successful")
+            return decoded_text
+
+        except Exception:
+            # Decoding failed - return None to trigger error in caller
+            return None
+
+    @classmethod
+    def decrypt_password(cls, encrypted_password: str) -> str | None:
+        """
+        Decrypt password field
+
+        Args:
+            encrypted_password: Encrypted password from frontend
+
+        Returns:
+            Decrypted password or None if decryption fails
+        """
+        return cls.decrypt_field(encrypted_password)
+
+    @classmethod
+    def decrypt_verification_code(cls, encrypted_code: str) -> str | None:
+        """
+        Decrypt verification code field
+
+        Args:
+            encrypted_code: Encrypted code from frontend
+
+        Returns:
+            Decrypted code or None if decryption fails
+        """
+        return cls.decrypt_field(encrypted_code)