A RFID tag (501), reader (502) and protocol allow a protected read operation in a two-step tag authentication with cipher-block cryptography. A challenge-response mechanism using a shared secret symmetric key (638) for tag authentication includes a challenge and information to read data from a tag's memory (637). Tag's response to the challenge-response mechanism includes the response to the reader's challenge and data from the tag's memory. A method embeds a protected write operation in a four-step reader authentication with cipher-block cryptography. The protocol allows a challenge-response mechanism using the shared secret symmetric key for reader authentication including a challenge and information to write data to the tag's memory. Reader's response to the challenge-response mechanism includes a response to the tag's challenge and data for writing to the tag's memory. Authenticated read and write data may be in plaintext, message authentication code (MAC)-protected, encrypted, or both encrypted and MAC protected.