Abstract: A RFID tag, a reader and a 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 for tag authentication includes a challenge and information to read data from a tag's memory. Tag's enhanced reply to the challenge-response mechanism includes a 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 enhanced reply 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.

Abstract: 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.

Abstract: 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.

Abstract: A RFID tag (500) includes an antenna (100) that includes a first dipole (110), a first feeder portion (130), a second dipole (120) and a second feeder portion (140). The first feeder portion is coupled to the first dipole at two locations a feeder length distance apart. The second feeder portion is coupled to the second dipole at two locations the feeder length distance apart. The feeder portions are also coupled to an antenna terminal (150). Impedance at the antenna terminal is determined, at least in part, by the feeder length distance. Each of two end portions of the first dipole distal from the first feeder portion is connected to a respective corresponding end portion of the second dipole distal from the second feeder portion, the first and second dipoles thereby forming a rectangle. The antenna is symmetrical about both a major and a minor axis of the rectangle.

Abstract: A RFID tag (500) includes an antenna (100) that includes a first dipole (110), a first feeder portion (130), a second dipole (120) and a second feeder portion (140). The first feeder portion is coupled to the first dipole at two locations a feeder length distance apart. The second feeder portion is coupled to the second dipole at two locations the feeder length distance apart. The feeder portions are also coupled to an antenna terminal (150). Impedance at the antenna terminal is determined, at least in part, by the feeder length distance. Each of two end portions of the first dipole distal from the first feeder portion is connected to a respective corresponding end portion of the second dipole distal from the second feeder portion, the first and second dipoles thereby forming a rectangle. The antenna is symmetrical about both a major and a minor axis of the rectangle.