In this thesis we will discuss the privacy issues in the RFID system. In the past any RFID reader can read from and write to the tags within the valid range in the neighborhood. When the articles are embedded with tags, they can be traced and monitored. Therefore it demonstrates the security holes as regards to information safety used. It shows that all information of articles after being attached with tags can be obtained without needing the permission from tag users. In general there two kinds of methods that provide the data security of RFID tags. One of the methods is to encrypt the data of tags. In the processes the data can be protected by substituting the plain-edited text with the cipher-edited text. Any data obtained by unauthorized readers will be not readable unless the data obtained can be decrypted. The other method is to set up confirmation between tags and readers. It means that if the data has already been confirmed before, the readers and tags will be mutually ascertained the right party. Therefore the readers can be allowed to obtain the data of tags and continue to carry out operations within the authorized ranges. The research in this thesis mainly uses HMAC inlayed with MD5 hash functions to prevent the unauthorized readers from invading the data information in the tags. The hatched method is applied to the passive RFID of EPC-128 Class Therefore it will not take too long read time that EPC-128 tags are encrypted.
