The two main types of pattern protection schemes are the feature transformation approach and the biometric cryptosystems approach. In feature transformation, a transformation function is applied to an original model and only the transformed model is stored in the database. Transform function parameters are usually derived from a password or random key. When the query model arrives, the same transformation function is applied to the model and it is transformed. The transformed model is now checked for a match in the database. According to the characteristics of the transformation function, they are divided into two types, namely salting and non-invertible transformations. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get the original try In salting, the transformation function is invertible, that is, if the adversary is able to get hold of the key and the transformed model, then he can get the original model. Therefore, the security of the salting process depends on the protection of the key or password used in the transformation, whereas in the case of non-invertible transformations, the transformation function is a one-way process and it is very computationally difficult to recover the original model from the transformed model even if the key is sacrificed. Initially, biometric cryptosystems were created to secure a cryptographic key using biometric traits or by creating cryptographic keys from biometric patterns. Additionally, the same techniques have been used to protect even biometric templates. In biometric cryptosystems, some public information about the model is usually stored, called support data. Therefore, biometric cryptosystems are also called assistive data-driven methods. The helper data cannot be used to revoke the original pattern or reveal any meaningful information about the original pattern, but is used during the matching process to extract the cryptographic key from the query pattern. Here, matching is an indirect process that is carried out by verifying the correctness of the extracted cryptographic key. Biometric cryptosystems are further classified into key binding and key generation approaches which depend on how the supporting data is obtained. When the support data is obtained by binding a key (independent of the biometric template) to the original biometric template, it is called a Key Binding biometric cryptosystem. It should be noted that with only the wizard data it is very difficult to obtain the original model. In a Key-Binding system, the matching is done by retrieving the key from the attendant data using the biometric template. On the other hand, if the assistance data is obtained only from the biometric template and even the cryptographic key is derived from the assistance data as well as the query biometric template, then it is called a biometric cryptosystem of generating key. Biometric cryptosystems and template transformation systems have their own advantages and disadvantages. Models being transformed can be easily revoked by changing the password or key. It is possible to design sophisticated algorithms and comparators that can robustly handle intra-user variations in the transformer biometric model, due to the..