Blind Signature: In the world of secret writing , a blind signature was introduced by David Chaum as a subset of digital signature in which the content of document is blinded before it is signed by the server(in this case)or any other trusted signing authority. This signature can be treated as one’s hand written signature and can be verified publically. The message can be unblended in the same way as it is performed in the digital signature.
Most of the times Blind signatures are used in cases, where the signer is the trusted third party whereas the sender of the message is different. So overall three parties involved in the communication which requires privacy-related protocols. Various applications of blind signature includes digital…show more content… Rabin in 1981. In introduces the concept where the message is send by the sender with 0.05 probability to the receiver, but problem with this theory is that sender is unaware that message is actually being received by the receiver or not. The technique used for signing the message in Rabin's oblivious transfer theory make use of most common techniques of public key cryptosystems named as RSA scheme.
In the world of secret writing, an oblivious transfer protocol is one in which client make request to the sender about a particular document and sender respond to this query by giving many pieces of information to the receiver without knowing which particular information is actually useful to the client.
A little bit more useful scheme for securing the privacy of data was introduced by Shimon Even, Oded Goldreich, and Abraham Lempel .In this technique there is a probability of one out of two oblivious transfer so it helps to reduce communication overhead between client and server. Results shows that this scheme perform pretty well in a multiparty…show more content… When the basic concept of these two protocols are combined together, they will construct the third protocol which is named as composite protocol. There is certain improvement made in the first protocol blind signature to remove its limitations Another protocol used is for oblivious transfer using 2 key method.
Protocol Model : The composite protocol requires an assumption of environment where two parties are involved, one is client and the other is server. The server contains overall database of digital content to which we can simply use the term records and client will have to search the database using a query to fetch a single record from the database. In this generalized model, there are many clients who want to interact with the database or server but are independent of each other. It is also assumed that the channel used for communication between client and server is secure and not even eavesdropping is possible during communication. It is also being assumed that a client is very well aware of what records are fetched from the database