Incremental Cryptography

The goal of incremental cryptography is the design of cryptographic algorithms with the property that having applied the algorithm to a document, it is possible to quickly update the result of the algorithm for a modified document, rather than having to re-compute it from scratch. Incremental cryptography offers considerable advantages in all settings where similar documents are processed by the same cryptographic transformation. For example if you want to send signed copies of the same letter to several people just changing in each letter the name of the recepient, instead of signing each copy from scratch, you can sign only one letter and then obtain the other signatures by fast update operations. Incrementality can be defined for all cryptographic primitives: digital signatures, encryption, hashing, authentication.