1
$\begingroup$

This question already has an answer here:

In the lectures I see, hash functions are always used when we want to sign a document $d$. My question is why they are used in digital signatures? Maybe, because it is more easy and fast to calculate the signature when is used a "block" signature scheme? Do you know some formal paper or book where this is described? I need that for my thesis.

$\endgroup$

marked as duplicate by yyyyyyy, otus, e-sushi Apr 23 '16 at 12:25

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

3
$\begingroup$

Bruce Schneier writes in Applied Cryptography (2nd ed., p. 38f):

In practical implementations, public-key algorithms are often too inefficient to sign long documents. To save time, digital signature protocols are often implemented with one-way hash functions (...). Instead of signing a document, Alice signs the hash of the document.

The references Schneier cites are:

  1. D. W. Davies and W. L. Price, "The Application of Digital Signatures Based on Public-Key Cryptosystems," Proc. of the Fifth International Computer Communications Conference, Oct 1980, pp. 525--530.
  2. D. W. Davies and W. L. Price, "The Application of Digital Signatures Based on Public-Key Cryptosystems," National Physical Laboratory Report DNACS 39/80, Dec 1980.
$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.