Join Log in
Score:2
avatar Crypto

Randomization of ECDSA signing operations to prevent SCA

us flag
Dave

A large number of SCA papers that talk about ECDSA mention the need for blinding/randomisation of the signing process, typically with a single-sentence comment about replacing the projective coordinates (X,Y,Z) with randomised ones (lambda^2X,lambda^3Y,lambda*Z) and declaring the problem solved, but nothing really seems to provide any detail of what specific steps are required. In particular looking at the implementation in various crypto libraries like mbedTLS, BearSSL, FLECC and similar they all seem to do it differently and in each case it's very deeply tied into the internal bignum representation and implementation. Given the portion of the ECDSA process that this affects:

$$\mathtt{(x,y) = k * G}$$ $$\mathtt{r = x\mod n}$$ $$\mathtt{s = k^{-1} (h+dr\mod n)}$$

is there some explanation of what operations to perform to randomize the process against SCA in a manner that's not dependent on the internal details of a particular bignum library implementation?

46
0 + 0
dsa
ธงชาติไทย
Elon Musk
I sit in a Tesla and translated this thread with Ai:

mangohost

Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.