Linked Questions

10 votes
3 answers

Why hash or salt when signing? [duplicate]

EDIT: Just wondering why was this question closed as a duplicate of a question asked almost 2 years after this one... I've seen an example of how to sign using RSA. Besides the signing itself (s = m^d ...
ispiro's user avatar
  • 2,025
1 vote
2 answers

Why is SHA256 used as a layer on top of Digital Signature [duplicate]

Digital Signatures use an asymmetric algorithm, meaning that if I want to apply a digital signature to a document I sign it with my own private key and send it to the recipient. The recipient, thanks ...
Tarta's user avatar
  • 129
3 votes
1 answer

Why hash function are used in digital signatures? [duplicate]

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 ...
juaninf's user avatar
  • 2,711
1 vote
0 answers

RSA - Why should we sign hash rather than raw content? [duplicate]

Apart from obvious performance considerations, is there any mathematical or crypto reasons that imply that we sign a hash rather than a raw content ? I read that it was because the hash must fit in ...
crypto-learner's user avatar
7 votes
3 answers

Do RSA signatures really need padding?

For encryption, we want identical plain-text's to encrypt to unique ciphers, also called Semantic Security. For Signatures, the plain-text (i.e. message hash) is not a secret. The plain-text, if you ...
randyrand's user avatar
  • 173
8 votes
5 answers

Why do we need to compute message digest of a message first while signing it?

Why is it more efficient to compute a message digest (message & signature) rather than sign the message directly?
Vinnie's user avatar
  • 105
3 votes
1 answer

Why the need to hash before signing small data?

I’ve got two questions: I’m doing the following: Data : uuid + int + nonce Signature: ECDSA(sha256(Data) ) To verify the signature: ...
jaybny's user avatar
  • 203
1 vote
2 answers

How is message length involved in public/private-key encryption?

I've just read this question regarding why to sign only the hash of a message. I kind of understood the answer, but the question arisen is now: Why can I encrypt any text messages with the same ...
user2084865's user avatar
5 votes
1 answer

Why ISO/IEC 9796 (signature with message recovery) instead of just encrypt the short message with private key?

I've had a look at “Practical Cryptanalysis of ISO/IEC 9796-2 and EMV Signatures” and read the very good answer and I understand that signature and ...
Kzar's user avatar
  • 153
3 votes
1 answer

Understanding SSL Certificate Signing

Original thread: Why hash the message before signing it with RSA? Please correct the diagram below so I can better understand how certificates are created and signed by a third party CA: https://i....
user3253260's user avatar
0 votes
1 answer

RSA signature send signature with encrypted message?

What is the correct procedure in sending an authenticated message, I've been researching and have been getting different answers, such as hash-then-sign [1], [2] , sign-then-encrypt [3] (but the link ...
user153882's user avatar
1 vote
2 answers

Public Key Encryption for Message Confidentiality

In public-key encryption, if the decryption algorithm is $$\text{Dec}(k_i,\text{Enc}(K_i,p))=p$$ where $k_i$ = receiver's private key and $K_i$ = receiver's public key what would be the algorithm for ...
Hardrocker's user avatar