Linked Questions

5 votes
2 answers
2k views

Do I really need to use the same private/public key pair in RSA?

So I'm making an Android application, I need my application to be only able to scan my own generated QR codes, and I want to make sure that nobody else can generate fake ones. The data isn't sensitive,...
OverCoder's user avatar
  • 273
6 votes
2 answers
4k views

Derive a secret from an RSA private key

What I want to do is deterministically derive a secure key from an RSA private key, such that the RSA private key cannot be derived from the secure key. The first approach that came to mind was ...
Cocowalla's user avatar
  • 450
0 votes
1 answer
3k views

What is the verification algorithm for verifying RSA signatures?

I am not able to find much information how how to verify RSA signatures. I have three values. Message = "Launch a missile." public key: ...
User's user avatar
  • 111
-5 votes
2 answers
1k views

How exactly does plaintext become ciphertext?

I'm having a hard time finding out how PlainText becomes Ciphertext. I understand that I do the following: PlainText -> RSA/AES/Whatever -> Ciphertext Can ...
Privateish's user avatar
1 vote
1 answer
1k views

Calculate if a digital signature is valid

In the book An Introduction to Mathematical Cryptography, it mentions a section on digital signatures and a theoretical example. I am having difficulty understanding the book and I was wondering if ...
Alex's user avatar
  • 11
4 votes
1 answer
598 views

What is the probability of attacking SHA1 used in RSA signature with small exponent?

There is RSA signature check which has following properties: RSA modulus N which is 2048-bit RSA public exponent equal 41 (0x29) Genuine Signature uses EMSA-PKCS1-v1_5 padding of SHA1 hash, however ...
desowin's user avatar
  • 163
0 votes
1 answer
915 views

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
2 votes
1 answer
551 views

Can I use asymmetric encryption for more powerful write-protection?

I have a game that I am developing which uses a locally-stored internal database. It does not matter to me whether a user can read the file (which, to me, means I don't need a symmetric cipher), but I ...
Mike Carpenter's user avatar
-3 votes
1 answer
799 views

How does the signature checking work in DKIM?

As far as I understand DKIM works like this: DKIM is not used to encrypt anything, the only purpose is to mark mails that are not really sent from the claimed domain as spam. the DKIM-enabled sending ...
rubo77's user avatar
  • 207
-1 votes
2 answers
214 views

Encrypt with private key decrypt with public key

I want to sign and transmit a short message, which contains a few simple hashes. My objective is not to prevent an attacker from inserting a fake message, but to ensure that the attacker cannot define ...
user23952's user avatar
1 vote
0 answers
224 views

Given N and e in RSA and the ability to get signature s for any message m, can you find the value of the private key d?

Given N and e in RSA and the ability to get signature s for any message m ($s=m^d \mod{n}$), can you find the value of the private key d?
Michael Blane's user avatar
0 votes
1 answer
121 views

What if the CSR is intercepted in transit while sending it to CA?

I was studying PKI the other day and I had a serious thinking about the following question. What is CSR? - It is a block of encoded text that is given to the CA when applying for an SSL certificate ...
KingsNeverDie's user avatar
0 votes
0 answers
22 views

RSA Digital Signatures Verification [duplicate]

I am trying to learn about RSA digital signatures, and have a question about the verification process. My understanding of the set-up is the following: The signer chooses two secret primes $p$ and $q$,...
Koda's user avatar
  • 101