Linked Questions

55 votes
2 answers
9k views

What security authorities and standards reject $e=3$ in RSA, when, and with what rationale?

In RSA, some security authorities and/or standards allow the public exponent $e=3$, others require or recommend $e>2^{16}$ (or perhaps some other minimum). I gathered the following: PKCS#1 allows $...
fgrieu's user avatar
  • 142k
15 votes
2 answers
3k views

Given enough RSA signature values, is it possible to determine the public key value?

Given enough RSA signature values, is it possible to determine which public key is required to verify the values? Could there be enough information to establish which key is required? Is there ...
Maarten Bodewes's user avatar
  • 92.9k
2 votes
4 answers
2k views

Is it more weak to encrypt with the private key RSA?

I have a simple question. Is it more weak to encrypt with the private key against the public key with RSA ? Like is it easier to "crack", "brake", "solve", "decrypt" when I encrypt with the private ...
Mathias Osterhagen's user avatar
2 votes
2 answers
3k views

Why is 0x10001 used as an RSA exponent so often?

Are there any other commonly used exponents? Why are they selected?
0x777C's user avatar
  • 163
2 votes
2 answers
806 views

In RFC 2313 (PKCS1/RSA) said you could recreate the Private key from 'n' and 'd', which later versions removed. Why?

RFC 2313 has this specific callout: ...
rip...'s user avatar
  • 123
3 votes
2 answers
3k views

Cracking RSA ciphertext without a public key

I'm looking for some clarification on whether or not I'm correct in how I'm thinking about this. From my understanding of RSA, the public key gives you the value $n$ (large prime $p$ times large ...
Filon's user avatar
  • 31
2 votes
1 answer
2k views

which exponent to be used for RSA e =3 or 65537 for RSASSAPSS signature verification

I have the public key and I dont know how to obtain Modulus and exponent. After referring stack overflow, I have used below command line to obtain e and M finally as mentioned below. openssl.exe rsa -...
danny's user avatar
  • 253
3 votes
1 answer
2k views

RSA: deduce the public key from message & signed message [duplicate]

In RSA, is deducing the public key from the (message, signed message) pair possible? If so, how can it be done?
B.Li's user avatar
  • 183
2 votes
1 answer
340 views

How to produce large list of BigInteger prime numbers (RSA) in fast and efficient way

Hello fellow experts here, in order to use RSA to encrypt and decrypt in a controlled environment, we will actually need to have a list of prime numbers to do so instead of using library generated RSA ...
Hern's user avatar
  • 159
1 vote
1 answer
1k views

In RSA, What does gcd(e,phi) != 1 means? Why always choose e = 2^n +1 not 2^n?

Recently I have few experiences with Questions in RSA which e is 2^n instead of 2^n+1, and that leads to gcd(e, phi) is not equal to 1... Won't this make the private key impossible to get? Is the ...
dlfls's user avatar
  • 11
0 votes
1 answer
651 views

RSA - Calculating $d$ given $\varphi (N)$ and $N$

From this discussion, I know that if I know $\varphi (N)$ and $N$ (where $N=pq$, $p$ and $q$ prime), then I can very easily get $p$ and $q$. Suppose I have the encrypted message $c$. I want to get ...
Peter_Pan's user avatar
  • 103
2 votes
0 answers
271 views

RSA: Find message (m) given that you know p,q, cp and cq where cp=m^dp mod p and cq = m^dq mod q

I have come across an RSA problem that goes like this: You have $p,q,cp,$ and $cq$. You know that $cp = (m^{dp}) \bmod p$ and $cq = (m^{dq}) \bmod q$ where $dp = d \bmod(p-1)$ and $dq = d \bmod(q-1)...
Dead Fury's user avatar