Questions tagged [rsa]
RSA is a common public key algorithm, which can be used for encryption and signature. It is a core component of most the security protocols used on the Internet, including the SSL/TLS protocol suite.
742
questions
6
votes
1
answer
6k
views
openssl ECDHE-RSA... cipher suite selected while using RSA server cert and ECDSA client cert
The scene:
s_server using RSA certificate.
s_client using ECC-ECDSA certificate.
Client authentication is required (option -Verify set on s_server)
Cipher-suite selected after handshake is ECDHE-...
6
votes
1
answer
3k
views
When should I generate new public & private keys using RSA?
I'm creating a huge, online mobile game. I have a few questions for you guys because my knowledge in cryptography and sending data across the network securely is kinda poor.
Some details:
Each user ...
6
votes
1
answer
4k
views
Where should I store a private key for a web application?
May be a duplicate of "How to store a private RSA key for an application?"
So I was asked to make a web interface in PHP that allows visitors to check the signature of a file using SHA 256 with RSA ...
6
votes
1
answer
9k
views
How ECDHE is signed by RSA in ECDHE_RSA cipher
About ciphers that use ECDHE as Key Exchange and RSA as Authentication:
How exactly this two algorithms work together, is ECDHE process encrypted by RSA public key?
What are the DH parameters?
...
6
votes
1
answer
2k
views
when should i use HMAC-based JWT?
I read a number of blog posts and found that it is tough to keep the secret-key a secret and if using a symmetric algorithm for JWT creation, the generator has the power to create as well as validate ...
6
votes
3
answers
3k
views
How much faster does a GPU or FPGA crack an RSA key compared to a CPU?
Are there any significant speed up in time on cracking an RSA key (either brute-force or factoring with general number field sieve) using a GPA or FPGA compared to a CPU? If there is a speed advantage,...
6
votes
1
answer
704
views
SSH raspberry pi security
I've setup an SSH server on my Raspberry Pi. I use RSA keys to login, I disabled root login, password authentication and I use port forwarding to login from outside my network.
I can see the ...
6
votes
2
answers
2k
views
Split RSA private key into two parts securely
Let's say I have a RSA key pair: N, E, D, in which N, E are the public part, D is the private part.
I'd like to split the private part into two pieces, D1 and D2, and store them in two different ...
6
votes
2
answers
14k
views
CSR with only public key with openssl
So I have been doing my research and haven't found anything specific enough to my problem. As the question title states, I want to make a CSR with only the public key.
What I have been able to do is ...
6
votes
2
answers
2k
views
Why did browsers deprecate 1024-bit RSA, but retain SHA-1?
I was reading Mozilla's security blog Phasing out Certificates with 1024-bit RSA Keys. Effectively, some browsers are deprecating 1024-bit RSA for CAs and Subordinate CAs because the certificate must ...
6
votes
1
answer
4k
views
Key generation: Differences between GnuPG classic, stable, modern?
I plan to create a 4096 bit RSA&RSA key pair:
gpg --gen-key --personal-digest-preferences SHA512 --cert-digest-algo SHA512
Is there any difference in generated key quality between versions 1.4 (...
6
votes
3
answers
846
views
Is generating an RSA key with password and then stripping it off more secure than no password at all?
Some time ago I came across this question on SO; it asks how to remove the passphrase from an existing RSA key using a PHP equivalent to the existing openssl rss command.
I've posted an answer with ...
6
votes
2
answers
2k
views
Is SSH public key authentication sufficient for protecting a server if IP Whitelisting is disabled?
I'm currently working for a startup company who maintains a server on AWS. Currently, our server is set up so that in order to access it via SSH, you need to be on a white listed IP (set up in AWS) ...
6
votes
2
answers
943
views
Could RSA be used as a block cipher?
I always thought that the reason we couldn't use it was because it required too many CPU cycle. But an answer from @TomLeek indicated that this was not the case :
https://security.stackexchange.com/a/...
6
votes
2
answers
1k
views
Security of PGP for Long-Term Storage
How secure are PGP/GPG encrypted mails?
I realize that it's probably fine for regular e-mail scenarios, but what about the security over longer time periods (>30 years)? Is the 4096 bit limit for ...
6
votes
1
answer
872
views
Does PKCS 1.5 padding make it possible for an attacker to extract the private key or not? Is PKCS 1.5 safe to use in authentication context?
Im currently writing a authentication app based on RSA, for Android that should be impossible to copy, even if you have physical access to a phone without lockscreen/PIN.
However, the HSM inside the ...
6
votes
1
answer
3k
views
How does signing work with Elliptic Curve Crypto?
So I have read up and have a decent understanding of how the crypto works with Elliptic Curve Cryptography. I also think I have an understanding of how signing works with things like Elliptic Curve ...
5
votes
2
answers
4k
views
Why do I get the error "dh key too small" when the RSA key is 2048 bits?
When I try to connect to the site https://api-mte.itespp.org with OpenSSL (openssl s_client -connect api-mte.itespp.org:443 -brief), it complains that the DH key is too small. But when I analyze its ...
5
votes
1
answer
1k
views
How to ensure identity for server-to-server communication over IP
How would one go about ensuring that a server at a given IP address is who it says it is? I need to send confidential data to another server at another IP address. If the server had a public domain it ...
5
votes
2
answers
571
views
Is it more secure for SSH clients to use a Private Key (RSA-2048) or a long random password (256 bits of entropy)?
What is more secure? An RSA-2048 key or a cryptographic 64 characters-long random HEX password?
I am asking this because as far as I understand, since the RSA-2048 key is a mathematical key, a ...
5
votes
1
answer
15k
views
Checking if an RSA private key is passphrase protected
I have generated an RSA key-pair on a computer, and I want to check if the RSA private key is encrypted (protected) with a passphrase.
Note that the problem is not that I forgot the passphrase, but ...
5
votes
2
answers
10k
views
What's the limit on the size of the data that public-key cryptos can handle?
Someone mentioned here that asymmetric encryption might not be appropriate for bulk data and gave an example of RSA with 100 bytes. Of course, I understand that it was a rough example. But it made me ...
5
votes
4
answers
5k
views
What is the easiest way for a newbie to RSA to create & use a key pair on Windows?
So I need to get a block of text sent to me over email from a friend, but before he sends it he wants a public RSA key from me.
Am wondering what is the simplest way for me as a newbie to generate ...
5
votes
2
answers
2k
views
Web & insecure HTTP - Using RSA for encrypting passwords on the client side
I used client side password hashing in my register and login project.
Its purpose is to prevent passive adversaries/eavesdroppers from discovering users' plaintext passwords when HTTP requests are in ...
5
votes
1
answer
8k
views
What is the meaning of public key parameter in the X.509 certificate?
While I am checking the fields of X.509 I've noticed there is field called public key parameter and its value is 05, what is the use of this field? I have searched and did not find a clear answer for ...
5
votes
4
answers
4k
views
RSA or ECDHE for x.509 certificates-what does each do?
I am relatively new to x.509 certificates, but recently i have been looking at the https connection padlock at the top of the screen. On certain websites, clicking on the pad informs me that the site ...
5
votes
2
answers
2k
views
Using Different Algorithms in Single PKI
Assume the following Public Key Infrastructure:
|Root CA (RSA)
|-Sub CA (RSA)
|-Sub CA (ECC)
Is there any rational that explains why this would not be an acceptable implementation?
Is the ...
5
votes
3
answers
909
views
Public part of SSH key (*.pub): Keep or destroy?
I have set up authentication with a remote system using SSH. I sent the sysadmin the public part of the SSH key (*.pub).
What are the implications of keeping this public key on my machine? Is it good ...
5
votes
2
answers
3k
views
generating RSA keys through the browser
HTML5 has the element that sends an SPKAC to the server (as I understand it).
But how do you do it in IE?
One CA's websites gives me the following prompt:
This Web site is attempting to perform a ...
5
votes
1
answer
3k
views
How could an attacker read the content of php session variables?
In my PHP code, I am generating an RSA keypair, sending the public key to the visitor and storing the private key in a session variable. Is it possible that an attacker might somehow be able to read ...
5
votes
1
answer
1k
views
Why are there leading 0x00 bytes in the subjectPublicKey field of a DER X.509 cert?
For a simple example, I'm using a 512-bit RSA cert to illustrate my question. The cert can be found in both DER and PEM form here. I've been going through the certificate using this ASN.1 decoder (the ...
5
votes
1
answer
5k
views
What is the difference between a digital signature and whole message encryption?
I am newbie in information security I am trying to understand the difference between a digital signature and encryption of a message.
Lets consider simple example of email message.
I understand how ...
5
votes
3
answers
1k
views
Secure Hash of a very short payload - is it possible?
I am looking to verify the integrity of a very small payload, approx 64 bytes, which will be stored in a QR code. I need to verify that the payload has not been generated or altered by an attacker. ...
5
votes
4
answers
1k
views
Generating deterministic X.509 certificates?
Is there a way to deterministically create an RSA private-key for an X.509 certificate, ideally through a library which has been vetted already?
i.e. user enters some phrase like "this is my private ...
5
votes
1
answer
5k
views
Most popular RSA key format
We are trying to decide on which RSA key format our application should use. The ideal format would be widely used and supported in most of the popular platforms/frameworks. This would make it easy for ...
5
votes
1
answer
4k
views
Is TLS 1.0 sufficiently secure for a bank?
I disabled SSL2 and SSL3 in my Firefox browser, version 24. I only enabled TLS 1.1 and 1.2. Unfortunately when I went to my bank's website, I found that it didn't work until I re-enabled TLS 1.0.
...
5
votes
1
answer
763
views
How bad an idea is intentionally using short RSA keys for signing CloudFront private-content URLs?
While pondering a question on SO about efficiently generating signed private-content URLs for CloudFront I decided to check what sorts of savings could be found by using a shorter RSA key. With the ...
5
votes
1
answer
2k
views
How large RSA-keys could the worlds combined computer power factorize in reasonable time?
If you combined every microprocessor on earth into one humongous computational cluster, how large RSA-keys could you factor in reasonable time (lets say a few years)?
I know from reading the answers ...
5
votes
1
answer
204
views
To what extent are countermeasures against side-channel attacks effective/ used regularly by everyone?
I'm doing an Extended Essay for IB right now and I'm doing it on how secure RSA is.
As side-channel attacks are one category of attack, I was wondering (as I am struggling with the conclusion) while ...
5
votes
2
answers
488
views
Passwordless website authentication scheme
Edit: This scheme has since been standardised as WebAuthn - go use that instead!
I have a userbase which really isn't all that inclined to create a secure password for a website. They're also almost ...
5
votes
2
answers
3k
views
Secret, Public, and Private Keys?
...and nonces. Can someone show an example of how this actually works using small intelligible numbers? For example:
secret key: "100"
public key: "10"
private key: "1000"
I am just trying to ...
5
votes
2
answers
357
views
Should I test my SSL certificate for "RSA Shared Primes" before using it?
There are several papers from 2012 that say it's possible to factor several moduli by factoring shared primes. The link above includes python sourcecode to verify and test for this fact.
Given this ...
5
votes
1
answer
5k
views
Which file encryption algorithm is used by Synology's Cloud Sync feature? [closed]
I'm trying to find out which encryption method is used by a piece of software I use, viz. the 'Cloud Sync' feature of Synology's DSM 6.0 running on a Synology NAS.
(Background. This Cloud Sync ...
5
votes
1
answer
2k
views
RSA fingerprint automatic change or have I been hacked?
today I tried to connect to my Digital Ocean VPS through Putty(kitty) as usual, but I got the message that the server's cached fingerprint had changed, and that it could be a security compromise.
I ...
5
votes
1
answer
2k
views
OpenVPN Key Size 1024 vs 2048 and Eavesdrop vs Access?
OpenVPN recommends using a 2048 RSA key size for greater security, however, the hardware I'm using is somewhat weak and defaults to using a 1024 RSA key size. I'm trying to determine if it's worth ...
5
votes
0
answers
2k
views
Manually verifying signature in S/MIME mail with openssl
I'm trying to manually verify the signature in an S/MIME signed email with openssl as part of a homework. While I have the mail and can extract the chain of certificates, I'm failing to extract the ...
4
votes
3
answers
4k
views
Password based RSA encryption
I recently learned (read) the math behind RSA encryption (algorithm). Now, I wonder if there is a way to use a custom password instead of the private key.
Imagine a web application, where user signs ...
4
votes
2
answers
2k
views
Is it less secure to encrypt an hexadecimal encoded string?
I'm implementing RSA public-private key encryption and decryption and the input of these functions is encoded as hexadecimal. The library I use (react-native-rsa) however only accepts plain strings ...
4
votes
1
answer
833
views
Are there any holes in this security design?
This design is for transport security between a client and a server. I'm planning on using it for a cloud storage system. I would like it to be secure against you-know-who.
I'm trying to prevent the ...
4
votes
2
answers
7k
views
Should the client or the server generate the client's public-private key pair?
Say I have a mobile messaging app. There is a central server that manages stuff (like a directory of users, onboarding, etc.) and there are all the clients.
My app is professional, so it uses ...