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.

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Authenticate user without knowing their password

I'm working on a project where each each user will have a public/private RSA key-pair. Users will be able to send encrypted messages to each other using the each target user's public key so that only ...
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214 views

For DHE_RSA_.. Cipher Suites what is RSA used for?

In addition to achieving PFS with DHE, we want as little as possible to be revealed when the server's private key is revealed. So, what is RSA used for in DHE_RSA cipher suites? What does the server ...
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1answer
686 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 ...
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775 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 ...
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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 ...
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278 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. ...
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1answer
860 views

Is my RSA signed data secure?

So with all of the FUDD (fear/uncertainty/doubt/disinformation) going around about RSA in light of Snowden leaks and other discoveries about backdoors into PRNG, I'm uncertain what this means to me... ...
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593 views

Which products are affected by NSA's ability to crack pseudo-random-number generator Dual_EC_DRBG? [closed]

After reading this article about RSA advising its customers not to use the default random-number generator in its encryption products - amid fears spooks can easily crack data secured by the ...
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1024-bit DHE vs 2048-bit RSA

Currently with apache/mod_ssl, if DHE is enabled then a 1024-bit ephemeral key will be used. I found the following quote in Adam Langley's blog: Ideally the DH group would match or exceed the RSA ...
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1answer
295 views

Does RSA encryption always pad small amounts of data to some larger size?

If I encrypt 160 bits (20 bytes) of data using an RSA 1024 private key, will the result always be 128 bytes? This seems to be the case in my experiements, but I want to be sure. For example, ...
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439 views

How can we trust PKI, for example, Verisign?

We want to send an encrypted message to Alice. We can ask her a public key over the network, encrypt with it a message and send that message back. It is bad, because someone can pretend to be Alice ...
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1answer
239 views

Reason for using Asymmetric encryption along with SHA256

I got a document with integration with another application. They mentioned I need to hash and then encrypt data with my private key before sending it over HTTPS. By doing this, they are making sure ...
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3answers
173 views

Devising encryption schemes and protocols

I am wondering how encryption schemes are developed and why certain decisions are made. For example. I have seen a company hash a string with SHA1 and then RSA encrypt it. Why? I've also seen the ...
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676 views

Designing a cryptographic file-sharing protocol

As a learning project, I am trying to implement a secure way to share files with a friend over dropbox. (I am not looking for existing software, I am doing this in order to learn how to do this ...
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4answers
2k 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 ...
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1answer
6k views

Create RSA public, private key pair having numbers generated already

I want to know to to generate working RSA key pair, with correct syntax. Let's say i have already generated somehow my numbers for 512bit key, which are: e = 00065537 d = ...
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2answers
142 views

Deciding whether to sign someones key

How do i decide whether to sign someones PGP public key? I was looking at some contact pages and they have a request for people to sign their public key. How serious of a commitment is it to sign ...
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1answer
152 views

Posting public key [closed]

Should I put my public key on my website so that people can securely contact me. I have seen personal sites where there public key is at the bottom of the page such as this site by the computer ...
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1answer
404 views

Does the NSA X-Keyscore apply for HTTPS traffic? [closed]

See X-Keyscore: NSA tool collects "nearly everything a user does on the internet". http://www.theguardian.com/world/2013/jul/31/nsa-top-secret-program-online-data Does anyone have a clue how they ...
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3answers
1k views

Is a passphrase-protected SSH private key susceptible to a dictionary attack?

If I have a passphrase-protected SSH private key, AND if this passphrase is sufficiently random and long (say, 20-, 30-, 40-characters long, or even more!), AND if I make this private key of ...
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2answers
291 views

OpenSSL dgst authentication failure

I've tried to replicate the workflow presented on this blog in OpenSSL: http://farid.hajji.name/blog/2009/07/27/public-key-cryptography-with-openssl/ However, authentication seems to fail despite ...
4
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2answers
243 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 ...
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3answers
617 views

Is it possible to prove which public key was used to encrypt a message?

Pretty much the title: If Alice sends a message to Bob that she encrypts with Bob's public key, is it possible for Eve to prove that the ciphertext was encrypted with Bob's public key, that the ...
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1answer
219 views

Development of asymmetric encryption algorithm? [closed]

I am planning to develop (make some minor changes) to asymmetric encryption (i.e. RSA). Any suggestions please?
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181 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 ...
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6k views

Key size difference between AES and RSA

Can I say that 128 bit using AES provide more security than 1024 using RSA?
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1answer
556 views

Do I need to keep certificate signing requests and public keys?

I've created an RSA key. Created a CSR. Got it signed and now I have my certificate. It's for a webserver running https. The public key can be generated from the private key, so I guess I don't need ...
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How long is a 2048-bit RSA key? [closed]

On stackoverflow: '2048 bits, or 1400 decimal digits' http://stackoverflow.com/questions/11832022/why-are-large-prime-numbers-used-in-rsa-encryption On Wikipedia: 'RSA-2048 has 617 decimal digits ...
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3answers
1k views

RSA key length vs. Shor's algorithm

I have just read a passage in Zeilinger's book about quantum world. My question is: Suppose there exist quantum computers. Given that a quantum computer can use Shor's algorithm, what key length ...
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Why does PGP use symmetric encryption and RSA?

Looking into the details of Pretty Good Privacy, I'm confused as to the reasoning behind encrypting the message with a session key and the key with the recipient's public key via RSA. I fail to see ...
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1answer
332 views

SSL: MITM possible if private key is known? [closed]

If a Man-in-the-middle has the private RSA key of the SSL encryption. It should be possible for the Man-in-the-middle to decode the entire HTTPS datastream right? So, then the encryption is ...
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2answers
1k views

Can the U.S. goverment crack encryption? [closed]

Does USA government have the sufficient processing power to crack keys in matter of seconds? Let say 2048-bit RSA, for example. Since the RSA algorithm was developed by USA government (NSA?), I ...
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262 views

RSA vs PBKDF2 for password storage (theoretical)

I know this is not the right way to store passwords, but I'm asking this from a theoretical perspective: Suppose a web site's passwords were encrypted with RSA asymmetric encryption and the private ...
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180 views

Verifying the authenticity of a public key without manual intervention?

In RSA encryption it is said that ensuring the authenticity of the public key can be as important as the protection of the private key. An effective way of doing this is to have key custodians ...
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Decrypt from cipher text encrypted using RSA

I am sniffing a client side application traffic and I found some encrypted data. I am not able to decrypt it. Information which I have is Public Key: ...
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Is there any particular reason to use Diffie-Hellman over RSA for key exchange?

I often see RSA being recommended as a method of key exchange. However, the Diffie-Hellman key exchange method appears to be secure as well. Is there any considerations one should take into account ...
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Why is RSA using fixed point type numbers?

Why does RSA use fixed-point numbers instead of floating-point? Are there too many floating-point implementations to choose from? Does fixed-point arithmetic increase the difficulty of factorization? ...
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1answer
376 views

RSA Possible Vulnerability?

Given c1 = cipher text of m encrypted with n1 and e Given c2 = cipher text of the same m encrypted with n2 and the same e, Is it possible to figure out either of the n's or m? I can't seem to solve ...
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Lessen impact of DoS attack on cpu-expensive login?

This is a follow-up to my previous question: Prevent DOS against RSA authentication. This question is also discusses a similar problem: Prevent denial of service attacks against slow hashing ...
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2answers
970 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 ...
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259 views

Prevent DOS against RSA authentication

In my current setup, the clients are bundled with the server's public key. The client encrypts a nonce and sends it to the server which uses its own nonce and the nonce received from the client to set ...
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1answer
596 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 ...
2
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2answers
168 views

Was DSA invented from RSA?

I'm wondering if the two algorithms are similar and whether DSA was really just based off RSA? Is DSA based on RSA and public key encryption? If so how does DSA introduce signing and makes it ...
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1answer
250 views

Does ciphersuite ECDH / ECDHE need hardware acceleration

I have started to read more about ECDH/ECDHE and am wondering if it has the similary issues as RSA - i.e. the processing power required for the decryption of private key is more than of the public ...
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RSA maximum bytes to encrypt, comparison to AES in terms of security?

What is the maximum number of bytes for encrypting a plaintext message using RSA that is reasonably secure and also efficient and would AES be better for the same size in bytes? The encryption doesn't ...
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2answers
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Questions to hybrid encryption. RSA with AES

I want to use a hybrid encryption in my application, so after reading a lot of lines I ended with this implemantation, please critizie it ;) (I want to stick to .Net) byte[] aesKey = ...
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1answer
635 views

zero knowledge proof - where do we use it?

zero knowledge proof, Where do we use it online? I thought we mostly use the RSA algorithm.
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323 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 ...
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1answer
299 views

Where is RSA Digital signature used in the online banking world?

When i do online banking, i sign my digital transaction with a digipass. Ive been told that it uses a RSA-based digital signature scheme. But an rsa digital signature (1024 bit for the modulus) is a ...
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781 views

Why is ECC more vulnerable than RSA in a post-quantum world?

Forgive me if this should be in the crypto sub, but sometimes the answers there are very mathematical and I would rather have an answer which is a bit lighter on the math but still strong on the tech ...