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1
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2answers
29 views

If I change any character in a private PEM, should the public PEM be different?

I'm generating a public PEM-format key from a private PEM-format key. I noticed that if I change a few characters near the end of the private PEM that the public PEM generated from the modified ...
1
vote
1answer
19 views

Encrypting multiple blocks with an asymmetric scheme

I have a general question how asymmetric schemes are usually implemented. Typically, there is a parameter in an asymmetric scheme which limits the message length. For example the modulus in RSA. I ...
0
votes
3answers
80 views

Why is symmetric encryption still used? [duplicate]

In symmetric encryption, the key responsibility is for the two parties involved (sender and receiver). Hence, it can be more vulnerable, and can cause accountability issue in cases ofthe key is ...
29
votes
7answers
4k views

How dangerous might be publishing a public key?

Maybe this question sounds obvious, but I wonder how dangerous might be publishing a public key for an asymmetric encryption system? I know public keys are meant for encrypting messages by anyone ...
3
votes
3answers
170 views

Why do you need to encrypt symmetric key?

I'm reading this pki article and as you can see near the bottom, the quick animation and description: The sending computer encrypts the document with a symmetric key, then encrypts the symmetric ...
0
votes
1answer
54 views

Key-Exchange Algorithms VS Local Key Generation?

I was wondering the difference in term of Security, Computational cost and Network overhead between the use of : A Key-Exchange Algorithm (e.g. Diffie–Hellman) to set up a symmetric key. The ...
-5
votes
1answer
113 views

What is the excellence of RSA vs my algorithm [closed]

I was wondering that what make RSA Asymmetric Cryptography Algorithm special. So I wrote a very simple algorithm that do the same work (Generate Public and Private Key) Now I want to ask you that What ...
2
votes
5answers
265 views

Is asymmetric encryption vulnerable to man-in-the-middle attacks?

I'm looking for ways to send private messages over a public channel, and in doing this I stumbled in asymmetric encryption, which is just perfect for what I was looking for at first - A and B ...
3
votes
7answers
243 views

How would I give an encryption key to only one person?

Let's say I have an encrypted message. I want to make it so that someone is able to decrypt it. The only way of giving it to them is online. For the purposes of this question, I can't call, mail or ...
16
votes
5answers
3k views

“Diffie-Hellman Key Exchange” in plain English

Can someone explain to me what is Diffie-Hellman Key Exchange in plain English? I have read in a non-tech news page that twitter has just implemented this technology which allows two persons to ...
2
votes
0answers
58 views

Main difference between Yahalom and Needham-Schroeder key exchange protocols

I am just wondering what is the main difference between the Yahalom and Needham-Schroeder key exchange protocols? Which protocol uses less computational power?
2
votes
1answer
201 views

How can I secure IP Multicast traffic?

I'm interested in securing IP Multicast traffic for content that will be sent globally with several low bandwidth receivers. I understand that simplified Broadcast encryption takes N public keys ...
1
vote
2answers
146 views

Can any asymmetric algorithms work with only a key-sized amount of randomness?

With 397 rolls of a fair 6-sided die (not my favorite use of time, but certainly not infeasible), I could generate more than 1024 random bits. Could I use those bits to generate a keypair that could ...
0
votes
2answers
238 views

Storing email adress encrypted but deterministically

As part of an application I am developing, I am required to store user email adresses on a cloud DB. The email address is not required to be in plain text for the normal operation of the application. ...
22
votes
5answers
2k views

Why is Bruce Schneier recommending symmetric crypto over public key crypto

I just read the article written by Bruce Schneier, the crypto guru. In the article, he says : Prefer symmetric cryptography over public-key cryptography. But, he doesn't shed any light as to ...
0
votes
1answer
148 views

Encrypted data transfer with middle node and asymmetric key

I'm looking forward to pass data from a node A to a node B using asymmetric cryptography, but with one (huge) constraint: When A sends data to B, it is possible that B is offline. I would like to be ...
1
vote
2answers
460 views

How to store Encryption Key on Shared Hosting?

I am currently designed Simple Online Patient Management System, but according to country Rule, sensitive data should be encrypted when used online, I did the encryption, and all sensitive fields ...
1
vote
1answer
61 views

Hybrid Encryption System - Is this unnecessary in this case? [closed]

I have a column in my database that I need to encrypt. The column can contain any arbitrary data. What I am thinking is to generate a public and private key pair first. Store the public key in a ...
1
vote
1answer
412 views

Is server-side cryptography with user-only access possible for email services?

I came across the Lavabit High Scalability Writeup and got curious. Do you use any particularly cool technologies or algorithms? The way we encrypt messages before storing them is relatively ...
2
votes
1answer
1k views

How to encrypt a short string to a short ciphertext using an asymmetric encryption?

I am using RSA to encrypt some text, so my system has already generated private and public keys. These keys I would like to use to encrypt/decrypt a short text (16 chars). The main condition is: ...
7
votes
3answers
485 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 ...
0
votes
1answer
714 views

How to use public key in ~/.ssh for asymmetrical encryption with OpenSSL

I want to do an asymmetrical file encryption: openssl genrsa -des3 -out private.key 4096 openssl rsa -in private.key -pubout -out public.key openssl rsautl -encrypt -pubin -inkey public.key -in a ...
6
votes
1answer
610 views

Why a symmetric key for HMAC?

I am working on securing a RESTful API and am using the Amazon AWS HMAC model as my guide. I am struggling with coming up with a secure way to store the symmetric keys on my end. What is the standard ...
2
votes
1answer
465 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 ...
4
votes
3answers
226 views

What SSL options should not be used?

What SSL options should be avoided, due to recently discovered weaknesses? This might include symmetric algorithms, or MAC functions.
7
votes
2answers
350 views

What asymetric scheme provides the shortest signature, while being secure?

I've had a look at several signature schemes (DSA, ECDSA for the most common ones), and am wondering about whether there exist a scheme that would have the following properties : Be asymmetric (one ...
11
votes
3answers
2k views

What specific padding weakness does OAEP address in RSA?

It's been recommended to use OAEP when padding messages to be encrypted via RSA, to prevent known plain text attacks. Can someone elaborate this in better detail? I'd specifically like to know the ...
0
votes
1answer
484 views

Can I ensure that a public key derived from a private key is unique?

In asymmetric cryptography, is it possible to ensure that public key derived from a given private key is unique, no matter the algorithm?
4
votes
1answer
228 views

Potential issues with Kim Dotcom's new proposed “encrypted webmail service”

Just spotted a Reddit thread about Kim Dotcom, of MegaUpload fame, planning to produce a secure webmail system that allows people to communicate securely, without the worry of having their messages ...
4
votes
2answers
3k views

How X509 Certificates are used for Encryption

I have small doubt regarding the process of X509. I am aware of OpenPGP Encryption/Decryption, where we generate the public key and private key. We can share the public key to vendors and they can ...
2
votes
3answers
4k views

Encrypt data within mobile app and send to web service

I'm developing a mobile application for Android and iOs. What is best practice when it comes to data encryption within the mobile application which will be sent to a web service? Basically I will ...
1
vote
1answer
694 views

Asymmetric crypto to store credentials in HTML LocalStorage

We are developing a Mobile web app where the users want (and it is a non relaxable requirement) to be logged for a very long time. The solution we are developing has a web-client part in HTML+JS and ...
4
votes
3answers
1k views

Is a 512 bit RSA key secure when used temporary?

Is a 512 bit RSA key secure when a new key gets generated and used approximately once a week? The key is only used for signing messages, not for encrypting sensitive data. This is for a system where ...
2
votes
3answers
1k views

KDC(Key Distribution Center) vs Asymmetric Key Exchange

Today I was reading notes about cryptography and I came across a problem that exists in Symmetric Key encryption, which is how to share the secret key across the network. 1st Method : Make use of ...
151
votes
8answers
63k views

Why not use larger cipher keys?

RSA Security commonly uses keys of sizes 1024-bit, 2048-bit or even 3072-bit. And most Symmetric algorithms only between 112-bit and 256-bit. I do realize that the current keys are secure enough for ...
0
votes
1answer
719 views

ECDH is better than plain RSA? [closed]

RSALabs recommend using at least 4096 bit long RSA keys to encrypt emails but we have some performance difficulty with 4096 RSA. my noob question is what is ECDH (i didn't understood from wikipedia ...
14
votes
6answers
1k views

Principle of asymmetric algorithm in plain english

I was giving a presentation to my colleagues about cryptography basics in which I explained about asymmetric algorithm and its use. One of the common question from the audience about asymmetric ...
5
votes
1answer
271 views

Most efficient key algorithm for a TLS server key?

Let's assume I want to setup a HTTPS service on a modern-but-no-so-speedy x86 server without any form of hardware cryptographic accelerator. Which key algorithm should I choose for the server key in ...
4
votes
2answers
1k views

Shared Secret, is it a public key or a private key?

Reading the Diffie-Hellman non mathematical explanation i found that some mathematical operations are performed on private-key and the recipient's public key to generate a "shared secret" on both ends ...
4
votes
4answers
656 views

Is asymmetric encryption ever recommended for long-term storage?

Is asymmetric encryption ever recommended for long-term storage of data, is it advisable for example to store data in a database such that: 1) A user enters data on a website, it is encrypted using a ...
3
votes
4answers
897 views

Asymmetric crypto: Decrypt own messages without having private key

I have built a messages system for my website. Users can send the admin messages which are stored in the DB after being AES-encrypted. I think that using asymmetric crypto (RSA through openssl) ...
1
vote
2answers
4k views

Encrypting string in javascript and decryption in java

I would like to know if someone know any library to do encryption in javascript and decryption in java. I have already tried many API, But getting not not getting same values in java. I want ...
5
votes
2answers
2k views

What asymmetric encryption algorithms are in common use beside RSA?

I am looking for an asymmetric encryption algorithm other than RSA?
3
votes
5answers
10k views

Is there a simple example of an Asymmetric encryption/decryption routine?

I can understand Java, Perl and JavaScript code very well. The rest, I have not studied, but I guess I could figure out how to read/translate. I would like to know what the simplest of Asymmetric ...