Cryptography is the practice and study of logical means used to achieve information confidentiality, integrity and authenticity. It covers, among other things, encryption (making some data unreadable except for those who know a given secret element, called a key), data hashing (in particular for ...

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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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423 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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1answer
453 views

ECDH and Forward Secrecy

I just read about ECDH and while getting a overview over the process, I noticed that this key exchange method does neither provide any forward secrecy, nor does it protect against replay-attacks, ...
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2answers
724 views

Symmetric or asymmetric encryption for JSON Web Token?

We're planning on using JSON Web Tokens (JWT) for our authentication server, and I am currently evaluating which encryption approach to take for the JWE token. There appear to be two options for ...
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2answers
422 views

How can i calculate the number of possible passwords?

I have found a flaw in a site where the password reset feature resets passwords in the following format UpperCaseLetter-Number-LowerCaseLetter-Number-LowerCaseLetter-Number-UpperCaseLetter ...
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4answers
1k views

Is there a length beyond which increasing password length provides no additional security?

Assuming that the password is stored hashed and salted, and that it is a string of random characters, is there a point where adding to password length doesn't add security? Since the hash will have a ...
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1answer
57 views

Parameters in output of password hashing function

A number of encryption functions include their tuning parameters in the output. For example, SCrypt, which I've been considering for an app I'm building, outputs in the following format: ...
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2answers
8k views

Why are GPUs so good at cracking passwords?

What is it about GPUs that lets them crack passwords so quickly? It seems like the driving force behind adopting good key-derivation functions for passwords (bcrpyt, PBKDF2, scrypt) instead of ...
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1answer
2k views

Exchange of DEK and KEK (encryption keys) between app server and key server

In my application, it is required to encrypt a user's data before inserting it into the mysql database. I am using AES algorithm to encrypt the data using a 256 bit hash (and is calling it Data ...
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2answers
444 views

Does it make any difference of the order Hashing and Encrypting in terms of security?

I am implementing a password vault program with java. I have programmed a triple DES for encryption and a SHA256 for hashing. My question is would it make any difference if I first hash the raw data ...
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3answers
158 views

Cryptography key gathering tool

I am wondering if there exist a tools which can return the value of the one of the private key if the following are known: 1) Encryption Algorithm 2) Public key 3) Plain text 4) Cipher text Or may be ...
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1answer
1k views

Why do PGP master keys only have a single subkey, and tie certification with signing by default?

After learning more about PGP subkeys and how to split apart the roles of (S)igning, (E)ncryption, (A)uthentication and (C)ertification, I discovered that in most cases(?) a default master key has a ...
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2answers
162 views

Many-time pad on image data, how to proceed?

I have raw image data that is XOR-encrypted with a fixed-size one-time pad repeated over the length of the image. I know what the format of the image data container is so I can successfully retrieve ...
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1answer
150 views

Security and authentication problem

We have a sample scenario and we would like to receive some feedback and some solutions regarding possible security schemes. First of all, lets imagine a real world scenario: Imagine that a user ...
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1answer
3k views

Will double encryption increase the security of cipher vs bruteforce?

Lets say, I have a function encrypt(mes,key) where : mes = message key = key Length of key is 64bits. Lets say, that only way to crack my cipher is brute force attack. If I use ...
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8answers
1k views

Is advanced mathematics relevant to security beyond cryptography?

Short question. The title says it all... is advanced mathematics (i.e. beyond the classic college level calculus sequence) relevant to any field of computer security besides cryptography? By relevant, ...
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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 ...
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3answers
303 views

Can encryption twice with two keys in different sequences lead to the same result?

I am looking for an encryption algorithm for one of my current papers. The basic requirement is that, suppose I have two keys k1 and k2, and the E(k1,t) means encrypt t with key k1. Are there any ...
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2answers
290 views

How high is the entropy of this salt-generating code? (No code-reading actually necessary)

What is the best method? Assumption: I have a function that generates a number of medium-high entropy bytes Step1: I generate 3 of these medium-high entropy bytes. Step2: I hash these bytes using a ...
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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 ...
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5answers
18k views

Cracking CISCO ASA Passwords

I've got a copy of a Cisco ASA config and i want to crack the following example passwords I've got the following lines in the config ASA Version 8.4(2) ! hostname ciscoasa enable ...
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2answers
181 views

Ethernet security

I have a simple question that many people probably have and yet there does not seem to be a topic on this. I am visiting a company for a meeting and I have my laptop with me. This company is our ...
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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 ...
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5answers
720 views

The security level in hash function

What is the difference in security between using part of message digest hash function or all the message digest hash function? and is there any equation can calculate the security for part or whole ...
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2answers
556 views

Is it reasonable to prevent timing attacks by using fixed processing time

I have systems that perform cryptographic operations within a SSL/TLS tunnel. My concern is that I may leak timing information when encrypting, decrypting, or hashing. Part 1 Is it a good idea to ...
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2answers
178 views

Securing Time Sensitive Data

I have a number of time sensitive, embargoed pieces of information that I need to distribute over the Internet and have received at a precise time. I'm currently dealing with the problem by uploading ...
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1answer
589 views

sha-512 vs sha-3? [duplicate]

Does the new SHA-3 Keccak hashing algorithm offer any benefits from SHA-512? "Even worse, none of the SHA-3 candidates is significantly better. When SHA-3 is announced, I'm going to recommend that, ...
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2answers
3k views

Why does OpenSSL not include AES-256-GCM? [closed]

I'm trying to implement AES-256-GCM in Ruby. Ruby's OpenSSL wrapper library and aead library both clearly seem to believe that OpenSSL itself supports this. However, neither 0.9.8r (which I had ...
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4answers
370 views

Is using the md5 hashing algorithm as method for authorization in an HTTP POST request unsafe?

I am creating a page on a website that will show a user some authorized information from another website, and that website uses a combination of the user's user-number and a secret passphrase hashed ...
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1answer
100 views

Securing the SOAP Messages

One of my clients wants to encrypt few sensitive information which will be transferred through webservices / SOAP. My client has the following suggestions: Encrypt the sensitive data with AES ...
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1answer
1k views

aes cfb 128 decryption /encryption problem between Erlang and PHP

Update 2 - it works Thanks to Tom Leek for his answer. The CFB mode of mycrypt for Rijndael uses a 8-bit feedback loop and not a feedback loop the length of the key/iv. You have to force it to use ...
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3answers
386 views

Use of rainbow tables with the NY Times hack?

The NY Times recently published a story about how they were hacked during a four month period. The hacks allegedly were carried out by part of the Chinese military. One part of the story that ...
2
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2answers
146 views

Easy protocol for email authentication

I'm cooking up a very simple system to send commands to a remote server via email. Everytime an email is sent to do_something@mydomain.net, the server runs a python script that does something ...
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4answers
493 views

Can an attacker reuse stolen SSL private key to recreate that domain on his server

Say my domain (https://example.com) SSL private key has been stolen and was not protected by a passphrase then. Can the attacker uses that key and certificate to host the same domain on different ...
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2answers
926 views

What are the differences between ssh generated keys(ssh-keygen) and OpenSSL keys (PEM)and what is more secure for ssh remote login?

I have learned there are 2 methods to make SSH remote login easier and secure , those are; ssh generated keys (using ssh-keygen)OpenSSH Keys PEM (.pem) keys usually generated with OpenSSL (Amazon ...
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2answers
221 views

What is the best way to generate keys in phpseclib?

I am using phpseclib implementation AES and HMAC. But I dont know the best way to create random keys for these. What is the best way to do? Is there any built in function in phpseclib to create keys ...
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2answers
662 views

What is the difference between protocols and algorithms? [closed]

I am learning network security and I can't understand the boundary line between protocols and algorithms. Are algorithms the concrete realization of the protocols? Are protocols composed of several ...
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5answers
722 views

Is SHA-1 encryption?

I have read that SHA-1 is a cryptographic hash function. On an exam, SHA-1 was given as a possible one-way encryption algorithm. Does SHA-1 require a key as input? Is a key required to qualify as ...
2
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4answers
985 views

SSH: reusing public keys and known-man-in-the-middle

Usually, people recommend to use a single private-public key pair everywhere (if we're not talking about a possibility of compromising the private key): Best Practice: “One per-user ssh key” or ...
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3answers
150 views

Maintain sensitive key between requests

EDIT: Reworked question. Previous version too poorly asked. On my website users write sensitive messages that must be kept secret. The entire user area is over SSL, so the communication between user ...
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1answer
143 views

Tracking information on HTTPS connection

My organization uses cyberoam firewall. They are monitoring all activities including my search text in Google, Wikipedia etc. So recently i changed to HTTPS versions and now using HTTPS connections of ...
0
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1answer
386 views

Is TLS secure when full eavesdropping on the network occurs? [duplicate]

Possible Duplicate: How is it possible that people observing an HTTPS connection being established wouldn’t know how to decrypt it? Alice connects to Bob's site via a TLS secured connection ...
3
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3answers
559 views

Hash Function Xor

For a hash function what is the best secure method, XOR or Concatenate: h(data1 XOR data2 XOR data3 XOR data4) ? or use h(data1||data2||data3||data4)?
3
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1answer
124 views

Updating stored, encrypted containers on a server

My scenario is this -- I want to store an encrypted container on a network server. This encrypted container should be accessible to others to download and decrypt/mount locally provided they have the ...
5
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1answer
148 views

Detecting PRNG Use from Output

Question: Is there a way to detect the use of a PRNG strictly from observing the output provided by an application? Background: During an audit of a key generating algorithm that I knew was based on ...
2
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1answer
177 views

Kerberos realm understanding

Could someone summarise why realms are necessary in Kerberos and the advantages of the concept. I'm struggling to isolate everything I know / beginning to understand into some well defined points for ...
4
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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 ...
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2answers
304 views

Can I use hardware token OTP to stop piracy?

Our firm sells an offline desktop (.exe) software, we are thinking of using OTP (from hardware token like in internet banking) to stop people from copying the software without permission. Basically, ...
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2answers
2k views

how strong is AES without salt

The AES cryto library provided to us from company, does not generate a different encrypted value for plain text. If text is "abcd" , it will generate the same encrypted value over multiple ...
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1answer
288 views

Storing Private Keys Generated on Server with specific User's Password Securely

I am currently building a system (PHP Web Application Framework) that creates an RSA Key Pair for a user to allow other users to send secure information from one to another. The public key is ...