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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How to hack someone ip address and remote control [on hold]

is it possible for hacking someone computer through ip address and remote control without permission that computer ,,, is there any software available for that , please tell me hacking tips
0
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2answers
32 views

What are the alternatives to ECDSA for an authentication protocol?

In an authentication protocol, S has a public/private key pair known to C, and S and C have established a secure channel (for example, using DH or ECDH, or any other key exchange protocol). C wishes ...
3
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1answer
191 views

Open source solution to capture and decrypt SSH traffic (with private key)?

I am looking for a free open source solution that is able to capture and decrypt SSH traffic given the fact that I can provide the server's RSA private key (something like SSH CryptoAuditor). Please ...
0
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1answer
33 views

Publicly Available API + Sensitive ID/Key Transmission Over HTTP

I've run into a predicament... I'm developing a mobile application that utilizes a server for various things. One portion is that it stores an id/key pair related to accessing and processing ...
2
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1answer
65 views

Bastion host that allows jailed users to SSH but protects private key

Basically, I'm trying to let the user use a private key without having read access to it. Use case: Employee needs to SSH to a server in the data center. There is 1 private key for all servers, ...
1
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1answer
162 views

Is my AES/CTR/RIPEMD encryption correctly implemented?

Below is my encryption implementation in PHP. It's based on mcrypt, and uses AES-128 in CTR mode along with a RIPEMD-128 HMAC for integrity checking. For brevity, I've inlined the functions for ...
7
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6answers
4k views

How would one fully protect himself against man in the middle-attacks?

Imagine I have a computer where all the trafic is being sent through the MitM. How would it be possible to have a secure connection through this setup? In this case it would be OK to design a new ...
2
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0answers
45 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 ...
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0answers
35 views

Generate a public key certificate signed by CA with OpenSSL [migrated]

I am working on a webservice that requires a signature in the sent and received messages. After sending a certificate request to the entity that will consume the webservice, they sent me (in addition ...
0
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1answer
88 views

Advice on using encryption and hashing

I'm going to rephrase a question I asked earlier, as I don't think anyone understood what I meant. Bascially I'm writting a web based password locker, which can have multiple accounts; so that users ...
0
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1answer
54 views

Securing a Shuffle Algorithm

After reading about writing a secure shuffle algorithm, I realized that my module that generates a password is only as strong as my PRNG, which in this case is Math.random(). I'm confused as to how to ...
0
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1answer
53 views

Using encryption and hashing

I'm writing a project to securely store and share passwords between users, I've been doing tons of research into encryption algorithms, CSPRNGs, hashing algorithms, key stretching etc... I just want ...
171
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7answers
122k views

RSA vs. DSA for SSH authentication keys

When generating SSH authentication keys on a Unix/Linux system with ssh-keygen, you're given the choice of creating a RSA or DSA key pair (using -t type). What is the difference between RSA and DSA ...
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3answers
85 views

When do governments allow export of cryptography software?

I see this notice in the TextSecure README: The U.S. Government Department of Commerce, Bureau of Industry and Security (BIS), has classified this software as Export Commodity Control Number (ECCN) ...
5
votes
1answer
96 views

How are chosen plaintext attacks against ECB implemented in the real world?

Reading up on attacks against AES i have seen countless examples of why ECB is bad, and the logic behind it i can understand, but i can't get my head around how these attacks actually work in the real ...
4
votes
2answers
135 views

How widely deployed is TLS with cipher ECDHE?

Microsoft deployed a patch for Windows 2012 R2 and Windows 8.1 that adds the following ciphers. Cipher suite Exchange Encryption Hash TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 DH ...
103
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8answers
7k views

Why are salted hashes more secure?

I know there are many discussions on salted hashes, and I understand that the purpose is to make it impossible to build a rainbow table of all possible hashes (generally up to 7 characters). My ...
2
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1answer
96 views

adding certificate that resides on smartcard to the microsoft store with private key ownership

how can we solve CryptAcquireCertificatePrivateKey fails with 0x8009200B when adding certificate from smartcard to local user store? in an enrollment system where users generate smartcard certificate ...
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3answers
77 views

Java AES encryption output length

I am trying to encrypt few database columns (string values) using Java AES algorithm. This is to protect certain sensitive data. For some users these data should decrypted. In Java AES encryption, if ...
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2answers
79 views

RSA-Based Signature Algorithms

From Beginning Cryptography with Java - chapter 4, digital signatures: Signatures are created using the RSA algorithm by applying the RSA algorithm using the private key and then distributing ...
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3answers
427 views

Protecting data through an XOR operation with sufficiently long keys

Suppose two parties S and D would like to protect a communication channel. Therefore, S and D exchange two sufficiently long key sequences SB und DB of random bits over a secure channel [e.g not over ...
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2answers
56 views

Some questions about crypto

How to determine what type of encoding/encryption has been used? This link discusses in the first answer a "128 bit" value. How do you know that it is 128-bit and what is a 128bit value? If I md5sum ...
0
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0answers
13 views

Is either brainpoolP320r1 or brainpoolP320t1 a SafeCurve? [migrated]

Not all elliptic curves are safe to use for cryptography, especially from an ECC safety perspective. The site http://safecurves.cr.yp.to/index.html shows that two tested Brainpool curves, ...
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1answer
154 views

Requiring 2 keys to access a content

I need to use an external service that can only be accessed by password. I don't like the idea of storing the plaintext password on the server, but AFAIK there's not much I can do. Considering this ...
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1answer
73 views

What keeps the private key safe if an attacker has both clear and encrypted copies of a message and the public key?

Let's say someone obtained a message in both clear text and in its encrypted copy with asymmetric cryptography, like RSA-2048. He also has the public keys. Is the private key still undiscoverable? ...
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2answers
3k views

Recommended Cipher Suites for TLS 1.0, 1.1 and 1.2

There are a lot of cipher suites defined in the in the specifications itself of TLS 1.0, 1.1 and 1.2. And furthermore, there exist RFCs which add even more cipher suites to a specific version (e.g. ...
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1answer
49 views

X509Certificate - How to set validation Policies?

I have an X509Certificate (say Certificate-A) for signing purpose. While validating this certificate, I have to check its path with Intermediate & Root certificate which I have implemented fully. ...
4
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3answers
339 views

comparing password hashing algorithms - PoC ideas?

OK so I just started working for a security consulting firm and we recommend SHA 256 (with salt) for password hashing because MD5 is too weak. I have read some brilliant answers (the list is too ...
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1answer
97 views

What are the enhancements of SHA1 compared to MD5?

I am looking for enhancements of SHA1 when its compared to MD5. But I am not talking about just heap sizes. I am talking about different enhancements than heap size. Also, I think md5 is faster than ...
2
votes
1answer
94 views

What cryptosystem makes the encrypted text look like random noise?

Suppose one wants to setup a cryptographic protocol in which 2 parties communicate using an encryption scheme that produces encrypted messages indistinguishable from random data (the desired property) ...
8
votes
1answer
838 views

Describe an example of indistinguishability obfuscation or functional encryption

As described in Perfecting the Art of Sensible Nonsense, a major breakthrough in cryptography research was published in the summer of 2013: Candidate Indistinguishability Obfuscation and Functional ...
1
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2answers
84 views

Expiring AES Key

Is there any way to make an "expiring" AES key? Here's scenario to give a better picture: Say Bob has some data which he would like to share with Alice. Alice has a public and private key, let's say ...
0
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0answers
13 views

How to get system-wide use of Intel's AES-NI acceleration with OpenSSL 0.9.8? [migrated]

I found the following instructions to get Intel's contrib OpenSSL 0.9.8 engine code on some Westmere-based systems that we have: $ wget https://www.openssl.org/contrib/intel-accel-1.5.tar.gz $ tar ...
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0answers
34 views

is collision attack possible on md5 if message is known partially [migrated]

Is it possible to find m' such that md5(m'+m1)=md5(m1+m2) if i know m2 and md5(m1+m2) ? is this a collision or pre-image attack. Also in this case is it possible to find m' and H such that ...
22
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6answers
17k views

Most secure password hash algorithm(s)?

What is/are currently the most cryptographically secure hashing algorithm(s)? (available in PHP) Speed is irrelevant, because I'm iterating the hash over a fixed time (rather than a fixed number of ...
1
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2answers
131 views

Is cryptography possible without volatile memory?

AFAIK, our current disk encryption methods (dm-crypt) preserve the key (as well as decrypted data) in RAM while the computer is running with an implicit assumption that the memory is volatile and key ...
1
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2answers
122 views

What is DVNC and how does it work?

As stated on their website: DVNC is not encryption but is a new branch of cryptography and information science. DVNC employs a new paradigm in secret keeping to keep your data secured. I ...
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0answers
24 views

How digital certificate works? [duplicate]

I am trying to understand the digital certificate concept , but I am confused , Below goes my understanding & question, We are using Digital certificate because if Bob & Alice share their ...
3
votes
1answer
533 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, ...
17
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6answers
5k 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 ...
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votes
2answers
133 views

If md5 is only insecure because of its speed, why doesn't this workaround make it reasonably secure?

I'm going to preface this by saying I have absolutely no clue when it comes to cryptography, but I'm posting this question because I'm very interested and I have no doubt there are some smart people ...
9
votes
3answers
870 views

HMAC Based Request Signing - Storing the Salt

I'm working on a (non high security) project that currently isn't live but might go live at some point. We have a REST API (implemented using Restlet and Neo4j) running on a server and an Android ...
1
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1answer
138 views

Why do you need a 4096-bit DSA Key when AES is only 256-bits?

This is something which I have been wondering and trying to find an answer for, but yet to come even remotely to one. Why do you need a 4096-bit DSA/El-Gamal key when AES uses only 256-bit keys?
67
votes
3answers
9k views

Is a rand from /dev/urandom secure for a login key?

Lets say I want to create a cookie for a user. Would simply generating a 1024 bit string by using /dev/urandom, and checking if it already exists (looping until I get a unique one) suffice? Or should ...
5
votes
1answer
613 views

What's keeping a malicious man in the middle server from forging a valid certificate

According to process of authenticating a server certificate: What's keeping a malicious server to fill up a valid server certificate since it knows all the things: Forged Server public key (man ...
3
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6answers
2k views

Are there any “real world” implementations of secret-sharing encryption schemes?

Imagine something like TrueCrypt where user A can decrypt his files, or any 3 of the 10 directors in his organization can decrypt user A's files. As I understand it this is similar to the way the ...
0
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1answer
88 views

Understanding cryptography practically [closed]

So I am interested in computer security, cryptography and security protocols. Thing is, everything I read is about theoretical usage of protocols, but how do those things work in real world? Is there ...
4
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2answers
4k views

Confusing about Ephemeral Diffie-Hellman

1 Does Ephemeral Diffie-Hellman support authentication? Quote from www.rsa.com/products/bsafe/documentation/mesuite21html/dev_guide/group_EPH_DH.html Ephemeral Diffie-Hellman does NOT provide ...
38
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4answers
8k views

Why should one not use the same asymmetric key for encryption as they do for signing?

In an answer to a question about RSA and PGP, PulpSpy noted this: It is possible to generate an RSA key pair using GPG (for both encryption and signing -- you should not use the same key for ...
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1answer
62 views

Secure end-to-end when part of conversation must be over HTTP

We have a situation where a user's identity can be verified as follows: the network provider knows the identity of the user and injects secure headers into the HTTP request, which our servers can use ...