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 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 ...
0
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1answer
106 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
64 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 ...
2
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2answers
89 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 ...
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3answers
101 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) ...
4
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1answer
107 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 ...
2
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1answer
224 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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2answers
84 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 ...
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1answer
78 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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1answer
105 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
107 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) ...
1
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2answers
91 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 ...
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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 ...
1
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2answers
141 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
125 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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votes
2answers
139 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 ...
4
votes
2answers
165 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 ...
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2answers
93 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 ...
1
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1answer
162 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?
5
votes
1answer
625 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 ...
0
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1answer
95 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 ...
0
votes
1answer
67 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 ...
0
votes
3answers
147 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 ...
3
votes
2answers
147 views

Is AES(Rijndael) faster than Blowfish?

I know theoretical that blowfish is much faster than aes. But I benchmarked several algorithms including aes and blowfish for 1MB, 5MB, 10MB etc. files in java 8 platform and bouncy castle library. In ...
3
votes
1answer
267 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
133 views

How do we estimate the time taken to crack a hash using brute force techniques

A German hacker famously managed to brute force crack a 160 bit SHA1 hash with passwords between 1 to 6 digits in 49 minutes. Now keeping everything constant (hardware, cracking technique - here ...
2
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1answer
88 views

Stream/Block encryption using XOR and Hash function?

Could a hash function like sha1 or ripemd-160 be used for secure key generation in a stream/block cipher? Obviously a repeated key like "abc123abc123abc123" would be bad, and a one time key pad would ...
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1answer
214 views

Safety of TrueCrypt hidden volumes

According to the documentation a hidden volume stays hidden because it appears as free space. In TrueCrypt free space always has random data in it, however in the case of a hidden volume it's not ...
2
votes
1answer
107 views

How secure is Vigenere cipher for random data?

Traditional situation It is easy to crack a ciphertext encrypted by Vigenere cipher, if you know the plaintext is in a natural language like English. There are two methods to discover the key used to ...
1
vote
1answer
40 views

Knowing Input&Output, How to determine encode method and the passkey that was used in encoding?

I've looked on this site and on SE. but I couldn't get a handle on this. Is there a way to find what type of encoding (and/or encode key) is being used? For example, I am testing a web ...
1
vote
1answer
93 views

Should I keep all UUIDv4 generated oAuth2 Bearer Tokens in my database to prevent an attack?

I generate oauth2 access and refresh tokens and store them in my database. I generate these tokens using UUID v4 and remove the dashes. I used to delete the tokens after they expire but now I store ...
0
votes
1answer
80 views

Public Key Authentication

Is there another way to verify someones public key without a CA signing it? A challenge-response authentication including some sort of UID of the smartphone? Smartphone A generates asymmetric key ...
3
votes
5answers
241 views

How does one know when a message is successfully decrypted? [duplicate]

How do people who decrypt encrypted messages know they have decrypted to the correct message? Do they just keep decrypting until the message is in English (or any other language), or is there a ...
1
vote
2answers
65 views

Symmetry meaning in cryptographic algorithms

When we refer to symmetry in cryptographic algorithms such as symmetric or assymetric does the symmetry refers only to the equality or not of the keys, or does it also refer to the symmetry of ...
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0answers
57 views

Asymmetric vs Symmetric Encryption Benchmarks

I have found these benchmarks in Crypto++'s site. http://www.cryptopp.com/benchmarks.html But I am, quite honestly, not entirely sure how to interpret them. I am really looking for a set of ...
1
vote
3answers
260 views

Why is RSA decryption slow?

I've been researching the disadvantages of using RSA for encryption, and one I've found repeatedly is that RSA decryption is slow, but I haven't seen an explanation as to why this is. Can anyone ...
0
votes
1answer
43 views

Is it safe to use the Keccak Algorithm to create the Key for a Serpent cipher?

I like to store some configuration but would encrypt them with the Serpent cipher. Is it safe to do this? When not, what is a better solution?
0
votes
1answer
175 views

Can I use crypto.getRandomValues to create a private key?

In the window.crypto spec: http://www.w3.org/TR/WebCryptoAPI/#RandomSource-interface It says explicitly: "Do not generate keys using the getRandomValues method. Use the generateKey method ...
3
votes
1answer
156 views

How to fix this broken crypto protocol?

I am considering a protocol where you upload a one time pad to a server, using public key encryption and then the result (using the pad) is sent back in plaintext: Alice uses Bobs RSA public key to ...
4
votes
1answer
354 views

Determine if private key belongs to certificate?

Given a certificate¹ and a private key file², how can I determine if the public key on the certificate matches the private key? My initial thought was to simply encrypt some text with the public key ...
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2answers
262 views

Are RSA 2048, ECDSA, and the SHA uncrackable in the sense that AES-256 is uncrackable?

The answer http://security.stackexchange.com/a/25392 has seemingly shown that AES-256 will not be directly cracked for at least the next 200 years (unless we manage to harvest the energy output of ...
3
votes
2answers
88 views

Crypto software: overwrite sensitive buffer

Is it common to implement crypto software in such a way that sensitive buffers are overwritten before free'ing memory? For example when they contain a private key or the plaintext message.
3
votes
2answers
123 views

What's a good time period before refreshing CSRF token of the user session?

I am using a form token to prevent CSRF attacks. Those tokens are stored and tied to a user's session. Now I want to refresh the token only every N minutes or hours so that the user's don't experience ...
0
votes
1answer
31 views

Is there a general name for this sort of cryptographic protocol?

Is there a general name for this sort of cryptographic protocol? If so what sort of assymetric/symmetric encryption functions tend to be used for this protocol?
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0answers
111 views

Storing private messages in a database

I am creating a portal where users can send private messages (PMs) for a very large audience. So I want to encrypt the messages and store them in the database. But I do not want to ask the users for ...
2
votes
1answer
61 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. ...
1
vote
1answer
93 views

Hashing password for secure storage (generating salt)

I wanted to check if the following means of generating a hash for storage of a password was secure. I have an username and password combo. In order to generate a secure hash, I am doing the ...
0
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0answers
266 views

Brute-Force/Dictionary attack against encypted file using PBKDF2 key derivation

I have been following this very useful post by Thomas. My use case is slightly different. I am developing a mobile application which requires some sensitive data to be stored on the device in a SQLite ...
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3answers
114 views

Decrypting Engima messages

Not really computer related, but I hope someone has the answer. How do people decode messages from an Enigma machine? I understand that if you knew the rotors, rotor positions, and plugboard the ...
4
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2answers
292 views

Is crypto.js vulnerable to heartbleed attack? [duplicate]

We are using 'crypto.js' in our application. Since 'crypto.js' uses open SSL ,are we vulnerable to heartbleeding attack? If yes, what can we do to prevent it?