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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4answers
402 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?
6
votes
1answer
691 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
votes
1answer
130 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
73 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 ...
1
vote
3answers
644 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
424 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
566 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 ...
1
vote
1answer
472 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
votes
1answer
149 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 ...
1
vote
1answer
655 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
253 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
124 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
210 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
87 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
307 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
81 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 ...
0
votes
1answer
142 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
957 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 ...
9
votes
5answers
2k views

Whenever an unhandled exception somehow makes it into production, is it safe, viable, etc. to print an encrypted stack trace to the end user?

Whenever an unhandled exception makes it into production somehow - whatever the reason - there's generally an option (especially with .NET programs) to print out a stack trace to the end user before ...
0
votes
1answer
52 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
242 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
182 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 ...
0
votes
0answers
154 views

RSA 4096 key size difference - “sig” and “sig 3”

Whenever I generate a new 4096 RSA key in my GPG program and export the public key to a text file, I get a text file containing a total of around 52 lines (it varies, one of them is 53 lines). ...
5
votes
1answer
1k 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 ...
1
vote
2answers
764 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
122 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.
0
votes
0answers
31 views

DTLS CertificateVerify doubt

In DTLS 1.2 RFC 6347, section 4.2.6: CertificateVerify and Finished messages have the same format as in TLS. Hash calculations include entire handshake messages, including DTLS-specific fields: ...
3
votes
2answers
203 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
39 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?
1
vote
0answers
624 views

OpenSSL: Bad Record MAC on TLS Heart Beat

I am trying to see the heartbleed bug in action with my OpenSSL server application. My server uses the OpenSSL library - openssl-1.0.1b I successfully connect with s_client (openssl-1.0.1b) to my ...
1
vote
0answers
149 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
71 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
119 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 ...
1
vote
0answers
797 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 ...
2
votes
3answers
137 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
votes
2answers
380 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?
0
votes
3answers
118 views

Cryptosytem Question [closed]

A file is encrypted and placed on a secure FTP server. An MD5 hash is taken of the file and also placed on the FTP server. A userlogs in to the server and downloads both files, however, the hash fails ...
0
votes
0answers
138 views

Gladman's file encryption library = AES in counter mode with HMAC-SHA1 authentication?

I would like to use Gladman's algorithm to create AES encrypted data in JavaScript. I use the Crypto-JS library, but its performance is horrible. PBKDF2 is terribly slow, so I switched to another ...
0
votes
1answer
76 views

Cryptographic Hash function [closed]

How can I implement a cryptographic hash function using the block cipher? I was wondering whether I can use AES in cipher block chaining mode to achieve this.
4
votes
1answer
155 views

Is there an actual use for OpenPGP authentication keys?

The OpenPGP specification (RFC 4880) describes, page 34, the different capabilities that an OpenPGP key may have; including: 0x20 - This key may be used for authentication. In GnuPG, one of the ...
4
votes
1answer
364 views

How would you know a certificate/private key if you extracted it from RAM? Or would you?

Related to, of course, the heartbleed vulnerability, I've been reading the news about the worst case scenario for this attack being the extraction of the SSL private key, because, of course, this ...
1
vote
1answer
279 views

How does CryptoDefense ransomware encrypt large data with a (relatively) small RSA key?

I recently encountered some news about the recently new Ransomware called CryptoDefense: it uses RSA 2048 to encrypt your valuables and offers the private key for a price. (It's already been solved ...
4
votes
1answer
103 views

Recommended symmetric key usage period

Let's assume that there are two nodes A and B connected over a network. Both have a single pre-shared symmetric key (e.g., AES-128) and exchange messages. What is the recommended period, until the ...
1
vote
1answer
513 views

What is default mode for AES encryption [closed]

What will be the default mode for AES encryption if we don't use any specific mode like ECB, CBC, OFB, CTR, etc. and just carry out the encryption without specifying any AES encryption mode.
1
vote
2answers
140 views

How can I analyze password recovery tokens?

All websites that support authenticated user interactions have a password recovery feature. Usually they will email the password reset link through which you can easily recover your account by typing ...
0
votes
1answer
156 views

Get PGP Private Key from RAM analysis RSAKeyFind

For an experiment, I'm trying to open a 2048-bit RSA encrypted mail on a image. Using this fresh image, I made a memory dump and analysed the dump for RSA keys. Now, several RSA keys have been ...
2
votes
1answer
248 views

PFS incentive during IKE Phase 2

I'm trying to see the actual point in implementing Perfect Forward Secrecy during Internet Key Exchange Phase 2, if it had already been used during Phase 1. Quoting the IKEv2 RFC: RFC 5596 ...
3
votes
2answers
160 views

What does the “period” of a random number generator measure?

What is "period" in the context of pseudo-random number generators? For example when someone says "The Mersenne Twister has a 2^19337−1 period" what does it mean? I would appreciate a simple as ...
1
vote
2answers
141 views

What are some examples of a block cipher's versatility over a stream cipher?

I understand that a block cipher can be made to act like a stream cipher at the cost of "losing versatility" of the block cipher for the sake of performance. I don't understand what I'd be losing. ...
-1
votes
1answer
453 views

Current Encryption Algorithms? [closed]

What are some encryption algorithms that are currently in use by secure websites, by operating systems, or by Secure USB thumb drive manufacturers. I am trying to do research on differences in speed ...