Tagged Questions

1
vote
1answer
78 views

Security of Salsa20 with some known plaintext?

Basic question- if I'm encoding a bunch of known filetypes with salsa20, will it still be secure if the plaintext header is known? Assume that a different IV and Key are generated before each file is ...
4
votes
1answer
199 views

repeating-key xor and hamming distance

I read that to break repeating-key xor you can do the following: try a keysize $n$ and compute the hamming distance between the first $n$ bits of the encrypted string and the bits $n+1$ to $2n$ of the ...
2
votes
1answer
53 views

Why constrain the message lengths in indistinguishability in the presence of an eavesdropper?

I need your help with a very basic concept in cryptography which I can't understand/prove on my own. I'm trying to prove and understand why, under "indistinguishability in the presence of an ...
6
votes
1answer
156 views

How would one crack a weak but unknown encryption protocol?

I asked a question on security.stackexchange, but was told it would be a better fit here: http://security.stackexchange.com/questions/32779/how-would-one-crack-a-weak-but-unknown-encryption-protocol ...
1
vote
1answer
53 views

What is total key space in transposition algorithms

How we can measure key space in transposition algorithms? Should we specify the method, like rail fence ?
5
votes
2answers
127 views

Security of tokenization of plain text conversations - cryptanalysis

I came across a marketing video here. They claim to perform AES encryption and tokenization of sensitive data, at the corporate gateway, before it leaves the company firewall destined for the public ...
4
votes
1answer
136 views

Question about why RSA is hard to attack

I think I understand why RSA is hard to attack but I'd like to get clarification if I actually do. Assume there are two people, Alice and Bob, who are attempting to communicate privately but that we ...
-2
votes
1answer
91 views

ASCII Message in TV show? [closed]

So I was watching a popular series tonight (Person Of Interest) when suddenly during a frame change I noticed a very quick blue screen with writing. At the time I never thought anything of it as it ...
4
votes
1answer
101 views

What is 'security margin'?

I have been academic papers about Rijndael, Serpent, and Twofish, and there is this term that is vague to me. I cannot find a tangible definition in google. Can someone briefly define, describe, ...
0
votes
0answers
47 views

How compute encrypt and decrypt runtime for agorithm [closed]

I programming RSA algorithm is the following two function in java language in my thesis ...
0
votes
0answers
47 views

How compared encryption algorithm in terms of efficiency

I doing to compare two algorithm cryptography. first algorithm is RSA cryptography and second algorithm is El Gamal elliptic curve cryptography. now I want a way to compare between two algorithm by ...
-2
votes
1answer
321 views

Is a steganographic technique which has a universal decoder novel/secure? [closed]

I've come up with an approach to steganography which needs review of both its cryptography and its math. There's a complete working implementation at https://github.com/bramcohen/DissidentX and the ...
1
vote
1answer
158 views

Is there a security analysis of CryptDB?

Its interesting to see critical thinking being applied to cryptDB in contrast to all the hoopla around it here . cryptDB is not a major theoretical breakthrough but potpourri of technologies to make ...
0
votes
0answers
81 views

How to encrypt OpenVPN setup traffic [closed]

I have an OpenVPN server and a client that can successfully connect to said server. The traffic over the tunnel is encrypted. The tunnel works quite well. However what is NOT encrypted (cleartext) is ...
0
votes
0answers
64 views

Need help with student project about IT security [closed]

I've been studying in university for computer security for 4 years. All students have to make a course project by the end of year. And I have some problems with it. I need help with the project's ...
20
votes
4answers
2k views

Is AES-256 weaker than 192 and 128 bit versions?

From a paper (via Schenier on Security's Another AES Attack) (emphasis mine): In the case of AES-128, there is no known attack which is faster than the 2128 complexity of exhaustive search. ...
1
vote
1answer
291 views

AES encryption for images [closed]

Why AES based encryption is not recommended for encrypting images with high redundancy in their content? for example, the encryption of an image which shows a bird in the blue sky. Most of the pixels ...
1
vote
3answers
217 views

How to encrypt data and know it will be secure for at least a few decades?

I want to encrypt a small amount (few kilobytes) of data and be fairly confident it will be secure against brute force decryption and advances in cryptanalysis for at least a a few decades (or more). ...
7
votes
4answers
1k views

What is the effect of the different AES key lengths?

How does a changing key length affects the ciphertext, not only in case of AES, but in general? I know that the key spaces become much larger and the number of rounds in case of AES changes, but is ...
0
votes
1answer
319 views

How to hack the new save encryption on ipad for uplink? [closed]

The new iPad version of Uplink appears to be using some new saving mechanic than the PC/Mac Version. Macs and PCs use 'RedShirt' but the iPad appears to instead be using 'SAV62' at the start of saves, ...
1
vote
2answers
160 views

Brute force a ciphered message?

I wrote my own cipher to encrypt messages. I would like to test a sample ciphered message to see how strong it is. Are there any tools for such task either in Windows or Linux ?
4
votes
3answers
205 views

Comparison: complexity measures vs. security

Assume that you want to compare several cryptographic primitives (say, encryption schemes), and choose one. You need to consider several complexity measures, such as the key length, encryption time, ...
3
votes
1answer
322 views

Does the Biclique attack on AES pose a credible risk to its security?

I have heard a lot about the biclique cryptanalysis research on AES, which as far as I know is the closest anyone has got to breaking AES. Exactly how close did they get? Does this attack propose a ...
2
votes
2answers
701 views

How can I do a brute force (ciphertext only) attack on an CBC-encrypted message?

Given a CBC ciphertext and IV, how can I find the encryption key? We are limited with an 8 chars key, each char in the range of [a..h], so I can generate every possible key (these are only $8^8 = ...
6
votes
4answers
485 views

Is compressing data prior to encryption necessary to reduce plaintext redundancy?

As explained in William Stallings' Book, in PGP encryption is done after compression, since it reduces redundancy. I couldn't relate encryption strength with redundancy. Could anyone explain more on ...
0
votes
0answers
46 views

Elliptic curve Cryptography [duplicate]

Possible Duplicate: Can we use elliptic curve cryptography in wireless sensors? How to map message character to point lies on Elliptic Curve? how to ecc used in wireless sensor networks? ...
8
votes
3answers
446 views

What is the best way to put a backdoor in an encryption system?

How can you put a backdoor into an encryption algorithm? Are there any techniques that can be used to reduce the time it takes to break a key? I am looking for practical examples encryption schemes ...
0
votes
0answers
109 views

What will be the way to go about deciphering this kind of cipher? [closed]

I've come across this cipher and have tried unsuccesfully to decipher it. http://codepad.org/aea7Wuyl The only 'hint' that I have gotten so far as to how I am supposed to crack it is the word ...
6
votes
3answers
2k views

Encryption/ciphers/codes in Chinese

I am quite curious as to how you can perform simple encryption for the Chinese language. Saw a similar question related to encryption/Chinese here: About cryptography in a character language, ...
1
vote
0answers
76 views

Two untrusted party want to exchange data: how to ensure each one gets the data it needs? [duplicate]

Possible Duplicate: Two untrusted party want to exchange data: how to insure each one gets the data it needs? I am trying to come up with what could maybe be a novel algorithm for an ...
2
votes
2answers
596 views

How can I break REDSHIRT / REDSHIRT2 encryption?

Recently, a user on Gaming.SE asked a question about whether the user password in the video game Uplink could be modified after being initially set. The game does not contain an option to change the ...
1
vote
1answer
449 views

Verilog simulation of Data Encryption Standard

I interested in developing DES(in verilog) for my college project.Can i get help in understanding the simulation results of DES encryption and decryption ? thanks in advance .
3
votes
2answers
646 views

Decrypting DES with decrypted and encrypted data

I got two 8 bytestrings One which is decrypted is: FF FF FF FF FF FF FF FF and one which is encrypted is: 16 05 78 B0 0A C2 78 7F Encryption mode is CipherMode.ECB I need the key used in DES ...
5
votes
1answer
261 views

If the PSK is known, is it possible to decrypt traffic from other clients in a WPA2 wlan network?

If in a public WLAN WPA2-PSK is used, but the PSK is more or less publicly available, does this mean that an attacker with that PSK can easily decrypt wlan traffic from/to other clients of that WLAN? ...
2
votes
2answers
153 views

Getting the encryption method and key from the encrypted data and the raw data

I have some pairs of plaintext and ciphertext data, from which I need to be able to decrypt the other passwords stored in the database. The password field typically contains something like ...
5
votes
2answers
853 views

How to attack a classical cipher using known partial plaintext?

I have a ciphertext generated by a classical cipher. I do not know what was cipher used to generate it. I do however have the beginning of the plaintext. What are the cryptanalysis approaches for ...