RC4 is a fast and simple stream cipher used correctly in SSL and incorrectly in WEP.
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4answers
5k views
Google is using RC4, but isn't RC4 considered unsafe?
Why is Google using RC4 for their HTTPS/SSL?
$ openssl s_client -connect www.google.com:443 | grep "Cipher is"
New, TLSv1/SSLv3, Cipher is RC4-SHA
Isn't RC4 ...
9
votes
2answers
251 views
Is RC4 a problem for password-based authentication?
This is a follow-up question to Does TLS use RC4-drop[n]?.
As mentioned in section 6 of RFC4345, there are weak distinguishers for RC4 keystreams available that even work for keystreams that ...
5
votes
2answers
91 views
How does one measure the decrease in security, if any, of RC4 when mapping to a specific range of values?
For a project using RC4, the output is to be mapped to values of 0 to 35. Thus, only 36 unique output values representing the letters A to Z and 0 to 9.
To avoid bias, the RC4 byte output (with a ...
5
votes
1answer
200 views
Does TLS use RC4-drop[n]?
According to many sources, the first few (n) bytes of the RC4 keystream are strongly biased, and therefore should be discarded before using the keystream to encrypt anything; this precaution is ...
4
votes
2answers
746 views
Is there a way to make RC4 (ARCFOUR) secure, or is it completely broken?
I need a method to authenticate a process with another in order to establish interprocess communication between them, to prevent malicious processes from trying to hook onto the system. Currently I ...
4
votes
2answers
810 views
RC4 Keylength Limits
While reading the Wiki page on RC4 I noticed that the key size must be in the range of 40–2,048 bits.
Why is that? Is there a reason it can't have a lower or higher length?
3
votes
2answers
115 views
Simple RC4 key generation scheme
I would like to ask you about your opinion on the following scheme of combining a master key and a nonce and stretching the result to the full 256-bytes RC4 key.
Master key $K_m$ is a pre-shared ...
3
votes
1answer
171 views
Does omitting the first two lines of RC4's pseudorandom generation algorithm weaken the cipher?
A particular educational software program published by a U.S. government agency uses a variant of RC4 to obfuscate its data files (see Stack Overflow question). The variant of RC4 in question is ...
3
votes
3answers
351 views
What is the PRG period of stream ciphers such as RC4 or Salsa20?
I am confused about how long a stream cipher can be used before you should change the key. To be concrete, let me use the stream cipher based on RC4 as an example.
Let's say I want to encrypt a very ...
3
votes
1answer
155 views
3
votes
1answer
166 views
Has there been any cryptanalysis of RC4-52?
Several websites ( such as Is there a secure cryptosystem that can be performed mentally? ) briefly mention RC4-52 as a modification of standard RC4.
RC4-52 has only with 52 instead of 256 elements ...
2
votes
2answers
148 views
How are constructs with data-dependent swaps and rotations cryptanalyzed?
Linear and differential cryptanalysis seem well suited for constructs with a (relatively) simple fixed structure of boolean expressions. But some ciphers incorporate swaps of array elements where the ...
2
votes
1answer
339 views
RC4 : Keystream reconstruction?
First, it's a step in some challenge found on the Internet, where we get an application and a file. The application must be feed with that file and a password (the password is the flag for the ...
1
vote
2answers
78 views
Can two rc4 encoded messages be XORed and decrypted if encrypted with the same key?
If I have the following:
E1 = RC4(M1, K);
E2 = RC4(M2, K);
If two different messages M1 and M2 are encrypted with the same key, K, can the key be recovered by ...
1
vote
1answer
59 views
RC4-52 by hand / pen-and-paper?
I've played a lot with VIC and enjoy its complexity and effectiveness as a field cipher . However RC4 has caught my attention lately and I've read there is a RC4-52 variant that can be done by hand.
...
0
votes
2answers
301 views
What is the time complexity of the RC4 encryption & decryption algorithms?
I'm trying to figure out what the time complexity of RC4 encryption & decryption algorithms is, in big-O-notation.
0
votes
1answer
230 views
0
votes
2answers
108 views
Do these 2 KSA shortcuts weaken RC4?
Alice securely gives Bob a secret key so they can exchange 10 different messages encrypted with RC4. (Messages will include a counter for uniqueness and a MAC for authentication.) For each message ...
0
votes
1answer
136 views
RC4 S-Box and Keystream
I'm studying the RC4 algorithm and I have the following questions:
On all questions assume that an expanded (2048-bit) key is used, and that the first 4096 bytes of the KeystreamIm are discarded.
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-1
votes
1answer
167 views
Because the algorithm is known, it is no longer a trade secret [closed]
In wiki about RC4 cipher they said,
Because the algorithm is known, it is no longer a trade secret.
Is that mean the cipher text will be more secure if the algorithm unknown to the attacker.
...
-1
votes
2answers
264 views
Double Encrypting with two different keys
In terms of security, would it be MORE or LESS secure to take, say, an RC4 output (or Serpent) or other, that is encrypted with one key, and to encrypt that output with AES (using a different key)?
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-2
votes
1answer
95 views
Why RC4 used constant 24bits for initial vector
Why RC4 used 24-bits constant value + 40 bits random values to generate key?
