Questions tagged [rc4]
RC4 is a fast and simple stream cipher used correctly in SSL and incorrectly in WEP.
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MS CryptoAPI RC4-1024 vs AES-128?
I'm trying to figure out MS CryptoAPI to generate a symmetric key on one computer then an RSA key on another, send over that public key to use to export the symmetric key to that other computer. I'm ...
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Question about the key in RC4
I am planning to develop a more secure version of the RC4 algorithm. Since I´m not an encryption expert, I´ld like you to help me find answers to the following questions:
Does the value of the key ...
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How do attacks on WEP work?
There is an abundance of tools and tutorials on how to break WEP encryption. However, I fail to find a nice resource that gives a clear break-down of why the attacks are possible. For example, I know ...
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Combined message separation?
I have two ciphertexts, I suppose that its RC4 with reused key. I have XORed both ciphertexts and obtained message containing combined cleartexts.
I suppose that the underlaying messages are written ...
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Can you help me understand how RC4-52 is done using 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.
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Books about stream ciphers
I am new to ciphers and for my assignment i have to implement a stream cipher algorithm without libraries (on my own). So my question is: Does anyone know about any GOOD books which have examples and ...
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Does RC4 continue to be used anywhere?
RC4 in TLS is now broken. But the breaking seems to have a lot to do with how web transactions work in general. Is there any application outside of the web where RC4 is still used? I know that WEP is ...
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Is it secure to use ciphertext feedback with RC4?
Consider the following modification of RC4 to give some "ciphertext feedback"
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RC4 system pitfalls
A system fell into my neck, where lots of files are splitted into several segments and encoded via RC4. RC4, because client side - slow computer, slow flash arithmetic ops - can only decode big blobs ...
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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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RC4 - Key scheduling Algorithm
I'm trying to understand the KSA algorithm of RC4 which apparently scrambles the array which will later be used by the PRGA to generate the keystream. My question is, does the seed used by the KSA ...
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Are Two Ciphers Better Than One? i.e. RC4 and AES
OK It's cringe time (or hopefully not)
I know this is probably a variation of an old and dragged out question or so you may think but let me ask away and hopefully get some insight.
Google a while ...
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When is AES chosen instead of a stream Cipher (e.g., RC4) during an SSL connection?
During an SSL handshake, the browser sends a list of cipher suites to the server, from which the server selects one option.
For data encryption, two of the several possibilities for the ciphers in ...
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RC4 Klein (or other) attack susceptibility question
What issues do yall see with the following in terms of key recovery and related key attacks:
RC4 used to "sign" a nonce:
3 byte nonce concatenated with 16 byte long term key > RC4 ...
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Two or more initialization vectors with the same key
I'm studying about WEP and I'm in doubt.
It seems that because it uses a initialization vector of 24 bits, which is relatively short, is easy to determine which key was used to encrypt the data.
But ...
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1st round attack on rc4
I'm trying to implement the 1st round attack on RC4 stream cipher according to Attacks on the RC4 stream cipher. For now I am interested in section 4.2 Attack on other key bytes. It works really fine ...
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Extracting RC4 and 3DES keys from system memory
I have read papers [1], [2] that have presented techniques on extracting symmetric encryption keys from memory during the process of encryption. There are tools [3] that can extract AES keys from ...
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Recovery of RC4 key when S-box 0 stage or 1st stage known
I've been exploring around, trying to understand if such thing is even possible. I have some RC4 ciphertext which I know it's plaintext and I would like to extract the key just from cipher and ...
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Difference between RC2, RC4, RC5 and RC6
Can anyone point out the core differences between these ciphers?
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How should I treat a new cipher release like Spritz?
I have been looking at both the paper as well as the sourcecode of Spritz — a spongy RC4-like stream cipher and hash function by Ronald L. Rivest and
Jacob Schuldt.
The paper states
We have also ...
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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.
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Attacks against RC4 when index $i$ is unknown
RC4 uses two 8-bit indices. One, $j$, is key-dependent and secret, and the other, $i$, increments by one for each byte output. The $i$ index is typically considered to be public, but what if the RC4 ...
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Is RC4 cipher just xoring plaintext with a random sequence seeded by key?
After reading about RC4, it seems that it's nothing else than:
the plaintext stream is just XOR'ed with a pseudo-random sequence that
is initialized/seeded with the key
Is there something else in ...
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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 ...
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I need a simple cryptographic code to put on a t-shirt
I never worked with cryptography but I wanted to add an easter egg on the design I'm making for a t-shirt. I need it to have a key that will be embroided on the front design wich is:
15122017
that ...
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How should k2 be produced in the RC4A stream cipher (A modification of RC4)?
RC4A is a slight modification of the simple RC4 stream cipher designed to strengthen it against a number of attacks. Here's that paper.
However in the paper, the second key ...
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If two hosts are using a transparent IP level authentication and encryption, is their communication subject to both MITM or replay attacks?
Encryption process for any outgoing packet to the specified "remote IP":
-original payload P is encrypted (the bytes after the IP header) using RC4 with the preestablished key ...
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Why Distance-128 relation in Plain texts is reflected in Cipher texts
The two text having relation as "\x10\x11" → "\x90\x91" (80+10) will have relation after encryption/decryption also in RC4. Following code clearly describes the problem I am mentioning.
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Randomness Test of Permuted Sequence
As we can generate a permuted sequence using KEY in KSA (Key Scheduling Algo) of RC4. Is there any way to check the randomness of the permuted sequence?
Let say I created 100 different permuted ...
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Understanding a security error with RC4 using the same key to encrypt on the client/server sides
This apparently was a bug with WhatsApp a while ago. I am endeavoring to recreate it and understand it.
The bug had to do with the fact that the same key was used to encrypt plaintext on both the ...
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RC4: Find the complete plain text of a ciphertext when we know part of the plaintext
I need to decrypt an encrypted file with RC4 to answer to a Internet challenge.
The file in question is a dump of a Teensy ROM and it is completely encrypted.
Luckily, it looks like it's a standard ...
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WEP: Why is the challenge string randomized?
In WEP, the 128-bit challenge string generated by an access point would allow for approximately 340 undecillion unique strings. Would it be problematic were a string to be reused? I suppose with $2^{...
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Mitigating weaknesses in RC4 [duplicate]
I've been researching RC4 and implementing it, and I was wondering, from the perspective of a cryptographer (a real one, not a fake one like me), what could be added to the RC4 algorithm to improve on ...
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Are there known practical attacks on RC4-dropN? [duplicate]
RC4 is known to leak information about the first few bytes of the ciphertext due to keystream biases.
However, are there known attacks on RC4-drop[N] where N is large enough, that leak information ...
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How to calculate LOW(b) and HIGH(b) in spritz cryptography
I try to implement spritz cryptography like this paper . But I don't know how to calculate LOW(b) and HIGH(b). In paper page 7.
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Is TLS_RSA_WITH_RC4_128_SHA still a secure cipher to use? [duplicate]
I have read numerous times that the RC4 cipher itself is considered broken in TLS. Still many websites are using the TLS_RSA_WITH_RC4_128_SHA configuration even to date.
Now, I know that sometimes ...
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What RC4 key value will completely invert $S$ after initial permutation?
What RC4 key value will completely invert $S$ after the initial permutation, so that $S[0] = 255, S[1] = 254, …, S[254] = 1, S[255] = 0$?
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How much stronger is RC4 if it is keyed with an RSA private key?
My idea is to generate a RSA 2048 bit key and use RC4 with the private RSA key to encrypt a stream of data. RC4 is weak because RC4 keys are small, 256-bit. But when we use RC4 with private RSA 2048 ...
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Does ssl_rsa_with_rc4_128_md5 have known weaknesses?
My bank's website uses HTTPS with the cipher suite ssl_rsa_with_rc4_128_md5.
What are the known weaknesses of this suite? Do they have a practical impact for ...
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RC4-40 with IV (32-bit) setup
I have taken this implementation of RC4 written in C.
I have 40-bit key and 32-bit IV (both in hex).
So, questions is about KSA step:
How should I transform hex key value into the char array? Just ...
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Is the RC4 KSA the same as an extractor?
I am studying the RC4 stream cipher, particularly when it used to be applied in the TLS/SSL protocol.
Is it safe to say the KSA acts like an extractor taking in the shared secret key, k (between ...
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Encryption Algorithms in Verilog code
Can we implement Encryption Algorithms like RC4,AES and DES in Verilog? if no what are the limitations?
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Why are des-cbc-hmac and rc4-hmac-exp considered weak in kerberos?
Kerberos uses des-cbc-hmac (mac and encrypt) and rc4-hmac-exp based on md5 (mac and encrypt I think) in their encryptions.
Those encryptions are considered as weak and should not be used. Why are they ...
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What authenticated encryption do kerberos use in windows?
I have learned about the kerberos protocol and seen that the windows version uses a couple of authenticated encryption schemas (like rc4-hmac-md5).
What type of authenticated encryption is it? Is it a:...
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RC4, finding key if we know plain text and ciphertext [duplicate]
Having plain text A , and cipher text B. Can we somehow retrieve key , when we want to decrypt text C which was also crypted with the same key?
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Is it possible to calculate key(0) and key(1) of ZipCrypto using key(2)?
Here is Zipcrypto decryption algorithm:
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Secure symmetric cryptography for low memory/CPU systems
I am looking for symmetric cryptography algorithms that can be implemented on chips with very few resources (about 256K RAM and 16MHz CPU).
An algorithm that works perfectly in this environment is RC4,...
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How can I decrypt an RC4 encrypted text when knowing the first 8 characters of the plain text secret?
I'm having difficulty decrypting a secret message as a part of a CTF and I was wondering how could I decrypt an encrypted text that has been encrypted with pycrypto RC4 and when the first 8 characters ...
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RC4: Known plaintext key, unknown key derivation
I am working with an older piece of software that generates encrypted backups that I'd like to decrypt. I have a plaintext key, a few examples of encrypted data and I'm pretty sure the data is ASCII, ...
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Incremental RC4 algorithm?
I am currently analysing a client-server application which apparently uses RC4. I've got the secret key and nonce and I was very surprised about the approach they encrypted the packets.
Since I am no ...
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