XOR, often written ⊕, is one of the basic operations on bits and bit-sequences. It is a building block of many cryptographic primitives (and some higher-level algorithms, like modes of operations).
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With sufficient randomness, is XOR an acceptable mechanism for encrypting?
I have heard criticism of various cryptosystems saying that "at their heart, they were just XOR."
Is this just ignorance, or is there something inherently wrong with XOR based ciphers?
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Why Addition Mod 32?
I was looking at the algorithm for Twofish, and I noticed that in some places a XOR is used, but in others, they use "addition modulo-32." What makes modulo-32 special? Why not always use XOR? Why not ...
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How to break an arbitrary XOR and Rotation based encryption?
I heard encryption based purely on XOR and Rotation is inherently weak. The paper Rotational Cryptanalysis of ARX says:
It is also easy to prove that omitting addition or rotation is devastating, ...
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How can I find two strings $m_1$ and $m_2$, knowing that I know $m_1 \oplus m_2$? [duplicate]
Possible Duplicate:
How does one attack a two-time pad (i.e. one time pad with key reuse)?
I recently started to follow the cryptography class of Dan Boneh on coursera.org and the first ...
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1answer
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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 ...
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2answers
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Where is the proof of security of Diffie's cipher?
There is an apparently provably secure cipher that was proposed by Diffie, but enhanced by R.A. Rueppel. The scheme, which was mentioned in Applied Cryptography, works like this:
Measure the length ...
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3answers
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Stream cipher add instead of xor
In a stream cipher, the bytes of the plaintext are usually XORed with the keystream to produce the ciphertext. Would there be anything wrong with adding the bytes instead (with overflow), if adding ...
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2answers
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Is it a good idea to use bitwise XOR on a set of MD5 sums?
I have designed an SQL aggregate function in Oracle that bitwise XORs all MD5 sums of the values stored in a column.
For example, if my table is:
...
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1answer
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XOR cipher for encrypting compiled C code
I'm exploring ways of encrypting Intel hex files we send to customers for flashing onto an embedded device. The embedded processor itself has a built-in mechanism that prevents anyone from reading the ...
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1answer
120 views
What is the name of this kind of protocol
There is a communication protocol that I believe creates the equivalent of a one time pad, with the downside that the secret message must be transferred multiple times. The protocol is so simple that ...
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1answer
114 views
A set of key pairs and one hash to secure them
I have a simple problem: I have a set of users' ECDSA key pairs, and say I want to encrypt them with a simple algorithm. I have access to one variable that uniquely identifies the user, so I hash it ...
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Layered XOR Cipher
I am aware of the vulnerabilities of simple xor ciphers and recently I came across a block cipher that claims to solve those vulnerabilities.
The cipher goes as follows with both the block and key ...
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2answers
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Attack XOR encryption of binary data compressed by zlib with known key length (very short key)
I am trying to break a packet format. The packet format simply packs several files into one big file. The file contents are plain. But the index data which contain offsets, file sizes and filenames ...
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2answers
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one-time pad key related attack [duplicate]
In one-time pads we always say do not use same key twice to encrypt ASCII messages, but if we use a random key to XOR a random ...
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1answer
169 views
Can we replace the XOR operation in DES with some other operation?
Can we replace the XOR operation in the DES algorithm with some other operation? If so, does it work for both encryption and decryption?
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2answers
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Secure Hash Function based on AES
How secure would a hash function be which appends an extra block of 16 zeroed out bytes to the end of the message and then AES-encrypts it with a well-known password (say the first 128 bits of pi) ...
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1answer
483 views
Deciphering a key from XOR encrypted cypher using boolean logic
Assume there's an unencrypted message A, and an encrypted message B. You know that message B was encrypted using a simple XOR method of A with a private key K, resulting in message B. Thus,
B = A ⊕ K
...
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