# Tag Info

## Hot answers tagged cryptanalysis

3

This is flawed: Cracking: The format leaks information on how often specific characters occur. For instance, if input message contains 6 o letters, there is likely much more 111 values than the most other values present. Such a small biases are sufficient for cryptoanalysis to break the message in many cases. Also, random.randint does not return random ...

2

A 16-bit cipher has $2^{16} = 65{,}536$ possible keys. Thus, if you try to decrypt your ciphertext with every possible key, that's how many different (and essentially random) plaintexts you'll get. Your calculation suggests that $\lceil2.46\rceil = 3$ bytes of ciphertext should be enough to uniquely identify the correct key, assuming that the plaintext ...

2

Yes, the Pseudo Random Number Generator (PRNG) in OpenSSL is Cryptographically Secure, which means it passes statistical tests, but as @Maarten Bodewes suggests in his comment, why not go one step further and use that PRNG directly, rather than through OpenSSL? OpenSSL can use EGD (which stands for Entropy Gathering Daemon). It is a process that taps into ...

2

Well, the previous answers assumed that you could ask for a single plaintext that consisted of multiple characters (possibly including the entire alphabet); I'll view it from the aspect of a plaintext consists of a single symbol. If the multiplication operation within the affine operation is integer multiplication (modulo the alphabet size), then it ...

2

In 2013, I visited the National Cryptologic Museum and researched/photographed the donated materials on the Chaocipher from the Byrne family. As it pertains to your question regarding the security of the cipher, it is true that while the original algorithm has been now been known for several years, to date no known cipher-text only decryption has yet been ...

1

Work factor is a more appropriate description because time factor is relative to processing power. Time factor, time complexity, computational complexity, and work factor, are used to describe the same thing. When someone says time complexity, they are probably not talking about actual time, but rather computation. Work factor would be something like "200 ...

1

For a (fixed-length) cipher to meet your first condition, it needs to be the case that it's no easier to guess the plaintext if you have the ciphertext than it is to guess the plaintext without the ciphertext. Now, suppose I send a random 1024-bit string XORed with $G(k)$ for some 128-bit $k$ and computationally secure $G$. The probability that my message is ...

1

No. One of the most important principles of cryptography is that knowing the encryption scheme cannot help someone attempting to decrypt the material without the key. The encryption used seems to be a reasonably well-written implementation of several standard algorithms, for which no practical attacks are known. Finding a way to crack these would be a major ...

1

Apple's RNG is cryptographically secure, provided it has had enough time to gather entropy. The early PRNG, though, was found to have problems in the iPhone as recently as iOS7, according to a researcher from Azimuth Security. I have not heard of any problems regarding the SecRandomCopyBytes() routine for a regular app, and there are lots of eyes on it.

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