# Tag Info

1

Elad Barkan has(Possibly had) a company called KeySee Software. In Elads's words: "KeySee supplies software for off-the-air interception of GSM communications, as well as consulting services for computer security and encryption." Knowing Elad, and the literature, I have every reason to believe they deliver what they promise. As others mentioned in ...

0

This kind of practical implementation will not be done typically by academic researchers and other open source researchers since the theoretical results, with enough practical details have already been published and are clearly indicating the weakness of A5. If it's done by government agencies for practical use it won't be published/advertised. And if some ...

1

Because a fixed and published permutation is known, linear and ever so reversible. It's very much like a bait & switch move, but without the switch(substitution). Security is built piecemeal from units of permutation & substitution(rounds). We can undo a singular publically published permutation, and it doesn't take any notice of a key(as it's fixed),...

1

On ECC, the private key is a value $k$ in the range $[0,q-1]$ where $q$ is the order of the group generated by a point $G$, with $q$ a prime number, and $Q = kG$ is the public key. The best known algorithm to solve this is Pollard's rho algorithm which runs asymptotically in $O(\sqrt{q})$. In your situation, part of $k$ is known, except the $72$ least ...

1

What is the difference between PKCS#1 v1.5 and PKCS#7? PKCS#7 makes use of cryptographic primitives defined by PKCS#1 v1.5. PKCS#7 is defined in RFC 2315. The modern PKCS#1 is v2.2 (also RFC 8017), and has a modern description of the schemes in PKCS#1 v1.5, including RSASSA-PKCS1-v1_5. Is verifying a PKCS#1 v1.5 signature the same as verifying ...

2

Is the following build stronger than 2DES or 3DES with 2 different keys (or even normal DES)? $DES(DES(x,k),\overline{k})$ It is only slightly stronger than DES; it is considerably easier to attack than 2DES or 3DES. The most practical attack against DES is brute force; simply try the various possible keys until you stumble on the correct one. With a ...

2

(too long for a comment) You can calculate $x_n$ directly by your formulas, if you know, how to calculate in a quadratic extension field of a prime field $\mathbb{F}_p$. Here is the code in python: # global parameters p = 65537 t = (p+1)/2 r = 313 s = 997 # from https://stackoverflow.com/a/9758173/99978 # modular inverse based on extended Euclidean ...

-1

It does not matter what encoding scheme you use for the message, as long as it is reversible: you should be able to recover the message from e. Assume you do not know $e$ or $R_x$ (the x-coordinate of $R$). You are given $$e \cdot R_x \mod p$$ For any possible message $e'$ that you could guess, there is some integer $n$ such that e'\cdot n \equiv e \cdot ...

Top 50 recent answers are included