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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 ...


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(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 ...


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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 ...


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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),...


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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 ...


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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 ...


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