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1

I've got a response form, Vincent Rijmen. Here the complete response; rcon is used in the computation of the roundkeys. AES192 and AES256 have less iterations of the roundkey computation, since each of these computations produced more than 128 bits of roundkey material. That’s why we need less rcon values. Paŭlo Ebermann's great answer gives some details ...


3

ECCDSA-keys can be merged such that the sum of two private keys $S=S_1+S_2$ yields a public key which is the sum of the respective public keys $P=P_1+P_2$. This is true, however it doesn't mean what you think it means; the $+$ operators in the two equations are two different operations. The first one is simple addition (modulo the order of the elliptic ...


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TL;DR: it is a matter of conventions and context that $e=1$ is allowed or not. Definitions of RSA vary: The original RSA article asks to first choose the private exponent $d$ as « a large, random integer which is relatively prime to $(p−1)\cdot(q−1)$ », then to compute $e$ as « the “multiplicative inverse” of $d$, modulo $(p−1)\cdot(q−1)$ ». This makes it ...


1

You have 10, 12, and 14 rounds respectively; however, they are not linear increments depending on the key schedule. For AES-192, you have 8 different values and you have 7 values for AES-256. The RCON value only changes with every round for AES-128. The RCON value (in hardware) is generated by a register that is 8-bits and increments every round. It wraps ...


4

From the same paper: Use a fixed position for the leading 1 in the secret key; Multiply the secret key by a small power of 2 to account for cofactors in the curve group and the twist group. The first one is to make the scalar multiplication with always the same number of iterations of the loop, for constant-time reasons. The second one makes sure that the ...


0

Needed to stay out of libgcrypt repository and instead remain focused within the higher level gnupg repository, specifically gnupg/g10/keyid.c. The keygrip_from_pk() function is what makes the public key algo specific calls to build the S expressions that feeds the lower level gcry_pk_get_keygrip() function used to calculate the binary keygrip array that is ...


4

the answer provided by @thesquaregroot is sufficient. However, I will only add the following: We can achieve something similar to RSA encryption by using Diffie-Hellman construction. This can be done by using ElGamal encryption scheme. Suppose say a server has the secret-public key pair ($s, y=g^s$). To send a message to the server, you proceed as follows: ...


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The purpose of Diffie-Hellman is solely to establish a shared key, $K$. Taken from Wikipedia: Traditionally, secure encrypted communication between two parties required that they first exchange keys by some secure physical means, such as paper key lists transported by a trusted courier. The Diffie–Hellman key exchange method allows two parties that have ...


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