# Tag Info

7

A safe prime is a prime number $p$ for which $(p-1)/2$ is also prime. The order of an element $g$ of the group $\mathbf{Z}^*_p$ (the integers modulo $p$, excluding 0) is the smallest integer $n$ such that $g^n\equiv 1\pmod{p}$; this is always a factor of $p-1$. The orders of the subgroups of the group generated by $g$ are the factors of the order of $g$; ...

5

Let's recall how discrete logarithms are solved in strong elliptic curve groups. The basic idea is to iteratively walk through many combinations of the form $x_i = a_iP + b_iQ$ until we find a distinguished one, i.e., one that shares some common property (like the lowest $k$ bits of $x_i$ set to 0). We accumulate enough distinguished points until we find a ...

1

TLSv1.1 doesn't have a different treatment of the key-exchange parameters than TLSv1.2 has. It's just a little less obvious. Let's dig into TLSv1.1 specification. On page 44 you'll find that ServerKeyExchange consists of ServerXXXParams params and Signature signed_params. Now on page 44 you'll actually find a definition of Signature. This definition signs ...

1

A client can indeed "regenerate" DH-keys. But this simply means he re-connects to the server. The Logjam attack works by recording the connection establishment and then compute the derived private key. For this attack to work the domain parameters of the DH-exchange need to remain unchanged as precomputation is neccessary. If you just reconnect the server ...

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