From: mdw Date: Wed, 30 Jan 2002 09:58:30 +0000 (+0000) Subject: MD hashing diagram. Suggestion of making a diagram in answers. X-Git-Tag: 1.1.0~7 X-Git-Url: https://git.distorted.org.uk/~mdw/doc/ips/commitdiff_plain/6606ff41fcf6918d7aee5d4da006e57dffee35c9 MD hashing diagram. Suggestion of making a diagram in answers. --- diff --git a/basics.tex b/basics.tex index 3874d3c..de5527b 100644 --- a/basics.tex +++ b/basics.tex @@ -560,6 +560,9 @@ But if your cryptography is no good, you may never know. g^{(i+1)}(x) = g_0(x) \cat g^{(i)}(g_1(x)). \]% Relate the security of $g^{(i)}$ to that of $g$. \answer% + The description of the function $g^{(i)}$ is deliberately terse and + unhelpful. It probably helps understanding if you make a diagram. + Let $A$ be an adversary running in time $t$ and attacking $g^{(i+1)}$. Firstly, we attack $g$: consider adversary $B(y)$: \{ \PARSE $y$ \AS $y_0, k\colon y_1$; $z \gets g^{(i)}$; $b \gets A(y_0 \cat z)$; \RETURN $b$;~\}. @@ -922,6 +925,23 @@ But if your cryptography is no good, you may never know. \end{proof} \begin{slide} + \head{Hash functions, \seq: Merkle-Damg\aa{}rd iterated hashing (cont.)} + + \vfil + $\begin{graph} + []!{0; <2cm, 0cm>: <0cm, 0.9cm>::} + *+=(1, 0)+[F]{\mathstrut I_0 = I} :[d] *+[F]{F}="f" + [urrr] *+=(3, 0)+[F]{\mathstrut x_0} :d"f" "f" :[d] + *+=(1, 0)+[F]{\mathstrut I_1} :[d] *+[F]{F}="f" + [urrr] *+=(3, 0)+[F]{\mathstrut x_1} :d"f" "f" :@{-->}[dd] + *+=(1, 0)+[F]{\mathstrut I_{n-1}} :[d] *+[F]{F}="f" + [urrr] *+=(3, 0)+[F]{\mathstrut x_{n-1}} :d"f" "f" :[d] + *+=(1, 0)+[F:thicker]{\mathstrut H(x) = I_n} + \end{graph}$ + \vfil +\end{slide} + +\begin{slide} \head{Hash functions, \seq: any-collision resistance} The statement usually made about a good' hash function $h$ is that it