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Steffen Jaeckel 2017-08-09 15:56:13 +02:00
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doc/crypt.tex
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@ -2546,9 +2546,17 @@ for all purposes you would normally use a hash for.
\chapter{Checksum Functions}
\mysection{CRC32 -- Cyclic redundancy check}
\mysection{Preface}
XXX-TODO see \url{https://en.wikipedia.org/wiki/Cyclic_redundancy_check}
The API for all checksum functions operate in mode: \textit{init} -- \textit{update} -- \textit{update} -- ... -- \textit{finish}.
The \textit{finish} functions allow to output a partial result if necessary.
\mysection{CRC-32 -- Cyclic redundancy check}
A Cyclic Redundancy Check is an error-detecting code, where LibTomCrypt implements CRC-32 with the polynomial \textit{0x04C11DB7}.
For further information see \url{https://en.wikipedia.org/wiki/Cyclic_redundancy_check}
\begin{verbatim}
void crc32_init(crc32_state *ctx);
@ -2556,9 +2564,11 @@ void crc32_update(crc32_state *ctx, const unsigned char *input, unsigned long le
void crc32_finish(crc32_state *ctx, void *hash, unsigned long size);
\end{verbatim}
\mysection{Adler32}
\mysection{Adler-32}
XXX-TODO see \url{https://en.wikipedia.org/wiki/Adler-32}
Adler-32 is a checksum algorithm.
For further information see \url{https://en.wikipedia.org/wiki/Adler-32}.
\begin{verbatim}
void adler32_init(adler32_state *ctx);
@ -5763,8 +5773,17 @@ At this point, we are pointing to the last node of the list. Lists are terminat
can walk up and down the nodes without keeping pointers lying around.
\subsubsection{Shrink'ing a Flexi List}
While decoding the flexi decoder will recursively decode an ASN.1 \textit{constructed} type it will store the decoded list
as well as the plain data that was decoded.
To free up this additional data a shrink function is provided.
\index{der\_sequence\_shrink()}
\begin{verbatim}
void der_sequence_shrink(ltc_asn1_list *in);
\end{verbatim}
This will free all the plain constructed data, but keep the decoded list intact.
\subsubsection{Free'ing a Flexi List}
To free the list use the following function.
@ -6084,6 +6103,28 @@ int rand_bn_upto( void *N,
This ensures that \textit{N} is set to a random MPI in the range $1 \le N < limit$.
\mysection{Helper functions}
\subsection{Zero'ing data}
XXX-TODO
\index{zeromem()}
\begin{verbatim}
void zeromem(volatile void *out, size_t outlen);
\end{verbatim}
\subsection{Constant-time memory compare}
XXX-TODO
\index{mem\_neq()}
\begin{verbatim}
int mem_neq(const void *a, const void *b, size_t len);
\end{verbatim}
\mysection{Dynamic Language Support}
\index{Dynamic Language Support}
Various LibTomCrypt functions require that their callers define a struct