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Diffstat (limited to 'Doc/lib/libsha.tex')
| -rw-r--r-- | Doc/lib/libsha.tex | 33 |
1 files changed, 26 insertions, 7 deletions
diff --git a/Doc/lib/libsha.tex b/Doc/lib/libsha.tex index d8a5c26..4d15abe 100644 --- a/Doc/lib/libsha.tex +++ b/Doc/lib/libsha.tex @@ -8,12 +8,12 @@ This module implements the interface to NIST's\index{NIST} secure hash algorithm,\index{Secure Hash Algorithm} known as SHA. It is used in -the same way as the \refmodule{md5} module:\ use the \function{new()} +the same way as the \refmodule{md5} module:\ use \function{new()} to create an sha object, then feed this object with arbitrary strings using the \method{update()} method, and at any point you can ask it for the \dfn{digest} of the concatenation of the strings fed to it -so far.\index{checksum!SHA} SHA digests are 160 bits instead of 128 -bits. +so far.\index{checksum!SHA} SHA digests are 160 bits instead of +MD5's 128 bits. \begin{funcdesc}{new}{\optional{string}} @@ -37,14 +37,33 @@ attributes of the sha objects returned by \function{new()}: \end{datadesc} -A sha object has all the methods the md5 objects have, plus one: +An sha object has the same methods as md5 objects: + +\begin{methoddesc}[sha]{update}{arg} +Update the sha object with the string \var{arg}. Repeated calls are +equivalent to a single call with the concatenation of all the +arguments, i.e.\ \code{m.update(a); m.update(b)} is equivalent to +\code{m.update(a+b)}. +\end{methoddesc} + +\begin{methoddesc}[sha]{digest}{} +Return the digest of the strings passed to the \method{update()} +method so far. This is a 20-byte string which may contain +non-\ASCII{} characters, including null bytes. +\end{methoddesc} \begin{methoddesc}[sha]{hexdigest}{} - Return the digest value as a string of hexadecimal digits. This may - be used to exchange the value safely in email or other non-binary - environments. +Like \method{digest()} except the digest is returned as a string of +length 40, containing only hexadecimal digits. This may +be used to exchange the value safely in email or other non-binary +environments. \end{methoddesc} +\begin{methoddesc}[sha]{copy}{} +Return a copy (``clone'') of the sha object. This can be used to +efficiently compute the digests of strings that share a common initial +substring. +\end{methoddesc} \begin{seealso} \seetitle[http://csrc.nist.gov/fips/fip180-1.txt]{Secure Hash Standard}{ |