\cfg{man-identity}{base64}{1}{2004-11-20}{Simon Tatham}{Simon Tatham}

\define{dash} \u2013{-}

\title Man page for \cw{base64}

\U NAME

\cw{base64} \dash stand-alone encoder and decoder for base64

\U SYNOPSIS

\c base64 [ -d ] [ filename ]
\e bbbbbb   bb     iiiiiiii
\c base64 -e [ -c width ] [ filename ]
\e bbbbbb bb   bb iiiii     iiiiiiii

\U DESCRIPTION

\cw{base64} is a command-line utility for encoding and decoding the
\q{base64} encoding.

This encoding, defined in
\W{http://www.ietf.org/rfc/rfc2045.txt}{RFC 2045}, is primarily used
to encode binary attachments in MIME e-mail, but is widely used in
many other applications as well. For example, the \q{Content-MD5}
mail header contains a small piece of base64; SSH private keys are
generally stored as base64-encoded blobs; and so on.

Other utilities, such as \cw{munpack}, exist which will take an
entire MIME-encoded message, identify the base64-encoded subparts,
and decode them. However, these utilities will not help you if you
need to inspect a Content-MD5 header or an SSH private key.

\cw{base64} is a very simple stand-alone encoder and decoder for the
base64 format \e{alone}. It does not try to understand MIME headers
or anything other than raw data.

\U OPTIONS

By default (if neither \cw{-d} or \cw{-e} is supplied), \cw{base64}
operates in decode mode.

\dt \cw{-d}

\dd Places \cw{base64} into decode mode. In this mode, it will read
from standard input or the supplied file name, ignore all characters
that are not part of the base64 alphabet, decode the ones that are,
and output the decoded data on standard output.

\dt \cw{-e}

\dd Places \cw{base64} into encode mode. In this mode, it will read
binary data from standard input or the supplied file name, encode it
as base64, and output the encoded data on standard output.

\dt \cw{-c} \e{width}

\dd If \cw{base64} is operating in encode mode, this controls the
number of base64 characters output per line of the encoded file.
Normally base64-reading applications do not care about this, so the
default of 64 characters per line is perfectly adequate.

\lcont{

The special value 0 will prevent \cw{base64} from ever writing a
line break in the middle of the data at all.

The base64 encoding converts between a group of three plaintext
bytes and a group of four encoded bytes. \cw{base64} does not
support breaking an encoded group across a line (although it can
handle it as input if it receives it). Therefore, the \e{width}
parameter passed to \cw{-c} must be a multiple of 4.

}

\U LICENCE

\cw{base64} is free software, distributed under the MIT licence.
Type \cw{base64 --licence} to see the full licence text.

\versionid $Id$