FAQ 9.18 How do I decode a MIME/BASE64 string?

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9.18: How do I decode a MIME/BASE64 string?

The MIME-Base64 package (available from CPAN) handles this as well as
the MIME/QP encoding. Decoding BASE64 becomes as simple as:

use MIME::Base64;
$decoded = decode_base64($encoded);

The MIME-Tools package (available from CPAN) supports extraction with
decoding of BASE64 encoded attachments and content directly from email
messages.

If the string to decode is short (less than 84 bytes long) a more direct
approach is to use the unpack() function's "u" format after minor
transliterations:

tr#A-Za-z0-9+/##cd; # remove non-base64 chars
tr#A-Za-z0-9+/# -_#; # convert to uuencoded format
$len = pack("c", 32 + 0.75*length); # compute length byte
print unpack("u", $len . $_); # uudecode and print



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