base64 - Man Page

base64-encode/decode binary data


package require Tcl  8

package require base64  ?2.4.2?

::base64::encode ?-maxlen maxlen? ?-wrapchar wrapchar? string

::base64::decode string


This package provides procedures to encode binary data into base64 and back.

::base64::encode ?-maxlen maxlen? ?-wrapchar wrapchar? string

Base64 encodes the given binary string and returns the encoded result. Inserts the character wrapchar every maxlen characters of output. wrapchar defaults to newline. maxlen defaults to 76.

Note that if maxlen is set to 0, the output will not be wrapped at all.

Note well: If your string is not simple ascii you should fix the string encoding before doing base64 encoding. See the examples.

The command will throw an error for negative values of maxlen, or if maxlen is not an integer number.

::base64::decode string

Base64 decodes the given string and returns the binary data. The decoder ignores whitespace in the string.


% base64::encode "Hello, world"
% base64::encode [string repeat xyz 20]
% base64::encode -wrapchar "" [string repeat xyz 20]
# NOTE: base64 encodes BINARY strings.
% set chemical [encoding convertto utf-8 "C\u2088H\u2081\u2080N\u2084O\u2082"]
% set encoded [base64::encode $chemical]
% set caffeine [encoding convertfrom utf-8 [base64::decode $encoded]]

Bugs, Ideas, Feedback

This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category base64 of the Tcllib Trackers []. Please also report any ideas for enhancements you may have for either package and/or documentation.

When proposing code changes, please provide unified diffs, i.e the output of diff -u.

Note further that attachments are strongly preferred over inlined patches. Attachments can be made by going to the Edit form of the ticket immediately after its creation, and then using the left-most button in the secondary navigation bar.


base64, encoding


Text processing


2.4.2 tcllib Text encoding & decoding binary data