This module provides data encoding and decoding as specified in
RFC 3548. This standard defines the Base16, Base32, and Base64
algorithms for encoding and decoding arbitrary binary strings into
text strings that can be safely sent by email, used as parts of URLs,
or included as part of an HTTP POST request. The encoding algorithm is
not the same as the uuencode program.
There are two interfaces provided by this module. The modern
interface supports encoding and decoding string objects using all
three alphabets. The legacy interface provides for encoding and
decoding to and from file-like objects as well as strings, but only
using the Base64 standard alphabet.
The modern interface, which was introduced in Python 2.4, provides:
b64encode( |
s[, altchars]) |
-
Encode a string use Base64.
s is the string to encode. Optional altchars must be a
string of at least length 2 (additional characters are ignored) which
specifies an alternative alphabet for the + and /
characters. This allows an application to e.g. generate URL or
filesystem safe Base64 strings. The default is None , for which
the standard Base64 alphabet is used.
The encoded string is returned.
b64decode( |
s[, altchars]) |
-
Decode a Base64 encoded string.
s is the string to decode. Optional altchars must be a
string of at least length 2 (additional characters are ignored) which
specifies the alternative alphabet used instead of the + and
/ characters.
The decoded string is returned. A TypeError is raised if
s were incorrectly padded or if there are non-alphabet
characters present in the string.
-
Encode string s using the standard Base64 alphabet.
-
Decode string s using the standard Base64 alphabet.
-
Encode string s using a URL-safe alphabet, which substitutes
- instead of + and _ instead of / in the
standard Base64 alphabet.
-
Decode string s using a URL-safe alphabet, which substitutes
- instead of + and _ instead of / in the
standard Base64 alphabet.
-
Encode a string using Base32. s is the string to encode. The
encoded string is returned.
b32decode( |
s[, casefold[, map01]]) |
-
Decode a Base32 encoded string.
s is the string to decode. Optional casefold is a flag
specifying whether a lowercase alphabet is acceptable as input. For
security purposes, the default is False .
RFC 3548 allows for optional mapping of the digit 0 (zero) to the
letter O (oh), and for optional mapping of the digit 1 (one) to either
the letter I (eye) or letter L (el). The optional argument
map01 when not None , specifies which letter the digit 1 should
be mapped to (when map01 is not None , the digit 0 is always
mapped to the letter O). For security purposes the default is
None , so that 0 and 1 are not allowed in the input.
The decoded string is returned. A TypeError is raised if
s were incorrectly padded or if there are non-alphabet characters
present in the string.
-
Encode a string using Base16.
s is the string to encode. The encoded string is returned.
b16decode( |
s[, casefold]) |
-
Decode a Base16 encoded string.
s is the string to decode. Optional casefold is a flag
specifying whether a lowercase alphabet is acceptable as input. For
security purposes, the default is False .
The decoded string is returned. A TypeError is raised if
s were incorrectly padded or if there are non-alphabet
characters present in the string.
The legacy interface:
-
Decode the contents of the input file and write the resulting
binary data to the output file.
input and output must either be file objects or objects that
mimic the file object interface. input will be read until
input.read() returns an empty string.
-
Decode the string s, which must contain one or more lines of
base64 encoded data, and return a string containing the resulting
binary data.
-
Encode the contents of the input file and write the resulting
base64 encoded data to the output file.
input and output must either be file objects or objects that
mimic the file object interface. input will be read until
input.read() returns an empty string. encode()
returns the encoded data plus a trailing newline character
('\n' ).
-
Encode the string s, which can contain arbitrary binary data,
and return a string containing one or more lines of
base64-encoded data. encodestring() returns a
string containing one or more lines of base64-encoded data
always including an extra trailing newline (
'\n' ).
An example usage of the module:
>>> import base64
>>> encoded = base64.b64encode('data to be encoded')
>>> encoded
'ZGF0YSB0byBiZSBlbmNvZGVk'
>>> data = base64.b64decode(encoded)
>>> data
'data to be encoded'
Release 2.5.2, documentation updated on 21st February, 2008.
See About this document... for information on suggesting changes.
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