base64 — RFC 3548: Base16, Base32, Base64 Data EncodingsThis 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 both base-64 alphabets defined in RFC 3548 (normal, and URL- and filesystem-safe). 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:
base64.b64encode(s[, altchars])Encode a string using 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.
base64.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 is
incorrectly padded. Characters that are neither
in the normal base-64 alphabet nor the alternative alphabet are
discarded prior to the padding check.
base64.standard_b64encode(s)base64.standard_b64decode(s)base64.urlsafe_b64encode(s)- instead of + and _ instead of / in the standard Base64 alphabet. The result can still contain =.base64.urlsafe_b64decode(s)- instead of + and _ instead of / in the standard Base64 alphabet.base64.b32encode(s)base64.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 is
incorrectly padded or if there are non-alphabet characters present in the
string.
base64.b16encode(s)Encode a string using Base16.
s is the string to encode. The encoded string is returned.
base64.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:
base64.decode(input, output)input.read() returns an empty string.base64.decodestring(s)base64.encode(input, output)input.read() returns an empty string. encode() returns the encoded data plus a trailing newline character ('\n').base64.encodestring(s)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'
See also
binascii