Python中的base64、base32实例

Base64编码解码

base64.b64encode(s[,altchars])：使用Base64编码字符串。s是要编码的字符串。altchars是用来替换+和/的字符串，在url和文件系统中它们有特殊含义，通常需要替换。

base64.b64decode(s[,altchars]): 解码Base64编码的字符串。s为要解码的字符串。altchars和b64encode相同。

请看python模块介绍中的实例：

>>> import base64

>>> encoded =base64.b64encode('data to be encoded')

>>> encoded

'ZGF0YSB0byBiZSBlbmNvZGVk'

>>> data =base64.b64decode(encoded)

>>> data

'data to be encoded'

下面是维基百科中的实例，包含了填充符：

>>> import base64

>>> s = '''Man isdistinguished, not only by his reason, but by this singular passion from otheranimals, which is a lust of the mind, that by a perseverance of delight in thecontinued and indefatigable generation of knowledge, exceeds the shortvehemence of any carnal pleasure.'''

>>> encoded_data =base64.b64encode(s)

>>> print(encoded_data)

TWFuIGlzIGRpc3Rpbmd1aXNoZWQsIG5vdCBvbmx5IGJ5IGhpcyByZWFzb24sIGJ1dCBieSB0aGlzIHNpbmd1bGFyIHBhc3Npb24gZnJvbSBvdGhlciBhbmltYWxzLCB3aGljaCBpcyBhIGx1c3Qgb2YgdGhlIG1pbmQsIHRoYXQgYnkgYSBwZXJzZXZlcmFuY2Ugb2YgZGVsaWdodCBpbiB0aGUgY29udGludWVkIGFuZCBpbmRlZmF0aWdhYmxlIGdlbmVyYXRpb24gb2Yga25vd2xlZGdlLCBleGNlZWRzIHRoZSBzaG9ydCB2ZWhlbWVuY2Ugb2YgYW55IGNhcm5hbCBwbGVhc3VyZS4=

>>>base64.b64decode(encoded_data)

'Man is distinguished, not only by hisreason, but by this singular passion from other animals, which is a lust of themind, that by a perseverance of delight in the continued and indefatigablegeneration of knowledge, exceeds the short vehemence of any carnal pleasure.'

Base64默认会使用+和/, 但是这2个字符在url中也有特殊含义。使用urlsafe可以解决这个问题。+替换为-，/替换为_。

import base64

encodes_with_pluses = chr(251)+ chr(239)

encodes_with_slashes = chr(255)*2

for originalin[ encodes_with_pluses, encodes_with_slashes]:

print'Original :', repr(original)

print'Standard encoding:', base64.standard_b64encode(original)

print'URL-safe encoding:', base64.urlsafe_b64encode(original)

print

执行结果：

# python base64_urlsafe.py

Original : '\xfb\xef'

Standard encoding: ++8=

URL-safe encoding: --8=

Original : '\xff\xff'

Standard encoding: //8=

URL-safe encoding: __8=

类似函数base64.standard_b64encode(s)，base64.standard_b64decode(s)。

Bsae32编码

Base32包含26个大写字母和2-7的数字。

base64.b32encode(s)：使用Base32编码字符串。s是要编码的字符串。

base64.b32decode(s[,casefold[, map01]])：解码Base32编码的字符串。s为要解码的字符串。casefold表示是否允许小写字母。map01表示允许0表示0,1表示L。

import base64

original_string ='This is the data, in the clear.'

print'Original:', original_string

encoded_string = base64.b32encode(original_string)

print'Encoded :', encoded_string

decoded_string = base64.b32decode(encoded_string)

print'Decoded :', decoded_string

执行结果：

$ python base64_base32.py

Original: This is the data, in theclear.

Encoded :KRUGS4ZANFZSA5DIMUQGIYLUMEWCA2LOEB2GQZJAMNWGKYLSFY======

Decoded : This is the data, in theclear.

Base16包含16个16进制大写数字。类似的有base64.b16encode(s)，base64.b16decode(s[, casefold]) 。

import base64

original_string ='This is the data, in the clear.'

print'Original:', original_string

encoded_string = base64.b16encode(original_string)

print'Encoded :', encoded_string

decoded_string = base64.b16decode(encoded_string)

print'Decoded :', decoded_string

执行结果：

# python base64_base16.py

Original: This is the data, in theclear.

Encoded :546869732069732074686520646174612C20696E2074686520636C6561722E

Decoded : This is the data, in theclear.