分类： Python

在进行SVG转换成PNG图片的时候，后续对转换后的图片使用PIL进行操作，结果发现锯齿严重。经过网上搜到，发现只能通过超采样然后缩放的方式来进行抗锯齿操作，效果还不错。

代码参考如下：

import os
import math
import cairosvg

temp_image = os.path.join(fileDir, "splash.png")

# PIL 本身不具备抗锯齿功能,输出的图片锯齿严重，我们进行四倍超采样，然后缩放的方式进行抗锯齿操作
scale = 4.0

# background_color='#FFFFFF'
# 注意如果不设置DPI，默认dpi是96 人眼低于326dpi的可见明显锯齿
cairosvg.svg2png(url=raw, write_to=temp_image, output_width=math.ceil(image_width*scale), dpi=400,
                 output_height=math.ceil(image_height*scale))

from PIL import Image
bg = Image.new("RGBA", (math.ceil(output_width*scale), math.ceil(output_height*scale)))
fg = Image.open(temp_image)
bg.paste(fg, (math.ceil((output_width - image_width)*scale/2),
         math.ceil((output_height - image_height)*scale/2)), fg)

bg.resize((output_width, output_height), Image.ANTIALIAS);
bg.save(out)
os.remove(temp_image)

参考链接

---

• Is there an antialiasing method for Python PIL?
• Python 修改图片的时候抗锯齿

在利用 Photoshop 等得到的 PNG 透明图中，一般都是包含 alpha channel 的.

但是IOS图标不允许图标中包含 Alpha通道。

下面的代码实现的功能：Remove PNG Transparency

#!/usr/bin/python3
#!--*-- coding:utf-8 --*--


def remove_transparency(img_pil, bg_colour=(255, 255, 255)):
    # Only process if image has transparency
    if img_pil.mode in ('RGBA', 'LA') or \
        (img_pil.mode == 'P' and 'transparency' in img_pil.info):
        # Need to convert to RGBA if LA format due to a bug in PIL (http://stackoverflow.com/a/1963146)
        alpha = img_pil.convert('RGBA').split()[-1]

        # Create a new background image of our matt color.
        # Must be RGBA because paste requires both images have the same format
        # (http://stackoverflow.com/a/8720632  and  http://stackoverflow.com/a/9459208)
        bg = Image.new("RGBA", img_pil.size, bg_colour + (255,))
        bg.paste(img_pil, mask=alpha)
        return bg

    else:
        return img_pil

From: Remove transparency/alpha from any image using PIL - stackoverflow

参考链接

---

Python - 移除PNG透明图的alpha通道

最近业务中需要用 Python 写一些脚本。尽管脚本的交互只是命令行 + 日志输出，但是为了让界面友好些，我还是决定用中文输出日志信息。

遇到了异常：

UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-3: ordinal not in range(128)  

为了解决问题，研究了一下 Python 的字符编码处理。网上也有不少文章讲 Python 的字符编码，但是看过一遍，觉得自己可以讲得更明白些。

下面先复述一下 Python 字符串的基础，熟悉此内容的可以跳过。

 1.引入

对应 C/C++ 的 char 和 wchar_t, Python 也有两种字符串类型，str 与 unicode：

# -*- coding: utf-8 -*-  
# file: example1.py  
import string  
  
# 这个是 str 的字符串  
s = '关关雎鸠'  
  
# 这个是 unicode 的字符串  
u = u'关关雎鸠'  
  
print isinstance(s, str)      # True  
print isinstance(u, unicode)  # True  
  
print s.__class__   # <type 'str'>  
print u.__class__   # <type 'unicode'>

前面的申明：# -*- coding: utf-8 -*- 表明，上面的 Python 代码由 utf-8 编码。

为了保证输出不会在 linux 终端上显示乱码，需要设置好 linux 的环境变量：export LANG=en_US.UTF-8

如果你和我一样是使用 SecureCRT，请设置 Session Options/Terminal/Appearance/Character Encoding 为 UTF-8 ，保证能够正确的解码 linux 终端的输出。

两个 Python 字符串类型间可以用 encode / decode 方法转换：

# 从 str 转换成 unicode  
print s.decode('utf-8')   # 关关雎鸠  
  
# 从 unicode 转换成 str  
print u.encode('utf-8')   # 关关雎鸠 

为什么从 unicode 转 str 是 encode，而反过来叫 decode? 

因为 Python 认为 16 位的 unicode 才是字符的唯一内码，而大家常用的字符集如 gb2312，gb18030/gbk，utf-8，以及 ascii 都是字符的二进制（字节）编码形式。把字符从 unicode 转换成二进制编码，当然是要 encode。

反过来，在 Python 中出现的 str 都是用字符集编码的 ansi 字符串。Python 本身并不知道 str 的编码，需要由开发者指定正确的字符集 decode。

(补充一句，其实 Python 是可以知道 str 编码的。因为我们在代码前面申明了 # -*- coding: utf-8 -*-，这表明代码中的 str 都是用 utf-8 编码的，我不知道 Python 为什么不这样做。)

如果用错误的字符集来 encode/decode 会怎样？

# 用 ascii 编码含中文的 unicode 字符串  
u.encode('ascii')  # 错误，因为中文无法用 ascii 字符集编码  
                   # UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-3: ordinal not in range(128)  
  
# 用 gbk 编码含中文的 unicode 字符串  
u.encode('gbk')  # 正确，因为 '关关雎鸠' 可以用中文 gbk 字符集表示  
                 # '\xb9\xd8\xb9\xd8\xf6\xc2\xf0\xaf'  
                 # 直接 print 上面的 str 会显示乱码，修改环境变量为 zh_CN.GBK 可以看到结果是对的  
  
# 用 ascii 解码 utf-8 字符串  
s.decode('ascii')  # 错误，中文 utf-8 字符无法用 ascii 解码  
                   # UnicodeDecodeError: 'ascii' codec can't decode byte 0xe5 in position 0: ordinal not in range(128)  
  
# 用 gbk 解码 utf-8 字符串  
s.decode('gbk')  # 不出错，但是用 gbk 解码 utf-8 字符流的结果，显然只是乱码  
                 # u'\u934f\u51b2\u53e7\u95c6\u5ea8\u7b2d'

这就遇到了我在本文开头贴出的异常：UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-3: ordinal not in range(128)

现在我们知道了这是个字符串编码异常。接下来, 为什么 Python 这么容易出现字符串编/解码异常？ 

这要提到处理 Python 编码时容易遇到的两个陷阱。第一个是有关字符串连接的：

# -*- coding: utf-8 -*-  
# file: example2.py  
  
# 这个是 str 的字符串  
s = '关关雎鸠'  
  
# 这个是 unicode 的字符串  
u = u'关关雎鸠'  
  
s + u  # 失败，UnicodeDecodeError: 'ascii' codec can't decode byte 0xe5 in position 0: ordinal not in range(128)  

简单的字符串连接也会出现解码错误？

陷阱一：在进行同时包含 str 与 unicode 的运算时，Python 一律都把 str 转换成 unicode 再运算，当然，运算结果也都是 unicode。

由于 Python 事先并不知道 str 的编码，它只能使用 sys.getdefaultencoding() 编码去 decode。在我的印象里，sys.getdefaultencoding() 的值总是 'ascii' ——显然，如果需要转换的 str 有中文，一定会出现错误。

除了字符串连接，% 运算的结果也是一样的：

# 正确，所有的字符串都是 str, 不需要 decode  
"中文：%s" % s   # 中文：关关雎鸠  
  
# 失败，相当于运行："中文：%s".decode('ascii') % u  
"中文：%s" % u  # UnicodeDecodeError: 'ascii' codec can't decode byte 0xe5 in position 0: ordinal not in range(128)  
  
# 正确，所有字符串都是 unicode, 不需要 decode  
u"中文：%s" % u   # 中文：关关雎鸠  
  
# 失败，相当于运行：u"中文：%s" % s.decode('ascii')  
u"中文：%s" % s  # UnicodeDecodeError: 'ascii' codec can't decode byte 0xe5 in position 0: ordinal not in range(128)  

我不理解为什么 sys.getdefaultencoding() 与环境变量 $LANG 全无关系。如果 Python 用 $LANG 设置 sys.getdefaultencoding() 的值，那么至少开发者遇到 UnicodeDecodeError 的几率会降低 50%。

另外，就像前面说的，我也怀疑为什么 Python 在这里不参考 # -*- coding: utf-8 -*- ，因为 Python 在运行前总是会检查你的代码，这保证了代码里定义的 str 一定是 utf-8 。

对于这个问题，我的唯一建议是在代码里的中文字符串前写上 u。另外，在 Python 3 已经取消了 str，让所有的字符串都是 unicode ——这也许是个正确的决定。

其实，sys.getdefaultencoding() 的值是可以用“后门”方式修改的，我不是特别推荐这个解决方案，但是还是贴一下，因为后面有用：

# -*- coding: utf-8 -*-  
# file: example3.py  
import sys  
  
# 这个是 str 的字符串  
s = '关关雎鸠'  
  
# 这个是 unicode 的字符串  
u = u'关关雎鸠'  
  
# 使得 sys.getdefaultencoding() 的值为 'utf-8'  
reload(sys)                      # reload 才能调用 setdefaultencoding 方法  
sys.setdefaultencoding('utf-8')  # 设置 'utf-8'  
  
# 没问题  
s + u  # u'\u5173\u5173\u96ce\u9e20\u5173\u5173\u96ce\u9e20'  
  
# 同样没问题  
"中文：%s" % u   # u'\u4e2d\u6587\uff1a\u5173\u5173\u96ce\u9e20'  
  
# 还是没问题  
u"中文：%s" % s  # u'\u4e2d\u6587\uff1a\u5173\u5173\u96ce\u9e20'  

可以看到，问题魔术般的解决了。但是注意！ sys.setdefaultencoding() 的效果是全局的，如果你的代码由几个不同编码的 Python 文件组成，用这种方法只是按下了葫芦浮起了瓢，让问题变得复杂。

另一个陷阱是有关标准输出的。

刚刚怎么来着？我一直说要设置正确的 linux $LANG 环境变量。那么，设置错误的 $LANG，比如 zh_CN.GBK 会怎样？（避免终端的影响，请把 SecureCRT 也设置成相同的字符集。）

显然会是乱码，但是不是所有输出都是乱码。

# -*- coding: utf-8 -*-  
# file: example4.py  
import string  
  
# 这个是 str 的字符串  
s = '关关雎鸠'  
  
# 这个是 unicode 的字符串  
u = u'关关雎鸠'  
  
# 输出 str 字符串, 显示是乱码  
print s   # 鍏冲叧闆庨笭  
  
# 输出 unicode 字符串，显示正确  
print u  # 关关雎鸠  

为什么是 unicode 而不是 str 的字符显示是正确的？ 首先我们需要了解 print。与所有语言一样，这个 Python 命令实际上是把字符打印到标准输出流 —— sys.stdout。而 Python 在这里变了个魔术，它会按照 sys.stdout.encoding 来给 unicode 编码，而把 str 直接输出，扔给操作系统去解决。

这也是为什么要设置 linux $LANG 环境变量与 SecureCRT 一致，否则这些字符会被 SecureCRT 再转换一次，才会交给桌面的 Windows 系统用编码 CP936 或者说 GBK 来显示。

通常情况，sys.stdout.encoding 的值与 linux $LANG 环境变量保持一致：

# -*- coding: utf-8 -*-  
# file: example5.py  
import sys  
  
# 检查标准输出流的编码  
print sys.stdout.encoding  # 设置 $LANG = zh_CN.GBK，  输出 GBK  
                           # 设置 $LANG = en_US.UTF-8，输出 UTF-8  
  
# 这个是 unicode 的字符串  
u = u'关关雎鸠'  
  
# 输出 unicode 字符串，显示正确  
print u  # 关关雎鸠  

但是，这里有 陷阱二：一旦你的 Python 代码是用管道 / 子进程方式运行，sys.stdout.encoding 就会失效，让你重新遇到 UnicodeEncodeError。

比如，用管道方式运行上面的 example4.py 代码：

python -u example5.py | more  
  
UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-3: ordinal not in range(128)  
None  

可以看到，第一：sys.stdout.encoding 的值变成了 None；第二：Python 在 print 时会尝试用 ascii 去编码 unicode.

由于 ascii 字符集不能用来表示中文字符，这里当然会编码失败。

怎么解决这个问题？ 不知道别人是怎么搞定的，总之我用了一个丑陋的办法：

# -*- coding: utf-8 -*-  
# file: example6.py  
import os  
import sys  
import codecs  
  
# 无论如何，请用 linux 系统的当前字符集输出：  
if sys.stdout.encoding is None:  
    enc = os.environ['LANG'].split('.')[1]  
    sys.stdout = codecs.getwriter(enc)(sys.stdout)  # 替换 sys.stdout  
  
# 这个是 unicode 的字符串  
u = u'关关雎鸠'  
  
# 输出 unicode 字符串，显示正确  
print u  # 关关雎鸠  

　　这个方法仍然有个副作用：直接输出中文 str 会失败，因为 codecs 模块的 writer 与 sys.stdout 的行为相反，它会把所有的 str 用 sys.getdefaultencoding() 的字符集转换成 unicode 输出。

# 这个是 str 的字符串  
s = '关关雎鸠'  
  
# 输出 str 字符串, 异常  
print s   # UnicodeDecodeError: 'ascii' codec can't decode byte 0xe5 in position 0: ordinal not in range(128)  

显然，sys.getdefaultencoding() 的值是 'ascii', 编码失败。

解决办法就像 example3.py 里说的，你要么给 str 加上 u 申明成 unicode，要么通过“后门”去修改 sys.getdefaultencoding()：

# 使得 sys.getdefaultencoding() 的值为 'utf-8'  
reload(sys)                      # reload 才能调用 setdefaultencoding 方法  
sys.setdefaultencoding('utf-8')  # 设置 'utf-8'  
  
# 这个是 str 的字符串  
s = '关关雎鸠'  
  
# 输出 str 字符串, OK  
print s   # 关关雎鸠

总而言之，在 Python 2 下进行中文输入输出是个危机四伏的事，特别是在你的代码里混合使用 str 与 unicode 时。

有些模块，例如 json，会直接返回 unicode 类型的字符串，让你的 % 运算需要进行字符解码而失败。而有些会直接返回 str, 你需要知道它们的真实编码，特别是在 print 的时候。

为了避免一些陷阱，上文中说过，最好的办法就是在 Python 代码里永远使用 u 定义中文字符串。另外，如果你的代码需要用管道 / 子进程方式运行，则需要用到 example6.py 里的技巧。

 2.python 自动解编码机制导致报错

1.string 和 unicode 对象合并

>>> s + u''
Traceback (most recent call last):
  File "<input>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe4 in position 0: ordinal not in range(128)
>>>

2.列表合并

>>> as_list = [u, s]
>>> ''.join(as_list)
Traceback (most recent call last):
  File "<input>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe4 in position 0: ordinal not in range(128)

3.格式化字符串

>>> '%s-%s'%(s,u)
Traceback (most recent call last):
  File "<input>", line 1, in <module>
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe4 in position 0: ordinal not in range(128)
>>>

4.打印 unicode 对象

#test.py
# -*- coding: utf-8 -*-
u = u'中文'
print u
#outpt
Traceback (most recent call last):
  File "/Users/zhyq0826/workspace/zhyq0826/blog-code/p20161030_python_encoding/uni.py", line 3, in <module>
    print u
UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-1: ordinal not in range(128)

5.输出到文件

>>> f = open('text.txt','w')
>>> f.write(u)
Traceback (most recent call last):
  File "<input>", line 1, in <module>
UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-1: ordinal not in range(128)
>>>

1，2，3 的例子中，python 自动用 ascii 把 string 解码为 unicode 对象然后再进行相应操作，所以都是 decode 错误， 4 和 5 python 自动用 ascii 把 unicode 对象编码为字符串然后输出，所以都是 encode 错误。

只要涉及到 unicode 对象和 string 的转换以及 unicode 对象输出、输入的地方可能都会触发 python 自动进行解码/编码，比如写入数据库、写入到文件、读取 socket 等等。

到此，这两个异常产生的真正原因了基本已经清楚了: unicode 对象需要编码为相应的 string(字符串)才可以存储、传输、打印，字符串需要解码为对应的 unicode 对象才能完成 unicode 对象的各种操作，len、find 等。

string.decode('utf-8') --> unicode
unicode.encode('utf-8') --> string

3.如何避免这些的错误

1.理解编码或解码的转换方向

无论何时发生编码错误，首先要理解编码方向，然后再针对性解决。

2.设置默认编码为 utf-8

在文件头写入

# -*- coding: utf-8 -*-

python 会查找: coding: name or coding=name，并设置文件编码格式为 name，此方式是告诉 python 默认编码不再是 ascii ，而是要使用声明的编码格式。

3.输入对象尽早解码为 unicode，输出对象尽早编码为字节流

无论何时有字节流输入，都需要尽早解码为 unicode 对象。任何时候想要把 unicode 对象写入到文件、数据库、socket 等外界程序，都需要进行编码。

4.使用 codecs 模块来处理输入输出 unicode 对象

codecs 模块可以自动的完成解编码的工作。

>>> import codecs
>>> f = codecs.open('text.txt', 'w', 'utf-8')
>>> f.write(u)
>>> f.close()

参考链接

---

python2.7 的中文编码处理，解决UnicodeEncodeError: 'ascii' codec can't encode character 问题

最近需要 Python 实现 AES 加解密操作，在目前的 macOS Big Sur (11.4) 上使用 PyCryptodome 或 PyCrypto 都会报错：

ImportError: No module named 'Crypto' 

经过测试，我们可以使用 cryptography 来实现这个功能，如下：

>>> import os
>>> from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
>>> key = os.urandom(32)
>>> iv = os.urandom(16)
>>> cipher = Cipher(algorithms.AES(key), modes.CBC(iv))
>>> encryptor = cipher.encryptor()
>>> ct = encryptor.update(b"a secret message") + encryptor.finalize()
>>> decryptor = cipher.decryptor()
>>> decryptor.update(ct) + decryptor.finalize()
b'a secret message'

参考 AES 算法实现代码：

#!/usr/bin/python
#
# aes.py: implements AES - Advanced Encryption Standard
# from the SlowAES project, http://code.google.com/p/slowaes/
#
# Copyright (c) 2008    Josh Davis ( http://www.josh-davis.org ),
#           Alex Martelli ( http://www.aleax.it )
#
# Ported from C code written by Laurent Haan ( http://www.progressive-coding.com )
#
# Licensed under the Apache License, Version 2.0
# http://www.apache.org/licenses/
#
import os
import sys
import math

class AES(object):
    '''AES funtions for a single block
    '''
    # Very annoying code:  all is for an object, but no state is kept!
    # Should just be plain functions in a AES modlule.
    
    # valid key sizes
    keySize = dict(SIZE_128=16, SIZE_192=24, SIZE_256=32)

    # Rijndael S-box
    sbox =  [0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67,
            0x2b, 0xfe, 0xd7, 0xab, 0x76, 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59,
            0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0, 0xb7,
            0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1,
            0x71, 0xd8, 0x31, 0x15, 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05,
            0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75, 0x09, 0x83,
            0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29,
            0xe3, 0x2f, 0x84, 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b,
            0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf, 0xd0, 0xef, 0xaa,
            0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c,
            0x9f, 0xa8, 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc,
            0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2, 0xcd, 0x0c, 0x13, 0xec,
            0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19,
            0x73, 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee,
            0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb, 0xe0, 0x32, 0x3a, 0x0a, 0x49,
            0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
            0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4,
            0xea, 0x65, 0x7a, 0xae, 0x08, 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6,
            0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a, 0x70,
            0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9,
            0x86, 0xc1, 0x1d, 0x9e, 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e,
            0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf, 0x8c, 0xa1,
            0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0,
            0x54, 0xbb, 0x16]

    # Rijndael Inverted S-box
    rsbox = [0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3,
            0x9e, 0x81, 0xf3, 0xd7, 0xfb , 0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f,
            0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb , 0x54,
            0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b,
            0x42, 0xfa, 0xc3, 0x4e , 0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24,
            0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25 , 0x72, 0xf8,
            0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d,
            0x65, 0xb6, 0x92 , 0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda,
            0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84 , 0x90, 0xd8, 0xab,
            0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3,
            0x45, 0x06 , 0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1,
            0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b , 0x3a, 0x91, 0x11, 0x41,
            0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6,
            0x73 , 0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9,
            0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e , 0x47, 0xf1, 0x1a, 0x71, 0x1d,
            0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b ,
            0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0,
            0xfe, 0x78, 0xcd, 0x5a, 0xf4 , 0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07,
            0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f , 0x60,
            0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f,
            0x93, 0xc9, 0x9c, 0xef , 0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5,
            0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61 , 0x17, 0x2b,
            0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55,
            0x21, 0x0c, 0x7d]

    def getSBoxValue(self,num):
        """Retrieves a given S-Box Value"""
        return self.sbox[num]

    def getSBoxInvert(self,num):
        """Retrieves a given Inverted S-Box Value"""
        return self.rsbox[num]

    def rotate(self, word):
        """ Rijndael's key schedule rotate operation.

        Rotate a word eight bits to the left: eg, rotate(1d2c3a4f) == 2c3a4f1d
        Word is an char list of size 4 (32 bits overall).
        """
        return word[1:] + word[:1]

    # Rijndael Rcon
    Rcon = [0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36,
            0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97,
            0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72,
            0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66,
            0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04,
            0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d,
            0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3,
            0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61,
            0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a,
            0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40,
            0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc,
            0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5,
            0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a,
            0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d,
            0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c,
            0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35,
            0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4,
            0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc,
            0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08,
            0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a,
            0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d,
            0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2,
            0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74,
            0xe8, 0xcb ]

    def getRconValue(self, num):
        """Retrieves a given Rcon Value"""
        return self.Rcon[num]

    def core(self, word, iteration):
        """Key schedule core."""
        # rotate the 32-bit word 8 bits to the left
        word = self.rotate(word)
        # apply S-Box substitution on all 4 parts of the 32-bit word
        for i in range(4):
            word[i] = self.getSBoxValue(word[i])
        # XOR the output of the rcon operation with i to the first part
        # (leftmost) only
        word[0] = word[0] ^ self.getRconValue(iteration)
        return word

    def expandKey(self, key, size, expandedKeySize):
        """Rijndael's key expansion.

        Expands an 128,192,256 key into an 176,208,240 bytes key

        expandedKey is a char list of large enough size,
        key is the non-expanded key.
        """
        # current expanded keySize, in bytes
        currentSize = 0
        rconIteration = 1
        expandedKey = [0] * expandedKeySize

        # set the 16, 24, 32 bytes of the expanded key to the input key
        for j in range(size):
            expandedKey[j] = key[j]
        currentSize += size

        while currentSize < expandedKeySize:
            # assign the previous 4 bytes to the temporary value t
            t = expandedKey[currentSize-4:currentSize]

            # every 16,24,32 bytes we apply the core schedule to t
            # and increment rconIteration afterwards
            if currentSize % size == 0:
                t = self.core(t, rconIteration)
                rconIteration += 1
            # For 256-bit keys, we add an extra sbox to the calculation
            if size == self.keySize["SIZE_256"] and ((currentSize % size) == 16):
                for l in range(4): t[l] = self.getSBoxValue(t[l])

            # We XOR t with the four-byte block 16,24,32 bytes before the new
            # expanded key.  This becomes the next four bytes in the expanded
            # key.
            for m in range(4):
                expandedKey[currentSize] = expandedKey[currentSize - size] ^ \
                        t[m]
                currentSize += 1

        return expandedKey

    def addRoundKey(self, state, roundKey):
        """Adds (XORs) the round key to the state."""
        for i in range(16):
            state[i] ^= roundKey[i]
        return state

    def createRoundKey(self, expandedKey, roundKeyPointer):
        """Create a round key.
        Creates a round key from the given expanded key and the
        position within the expanded key.
        """
        roundKey = [0] * 16
        for i in range(4):
            for j in range(4):
                roundKey[j*4+i] = expandedKey[roundKeyPointer + i*4 + j]
        return roundKey

    def galois_multiplication(self, a, b):
        """Galois multiplication of 8 bit characters a and b."""
        p = 0
        for counter in range(8):
            if b & 1: p ^= a
            hi_bit_set = a & 0x80
            a <<= 1
            # keep a 8 bit
            a &= 0xFF
            if hi_bit_set:
                a ^= 0x1b
            b >>= 1
        return p

    #
    # substitute all the values from the state with the value in the SBox
    # using the state value as index for the SBox
    #
    def subBytes(self, state, isInv):
        if isInv: getter = self.getSBoxInvert
        else: getter = self.getSBoxValue
        for i in range(16): state[i] = getter(state[i])
        return state

    # iterate over the 4 rows and call shiftRow() with that row
    def shiftRows(self, state, isInv):
        for i in range(4):
            state = self.shiftRow(state, i*4, i, isInv)
        return state

    # each iteration shifts the row to the left by 1
    def shiftRow(self, state, statePointer, nbr, isInv):
        for i in range(nbr):
            if isInv:
                state[statePointer:statePointer+4] = \
                        state[statePointer+3:statePointer+4] + \
                        state[statePointer:statePointer+3]
            else:
                state[statePointer:statePointer+4] = \
                        state[statePointer+1:statePointer+4] + \
                        state[statePointer:statePointer+1]
        return state

    # galois multiplication of the 4x4 matrix
    def mixColumns(self, state, isInv):
        # iterate over the 4 columns
        for i in range(4):
            # construct one column by slicing over the 4 rows
            column = state[i:i+16:4]
            # apply the mixColumn on one column
            column = self.mixColumn(column, isInv)
            # put the values back into the state
            state[i:i+16:4] = column

        return state

    # galois multiplication of 1 column of the 4x4 matrix
    def mixColumn(self, column, isInv):
        if isInv: mult = [14, 9, 13, 11]
        else: mult = [2, 1, 1, 3]
        cpy = list(column)
        g = self.galois_multiplication

        column[0] = g(cpy[0], mult[0]) ^ g(cpy[3], mult[1]) ^ \
                    g(cpy[2], mult[2]) ^ g(cpy[1], mult[3])
        column[1] = g(cpy[1], mult[0]) ^ g(cpy[0], mult[1]) ^ \
                    g(cpy[3], mult[2]) ^ g(cpy[2], mult[3])
        column[2] = g(cpy[2], mult[0]) ^ g(cpy[1], mult[1]) ^ \
                    g(cpy[0], mult[2]) ^ g(cpy[3], mult[3])
        column[3] = g(cpy[3], mult[0]) ^ g(cpy[2], mult[1]) ^ \
                    g(cpy[1], mult[2]) ^ g(cpy[0], mult[3])
        return column

    # applies the 4 operations of the forward round in sequence
    def aes_round(self, state, roundKey):
        state = self.subBytes(state, False)
        state = self.shiftRows(state, False)
        state = self.mixColumns(state, False)
        state = self.addRoundKey(state, roundKey)
        return state

    # applies the 4 operations of the inverse round in sequence
    def aes_invRound(self, state, roundKey):
        state = self.shiftRows(state, True)
        state = self.subBytes(state, True)
        state = self.addRoundKey(state, roundKey)
        state = self.mixColumns(state, True)
        return state

    # Perform the initial operations, the standard round, and the final
    # operations of the forward aes, creating a round key for each round
    def aes_main(self, state, expandedKey, nbrRounds):
        state = self.addRoundKey(state, self.createRoundKey(expandedKey, 0))
        i = 1
        while i < nbrRounds:
            state = self.aes_round(state,
                                   self.createRoundKey(expandedKey, 16*i))
            i += 1
        state = self.subBytes(state, False)
        state = self.shiftRows(state, False)
        state = self.addRoundKey(state,
                                 self.createRoundKey(expandedKey, 16*nbrRounds))
        return state

    # Perform the initial operations, the standard round, and the final
    # operations of the inverse aes, creating a round key for each round
    def aes_invMain(self, state, expandedKey, nbrRounds):
        state = self.addRoundKey(state,
                                 self.createRoundKey(expandedKey, 16*nbrRounds))
        i = nbrRounds - 1
        while i > 0:
            state = self.aes_invRound(state,
                                      self.createRoundKey(expandedKey, 16*i))
            i -= 1
        state = self.shiftRows(state, True)
        state = self.subBytes(state, True)
        state = self.addRoundKey(state, self.createRoundKey(expandedKey, 0))
        return state

    # encrypts a 128 bit input block against the given key of size specified
    def encrypt(self, iput, key, size):
        output = [0] * 16
        # the number of rounds
        nbrRounds = 0
        # the 128 bit block to encode
        block = [0] * 16
        # set the number of rounds
        if size == self.keySize["SIZE_128"]: nbrRounds = 10
        elif size == self.keySize["SIZE_192"]: nbrRounds = 12
        elif size == self.keySize["SIZE_256"]: nbrRounds = 14
        else: return None

        # the expanded keySize
        expandedKeySize = 16*(nbrRounds+1)

        # Set the block values, for the block:
        # a0,0 a0,1 a0,2 a0,3
        # a1,0 a1,1 a1,2 a1,3
        # a2,0 a2,1 a2,2 a2,3
        # a3,0 a3,1 a3,2 a3,3
        # the mapping order is a0,0 a1,0 a2,0 a3,0 a0,1 a1,1 ... a2,3 a3,3
        #
        # iterate over the columns
        for i in range(4):
            # iterate over the rows
            for j in range(4):
                block[(i+(j*4))] = iput[(i*4)+j]

        # expand the key into an 176, 208, 240 bytes key
        # the expanded key
        expandedKey = self.expandKey(key, size, expandedKeySize)

        # encrypt the block using the expandedKey
        block = self.aes_main(block, expandedKey, nbrRounds)

        # unmap the block again into the output
        for k in range(4):
            # iterate over the rows
            for l in range(4):
                output[(k*4)+l] = block[(k+(l*4))]
        return output

    # decrypts a 128 bit input block against the given key of size specified
    def decrypt(self, iput, key, size):
        output = [0] * 16
        # the number of rounds
        nbrRounds = 0
        # the 128 bit block to decode
        block = [0] * 16
        # set the number of rounds
        if size == self.keySize["SIZE_128"]: nbrRounds = 10
        elif size == self.keySize["SIZE_192"]: nbrRounds = 12
        elif size == self.keySize["SIZE_256"]: nbrRounds = 14
        else: return None

        # the expanded keySize
        expandedKeySize = 16*(nbrRounds+1)

        # Set the block values, for the block:
        # a0,0 a0,1 a0,2 a0,3
        # a1,0 a1,1 a1,2 a1,3
        # a2,0 a2,1 a2,2 a2,3
        # a3,0 a3,1 a3,2 a3,3
        # the mapping order is a0,0 a1,0 a2,0 a3,0 a0,1 a1,1 ... a2,3 a3,3

        # iterate over the columns
        for i in range(4):
            # iterate over the rows
            for j in range(4):
                block[(i+(j*4))] = iput[(i*4)+j]
        # expand the key into an 176, 208, 240 bytes key
        expandedKey = self.expandKey(key, size, expandedKeySize)
        # decrypt the block using the expandedKey
        block = self.aes_invMain(block, expandedKey, nbrRounds)
        # unmap the block again into the output
        for k in range(4):
            # iterate over the rows
            for l in range(4):
                output[(k*4)+l] = block[(k+(l*4))]
        return output


class AESModeOfOperation(object):
    '''Handles AES with plaintext consistingof multiple blocks.
    Choice of block encoding modes:  OFT, CFB, CBC
    '''
    # Very annoying code:  all is for an object, but no state is kept!
    # Should just be plain functions in an AES_BlockMode module.
    aes = AES()

    # structure of supported modes of operation
    modeOfOperation = dict(OFB=0, CFB=1, CBC=2)

    # converts a 16 character string into a number array
    def convertString(self, string, start, end, mode):
        if end - start > 16: end = start + 16
        if mode == self.modeOfOperation["CBC"]: ar = [0] * 16
        else: ar = []

        i = start
        j = 0
        while len(ar) < end - start:
            ar.append(0)
        while i < end:
            ar[j] = ord(string[i])
            j += 1
            i += 1
        return ar

    # Mode of Operation Encryption
    # stringIn - Input String
    # mode - mode of type modeOfOperation
    # hexKey - a hex key of the bit length size
    # size - the bit length of the key
    # hexIV - the 128 bit hex Initilization Vector
    def encrypt(self, stringIn, mode, key, size, IV):
        if len(key) % size:
            return None
        if len(IV) % 16:
            return None
        # the AES input/output
        plaintext = []
        iput = [0] * 16
        output = []
        ciphertext = [0] * 16
        # the output cipher string
        cipherOut = []
        # char firstRound
        firstRound = True
        if stringIn != None:
            for j in range(int(math.ceil(float(len(stringIn))/16))):
                start = j*16
                end = j*16+16
                if  end > len(stringIn):
                    end = len(stringIn)
                plaintext = self.convertString(stringIn, start, end, mode)
                # print 'PT@%s:%s' % (j, plaintext)
                if mode == self.modeOfOperation["CFB"]:
                    if firstRound:
                        output = self.aes.encrypt(IV, key, size)
                        firstRound = False
                    else:
                        output = self.aes.encrypt(iput, key, size)
                    for i in range(16):
                        if len(plaintext)-1 < i:
                            ciphertext[i] = 0 ^ output[i]
                        elif len(output)-1 < i:
                            ciphertext[i] = plaintext[i] ^ 0
                        elif len(plaintext)-1 < i and len(output) < i:
                            ciphertext[i] = 0 ^ 0
                        else:
                            ciphertext[i] = plaintext[i] ^ output[i]
                    for k in range(end-start):
                        cipherOut.append(ciphertext[k])
                    iput = ciphertext
                elif mode == self.modeOfOperation["OFB"]:
                    if firstRound:
                        output = self.aes.encrypt(IV, key, size)
                        firstRound = False
                    else:
                        output = self.aes.encrypt(iput, key, size)
                    for i in range(16):
                        if len(plaintext)-1 < i:
                            ciphertext[i] = 0 ^ output[i]
                        elif len(output)-1 < i:
                            ciphertext[i] = plaintext[i] ^ 0
                        elif len(plaintext)-1 < i and len(output) < i:
                            ciphertext[i] = 0 ^ 0
                        else:
                            ciphertext[i] = plaintext[i] ^ output[i]
                    for k in range(end-start):
                        cipherOut.append(ciphertext[k])
                    iput = output
                elif mode == self.modeOfOperation["CBC"]:
                    for i in range(16):
                        if firstRound:
                            iput[i] =  plaintext[i] ^ IV[i]
                        else:
                            iput[i] =  plaintext[i] ^ ciphertext[i]
                    # print 'IP@%s:%s' % (j, iput)
                    firstRound = False
                    ciphertext = self.aes.encrypt(iput, key, size)
                    # always 16 bytes because of the padding for CBC
                    for k in range(16):
                        cipherOut.append(ciphertext[k])
        return mode, len(stringIn), cipherOut

    # Mode of Operation Decryption
    # cipherIn - Encrypted String
    # originalsize - The unencrypted string length - required for CBC
    # mode - mode of type modeOfOperation
    # key - a number array of the bit length size
    # size - the bit length of the key
    # IV - the 128 bit number array Initilization Vector
    def decrypt(self, cipherIn, originalsize, mode, key, size, IV):
        # cipherIn = unescCtrlChars(cipherIn)
        if len(key) % size:
            return None
        if len(IV) % 16:
            return None
        # the AES input/output
        ciphertext = []
        iput = []
        output = []
        plaintext = [0] * 16
        # the output plain text character list
        chrOut = []
        # char firstRound
        firstRound = True
        if cipherIn != None:
            for j in range(int(math.ceil(float(len(cipherIn))/16))):
                start = j*16
                end = j*16+16
                if j*16+16 > len(cipherIn):
                    end = len(cipherIn)
                ciphertext = cipherIn[start:end]
                if mode == self.modeOfOperation["CFB"]:
                    if firstRound:
                        output = self.aes.encrypt(IV, key, size)
                        firstRound = False
                    else:
                        output = self.aes.encrypt(iput, key, size)
                    for i in range(16):
                        if len(output)-1 < i:
                            plaintext[i] = 0 ^ ciphertext[i]
                        elif len(ciphertext)-1 < i:
                            plaintext[i] = output[i] ^ 0
                        elif len(output)-1 < i and len(ciphertext) < i:
                            plaintext[i] = 0 ^ 0
                        else:
                            plaintext[i] = output[i] ^ ciphertext[i]
                    for k in range(end-start):
                        chrOut.append(chr(plaintext[k]))
                    iput = ciphertext
                elif mode == self.modeOfOperation["OFB"]:
                    if firstRound:
                        output = self.aes.encrypt(IV, key, size)
                        firstRound = False
                    else:
                        output = self.aes.encrypt(iput, key, size)
                    for i in range(16):
                        if len(output)-1 < i:
                            plaintext[i] = 0 ^ ciphertext[i]
                        elif len(ciphertext)-1 < i:
                            plaintext[i] = output[i] ^ 0
                        elif len(output)-1 < i and len(ciphertext) < i:
                            plaintext[i] = 0 ^ 0
                        else:
                            plaintext[i] = output[i] ^ ciphertext[i]
                    for k in range(end-start):
                        chrOut.append(chr(plaintext[k]))
                    iput = output
                elif mode == self.modeOfOperation["CBC"]:
                    output = self.aes.decrypt(ciphertext, key, size)
                    for i in range(16):
                        if firstRound:
                            plaintext[i] = IV[i] ^ output[i]
                        else:
                            plaintext[i] = iput[i] ^ output[i]
                    firstRound = False
                    if originalsize is not None and originalsize < end:
                        for k in range(originalsize-start):
                            chrOut.append(chr(plaintext[k]))
                    else:
                        for k in range(end-start):
                            chrOut.append(chr(plaintext[k]))
                    iput = ciphertext
        return "".join(chrOut)


def append_PKCS7_padding(s):
    """return s padded to a multiple of 16-bytes by PKCS7 padding"""
    numpads = 16 - (len(s)%16)
    return s + numpads*chr(numpads)

def strip_PKCS7_padding(s):
    """return s stripped of PKCS7 padding"""
    if len(s)%16 or not s:
        raise ValueError("String of len %d can't be PCKS7-padded" % len(s))
    numpads = ord(s[-1])
    if numpads > 16:
        raise ValueError("String ending with %r can't be PCKS7-padded" % s[-1])
    return s[:-numpads]

def encryptData(key, data, mode=AESModeOfOperation.modeOfOperation["CBC"]):
    """encrypt `data` using `key`

    `key` should be a string of bytes.

    returned cipher is a string of bytes prepended with the initialization
    vector.

    """
    key = map(ord, key)
    if mode == AESModeOfOperation.modeOfOperation["CBC"]:
        data = append_PKCS7_padding(data)
    keysize = len(key)
    assert keysize in AES.keySize.values(), 'invalid key size: %s' % keysize
    # create a new iv using random data
    iv = [ord(i) for i in os.urandom(16)]
    moo = AESModeOfOperation()
    (mode, length, ciph) = moo.encrypt(data, mode, key, keysize, iv)
    # With padding, the original length does not need to be known. It's a bad
    # idea to store the original message length.
    # prepend the iv.
    return ''.join(map(chr, iv)) + ''.join(map(chr, ciph))

def decryptData(key, data, mode=AESModeOfOperation.modeOfOperation["CBC"]):
    """decrypt `data` using `key`

    `key` should be a string of bytes.

    `data` should have the initialization vector prepended as a string of
    ordinal values.
    """

    key = map(ord, key)
    keysize = len(key)
    assert keysize in AES.keySize.values(), 'invalid key size: %s' % keysize
    # iv is first 16 bytes
    iv = map(ord, data[:16])
    data = map(ord, data[16:])
    moo = AESModeOfOperation()
    decr = moo.decrypt(data, None, mode, key, keysize, iv)
    if mode == AESModeOfOperation.modeOfOperation["CBC"]:
        decr = strip_PKCS7_padding(decr)
    return decr

def generateRandomKey(keysize):
    """Generates a key from random data of length `keysize`.    
    The returned key is a string of bytes.    
    """
    if keysize not in (16, 24, 32):
        emsg = 'Invalid keysize, %s. Should be one of (16, 24, 32).'
        raise ValueError, emsg % keysize
    return os.urandom(keysize)

def testStr(cleartext, keysize=16, modeName = "CBC"):
    '''Test with random key, choice of mode.'''
    print 'Random key test', 'Mode:', modeName
    print 'cleartext:', cleartext
    key =  generateRandomKey(keysize)
    print 'Key:', [ord(x) for x in key]
    mode = AESModeOfOperation.modeOfOperation[modeName]
    cipher = encryptData(key, cleartext, mode)
    print 'Cipher:', [ord(x) for x in cipher]
    decr = decryptData(key, cipher, mode)
    print 'Decrypted:', decr
    
    
if __name__ == "__main__":
    moo = AESModeOfOperation()
    cleartext = "This is a test with several blocks!"
    cypherkey = [143,194,34,208,145,203,230,143,177,246,97,206,145,92,255,84]
    iv = [103,35,148,239,76,213,47,118,255,222,123,176,106,134,98,92]
    mode, orig_len, ciph = moo.encrypt(cleartext, moo.modeOfOperation["CBC"],
            cypherkey, moo.aes.keySize["SIZE_128"], iv)
    print 'm=%s, ol=%s (%s), ciph=%s' % (mode, orig_len, len(cleartext), ciph)
    decr = moo.decrypt(ciph, orig_len, mode, cypherkey,
            moo.aes.keySize["SIZE_128"], iv)
    print decr
    testStr(cleartext, 16, "CBC")

参考链接

---

• Cryptography Symmetric encryption
• aes.py: implements AES - Advanced Encryption Standard
• ImportError: No module named 'Crypto' on a Mac

系统输入cmd：
windows 解决方法：

python -m ensurepip

升级pip版本:

pip install --upgrade pip

linux解决方法：

$ python -m ensurepip

$ sudo easy_install pip

$ python -m pip install --upgrade pip

参考链接

---

使用pip安装模块时提示： No module named pip

最近在处理服务器接口的时候，需要使用`Python`模拟发送表单数据到服务器，搜索了一下，找到如下例子：

# encoding=utf8
import urllib
import urllib2
import httplib
import os

HOST = 'xx.xx.xx.xx'
PORT = 8000
P_ID = xx
U_NAME = 'xxx'
API_KEY = 'xxx'
API_SEC = 'xxx'
UP_APK = xx

def sign(src, key):
  HEX_CHARS = [ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' ]
  from hashlib import sha1
  import hmac
  hashed = hmac.new(key, src, sha1)
  sv = str(hashed.digest())
  ret = ''
  for b in bytearray(sv):
    bite = b & 0xff
    ret += HEX_CHARS[ bite >> 4 ]
    ret += HEX_CHARS[ bite & 0xf ]
  return ret

def encode_multipart_formdata(fields, files):
  """
  fields is a sequence of (name, value) elements for regular form fields.
  files is a sequence of (name, filename, value) elements for data to be uploaded as files
  Return (content_type, body) ready for httplib.HTTP instance
  """
  import random
  BOUNDARY = '----------%s' % ''.join(random.sample('0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIGKLMNOPQRSTUVWXYZ', 62))
  CRLF = '\r\n'
  L = []
  for (key, value) in fields:
    L.append('--' + BOUNDARY)
    L.append('Content-Disposition: form-data; name="%s"' % key)
    L.append('')
    L.append(value)
  for (key, filename, value) in files:
    L.append('--' + BOUNDARY)
    L.append('Content-Disposition: form-data; name="%s"; filename="%s"' % (key, filename))
    L.append('Content-Type: %s' % get_content_type(filename))
    L.append('')
    L.append(value)
  L.append('--' + BOUNDARY + '--')
  L.append('')
  body = CRLF.join(L)
  content_type = 'multipart/form-data; boundary=%s' % BOUNDARY
  return content_type, body, BOUNDARY

def get_content_type(filename):
  import mimetypes
  return mimetypes.guess_type(filename)[0] or 'application/octet-stream'

def post_apk_sign(apk_file):
  filename = os.path.basename(apk_file)
  url = 'http://' + HOST + ':' + str(PORT) + 'xxx'
  fields = [('un', U_NAME), ('p_id', str(P_ID)), ('up_type', str(UP_APK))]
  with open(apk_file, 'r') as f:
    files = [('apk_file', filename, f.read())]
  content_type, body, boundary = encode_multipart_formdata(fields, files)
  si = sign(API_KEY + str(P_ID) + str(UP_APK) + U_NAME, API_SEC)
  # print si
  req = urllib2.Request(url)
  req.add_header('api_key', API_KEY)
  req.add_header('sign', si)
  req.add_header('Content-Type', 'multipart/form-data; boundary='+boundary)
  resp = urllib2.urlopen(req, body)
  res = resp.read()
  print res

if __name__=='__main__':
  # b38d73bb278800dd3c0c3cf11ad20c106d17944c
  # print(sign(b'123test123456', b'456'))

  apk_file = 'xxx.apk'
  post_apk_sign(apk_file)

参考链接

---

• Http client to POST using multipart/form-data
• python urllib3 multipart/form-data 的坑
• Python发送form-data请求及拼接form-data内容的方法
• Implementation HMAC-SHA1 in python