base64_table.json

{"110000": "w", "110001": "x", "110101": "1", "110100": "0", "010100": "U", "010101": "V", "001100": "M", "001101": "N", "011110": "e", "011111": "f", "001001": "J", "001000": "I", "011011": "b", "011010": "a", "000110": "G", "000111": "H", "000011": "D", "000010": "C", "100100": "k", "100101": "l", "111100": "8", "111101": "9", "100010": "i", "100011": "j", "101110": "u", "101111": "v", "111001": "5", "111000": "4", "101011": "r", "101010": "q", "110011": "z", "110010": "y", "010010": "S", "010011": "T", "010111": "X", "010110": "W", "110110": "2", "110111": "3", "011000": "Y", "011001": "Z", "001111": "P", "001110": "O", "011101": "d", "011100": "c", "001010": "K", "001011": "L", "101101": "t", "000000": "A", "000001": "B", "100111": "n", "100110": "m", "000101": "F", "000100": "E", "111111": "/", "111110": "+", "100001": "h", "100000": "g", "010001": "R", "010000": "Q", "101100": "s", "111010": "6", "111011": "7", "101000": "o", "101001": "p"}

mkBase64Table.py

#!/usr/bin/env python

import io
import json

def main():
    dict = {}
    n = 0

    # A~Z
    for i in range(ord('A'), ord('Z') + 1):
        char = unichr(i)
        bin = format(n, 'b').zfill(6)
        dict[str(bin)] = char
        print bin, char
        n += 1

    # a~z
    for i in range(ord('a'), ord('z') + 1):
        char = unichr(i)
        bin = format(n, 'b').zfill(6)
        dict[str(bin)] = char
        print bin, char
        n += 1

    # 0~9
    for i in range(0, 10):
        bin = format(n, 'b').zfill(6)
        dict[str(bin)] = str(i)
        print bin, i
        n+=1

    # +
    bin = format(n, 'b').zfill(6)
    dict[str(bin)] = '+'

    n+=1
    bin = format(n, 'b').zfill(6)
    dict[str(bin)] = '/'

    f = open('base64_table.json', "w")
    f.write(json.dumps(dict))
    f.close()

if __name__ == '__main__':
    main()

string2base64.py

#!/usr/bin/env python

import sys
import json

# 1文字が8バイトで表される
BYTE_SIZE = 8

# 文字列textをバイナリの文字列に変換する
def str2bin(s):
    binStr = ""
    
    #ord関数で文字をASCIIコードへ変換し、
   	#シフト演算で各桁のビットを取り出す
    for c in s:
        for i in range(BYTE_SIZE):
            binStr += str((ord(c) >> (BYTE_SIZE - (i + 1))) & 1)
    return binStr

# 文字列sを文字数nで分割したリストを返す
# (例)
# split("abcdef", 2) => [["ab"], ["cd"], ["ef"]]
def split(s, n):
    return [s[i:i+n] for i in range(0, len(s), n)]


# 文字列sを文字数nで分割した時に足りない部分を文字cで埋める
# (例)
# fillInBlank("abcd", 6, "==") => "abcd=="
def fillInBlank(s, n, c):
    mod = len(s) % n
    
    # 割り切れた場合は何も処理をしない
    if mod == 0: return s 

	# 割り切れなかった場合、残りの部分を埋める
    margin = n - mod
    return s + c * margin

# main関数         
def main():

	# コマンドの引数を受け取る
	argvs = sys.argv
    argc = len(argvs)
    
    # 引数が1つじゃなかったら無かったら、処理をせず終了
    if argc != 2:
        print "Usage:\n$ python %s CONVERT_STRING" % argvs[0]
        quit()

	# 1. 文字列をバイナリ文字列に変換
    binStr = str2bin(argvs[1])

	# 2. バイナリを6ビットづつに分割
    splitCount  =6
    s = split(binStr, splitCount)

	# 最後の2ビットが余るので,6ビットになるように0を追加する
    s[-1] = fillInBlank(s[-1], 6, "0")

	# 変換表の辞書を読み込み
    tableFile = open("base64_table.json", "r")
    base64Dict = json.loads(tableFile.read())

    result = ""

    for i in s:
        result += base64Dict[i]

    print result

    print fillInBlank(result, 4, "=")
    
if __name__ == '__main__':
	main()