Python实现base64算法
def encode_base64(text): r""" >>> encode_base64('WELCOME to base64 encoding 😁') 'V0VMQ09NRSB0byBiYXNlNjQgZW5jb2Rpbmcg8J+YgQ==' >>> encode_base64('AÅᐃ𐀏🤓') 'QcOF4ZCD8JCAj/CfpJM=' >>> encode_base64('A'*60) 'QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB\r\nQUFB' """ base64_chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" byte_text = bytes(text, "utf-8") # put text in bytes for unicode support r = "" # the result c = -len(byte_text) % 3 # the length of padding p = "=" * c # the padding s = byte_text + b"\x00" * c # the text to encode i = 0 while i < len(s): if i > 0 and ((i / 3 * 4) % 76) == 0: r = r + "\r\n" # for unix newline, put "\n" n = (s[i] << 16) + (s[i + 1] << 8) + s[i + 2] n1 = (n >> 18) & 63 n2 = (n >> 12) & 63 n3 = (n >> 6) & 63 n4 = n & 63 r += base64_chars[n1] + base64_chars[n2] + base64_chars[n3] + base64_chars[n4] i += 3 return r[0 : len(r) - len(p)] + p def decode_base64(text): r""" >>> decode_base64('V0VMQ09NRSB0byBiYXNlNjQgZW5jb2Rpbmcg8J+YgQ==') 'WELCOME to base64 encoding 😁' >>> decode_base64('QcOF4ZCD8JCAj/CfpJM=') 'AÅᐃ𐀏🤓' >>> decode_base64("QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB\r\nQUFB") 'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA' """ base64_chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" s = "" for i in text: if i in base64_chars: s += i c = "" else: if i == "=": c += "=" p = "" if c == "=": p = "A" else: if c == "==": p = "AA" r = b"" s = s + p i = 0 while i < len(s): n = ( (base64_chars.index(s[i]) << 18) + (base64_chars.index(s[i + 1]) << 12) + (base64_chars.index(s[i + 2]) << 6) + base64_chars.index(s[i + 3]) ) r += bytes([(n >> 16) & 255]) + bytes([(n >> 8) & 255]) + bytes([n & 255]) i += 4 return str(r[0 : len(r) - len(p)], "utf-8") def main(): print(encode_base64("WELCOME to base64 encoding 😁")) print(decode_base64(encode_base64("WELCOME to base64 encoding 😁"))) if __name__ == "__main__": main()