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@WilliamHYZhang @mikelfried @gerroo @laurent-pck @chttrjeankr
88 lines (69 sloc) 2.4 KB
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()
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