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BASE系列

2023-05-17 94

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简介： BASE系列

BASE64

编码对象: ascill字符
原理:

将每个字符的8位ascill码组合在一起，保证组合后的长度是24的倍数，不足的在后面添0
将组合好的字符串以6位一组拆分

将六位二进制转为十进制，并查字符表

数值	字符	数值	字符	数值	字符	数值	字符
0	A	16	Q	32	g	48	w
1	B	17	R	33	h	49	x
2	C	18	S	34	i	50	y

3	D	19	T	35	j	51	z
4	E	20	U	36	k	52	0
5	F	21	V	37	l	53	1
6	G	22	W	38	m	54	2
7	H	23	X	39	n	55	3

8	I	24	Y	40	o	56	4
9	J	25	Z	41	p	57	5
10	K	26	a	42	q	58	6
11	L	27	b	43	r	59	7
12	M	28	c	44	s	60	8

13	N	29	d	45	t	61	9
14	O	30	e	46	u	62	+
15	P	31	f	47	v	63	/

注意，最后面的数为0的不需要查表，替换为"="
举例
编码: ab

转为ascill码: 01100001 01100010

长度为12，不是24的倍数，补0 : 01100001 01100010 00000000

分组: 011000 010110 001000 000000

转为10进制: 24 22 8 0

最后有一个0，替换为"+", 其余查表: Y W I =

所以ab编码后的密文为: YWI=

代码

# write in 2021/6/21
import re
DIC = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
def is_ascii(char):
  if ord(char) >= 0 and ord(char) <= 127:
    return True
  return False
def encrypt_base64(string):
  bin_string = ""
  ciphertext = ""
  num = 0
  length = len(string)
  for char in string:
    # 异常检测
    if not is_ascii(char):
      return -1
    bin_string += ("00000000" + str(bin(ord(char)))[2::])[-8::]
  #print(length)
  if length % 3 == 1:
    bin_string += "0"*4
    num = 2
  elif length % 3 == 2:
    bin_string += "0"*8
    num = 1
  bin_list = re.findall(".{6}",bin_string)
  for i in bin_list:
    ciphertext += DIC[int(i,2)]
  return ciphertext + "="*num
def decrypt_base64(ciphertext):
  plaintext = ""
  bin_string = ""
  print(ciphertext)
  num = ciphertext.count("=")
  #print(num)
  if num:
    ciphertext = ciphertext[0:-num:]
  #print(ciphertext)
  for i in ciphertext:
    # 异常检测
    if i not in DIC:
      return -1
    bin_string += ("0"*6 + str(bin(DIC.index(i)))[2::])[-6::]
  bin_list = re.findall(".{8}", bin_string)
  print(bin_list)
  for i in bin_list:
    plaintext += chr(int(i, 2))
  return plaintext
# 01000000
if __name__ == '__main__':
  print("Aabc ",encrypt_base64("Aabc"))
  print("Aabc ",decrypt_base64(encrypt_base64("Aabc")))

BASE32

编码对象: ascill字符
原理：

将每个字符转为8位ascill码，组合在一起，需要保证长度是40的倍数，不足的在后面补0
将组合后的串以每五位分割开来
将五位的二进制转为十进制，在查表:

数值	字符	数值	字符	数值	字符	数值	字符
0	A	8	I	16	Q	24	Y
1	B	9	j	17	R	25	Z
2	C	10	K	18	S	26	2
3	D	11	L	19	T	27	3

4	E	12	M	20	U	28	4
5	F	13	N	21	V	29	5
6	G	14	O	22	W	30	6
7	H	15	P	23	X	31	7

注意：最后的0不需要查表, 替换为"="
代码

# write in 2021/6/22
import re
DIC = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"
def is_ascii(char):
  if ord(char) >= 0 and ord(char) <= 127:
    return True
  return False
def encrypt_base32(string):
  bin_string = ""
  ciphertext = ""
  num = 0
  length = len(string)
  for char in string:
    # 异常检测
    if not is_ascii(char):
      return -1
    bin_string += ("00000000" + str(bin(ord(char)))[2::])[-8::]
  #print(length)
  if length % 5 == 1:
    bin_string += "0"*2
    num = 6
  elif length % 5 == 2:
    bin_string += "0"*4
    num = 4
  elif length % 5 == 3:
    bin_string += "0"
    num = 3
  elif length % 5 == 4:
    bin_string += "0"*3
    num = 1
  bin_list = re.findall(".{5}",bin_string)
  print(bin_list)
  for i in bin_list:
    ciphertext += DIC[int(i,2)]
  return ciphertext + "="*num
def decrypt_base32(ciphertext):
  plaintext = ""
  bin_string = ""
  #print(ciphertext)
  num = ciphertext.count("=")
  print(num)
  if num:
    ciphertext = ciphertext[0:-num:]
  #print(ciphertext)
  for i in ciphertext:
    # 异常检测
    if i not in DIC:
      return -1
    bin_string += ("0"*5 + str(bin(DIC.index(i)))[2::])[-5::]
  bin_list = re.findall(".{8}",bin_string)
  for i in bin_list:
    plaintext += chr(int(i,2))
  return plaintext
if __name__ == '__main__':
  print("Aabc ",encrypt_base32("Aabc"))
  print("Aabc ",decrypt_base32(encrypt_base32("Aabc")))

BASE16

编码对象: ascill字符
原理:

将字符转为8位ascill码，并组合在一起

将字符以每4位一组分割
将4位二进制转为十进制
查表:

数值	字符	数值	字符	数值	字符	数值	字符

0	0	4	4	8	8	12	c
1	1	5	5	9	9	13	d
2	2	6	6	10	a	14	e
3	3	7	7	11	b	15	f

代码

# write in 2021/6/22
import re
DIC = "0123456789ABCDEF"
def is_ascii(char):
  if ord(char) >= 0 and ord(char) <= 127:
    return True
  return False
def encrypt_base16(string):
  bin_string = ""
  ciphertext = ""
  length = len(string)
  for char in string:
    # 异常检测
    if not is_ascii(char):
      return -1
    bin_string += ("00000000" + str(bin(ord(char)))[2::])[-8::]
  #print(length)
  bin_list = re.findall(".{4}",bin_string)
  print(bin_list)
  for i in bin_list:
    ciphertext += DIC[int(i,2)]
  return ciphertext
def decrypt_base16(ciphertext):
  plaintext = ""
  bin_string = ""
  #print(ciphertext)
  for i in ciphertext:
    # 异常检测
    if i not in DIC:
      return -1
    bin_string += ("0"*4 + str(bin(DIC.index(i)))[2::])[-4::]
  bin_list = re.findall(".{8}",bin_string)
  for i in bin_list:
    plaintext += chr(int(i,2))
  return plaintext
if __name__ == '__main__':
  print("Aabc ",decrypt_base16("Aabc"))
  print("Aabc ",decrypt_base16(encrypt_base16("Aabc")))

文章标签：

C语言

BASE系列

BASE64

BASE32

BASE16

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