3-ReDecryptedCode.py

#coding=utf-8
import hashlib

def sha1(string):
    return hashlib.sha1(string).hexdigest()


def calc(strSHA1):
    r = 0
    for i in strSHA1:
        r += int('0x%s' % i, 16)

    return r


def encrypt(plain, key, cipherText):
    keySHA1 = sha1(key)
    intSHA1 = calc(keySHA1)
    cipherTextLength=len(cipherText)/4
    plainum=[]
    r = []
    cipher=[]

    for i in range(cipherTextLength):
        # 将 cipherText 转化为数字 list
        cipher.append(int(cipherText[4*i : 4*i+4]))

    for i in range(cipherTextLength):
        # 计算 plainText
        plain += chr(cipher[i] - int('0x%s' % keySHA1[i % 40], 16) + intSHA1)
        plainum.append(cipher[i] - int('0x%s' % keySHA1[i % 40], 16) + intSHA1)

        r.append(ord(plain[i]) + int('0x%s' % keySHA1[i % 40], 16) - intSHA1)
        intSHA1 = calc(sha1(plain[:i + 1])[:20] + sha1(str(intSHA1))[:20])

    print plainum
    return ''.join(map(lambda x: str(x), r)), plain


if __name__ == '__main__':
    #key = raw_input('[*] Please input key:')
    f_key = open('_DecodeFile.txt', 'r')
    key = f_key.read().decode('utf8').encode('ascii','ignore')
    f_key.close()
    #plain = raw_input('[*] Please input flag:')
    plain = ''
    cipherText = '-185-147-211-221-164-217-188-169-205-174-211-225-191-234-148-199-198-253-175-157-222-135-240-229-201-154-178-187-244-183-212-222-164'
    (encryptText, plain) = encrypt(plain, key, cipherText)
    if encryptText == cipherText:
        print '[>] Congratulations! Flag is: %s' % plain
        exit()
    else:
        print '[!] Key or flag is wrong, try again:)'
        exit()