Easy

根据给出的加密算法和密文

编写一个解密程序

def rc4(key, data):
    key_length = len(key)
    s = list(range(256))
    j = 0
    for i in range(256):
        j = (j + s[i] + ord(key[i % key_length])) % 256
        s[i], s[j] = s[j], s[i]
​
    i = j = 0
    output = bytearray()
    for byte in data:
        i = (i + 1) % 256
        j = (j + s[i]) % 256
        s[i], s[j] = s[j], s[i]
        k = s[(s[i] + s[j]) % 256]
        output.append(byte ^ k)
​
    return bytes(output).decode('utf-8', errors='ignore')
​
key = "hello world"
ciphertext = "d8d2963e0d8ab8533d2a7fe296c529233924"
ciphertext += "6eba0d292d5752578359322c3a77892dfa7261b84f"
​
flag_length = 40
flag = rc4(key, bytes.fromhex(ciphertext))
​
flag = flag[:flag_length]
print("Decrypted flag:", flag)

拿到flag

Decrypted flag: WuCup{55a0a84f86a6ad40006f014619577ad3}

Sign WEB

进入环境提示

passwd:sgin

中国蚁剑连上

然后找到flag文件就好

sign misc

一眼16进制

转字符，得