part3.py

k = "Pl3as_d0"+"n't_cR45"+"h_1n_+h!"+"s_fUnC+1"+"0n"
s = "+U]\x93\xa0C\xdd\x14"+"CR}\xe5"
print len(k), len(s)

b = []
j = 0


cnt = 0xf6

#key scheduling algorithm
def KSA(key):
    keylength = len(key)

    S = range(cnt)

    j = 0
    for i in range(cnt):
        j = (j + S[i] + key[i % keylength]) % cnt
        S[i], S[j] = S[j], S[i]  # swap

    return S


#Psudo-random generation algorithm
def PRGA(S):
    i = 0
    j = 0
    while True:
        i = (i + 1) % cnt
        j = (j + S[i]) % cnt
        S[i], S[j] = S[j], S[i]  # swap

        K = S[(S[i] + S[j]) % cnt]
        yield K


def RC4(key):
    S = KSA(key)
    return PRGA(S)


a = RC4([ord(x) for x in k])

b = []
l = len(s)
i = 0
for c in a:
	if i >= l:
		break
	b.append(chr(ord(s[i]) ^ c))
	i += 1

print ''.join(b)