z-hacker

This is a task that is a little bit different than usual.

Little Z decided to store some secrets by encrypting them. Your job is to break the encryption and prove to Little Z that he has to use better encryption algorithm in future.

Little Z's secrets are all text sentences (in English), each is composed of small letters of English alphabet and space characters, and is 20 characters long. The encryption is done in the following way. Little Z generated a key that is 20 bytes long, then he applies xor operation on each of the sentences (characters ASCII values) and the key.

Let one sentence be S, and the generated key be P. Then the encrypted sentence C will have 20 bytes where C_i = ASCII(S_i) xor P_i

You are given the byte values of all the encrypted (10) sentences, they are:

1:
77 41 87 80 73 59 6 80 8 87 76 64 126 68 37 80 80 5 47 77
2:
72 96 84 69 75 42 6 94 71 3 87 73 59 67 48 3 69 66 33 74
3:
72 96 66 73 5 56 71 94 8 66 74 65 126 83 39 79 93 5 47 77
4:
86 40 76 4 73 59 82 10 92 75 65 5 58 73 39 80 4 71 41 87
5:
86 40 70 86 64 126 79 89 8 78 93 5 43 72 36 70 86 82 37 66
6:
73 47 84 4 65 49 6 83 71 86 4 82 63 72 52 3 80 74 96 65
7:
82 44 70 65 85 55 72 77 8 74 87 5 60 73 50 74 74 66 96 87
8:
76 57 3 76 68 55 84 73 93 87 4 76 45 6 51 87 81 85 41 71
9:
78 54 70 86 5 42 78 79 90 70 4 76 45 6 46 76 80 5 40 76
10:
73 41 80 4 70 63 75 79 90 66 4 82 49 84 43 80 4 70 47 76

But somehow you overheard that some of the secret sentences contain the text "little z" (without quotes)