--> [Original post](https://www.hackinprovence.fr/balccon-xoared-writeup/) <--
[Note: the code sections autowrap on this site, which really damages the understanding of this challenge (please see the previous link)]
The goal is to decrypt some binary data. The title implies that there is some sort of XOR cypher. Let's look at the blob in an hex view:
```        00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f       0  08 b3 9e e9 66 34 93 24 a3 ce 21 7f 96 47 ac 37  ....f4.$..!..G.7    10  7b 66 61 63 74 6f 72 73 3f 7d 83 95 6a f8 b8 fb  {factors?}..j...    20  57 a9 34 11 86 26 2b 63 95 fc 00 18 a4 a4 e4 4d  W.4..&+c.......M    30  20 a5 1a b5 cb 0e 40 88 5f a1 09 6b 09 6b 0c 6f   .....@._..k.k.o    40  43 44 69 0e 67 88 85 7a e9 a8 d6 4b 93 39 2b 85  CDi.g..z...K.9+.    50  1c 03 73 b9 ec 17 22 a9 8f f0 7b 1e b3 1f 9a f4  ..s..."...{.....    60  10 58 85 61 b1 66 61 66 70 20 59 59 75 73 05 77  .X.a.fafp YYus.w    70  98 94 6a c4 b4 ec 46 a9 3a 11 ad 0c 2f 63 ae d6  ..j...F.:.../c..    80  1a 09 bd b9 ce 6d 1b 9c 20 84 ec 1d 66 95 0e bb  .....m.. ...f...    90  09 7a 4a 46 3a 68 43 7e 63 15 66 88 b9 76 fe b9  .zJF:hC~c.f..v..    a0  d6 45 93 12 01 81 1c 38 59 a3 fd 0e 3f 83 af cb  .E.....8Y...?...    b0  42 24 82 38 89 d2 0d 09 9f 61 a0 25 4c 50 77 20  B$.8.....a.%LPw     c0  63 53 6e 72 05 4b 94 83 7b c4 ba ec 6d 83 3e 11  cSnr.K..{...m.>.    d0  96 26 35 72 b7 cb 30 29 86 80 f4 5c 3c 8f 06 99  .&5r..0)...\<...    e0  bd 07 66 84 4d 96 3f 7d 4a 7c 30 73 42 7e 5f 19  ..f.M.?}J|0sB~_.    f0  71 99 b9 78 fe 92 fc 41 93 29 2b 9b 0d 21 44 89  q..x...A.)+..!D.   100  dd 35 06 b9 9e ec 51 02 9f 69 93 d2 1c 4a b2 57  .5....Q..i...J.W
        [...]
   6c0  95 f0 37 7a b9 78 b2 2f 76 58 71 0c 7e 00 69 5f  ..7z.x./vXq.~.i_   6d0  09 67 b2 8f 61 e8 a8 ea 47 84 28 2b 8b 1c 28 59  .g..a...G.(+..(Y   6e0  bd ec 2c                                         ..,```
There's text ("{factors}", "fafp YYus", ...) but data seems misaligned. If it is a repeating XOR key that encode text, we should be able to see alignment. I tried some alignments, but then I remarked that the length of the blob is 1763, which equals to 41 times 43. 43's a charm:
```     0  08 b3 9e e9 66 34 93 24 a3 ce 21 7f 96 47 ac 37 7b 66 61 63 74 6f 72 73 3f 7d 83 95 6a f8 b8 fb 57 a9 34 11 86 26 2b 63 95 fc 00  ....f4.$..!..G.7{factors?}..j...W.4..&+c...    2b  18 a4 a4 e4 4d 20 a5 1a b5 cb 0e 40 88 5f a1 09 6b 09 6b 0c 6f 43 44 69 0e 67 88 85 7a e9 a8 d6 4b 93 39 2b 85 1c 03 73 b9 ec 17  ....M .....@._..k.k.oCDi.g..z...K.9+...s...    56  22 a9 8f f0 7b 1e b3 1f 9a f4 10 58 85 61 b1 66 61 66 70 20 59 59 75 73 05 77 98 94 6a c4 b4 ec 46 a9 3a 11 ad 0c 2f 63 ae d6 1a  "...{......X.a.fafp YYus.w..j...F.:.../c...    81  09 bd b9 ce 6d 1b 9c 20 84 ec 1d 66 95 0e bb 09 7a 4a 46 3a 68 43 7e 63 15 66 88 b9 76 fe b9 d6 45 93 12 01 81 1c 38 59 a3 fd 0e  ....m.. ...f....zJF:hC~c.f..v...E.....8Y...    ac  3f 83 af cb 42 24 82 38 89 d2 0d 09 9f 61 a0 25 4c 50 77 20 63 53 6e 72 05 4b 94 83 7b c4 ba ec 6d 83 3e 11 96 26 35 72 b7 cb 30  ?...B$.8.....a.%LPw cSnr.K..{...m.>..&5r..0    d7  29 86 80 f4 5c 3c 8f 06 99 bd 07 66 84 4d 96 3f 7d 4a 7c 30 73 42 7e 5f 19 71 99 b9 78 fe 92 fc 41 93 29 2b 9b 0d 21 44 89 dd 35  )...\<.....f.M.?}J|0sB~_.q..x...A.)+..!D..5   102  06 b9 9e ec 51 02 9f 69 93 d2 1c 4a b2 57 a7 25 76 5a 6c 21 63 6f 62 65 14 4b 9a 83 50 ee be ec 56 a9 24 00 8f 3b 1f 52 8c f2 0a  ....Q..i...J.W.%vZl!cobe.K..P...V.$..;.R...   12d  18 a1 93 d2 41 6d 95 06 88 fe 2a 50 83 4d ac 35 66 4b 7c 0c 7f 55 6f 5f 17 71 b2 93 7c fe a9 d6 5b 82 30 36 b1 2d 1a 7d b3 ec 12  ....Am....*P.M.5fK|..Uo_.q..|...[.06.-.}...   158  15 9f 83 bd 4b 02 8e 2a be e4 1b 4a 88 5d bc 24 76 66 60 36 72 6f 6c 65 3f 61 9e 83 6b c4 a4 fd 4f b4 0e 20 b4 02 25 63 ab e1 2c  ....K..*...J.].$vf`6role?a..k...O.. ..%c..,   183  05 f0 89 d2 50 2e b8 30 8f fe 10 5a 98 4c ac 09 6a 5c 6d 0c 71 55 44 75 13 71 89 b9 66 ef b0 cb 71 a2 0b 0f 8b 1c 3d 6e 95 f1 43  ....P..0...Z.L..j\m.qUDu.q..f...q.....=n..C   1ae  0f 9f 92 fe 66 34 89 2a 84 ee 00 4b 88 61 b0 33 67 66 6e 36 59 45 68 65 04 4b 84 92 72 d9 8e dd 74 8d 34 11 93 11 03 7e fa fb 2c  ....f4.*...K.a.3gfn6YEhe.K..r...t.4....~..,   1d9  14 b3 a4 e4 57 2e 82 3a 94 ff 10 66 94 5b bd 09 64 5c 46 26 75 55 7f 5f 09 60 90 a4 4c cf 8b f2 4b 93 2c 1c ad 01 6c 74 95 e0 00  ....W..:...f.[..d\F&uU._.`..L...K.,...lt...   204  22 a9 95 fe 5c 3e 92 2b 84 d2 0c 5c 99 61 be 33 4c 4c 6a 36 62 6f 72 74 1d 56 ae b2 49 e0 b4 ec 53 9e 12 0c c2 0b 03 6f b9 d6 1a  "...\>.+...\.a.3LLj6bort.V..I...S......o...   22f  13 b3 9e ee 4c 2f 82 06 98 e8 01 66 9a 5b 96 23 60 5c 7d 0c 6f 44 66 42 23 40 ab 9d 76 fe ac e1 6d 8e 7d 06 ad 10 2f 59 a3 e7 00  ....L/.....f.[.#`\}.oDfB#@..v...m.}.../Y...   25a  18 a3 8e ff 5c 02 9e 3c 95 d2 02 5c b2 4b ba 33 77 66 70 27 7b 72 58 54 26 6f 94 83 6e f3 92 f1 02 84 12 1d 81 26 35 68 b9 ec 10  ....\..<...\.K.3wfp'{rXT&o..n........&5h...   285  08 b2 9e d2 40 38 93 06 96 e8 2a 4c 9e 5b ad 09 7a 4d 64 11 45 64 5d 7b 19 71 8c 8e 50 e3 fd fb 6d 9f 3e 2b 9b 17 2f 63 a9 fc 01  ....@8....*L.[..zMd.Ed]{.q..P...m.>+../c...   2b0  18 9f 82 e8 4d 02 90 3c be f8 06 5c 89 61 a0 22 6e 7b 5a 07 40 4b 62 65 01 7c b2 9e 3f e9 92 e0 41 a9 24 1a 81 1c 3f 73 b8 ec 2c  ....M..<...\.a."n{Z.@Kbe.|..?...A.$...?s..,   2db  04 a5 8f d2 4e 38 b8 2c 92 e8 11 66 84 4a b4 14 50 6d 5f 28 7f 55 7a 68 3f 6c dd 94 50 f2 be d6 5b 98 3e 11 91 0c 2e 63 95 f0 16  ....N8.,...f.J..Pm_(.Uzh?l..P...[.>....c...   306  09 9f 8c e8 66 28 94 3c 85 d2 1c 4d 90 7c 8a 02 55 42 60 36 67 58 44 78 50 66 b2 8f 7c c4 a4 e7 41 93 2e 01 80 1c 03 7f af fd 2c  ....f(.<...M.|..UB`6gXDxPf..|...A.........,   331  0a a5 a4 f8 4a 38 83 06 88 f9 08 7b ae 6a 8f 2d 6a 5c 78 3b 59 48 2b 72 3f 7d 9e b9 66 f5 be ec 51 83 3f 11 ad 00 39 72 95 fe 16  ....J8.....{.j.-j\x;YH+r?}..f...Q.?...9r...   35c  22 b5 88 e8 5d 02 8e 2d 9c cf 36 6d ab 45 b0 33 72 51 46 2b 36 42 44 69 13 4b 84 88 7c fe ae fc 40 93 12 0d 97 0d 03 71 af d6 06  "...]..-..6m.E.3rQF+6BDi.K..|[email protected]...   387  0e a5 9f d2 50 29 9a 1b a2 d9 33 42 94 5b a8 3e 4c 41 29 21 59 59 68 5f 09 7a 9e 83 6c ee bf ec 6d 8f 28 00 ad 0e 39 59 bf fa 16  ....P)....3B.[.>LA)!YYh_.z..l...m.(...9Y...   3b2  19 9f 92 f9 44 1f a4 0d a7 f6 0c 5c 8c 56 96 2e 23 4b 46 3a 75 6f 72 6e 13 71 8e 93 7d fe 92 f0 57 82 12 03 97 26 29 75 af ed 2c  ....D......\.V..#KF:uorn.q..}...W....&)u..,   3dd  14 b4 86 cf 7a 09 a1 22 98 e8 14 51 b2 46 f9 24 4c 50 6a 0c 6f 5e 68 65 03 61 9f 83 50 e2 a8 fd 6d 81 28 2b 87 0a 39 62 95 e0 07  ....z.."...Q.F.$LPj.o^he.a..P...m.(+..9b...   408  00 82 b8 d9 7f 26 9e 3c 80 e5 2a 41 dd 4c 96 3f 60 66 70 3d 75 55 78 75 12 71 b2 9f 6a ef 92 fe 57 a9 38 07 97 1d 03 6f be f4 31  .....&.<..*A.L.?`fp=uUxu.q..j...W.8....o..1   433  3e 94 bd f6 40 38 86 31 be f5 45 4b b2 57 ba 09 7a 57 6a 36 65 45 69 65 3f 6d 88 92 50 ec a8 d6 47 85 28 10 ad 10 28 7b 88 ca 27  >[email protected]?m..P...G.(...({..'   45e  3b bb 82 e8 58 35 b8 21 d1 ff 2a 50 9e 61 a0 38 60 5c 7a 26 74 55 44 79 05 60 b2 91 6a c4 b8 fa 57 92 12 1d 86 04 1e 45 9e cf 08  ;...X5.!..*P.a.8`\z&tUDy.`..j...W......E...   489  04 a5 9a e5 66 25 d7 2b be e4 06 66 84 50 ba 33 70 4c 6b 36 59 49 7e 74 3f 63 88 b9 7a e8 a8 ed 6d 9f 39 09 b0 3a 08 40 b1 f0 16  ....f%.+...f.P.3pLk6YI~t?c..z...m.9..:.@...   4b4  1c a8 a4 f5 09 2f b8 30 92 d2 1c 57 9e 5b aa 23 61 5c 46 2a 63 44 44 77 05 4b 98 95 6a ff 92 e0 46 8b 0f 37 a6 3f 27 7f af e8 1b  ...../.0...W.[.#a\F*cDDw.K..j...F..7.?'....   4df  22 b8 cb ff 66 34 94 06 88 e3 06 5c 8e 4b bb 33 4c 40 7c 27 59 47 7e 5f 15 67 88 82 50 f2 b9 f4 70 b5 19 32 89 00 39 67 a2 d6 0b  "...f4.....\.K.3L@|'YG~_.g..P...p..2..9g...   50a  4d b2 a4 e4 4a 02 8e 37 92 e8 16 4c 9f 5b 96 2f 76 4d 46 24 63 6f 6e 73 05 70 b2 8f 7b e6 8f ca 66 b0 36 0d 97 18 34 59 b2 b9 01  M...J..7...L.[./vMF$cons.p..{...f.6...4Y...   535  22 a9 88 d2 50 33 94 3c 82 f8 07 5c b2 47 ac 22 4c 4e 7c 0c 73 43 7e 64 3f 7d 99 9b 4d d8 99 cf 49 8f 28 15 9a 26 24 36 b8 d6 1a  "...P3.<...\.G."LN|.sC~d?}..M...I.(..&$6...   560  0e 9f 92 e3 4a 38 84 2c 93 e8 2a 40 88 4a 96 21 76 66 6c 20 63 54 44 69 14 69 af a5 5b dd b6 f0 57 97 25 2b 8a 49 2e 59 a3 fa 2c  ....J8.,..*@.J.!vfl cTDi.i..[...W.%+.I.Y..,   58b  14 ae 88 e8 5a 28 95 3c be f4 10 4d b2 49 ac 09 66 4a 7c 37 59 59 6f 7d 22 57 b9 a0 74 e2 a8 e8 5a a9 35 44 80 26 35 75 95 e0 1d  ....Z(.<...M.I..fJ|7YYo}"W..t...Z.5D.&5u...   5b6  0e a5 98 f8 4b 38 b8 20 84 f9 2a 4e 88 61 bc 25 76 5d 46 3a 72 4d 59 43 34 52 96 9f 6a fa a5 d6 4a c6 3f 2b 9b 0a 03 6f a4 fa 16  ....K8. ..*N.a.%v]F:rMYC4R..j...J.?+...o...   5e1  1e b5 89 e8 66 24 82 2d be fa 10 66 98 4d ac 32 4c 50 6d 2e 44 73 4f 46 1b 6d 88 87 67 c4 b5 b9 40 a9 24 07 ad 10 32 75 af ea 06  ....f$.-...f.M.2LPm.DsOF.m..g...@.$...2u...   60c  0f a5 a4 f4 5c 29 b8 2e 84 d2 00 4a 88 5a 96 3f 67 44 5b 10 52 76 60 79 05 75 85 b9 77 ab bf d6 5b 85 12 1d 9c 0a 39 65 bf fb 16  ....\).....J.Z.?gD[.Rv`y.u..w...[.....9e...   637  22 b9 9e f9 66 2a 82 06 94 fe 10 5d b2 57 bd 2b 51 7a 4d 15 7d 49 7e 61 08 4b 95 d6 7d c4 a4 fa 6d 9f 23 07 97 1a 29 74 af d6 0a  "...f*.....].W.+QzM.}I~a.K..}...m.#...)t...   662  18 b4 a4 fa 5c 02 92 2a 84 e9 2a 50 99 43 8b 15 47 7f 62 2a 63 51 73 5f 18 24 9f b9 66 e8 92 e0 5c 85 28 17 87 0b 39 59 b3 ec 07  ....\..*..*P.C..G.b*cQs_.$..f...\.(...9Y...   68d  22 b7 9e d2 4c 2e 82 3d be e4 01 44 af 7d 9d 10 68 40 7c 32 6e 6f 63 30 12 4b 84 95 50 f2 a3 fa 57 95 38 06 97 26 25 63 be d6 04  "...L..=...D.}..h@|2noc0.K..P...W.8..&%c...   6b8  18 9f 8e fe 5c 39 b8 30 95 f0 37 7a b9 78 b2 2f 76 58 71 0c 7e 00 69 5f 09 67 b2 8f 61 e8 a8 ea 47 84 28 2b 8b 1c 28 59 bd ec 2c  ....\9.0..7z.x./vXq.~.i_.g..a...G.(+..(Y..,```
The key is probably of length 43.
Each column of text is xored with the same character. To find out which one, we could analyze the frequencies. But we can only do that on single columns. This makes text to analyze very short...
When doing this, we see a strange pattern appearing. Here is the count of the symbols for each columns. The number is the number of times it appears in the column.
```Counter({'"': 7, '\x18': 6, '\x0e': 3, '\x14': 3, '\x04': 2, '\x08': 2, '\t': 2, '\x0f': 2,         '\x00': 1, '\x05': 1, '\x1e': 1, '\n': 1, '?': 1, ';': 1, ')': 1, '\x15': 1, '\x06': 1, 'M': 1, '\x19': 1, '\x1c': 1, '\x13': 1, '>': 1})Counter({'\x9f': 7, '¥': 6, '³': 3, '©': 3, '¹': 2, 'µ': 2, '´': 2, '²': 2,         '®': 1, '»': 1, '\x82': 1, '\x94': 1, '\x86': 1, '¤': 1, '½': 1, '·': 1, '¡': 1, '¨': 1, '¸': 1, '\x83': 1, '£': 1, 'ð': 1})Counter({'f': 7, '\\': 6, 'P': 3, 'J': 3, '@': 2, 'M': 2, 'L': 2, 'K': 2,         ']': 1, '\x7f': 1, 'N': 1, 'D': 1, '{': 1, 'm': 1, 'z': 1, 'A': 1, '\t': 1, 'B': 1, 'Q': 1, 'W': 1, 'Z': 1, 'X': 1})[...]Counter({'D': 7, '~': 6, 'h': 3, 'r': 3, 'b': 2, 'o': 2, 'i': 2, 'n': 2,         '`': 1, 'c': 1, ']': 1, '+': 1, 'u': 1, 's': 1, 'O': 1, 'f': 1, '\x7f': 1, 'z': 1, 'Y': 1, 'l': 1, 'X': 1, 'x': 1})Counter({'_': 7, 'e': 6, 's': 3, 'i': 3, 't': 2, 'r': 2, 'y': 2, 'u': 2,         'w': 1, 'T': 1, 'h': 1, '{': 1, 'B': 1, 'c': 1, '0': 1, 'C': 1, 'n': 1, 'd': 1, '}': 1, 'a': 1, 'F': 1, 'x': 1})[...]```
There is always, in each column, exactly 7 times the same character.
The last one is very interesting: there is only letters and symbols in it. "{" and "}" appear once. It could be the flag. This tells that "_" is the most common symbol in the flag.
Now we can choose a number to xor the most probable letter in each column, so that when xored with it, it would make a "_":
```0x22 ^ 0x5f = 0x7d  # ord('"') ^ ord("_")0x9f ^ 0x5f = 0xc0  # 0x9f was already not an ASCII char[...]```
Now we have a passphrase that makes "_" the most common symbol in each column (it is not composed of ASCII letters, so I did not print it).
Then we XOR the blob with the repeating password, and obtain the flag:
```default        00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f 20 21 22 23 24 25 26 27 28 29 2a       0  75 73 65 64 5f 69 74 7d 42 43 54 46 7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73  used_it}BCTF{yeah_x0r_is_insecure_yet_we_us    2b  65 64 5f 69 74 7d 42 43 54 46 7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64  ed_it}BCTF{yeah_x0r_is_insecure_yet_we_used    56  5f 69 74 7d 42 43 54 46 7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69  _it}BCTF{yeah_x0r_is_insecure_yet_we_used_i    81  74 7d 42 43 54 46 7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d  t}BCTF{yeah_x0r_is_insecure_yet_we_used_it}    ac  42 43 54 46 7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d 42 43  BCTF{yeah_x0r_is_insecure_yet_we_used_it}BC    d7  54 46 7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d 42 43 54 46  TF{yeah_x0r_is_insecure_yet_we_used_it}BCTF   102  7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d 42 43 54 46 7b 79  {yeah_x0r_is_insecure_yet_we_used_it}BCTF{y   12d  65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d 42 43 54 46 7b 79 65 61  eah_x0r_is_insecure_yet_we_used_it}BCTF{yea   158  68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d 42 43 54 46 7b 79 65 61 68 5f  h_x0r_is_insecure_yet_we_used_it}BCTF{yeah_   183  78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d 42 43 54 46 7b 79 65 61 68 5f 78 30  x0r_is_insecure_yet_we_used_it}BCTF{yeah_x0   1ae  72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d 42 43 54 46 7b 79 65 61 68 5f 78 30 72 5f  r_is_insecure_yet_we_used_it}BCTF{yeah_x0r_   1d9  69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d 42 43 54 46 7b 79 65 61 68 5f 78 30 72 5f 69 73  is_insecure_yet_we_used_it}BCTF{yeah_x0r_is   204  5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d 42 43 54 46 7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69  _insecure_yet_we_used_it}BCTF{yeah_x0r_is_i   22f  6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d 42 43 54 46 7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73  nsecure_yet_we_used_it}BCTF{yeah_x0r_is_ins   25a  65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d 42 43 54 46 7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63  ecure_yet_we_used_it}BCTF{yeah_x0r_is_insec   285  75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d 42 43 54 46 7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 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61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65  sed_it}BCTF{yeah_x0r_is_insecure_yet_we_use   3b2  64 5f 69 74 7d 42 43 54 46 7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f  d_it}BCTF{yeah_x0r_is_insecure_yet_we_used_   3dd  69 74 7d 42 43 54 46 7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74  it}BCTF{yeah_x0r_is_insecure_yet_we_used_it   408  7d 42 43 54 46 7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d 42  }BCTF{yeah_x0r_is_insecure_yet_we_used_it}B   433  43 54 46 7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d 42 43 54  CTF{yeah_x0r_is_insecure_yet_we_used_it}BCT   45e  46 7b 79 65 61 68 5f 78 30 72 5f 69 73 5f 69 6e 73 65 63 75 72 65 5f 79 65 74 5f 77 65 5f 75 73 65 64 5f 69 74 7d 42 43 54 46 7b  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`BCTF{yeah_x0r_is_insecure_yet_we_used_it}` which is of length 41 and repeated 43 times.