26 lines
1.1 KiB
Markdown
26 lines
1.1 KiB
Markdown
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# CHALLENGE DecryptThis
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A moderate encryption-challange.
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## Description
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I made an awesome encryption tool to send secret messages to my mother, but forgot to make a decryption tool...
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Anyway, now I'm stuck with these messages without knowing what they mean.
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* `>tmGUYjG<V1Y=S6P>QZtc|;6y?tFE<V)HxFH8t@Gd6>')IB5ucG7H,JT`
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* `Bx1inr2m[u"J_u:TBU3MQb(QZX7S8@iz7/Q$hXW3d{eC:-5AgN8\H:d9LS`
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* `rJ6nrv4oLfDlMcMgFYHbizEn/M8ImT9eZ4EIH5j]2m9Af^KL6WHG@]~99SNt`
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## Flag
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`IG{DeWielenVanDeBusGaanRondEnRond_RondEnRond}`
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## Given files
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`decrypt.php`
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Should be uploaded to a server first.
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## How the challenge works
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The encryption is a variant of Vignere, where the codeword is 7-14 characters and is hidden in the message. EG. if the coded message is _xxxxxxxxxx_ and the codeword _ABC_, the code will be _xAxBxCxxxxxxCx_. The second last character represents the lenth of the codeword (here C = 3).
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The best way to solve would be to try a few strings containing only one character like _AAAAAAAAAAAA_ to figure out how the encryption works.
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As the encrypted flags (this ia 3 times the same flag) are quiet long, quickly programming an encryption tool will save a lot of time.
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