Crypto: TWFu

Challenge Description

Based

Attachment

UklTQ3ttYXliZV90aGVfcmVhbF9mbGFnX3dhc190aGVfZnJpZW5kc193ZV9tYWRlX2Fsb25nX3RoZV93YXkhfQ==

Approach

This is not a cipher, but instead an encoding. The tells here is that

• == at the end, which is the padding byte used by Base64.
• Length is a multiple of 4, required for Base64.
• Alphabet only uses upper/lowercase ASCII, numbers and the padding byte - a subset of the Base64 alphabet

From here, any standard Base64 decoder works. For example:

• CyberChef: From Base64
• CLI:

  $ echo 'UklTQ3ttYXliZV90aGVfcmVhbF9mbGFnX3dhc190aGVfZnJpZW5kc193ZV9tYWRlX2Fsb25nX3RoZV93YXkhfQ==' | base64 -d
  RISC{maybe_the_real_flag_was_the_friends_we_made_along_the_way!}
  $