Cheer of CPU
Did you hear a cheer of CPU?
The flag is the SHA-256 checksum of the program's output.
ruby -rdigest/sha2 -e 'puts Digest::SHA256.hexdigest("OUTPUT HERE".strip).downcase'
The question's binary in tkbctf4 is compiled with:
- Mac OS X 10.10 (Yosemite) SDK
- Xcode 6.1
This program depends on CryptoSwift. Its source code is not included this repository. I use Cryptoswift 0.0.2 release.
Clone the CryptoSwift repository (or download tarball), copy the
Cryptoswift directory to the same directory which includes
swiftc -sdk /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk -module-name cheerofcpu ArrayExtension.swift ByteExtension.swift NSDataExtension.swift StringExtension.swift IntExtension.swift Utils.swift CryptoHashBase.swift ChaCha20.swift Cipher.swift CRC.swift MD5.swift SHA1.swift SHA2.swift Hash.swift cheerofcpu.swift
What is "Cheer of CPU"?
He said that it is similar to Haskell's syntax...
Mei Akizuru (@maytheplic)
I won't accept any complaint about the environment required to run this binary, i.e., executable file format or bitness. ;-)