I've learnt how to save a RSA private key as a PEM file using Haskell. https://github.com/msakai/tmctf2015-qualifier/commit/09ac6189f301616bffdf9d78f296d5778e831662 #tmctf

References
* 「backdoorCTF 2014 Write-up - kusano_kの日記」 http://d.hatena.ne.jp/kusano_k/20140323/1395571265
* 「RSA 秘密鍵/公開鍵ファイルのフォーマット - bearmini's blog」 http://bearmini.hatenablog.com/entry/2014/02/05/143510
* https://hackage.haskell.org/package/pem
* https://hackage.haskell.org/package/asn1-encoding