Ed25519-sign the flag with the same private key and implementation flaw used to sign the messages below. The flag is the base64 representation of the signature.

Public key: 5bfcb1cd3938f3f6f3092da5f7d7a1bdb1d694a725d0585a99208787554e110d

Message: sctf.io
Signature: 68299a51b6b592e2db83c26ca3594bdd81bdbb9f11c597a1deb823da7c8b9de8e2224855125b1acbeab1468bf4860c1eeb05b6d2375e2214c55bdfe808a6c106

Message: 2016 Q1
Signature: 68299a51b6b592e2db83c26ca3594bdd81bdbb9f11c597a1deb823da7c8b9de825ad01a05a0cce69258d41d42ed046956e7d4586eb21ff031bf8ac03243d5e04