cicadakeyfake?

E:\projects\cicada\stage2>gpg -a -se -r 7A35090F response1.txt

You need a passphrase to unlock the secret key for
user: "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
XXXX-bit XXX key, ID XXXXXXXX, created XXXXXXXXX

gpg: 671DDEB1: There is no assurance this key belongs to the named user

pub  4096R/671DDEB1 2012-01-05 Cicada 3301 (845145127)
 Primary key fingerprint: 6D85 4CD7 9333 22A6 01C3  286D 181F 01E5 7A35 090F
      Subkey fingerprint: DEC5 7731 ACCB FD11 EEBA  1343 4D39 0ECF 671D DEB1

It is NOT certain that the key belongs to the person named
in the user ID.  If you *really* know what you are doing,
you may answer the next question with yes.

Use this key anyway? (y/N) y
File `response1.txt.asc' exists. Overwrite? (y/N) y

E:\projects\cicada\stage2>gpg --decrypt response1.txt.asc
gpg: encrypted with 4096-bit RSA key, ID 671DDEB1, created 2012-01-05
      "Cicada 3301 (845145127)"
gpg: decryption failed: No secret key