I hereby claim:
- I am cosn on github.
- I am cos (https://keybase.io/cos) on keybase.
- I have a public key whose fingerprint is 9C95 9B30 9BC2 730B 9AD1 ABBF A8DC 6C99 23B7 2A7D
To claim this, I am signing this object:
{
    "body": {
        "key": {
            "fingerprint": "9c959b309bc2730b9ad1abbfa8dc6c9923b72a7d",
            "host": "keybase.io",
            "key_id": "a8dc6c9923b72a7d",
            "uid": "4826e5767ebadb52c4ea81735c184500",
            "username": "cos"
        },
        "service": {
            "name": "github",
            "username": "cosn"
        },
        "type": "web_service_binding",
        "version": 1
    },
    "ctime": 1393894473,
    "expire_in": 157680000,
    "prev": null,
    "seqno": 1,
    "tag": "signature"
}with the PGP key whose fingerprint is
9C95 9B30 9BC2 730B 9AD1  ABBF A8DC 6C99 23B7 2A7D
(captured above as body.key.fingerprint), yielding the PGP signature:
-----BEGIN PGP MESSAGE-----
Version: Keybase OpenPGP JS 0.0.1
Comment: https://keybase.io/crypto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=07dx
-----END PGP MESSAGE-----
And finally, I am proving ownership of the github account by posting this as a gist.
Consider the the keybase command line program.
# look me up
keybase id cos
# encrypt a message to me
keybase encrypt cos -m 'a secret message...'
# ...and more...