Decrypt decrypts a message using the given private key which was encrypted by `Encrypt`.

Encrypt encrypts a message under the given public key, suitable for decrypting via `Decrypt`.

GenerateKey generates a new RSA private key with key length WEIRD_KEY_LENGTH.

GetSSHPublicKey generates a public key suitable for openssh (and thus GitHub) from a private key.

IsValidSendMeASecretKey checks if the key fetched from GitHub is the key uploaded by send-me-a-secret.

ReadPrivateKeyFromFile reads an rsa private key from ~/.send-me-a-secret This path is not configurable; don't want a user to be able to forget where they saved their key.

WritePrivateKeyToFile writes an rsa private key to ~/.send-me-a-secret This path is not configurable; don't want a user to be able to forget where they saved their key.

Github strips out comments and doesn't allow options on public keys, and I haven't figured out an elegant way to mark a public key as belonging to send-me-a-secret without doing something weird like creating a gist or updating a bio to point to the right key.