Editing 1553: Public Key

{{comic
| number    = 1553
| date      = July 20, 2015
| title     = Public Key
| image     = public_key.png
| titletext = I guess I should be signing stuff, but I've never been sure what to sign. Maybe if I post my private key, I can crowdsource my decisions about what to sign.
}}

==Explanation==
In {{w|public-key cryptography}}, two keys are generated for a user. The public key can be used to {{w|encryption|encrypt}} messages, but not decrypt them. The private key is necessary for decryption, and as its name implies, is meant to be used solely by the user.

Since the public key is initially designated to be shared, anyone who has that key can send the user an encrypted message that only the user can decrypt. [[Cueball]] has been following this rule, but he notices that it appears nobody has ever used his public key for anything. He contemplates sharing his ''private'' key, which he believes would generate more interest in him personally. However, he appears to overlook the fact that doing so would allow anyone to decrypt messages sent to him, thus defeating the entire purpose of encryption. (Although some systems can confirm the message sender by having a secret encryption key and a public decryption one, though this is negated again if both keys are released.)

If Cueball had initially released his private key instead of his public one, it would make no difference, since the importance is in keeping one key private - the keys themselves do not hold "private" or "public" roles until one is released and becomes the public key. However, since Cueball has already released his public key, releasing his private key would compromise the key pair. Even if he attempted to remove records of his public key, chances are that some sites would still have it somewhere.

The title text refers to another feature of Public-key cryptography: In addition to assuring that certain messages can only be read by a specific key owner, it can also assure that certain messages could only have been ''written'' by a specific key owner, by "signing" it using the private key. Anyone can read a signed message, but readers with the public key can then verify that the owner of the private key wrote (or at least signed) the message, rather than someone pretending to be the owner. If Cueball published his private key, then anybody could sign any message as him, effectively impersonating him and also defeating the purpose of encryption.

{{w|Crowdsourcing}} is the term used for delegating work or tasks to a largely volunteered and uncontrolled set of people on the Internet.  It is similar in concept to {{w|outsourcing}}, in which work is delegated to an external source of labor, typically a company in a foreign country. Famous instances of crowdsourcing include {{w|reCAPTCHA}} (in which users both verify they are human and help digitize words and phrases in books that digitization software cannot understand) and [http://www.ideaconnection.com/open-innovation-success/Crowdsourcing-Down-on-the-Farm-00304.html a farm in the UK] in which ordinary Internet users make decisions about how the farm is run.  

When Cueball first created the key pair, he imagined it would be something he used from time to time, for reading messages only intended for him or for sending "signed" messages.  Since nothing of the sort happened, he imagines releasing both keys might cause some activity, and at this point he is happier with a "bad" outcome than with a boring one.

[[Randall]] previously ironically mentioned a public key in [[370: Redwall]].

==Transcript==
:[In the first panel, Cueball is sitting in a chair and is using a laptop.]
:Cueball (thinking): I've been posting my public key for 15 years now, but no one has ever asked me for it or used it for anything as far as I can tell.

:[This is followed by two beat panels where Cueball just sits there. doing nothing, not even thinking.]

:[In the final panel he again uses his laptop and thinks.]
:Cueball (thinking): Maybe I should try posting my ''private'' key instead.

{{comic discussion}}
[[Category:Cryptography]]
[[Category:Comics featuring Cueball]]