CofDrop for Anonymous and Private Communications

CofDrop, short for "Coffin Drop", is a new application and method for anonymous and private communications using public key cryptography. Like other messaging apps, CofDrop ensures privacy by end-to-end encryption, but CofDrop adds an extra level of anonymity. While existing messaging applications protect the privacy of message contents by end-to-end encryption, the identities of the communicating parties ("meta-data") may be revealed through eavesdropping or traffic analysis attacks. CofDrop offers strong protection of anonymity against traffic analysis by using a different method - drop-and-pickup - than existing messaging applications that route messages to recipients. CofDrop is a cryptographic analogue of traditional dead drops used by spies, but cryptography enables far more anonymity than physical dead drops. Anyone can drop encrypted messages anonymously to the CofDrop system (which may be visualised as an invisible post office box). Messages are invisible except to the recipient with the proper cryptographic key. The simple dead drop operation needs no personal information or meta-data to be used by the system, and no personal information or meta-data can be compromised by intercepting messages or hacking into the CofDrop system. Even a message's recipient does not know the sender unless the sender writes his or her identity within the message. CofDrop can be used to transfer messages or any type of file. Photo, movie, or document apps can use CofDrop as an alternative to email or texts to share files with an extra level of anonymity and privacy. CofDrop can be useful not only to consumers but also organisations dependent on private communications such as police receiving anonymous tips, journalists receiving stories, social services receiving reports of abuse or harassment, anti-censorship and privacy advocates, and intelligence agencies.