A system and method for encryption, transmission and decryption of data based on a publicly or other wide area broadcast random number sequence. Encryption is by a selected subsequence from the broadcast random number sequence, the selection being at a sample time relative to a synchronization event, with the sample time calculated based on a private key. Decryption uses the same private key to select the same subsequence from the broadcast random number sequence, as detection by the sender and receiver of the synchronization event and a sampling time based on a commonly known private key allows the sampling to be synchronous. Alternative embodiments employ trusted agents if the tender and receiver do not have a common private key.