A method for encryption of blocks of data (201-206) is provided including the steps of: encrypting (301) a block of data using a current random number (211-216) generated for the block of data (201-206); encoding (303) the current random number using one or more of a set of previous random numbers, each of the set of previous random numbers having been used to encrypt a previously sent block of data; and transmitting (304) the encrypted block of data (241-246) with the one or more versions of the encoded current random number (272-276), each version for a different one of the previous random numbers. A method for decryption of blocks of data is provided including the steps of: receiving (401) an encrypted block of data (241-246) with the one or more versions of an encoded current random number, each version for a different one of the previous random numbers (272-276); selecting (402) one of a set of previously received blocks of data for which the random number is available (291-296); decoding (403) the current random number using the random number of the selected previously received block of data; and decrypting (404) the received encrypted block of data (241-246) using the decoded current random number.