Public-key cryptography has been widely accepted as the method in which data is encrypted, using algorithms such as the widely known and popularly used RSA algorithm. However, management of the public-key and its storage is an on-going issue. To avoid these problems the symmetric-key approach can be taken, where there is only one key and it must be kept secret. Presented in this paper is a new cipher based on symmetric-key cryptography, called the NASA/Kennedy Cipher (N/KC), and further designed as a block cipher using 128-bit blocks. The minimum key size is set at 128 bits with a maximum allowable of 2048 bits, modulus 2. The main focus of this work is encryption of image data for the purpose of protecting intellectual properties. However, empirical results are presented on N/KC's ability of encrypting and decrypting text data in the form of vectors and documents as well. © 2005 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 15, 178–188, 2005