A method includes identifying a string and parameters. The parameters include a coding frame, elements, and a travel path. The method includes traversing the travel path to yield an output artifact. Responsive to no active element at a next position, the method includes filling the next position from the front of the string and advancing one character and one position. Responsive to an element at the next position, the method includes filling the next position from the end of the string, decrementing one character, and determining an attack position. Responsive to the attack position existing, the method includes setting the next position to the attack position. Responsive to no attack position existing, the method includes advancing the next position according to the travel path. The method results in the output artifact encoding the string. A corresponding method decodes the output artifact. Corresponding computer program products and computer systems are disclosed.