1. A system, comprising: a first device and a second device, wherein the first device receives a challenge provided from a second device, wherein the challenge includes an encoding algorithm and a request for credentials from the first device, wherein a response to the challenge is output, from the first device to the second device, wherein the response includes an image, the image including articles of evidence arranged according to the encoding algorithm, wherein the second device assembles a key from the articles of evidence and wherein the key permits the first device with access to a desired resource, wherein the image is a composite image formed of first and second images, the articles of evidence including a first article of evidence found in a polygon arranged at a particular location in the first image and a second article of evidence found in a polygon arranged at a particular location in the second image, the first article of evidence including one of the requested credentials, the second article of evidence including another one of the requested credentials, the key being assembled by extracting the first and second articles of evidence from the composite image.