Abstract: Data transfer using barcodes is described. In one example data can be transferred between a first device and a second device in close proximity to each other using repeating barcode sequences. For example at the first device a data item can be encoded as a sequence of barcodes, each barcode includes an indicator of the number of barcodes in the sequence and the position of the barcode in the sequence. To receive the data at a second device the barcode sequence can be captured and stored, for example using a digital camera associated with the device, and the barcodes subsequently decoded using the captured sequence. The data contained in each of the barcodes in the sequence can be reassembled by the receiving device to obtain the transmitted data.

Abstract: Methods and devices for providing verifiable identity information using a mobile device, the method comprising receiving a challenge value, from a guard device, at the mobile device, generating a response value based on the challenge value and a private key associated with the mobile device, and providing the response value and identity information to the guard device.