A system (100) for providing a user device (102) access to a resource or data is disclosed. The system (100) comprises: the user device (102) comprising: a light detector (104) configured to detect light (130) emitted by a light source (122), which light (130) comprises an embedded code comprising a light source identifier of the light source (122), a communication unit (108) configured to communicate with a network device (112), a processor (106) configured to retrieve the light source identifier from the light (130), and to communicate the light source identifier to the network device (112). The system (100) further comprises the network device (112), comprising: a receiver (114) configured to receive the light source identifier from the user device (102), and a controller (116) configured to identify the light source (122) based on the light source identifier, to encrypt an access key or data with a public key corresponding to a private key, and to control the light source (122) such that the light (130) comprises an updated embedded code comprising the encrypted access key or the encrypted data. The processor (106) of the user device (102) is further configured to retrieve the encrypted access key or the encrypted data from the updated embedded code comprised in the light (130), and to decrypt the encrypted access key or the encrypted data with the private key, and access the resource with the decrypted access key or retrieve the decrypted data.