A device, system and method for fast and secure Proxy Re-Encryption (PRE) using key switching. A first user is assigned first encryption and decryption keys and a second user is assigned second encryption and decryption keys. First encrypted data encrypted with the first encryption key may be re-encrypted using a proxy re-encryption key to simultaneously switch encryption keys by adding the second encryption key and cancelling the first encryption key by the first decryption key to transform the first encrypted data encrypted by the first encryption key to second encrypted data encrypted by the second encryption key, without decrypting the underlying data. The second user may be the sole system device that possesses the (e.g., private) second decryption key to decrypt the second encrypted data.