A system for transmitting an encrypted message, comprising a server (100, 702), a sender device (200, 704), and a mobile device (300, 706); the server (100, 702) for the system, comprising: - a signature device configured to determine a measured location signature of the mobile device (300, 706); - wherein the measured location signature comprises a result of a triangulation performed by one or more trusted base stations on one or more signals received from the mobile device (300, 706) or a measurement of one or more signals received from the mobile device (300, 706) by the one or more trusted base stations, wherein the one or more received signals comprise modifications of one or more signals transmitted from the mobile device (300, 706) as the one or more transmitted signals travel through a communication channel to the one or more trusted base stations; the server (100, 702) further comprising: - a receiver configured to receive a location information from the sender device, and - a look-up unit configured to determine one or more location signatures that correspond to the location information; and - a transmitter is configured to transmit a decryption key to the mobile device only if the look-up unit determines that the measured location signature of the mobile device corresponds to the location information; the sender device comprising: - a receiver configured to receive a public key from the mobile device (300, 706) and to receive an encryption key from the server; - an encryptor configured to encrypt a bit-wise sum of a message and a random string of a same length as the message using the public key to generate an encrypted message and to encrypt the random string using the encryption key to generate an encrypted random string, and - a transmitter configured to transmit the location information to the server and the encrypted message and the encrypted random string to the mobile device; and the mobile device comprising: - a key generator configured to generate the public key and a private key corresponding to the public key; - a transmitter configured to transmit the public key to the sender device (200, 704); - a receiver configured to receive the encrypted message and the encrypted random string from the sender device and the decryption key from the server; - a decryptor configured to decrypt the encrypted random string using the decryption key, to decrypt the encrypted message using the private key and to recover the message by combining the decrypted random string and the decrypted bit-wise sum of the random string and the message. - a signature device configured to determine a measured location signature of the mobile device (300, 706); - wherein the measured location signature comprises a result of a triangulation performed by one or more trusted base stations on one or more signals received from the mobile device (300, 706) or a measurement of one or more signals received from the mobile device (300, 706) by the one or more trusted base stations, wherein the one or more received signals comprise modifications of one or more signals transmitted from the mobile device (300, 706) as the one or more transmitted signals travel through a communication channel to the one or more trusted base stations; - a receiver configured to receive a location information from the sender device, and - a look-up unit configured to determine one or more location signatures that correspond to the location information; and - a transmitter is configured to transmit a decryption key to the mobile device only if the look-up unit determines that the measured location signature of the mobile device corresponds to the location information; - a receiver configured to receive a public key from the mobile device (300, 706) and to receive an encryption key from the server; - an encryptor configured to encrypt a bit-wise sum of a message and a random string of a same length as the message using the public key to generate an encrypted message and to encrypt the random string using the encryption key to generate an encrypted random string, and - a transmitter configured to transmit the location information to the server and the encrypted message and the encrypted random string to the mobile device; and - a key generator configured to generate the public key and a private key corresponding to the public key; - a transmitter configured to transmit the public key to the sender device (200, 704); - a receiver configured to receive the encrypted message and the encrypted random string from the sender device and the decryption key from the server; - a decryptor configured to decrypt the encrypted random string using the decryption key, to decrypt the encrypted message using the private key and to recover the message by combining the decrypted random string and the decrypted bit-wise sum of the random string and the message.