Secure messaging

A method for transmitting an encrypted message from a messaging server to a handset comprising:

• receiving, from a sender computer, at the messaging server, a message to be sent to the handset and a handset identifier that identifies the handset;
• wherein the handset identifier is a Mobile Station International Subscriber Directory Number (MSISDN);
• determining, at the messaging server, that the handset is not registered with the messaging server;
• facilitating, at the messaging server, the registration of the handset by:
• sending a notification to the handset requesting registration using the handset identifier and a temporary password generated by the messaging server,
• receiving a return handset identifier and a return password from a handset application installed on or native to the handset, and
• comparing the temporary password and the return password thereby to authenticate the handset identifier,
• receiving from the handset a handset encryption key for storage with the handset identifier, wherein the handset encryption key is a public key generated during asymmetric key generation by the handset application, and
• storing the handset encryption key against the handset identifier at the messaging server;
• encrypting, at the messaging server, the received message using the public handset encryption key;
• and
• sending the encrypted message to the handset to be decrypted after receipt thereof by a private key corresponding to the received public key, the private key associated with the handset identifier and generated by the handset application, the private key stored on the handset and neither transmitted to nor stored on the messaging server in any form.

A method for transmitting an encrypted message from a messaging server to a handset comprising:

• receiving, from a sender computer, at the messaging server, a message to be sent to the handset and a handset identifier that identifies the handset;
• wherein the handset identifier is a Mobile Station International Subscriber Directory Number (MSISDN);
• determining, at the messaging server, that the handset is not registered with the messaging server;
• facilitating, at the messaging server, the registration of the handset by:
• sending a notification to the handset requesting registration,
• receiving a first temporary password from the handset, the first temporary password generated by a handset application installed on or native to the handset,
• receiving a return handset identifier and a second temporary password from the handset,
• comparing the first temporary password with the second temporary password thereby to authenticate the handset identifier,
• receiving from the handset a handset encryption key for storage with the handset identifier, wherein the handset encryption key is a public key generated during asymmetric key generation by the handset application, and
• storing the handset encryption key against the handset identifier at the messaging server;
• encrypting, at the messaging server, the received message using the public handset encryption key;
• and
• sending the encrypted message to the handset to be decrypted after receipt thereof by a private key corresponding to the received public key, the private key associated with the handset identifier and generated by the handset application, the private key stored on the handset and neither transmitted to nor stored on the messaging server in any form.

A computer system comprising:

• a memory;
• a processor;
• and
• instructions stored in the memory and configured to be executed by the processor to perform:
• receiving, from a sender computer, a message to be sent to the handset and a Mobile Station International Subscriber Directory Number (MSISDN) of the handset;
• determining that the handset is not registered with the messaging server;
• facilitating the registration of the handset by:
• sending a notification to the handset requesting registration,
• receiving a temporary password and an instance of the MSISDN of the handset from the handset,
• authenticating the MSISDN if the received temporary password matches a second temporary password,
• receiving from the handset a handset encryption key for storage with the MSISDN, wherein the handset encryption key is a public key generated based at least in part on the MSISDN during asymmetric key generation by a handset application installed on or native to the handset, and
• storing the handset encryption key against the MSISDN at the messaging server;
• and
• encrypting the received message using the public handset encryption key and sending the encrypted message to the handset to be decrypted by a private key corresponding to the received public key, the private key generated based at least in part on the MSISDN and generated by the handset application, the private key stored on the handset and neither transmitted to nor stored on the messaging server in any form.

A method for registering a handset to enable the secure sending of a message to the handset, the method comprising:

• receiving, from a handset application installed on or native to the handset, a first instance of a handset identifier that identifies the handset;
• wherein the handset identifier is a Mobile Station International Subscriber Directory Number (MSISDN);
• generating, at the messaging server, a temporary password;
• transmitting the temporary password to the handset using the first instance of the handset identifier;
• receiving a return password from the handset along with a second instance of the handset identifier;
• comparing the temporary password with the return password to authenticate the handset identifier;
• in the event that the temporary password and the return password match, transmitting an authentication acknowledgement back to the handset;
• and
• receiving an encryption key in the form of a handset encryption key that identifies a handset identifier, wherein the handset encryption key is a public key generated during asymmetric key generation by a handset application installed on or native to the handset, which key is stored at the messaging server against the handset identifier, with the corresponding private encryption key generated by the handset application stored ont eh handset and not stored on or transmitted to the messaging server in any form.

A method for registering a handset to enable the secure sending of a message to the handset, the method comprising:

• receiving, at the messaging server, a first temporary password and a first instance of a handset identifier from a handset application installed on or native to the handset;
• wherein the handset identifier is a Mobile Station International Subscriber Directory Number (MSISDN);
• receiving, at the messaging server, a second temporary password and a second instance of the handset identifier from the handset;
• comparing the first and second temporary passwords with each other;
• in the event of a match, transmitting an authentication acknowledgement back to the handset;
• and
• receiving an encryption key in the form of a handset encryption key that identifies the handset identifier of the handset, wherein the handset encryption key is a public key generated using the handset identifier during asymmetric key generation by the handset application, which key is stored at the messaging server against the handset identifier, with the corresponding private encryption key generated by the handset application and stored on the handset and not stored on or transmitted to the messaging server in any form.