Method off-line authentication on a limited-resource device

A mobile device comprising:

• means for obtaining a public key associated with a service provider for the mobile device, wherein the public key has a corresponding private key and the public key and private key are used for asymmetric cryptography;
• means for storing the public key for authenticating access requests when the mobile device is off-line;
• means for receiving an access request to restricted functions of the mobile device while the mobile device is off-line, wherein the access request includes username, an access privilege, and a password, the password derived from the username and access privilege digitally signed by the private key;
• and
• means for authenticating the access request by using the public key to validate the password;
• wherein the password is a message authentication code of the username and access privilege signed by the private key.

A mobile device, comprising:

• a communication component for receiving a public key associated with a service provider for the mobile device, wherein the public key has a corresponding private key and the public key and private key are used for asymmetric cryptography;
• a storage device coupled to the communication module, the storage device for storing the public key for authentication access requests when the mobile device is off-line;
• and
• a processor coupled to the storage device and communication module, the processor configured to receive an access request to restricted functions of the mobile device while the mobile device is off-line, wherein the access request includes username, an access privilege, and a password, the password derived from the username and access privilege digitally signed by the private key, and authenticate the access request by using the public key to validate the password;
• wherein the password is a message authentication code of the username and access privilege signed by the private key.

A machine-readable medium having one or more instructions for authenticating off-line access to a mobile device, which when executed by a processor causes the processor to:

• obtain a public key associated with a service provider for the mobile device, wherein the public key has a corresponding private key and the public key and private key are used for asymmetric cryptography;
• store the public key for authenticating access requests when the mobile device is off-line;
• receive an access request to restricted functions of the mobile device while the mobile device is off-line, wherein the access request includes username, an access privilege, and a password, the password derived from the username and access privilege digitally signed by the private key;
• and
• authenticate the access request by using the public key to validate the password;
• wherein the password is a message authentication code of the username and access privilege signed by the private key.