Data protection for a mobile device

1. A data protection method for a mobile device, the method comprising:

storing encrypted data in a memory element of the mobile device;

storing, in the mobile device, a local copy of a decryption key to decrypt the encrypted data, wherein accessing the local copy of the decryption key entails user entry of first authentication data at the mobile device;

determining whether a key server located remotely from the mobile device is available to communicate with the mobile device, the key server storing a remote copy of the decryption key, wherein accessing the remote copy of the decryption key entails user entry of second authentication data at the mobile device, the second authentication data being different from the first authentication data;

when the key server is not available to communicate with the mobile device, decrypting the encrypted data with the local copy of the decryption key, provided a user enters the first authentication data to the mobile device;

when the key server is available to communicate with the mobile device, receiving the remote copy of the decryption key from the key server, provided the user enters the second authentication data to the mobile device; and

decrypting the encrypted data using the local or the remote copy of the decryption key to generate unencrypted data.

2. A method according to claim 1 , wherein the remote copy of the decryption key is encrypted when received from the key server, and wherein the method further comprises:

decrypting the encrypted remote copy of the decryption key.

3. A method according to claim 2 further comprising:

storing the remote copy of the decryption key in a cache memory for a user-settable caching period; and

clearing the remote copy of the decryption key from the cache memory when the user-settable caching period expires.

4. A method according to claim 1 , wherein the second authentication data comprises a password entered by the user at the mobile device.

5. A method according to claim 4 , further comprising communicating the password to the key server by:

generating an authentication request message that conveys the password;

encrypting the authentication request message to obtain an encrypted authentication request message; and

transmitting the encrypted authentication request message to the key server.

6. A method according to claim 1 , further comprising transmitting the unencrypted data to a destination device.

7. A method according to claim 6 , further comprising deleting the unencrypted data from the mobile device after transmitting the unencrypted data to the destination device.

8. A method according to claim 1 , further comprising providing access to the unencrypted data to a destination device that is remote from the mobile device.

9. A method according to claim 8 , further comprising deleting the unencrypted data from the mobile device after providing access to the unencrypted data to the destination device.

10. A method according to claim 1 , further comprising:

receiving an encryption key from the key server; and

encrypting data, using the encryption key, to generate the encrypted data.

11. A method according to claim 1 , further comprising providing a destination device access to the unencrypted data prior to storing the remote copy of the decryption key in a cache memory of the mobile device for a user-settable caching period.

12. The method according to claim 1 , implemented by the mobile device.

13. A method according to claim 12 , wherein the mobile device implements the method using firmware or software executable by a processing device to determine whether to decrypt the encrypted data with the local copy of the decryption key or to receive the remote copy of the decryption key from the key server.

14. A method according to claim 12 , wherein the mobile device implements the method using at least one programmable logic device that is configured to determine whether to decrypt the encrypted data with the local copy of the decryption key or to receive the remote copy of the decryption key from the key server.

15. A system comprising:

a mobile device comprising a processing architecture configured to:

store encrypted data in a memory element of the mobile device;

store, in the mobile device, a local copy of a decryption key to decrypt the encrypted data, wherein accessing the local copy of the decryption key entails user entry of first authentication data at the mobile device;

determine whether a key server located remotely from the mobile device is available to communicate with the mobile device, the key server being configured to store a remote copy of the decryption key, wherein accessing the remote copy of the decryption key entails user entry of second authentication data at the mobile device, the second authentication data being different from the first authentication data;

when the key server is not available to communicate with the mobile device, decrypt the encrypted data with the local copy of the decryption key, provided a user enters the first authentication data to the mobile device;

when the key server is available to communicate with the mobile device, receive the remote copy of the decryption key from the key server, provided the user enters the second authentication data to the mobile device; and

decrypt the encrypted data using the local or the remote copy of the decryption key to generate unencrypted data.

16. A system according to claim 15 , further comprising the key server.

17. A system according to claim 15 , wherein the processing architecture of the mobile device comprises firmware or software executable by a processing device to determine whether to decrypt the encrypted data with the local copy of the decryption key or to receive the remote copy of the decryption key from the key server.

18. A system according to claim 15 , wherein the processing architecture of the mobile device comprises at least one programmable logic device that is configured to determine whether to decrypt the encrypted data with the local copy of the decryption key or to receive the remote copy of the decryption key from the key server.

19. A system according to claim 15 , wherein the remote copy of the decryption key is encrypted when received from the key server by the mobile device, and wherein the processing architecture of the mobile device is further configured to:

decrypt the encrypted remote copy of the decryption key.

20. A system according to claim 19 , wherein the processing architecture of the mobile device is further configured to:

store the remote copy of the decryption key in a cache memory for a user-settable caching period; and

clear the remote copy of the decryption key from the cache memory when the user-settable caching period expires.