Device-based PIN authentication process to protect encrypted data
Techniques are disclosed for providing a device-based PIN authentication process used to protect encrypted data stored on a computing system, such as a tablet or mobile device. A client component and a server component each store distinct cryptographic keys needed to access encrypted data on the client. The mobile device stores a vault encryption key used to decrypt encrypted sensitive data stored on the mobile device. The vault key is encrypted using a first encryption key and stored on the mobile device. The first encryption key is itself encrypted using a second encryption key. The second encryption key is derived from the PIN value.
1. A computer-implemented method for securely storing encrypted data on a computing device that includes a microprocessor and memory, the method comprising:
receiving a data encryption key derived from a password, wherein the data encryption key is used to encrypt data on the computing device;
encrypting the data encryption key using a first encryption key;
storing the encrypted data encryption key on the computing device;
encrypting the first encryption key using a second encryption key,
wherein the second encryption key is derived from a user-supplied value entered on the computing device and a salt input to a password key based derivation function, and
wherein the salt is rotated following a request to access the encrypted data on the computing device, and
wherein the user-supplied value is different from the password; and
sending the encrypted first encryption key to a remote server.
2. The method of claim 1 , further comprising:
generating, from the user supplied value, a lookup key;
generating a device key; and
sending the lookup key and the device key to the remote server,
wherein remote server uses the device key and the lookup key as an index to the encrypted first encryption key stored on the server.
3. The method of claim 2 , further comprising:
in response to the request to access encrypted data stored on the computing device:
regenerating, using the user-supplied value, the lookup key and the second encryption key;
sending the regenerated lookup key and the device key to the remote server;
in response, receiving the encrypted first encryption key from the remote server;
decrypting, using regenerated second encryption key, the encrypted first encryption key received from the remote server to recover the first encryption key; and
decrypting, using recovered first encryption key, the encrypted data encryption key stored on the client device.
4. The method of claim 1 , wherein the user-supplied value is a PIN value.
5. The method of claim 1 , wherein the computing device is a mobile computing device.
6. A non-transitory computer-readable storage medium storing instructions, which, when executed on a microprocessor, performs an operation for securely storing encrypted data on a computing device that includes memory and the microprocessor, the operation comprising:
receiving a data encryption key derived from a password,
wherein the data encryption key is used to encrypt data on the computing device;
encrypting the data encryption key using a first encryption key;
storing the encrypted data encryption key on the computing device;
encrypting the first encryption key using a second encryption key,
wherein the second encryption key is derived from a user-supplied value entered on the computing device and a salt input to a password key based derivation function, and
wherein the salt is rotated following a request to access the encrypted data on the computing device, and
wherein the user-supplied value is different from the password; and
sending the encrypted first encryption key to a remote server.
7. The computer-readable storage medium of claim 6 , wherein the operation further comprises:
generating, from the user supplied value, a lookup key;
generating a device key; and
sending the lookup key and the device key to the remote server,
wherein remote server uses the device key and the lookup key as an index to the encrypted first encryption key stored on the server.
8. The computer-readable storage medium of claim 7 , wherein the operation further comprises:
in response to the request to access encrypted data stored on the computing device:
regenerating, using the user-supplied value, the lookup key and the second encryption key;
sending the regenerated lookup key and the device key to the remote server;
in response, receiving the encrypted first encryption key from the remote server;
decrypting, using regenerated second encryption key, the encrypted first encryption key received from the remote server to recover the first encryption key; and
decrypting, using recovered first encryption key, the encrypted data encryption key stored on the client device.
9. The computer-readable storage medium of claim 6 , wherein the user-supplied value is a PIN value.
10. The computer-readable storage medium of claim 6 , wherein the computing device is a mobile computing device.
11. A computing device, comprising:
a microprocessor and
a memory hosting an application, which, when executed on the microprocessor, performs an operation for securely storing encrypted data on the computing device, the operation comprising:
receiving a data encryption key derived from a password,
wherein the data encryption key is used to encrypt data on the computing device,
encrypting the data encryption key using a first encryption key,
storing the encrypted data encryption key on the computing device,
encrypting the first encryption key using a second encryption key,
wherein the second encryption key is derived from a user-supplied value entered on the computing device and a salt input to a password key based derivation function, and
wherein the salt is rotated following a request to access the encrypted data on the computing device, and
wherein the user-supplied value is different from the password, and
sending the encrypted first encryption key to a remote server.
12. The computing device of claim 11 , wherein the operation further comprises:
generating, from the user supplied value, a lookup key;
generating a device key; and
sending the lookup key and the device key to the remote server,
wherein remote server uses the device key and the lookup key as an index to the encrypted first encryption key stored on the server.
13. The computing device of claim 12 , wherein the operation further comprises:
in response to the request to access encrypted data stored on the computing device:
regenerating, using the user-supplied value, the lookup key and the second encryption key;
sending the regenerated lookup key and the device key to the remote server;
in response, receiving the encrypted first encryption key from the remote server;
decrypting, using regenerated second encryption key, the encrypted first encryption key received from the remote server to recover the first encryption key; and
decrypting, using recovered first encryption key, the encrypted data encryption key stored on the client device.
14. The computing device of claim 11 , wherein the user-supplied value is a PIN value.