Secure internal user authentication leveraging public key cryptography and key splitting

• US 10,637,658 B2
• Filed: 03/31/2017
• Issued: 04/28/2020
• Est. Priority Date: 01/25/2017
• Status: Active Grant

• Current Assignee: Salesforce.com, Inc.
• Original Assignee: Salesforce.com, Inc.
• Inventors: Peddada, Prasad, Elgamal, Taher
• Primary Examiner(s): Feild, Lynn D
• Assistant Examiner(s): Almamun, Abdullah
• Application Number:
  US15/476,833
• Publication Number:
  US 20180212762A1
• Time in Patent Office: 1,124 Days
• CPC Class Codes: G06F 21/34 involving the use of external additional devices, e.g. dongles or smart cards
• CPC Class Codes: H04L 9/085 Secret sharing or secret splitting, e.g. threshold schemes
• CPC Class Codes: H04L 9/3234 involving additional secure or trusted devices, e.g. TPM, smartcard, USB or software token network architectures or network communication protocols for supporting authentication of entities using an additional device in a packet data network H04L63/0853
• CPC Class Codes: H04L 9/3271 using challenge-response

Abstract

In a computing system, methods for secure OS level login authentication for internal users to access servers. Some or all servers in a group each utilize a local ID Service for generating and validating a challenge responsive to an OS login request. The challenge is processed in a centralized secure server HSM. Rather than copying individual user public keys to each host in the data center, we need only copy the public key of the HSM to each host in the group. When a user attempts OS level login to a host, it encrypts the challenge using the public key of the HSM and forwards the request for processing in the HSM. There, it decrypts the challenge using the private key in the HSM and re-encrypts the challenge with the public key of the individual user. The user'"'"'s mobile device, previously registered, is required to complete the authentication process.

Claims

1. A computer-implemented authentication method to authenticate a user to permit OS level login to a server in a computing system, comprising the steps of:

registering an internal user including acquiring an asymmetric encryption key pair associated with the user, the key pair consisting of a public key and a private key;

splitting the user'"'"'s private key into plural private key fragments;

storing one of the user'"'"'s private key fragments securely in a mobile device associated with the user;

storing the user'"'"'s public key and a different one of the plural private key fragments in a datastore accessible to the server;

at the server, receiving an OS level login request;

responsive to the login request, generating a random challenge, and transmitting the random challenge in encrypted form from the server to a security system component provisioned on a second, secure server;

at the server, receiving from the security system component, the random challenge re-encrypted using the user'"'"'s public key, and a partial decryption result generated using the user'"'"'s private key fragment stored in the datastore;

transmitting the re-encrypted challenge and the partial decryption result to the mobile device associated with the user;

receiving a token authenticator entered at the server;

testing validity of the token authenticator so as to demonstrate that the user who made the login request had access to the said mobile device, and that the mobile device correctly completed decryption of the challenge and generated the token authenticator based on the decrypted challenge; and

permitting the OS level login request, conditioned on an affirmative result of the validity testing.

2. The method of claim 1 including:

acquiring an asymmetric encryption key pair for OS level login authentication for a first group of machines, the encryption key pair consisting of an OS level login public key and an OS level login private key;

storing the OS level login public key in a manner accessible to the server OS for use in encrypting the challenge; and

storing the OS level login private key securely in the security system for use in decrypting the challenge.

3. The method of claim 2 wherein said transmitting the random challenge in encrypted form from the server to the security system component includes encrypting the challenge using the OS level login public key.

4. The method of claim 3 and further comprising:

providing a login mobile application executable on a mobile device, the mobile application configured to cause a processor of the mobile device to—

acquire an asymmetric key consisting of a public key and a private key;

associate the public key and the private key with a user of the mobile device;

split the private key into plural private key fragments, so that a sum of the plural private key fragments equals the private key;

securely store at least one of the private key fragments on the mobile device; and

transmit a different one of the private key fragments to a server in connection with registration of the user, mobile device pair on the server.

5. The method of claim 4 wherein the mobile application is further configured to cause a processor of the mobile device to—

receive an encrypted challenge and a partial decryption result;

complete decryption of the challenge using the partial decryption result and the private key fragment stored on the mobile device;

generate a token authenticator based on the decrypted challenge; and

output the token authenticator to a user interface of the mobile device as a single-use token.

6. The method of claim 3 and further comprising:

providing a login mobile application executable on a mobile device, the mobile application configured to cause a processor of the mobile device to register a user of the mobile device with the ID Service of the computing system;

wherein said registration includes—

splitting the user'"'"'s private key into plural private key fragments;

storing one of the user'"'"'s private key fragments in the mobile device; and

sending the user'"'"'s public key and a different one of the plural private key fragments to the computing system.

7. The method of claim 3 including provisioning the security system for execution on a hardware security module (HSM).

8. The method of claim 3 including:

acquiring a second asymmetric encryption key pair associated with a second OS level login, the second encryption key pair consisting of a second OS level login public key and a second OS level login private key;

storing the second OS level login public key in a manner accessible to a second group of machines; and

storing the second OS level login private key securely in the security system component to support authenticating users for login to the second group of machines.

9. The method of claim 8 wherein the second group of machines is defined by data center, a geographic location, cluster, or role of the second group of machines.

10. The method of claim 3 including:

persisting user data in the datastore including a plurality of different internal users'"'"' individual public keys and private key fragments;

updating the user data to include additional internal users'"'"' data based on authorization of the additional internal users to OS level login to the first group of machines; and

removing from the datastore user data of internal users who are no longer authorized for OS level login to the first group of machines;

thereby managing OS level login access for the entire computing system based on the datastore without requiring internal users to use individual passwords.

11. The method of claim 3 wherein testing validity of the token authenticator includes at least one of checking a timestamp relative to a predetermined time to live of the challenge, or checking a number of failed login attempts relative to a predetermined limit.

12. The method of claim 3 wherein the token authenticator includes a cryptographic (one-way) hash function or digest of the decrypted challenge.

13. The method of claim 3 wherein:

the first group of machines comprises application servers; and

the second group of machines comprises storage servers.

14. A non-transitory, computer readable medium storing instructions executable by a processor to cause the processor to realize a security system component including carrying out the steps of:

receiving from an application server a random challenge generated in response to an OS level login request at the application server, the random challenge encrypted using an OS level login public key;

decrypting the encrypted challenge using an OS level login private key that is associated with the OS level login public key so as to recover the challenge;

re-encrypting the challenge using a public key of a user identified in connection with the login request;

partially decrypting the re-encrypted challenge using a stored private key fragment of the user to form a partial decryption result;

transmitting the re-encrypted challenge and the partial decryption result to a mobile device associated with the user;

receiving a token authenticator associated with the login request; and

testing validity of the token authenticator so as to determine that the user who made the login request had access to the said mobile device, and that the mobile device correctly completed decryption of the challenge and generated the token authenticator based on the decrypted challenge.

15. The non-transitory, computer readable medium of claim 14 wherein the stored instructions further cause the processor to conduct additional validity testing of the token authenticator based on a time to live of the challenge.

16. A system comprising:

an application server computer having an operating system;

the application server computer including a first network interface configured for communications over an internal network and a second network interface configured for communications over an external network;

a secure server communicatively coupled to the internal network to enable communications with the application server computer;

an ID Service provisioned on the application server computer;

a security system provisioned on the secure server and configured for interaction with the ID Service;

a datastore accessible via the internal network, the datastore persisting selected user data, including, for at least one user who is authorized for OS level login to the application server computer, a public key of an asymmetric encryption key pair associated with the user, a private key fragment based on a private key of the encryption key pair associated with the user, and an identifier of a mobile device associated with the user;

an asymmetric encryption key pair associated with OS level login to the application server computer;

wherein a public key of the OS level login key pair is stored on the application server computer in a manner accessible to the OS, and a private key of the OS level login key pair is stored on the secure server in a secure manner so that it is not accessible over the internal network; and

wherein the OS is configured to receive a login request and to utilize the ID Service and the security system to authenticate a user identified in the login request, wherein the OS is configured to, responsive to the login request—

generate a random challenge;

encrypt the random challenge using the OS level login public key;

transmit the encrypted challenge to the security system;

responsive to the encrypted challenge, receive from the security system a re-encrypted challenge and a partial decryption result associated with the re-encrypted challenge;

transmit the re-encrypted challenge and the partial decryption result to the mobile device associated with the user identified in the login request;

receive a token authenticator at the application server;

test validity of the received token authenticator based at least in part on the random challenge; and

enable the OS level login request conditioned on an affirmative result of the validity test.

17. The system of claim 16 wherein the secure server hosts a security module.

18. The system of claim 16 wherein the security system is configured to—

decrypt the encrypted challenge using the private key of the OS level login key pair;

re-encrypt the challenge using the public key associated with the user; and

partially decrypt the re-encrypted challenge using the fragment of the private key associated with the user to form the partial decryption result.

19. The system of claim 18 wherein the OS is further configured to receive the login request and the token authenticator at a user interface of the application server.