DESC:FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
[SEE SECTION 10, RULE 13]

TOKEN BASED SECURITY SYSTEM
AND METHOD THEREOF

BHARAT ELECTRONICS LIMITED
WITH ADDRESS:
OUTER RING ROAD, NAGAVARA, BANGALORE 560045, INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
FIELD OF INVENTION
[0001] The present disclosure relates generally to data security and particularly to security of data storage devices.

BACKGROUND
[0002] Secure storage system provides security for data at rest. Security for data at rest is more critical than the security for data in motion or data in use. In case of data at rest, the data is available for analysis for longer duration than data in motion or data in use. Hence, it becomes crucial to handle data at rest. One of the ways to handle data at rest, is to generate different secret keys for encrypting data stored at different sector locations in storage system. However, storing multiple secret keys and generating different secret keys for different address locations is difficult. It also becomes more crucial to handle the secret key for encryption for data at rest. In case if different secret keys are used for each sector location for data encryption, storing the multiple secret keys and generating different secret keys for different address locations is a difficult task. In case if same secret key is used for different address locations for data encryption, it makes available a set of data encrypted with the same key for further analysis. Such set of data is more untrustworthy towards the analysis. A separate device can be used for storing the secret keys. But in that case, the device security and authenticity need to be verified. Such devices can further have security issues related with secret key generation and storage.
[0003] United States Patent application number US20100174913A1 describes a “multi-factor authentication system for encryption key storage and method of operation therefor”. This method authenticates a user by a token and provides a key from the token to a computer system after authenticating the user. Further, the computer system uses this key to encrypt/decrypt the data. In this case, the method describes transferring a single key along with user authentication.
[0004] United States Patent application number US009128876B2 describes a “memory location specific data encryption key”. This method describes that content at memory location is encrypted using the encryption key which is generated based on a random number and the same memory location. A unique pointer value is associated with each of a plurality of locations of a memory and an encryption key is generated based on the unique pointer value and the random number. In some examples, the random number is unique to a power-up cycle of a system comprising the memory or it is generated based on a time at which the data is to be stored by the memory at the selected memory location. This method describes the generation of a key specific to the memory location of the storage system.
[0005] There is still a need for an efficient and end-to-end security system and an effective security method for storage systems.

SUMMARY
[0006] This summary is provided to introduce concepts related to a token-based method for securing a storage system and a token-based security system. This summary is neither intended to identify essential features of the present invention nor is it intended for use in determining or limiting the scope of the present invention.
[0007] In an embodiment of the present invention, a token-based method for securing a storage system is provided. A token receives a password. The token validates the received password. The token generates a key based on the validated password and a stored user ID. The token decrypts an n-secret key table and a token ID based on the generated key. The token securely exchanges a symmetric key with the storage system. The token encrypts the n-secret key table and the token ID based on the exchanged symmetric key. The token transmits the encrypted n-secret key table and the encrypted token ID to the storage system.
[0008] In an embodiment of the present invention, a token-based security system is provided. The token-based security system includes a storage system and a token. The token receives a password. The token validates the received password. The token generates a key based on the validated password and a stored user ID. The token decrypts an n-secret key table and a token ID based on the generated key. The token securely exchanges a symmetric key with the storage system. The token encrypts the n-secret key table and the token ID based on the exchanged symmetric key. The token transmits the encrypted n-secret key table and the encrypted token ID to the storage system.
[0009] In an embodiment, the storage system decrypts the n-secret key table and the token ID based on the symmetric key. The storage system verifies the decrypted token ID. The storage system generates an index corresponding to a storage sector using an index generator. The storage system selects a secret key from the n-secret key table for said sector based on the generated index.
[0010] In an embodiment, the token computes a hash value of the received password. The token matches the hash value with a stored hash value. The token validates the received password when the computed hash value matches the stored hash value.
[0011] In an embodiment, index generator generates the index based on a system ID corresponding to the storage system and a sector address corresponding to the storage sector, wherein the index is a logn-bit value.
[0012] In an embodiment, the n-secret key table and the token ID is cryptographically stored in the token.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[0013] The detailed description is described with reference to the accompanying figures.
[0014] Figure 1 illustrates a schematic block diagram of a token-based security system in accordance with an embodiment of the present invention.
[0015] Figure 2 illustrates a secure storage system protocol architecture in accordance with an embodiment of the present invention.
[0016] Figure 3 illustrates a flowchart of a method for token authentication and n-secret key table retrieval in accordance with an embodiment of the present invention.
[0017] Figure 4 illustrates a flowchart of a method for an n-secret key table transfer from a token to a storage system in accordance with an embodiment of the present invention.
[0018] Figure 5 illustrates a flowchart of a method for retrieval of a secret key from an n-secret key table for every sector in a storage system in accordance with an embodiment of the present invention.
[0019] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative systems embodying the principles of the present invention.
[0020] Similarly, it will be appreciated that any flow chart, flow diagram, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.

DETAILED DESCRIPTION
[0021] The various embodiments of the present invention provide a token-based method for securing a storage system and a token-based security system.
[0022] In the following description, for purpose of explanation, specific details are set forth in order to provide an understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these details.
[0023] One skilled in the art will recognize that embodiments of the present invention, some of which are described below, may be incorporated into a number of systems.
[0024] However, the systems and methods are not limited to the specific embodiments described herein. Further, structures and devices shown in the figures are illustrative of exemplary embodiments of the present invention and are meant to avoid obscuring of the present invention.
[0025] Furthermore, connections between components and/or modules within the figures are not intended to be limited to direct connections. Rather, these components and modules may be modified, re-formatted or otherwise changed by intermediary components and modules.
[0026] The appearances of the phrase “in an embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
[0027] In an embodiment, the present invention provides a token-based security system with a protocol which provides multiple secret keys to encrypt and decrypt data sectors within the secure storage system. The token-based security system includes the token. The protocol generates and stores multiple secret keys on the token. The token is securely authenticated by itself and by the storage system at multiple levels, thereby providing end-to-end security to the stored data. The protocol provides details of storing the multiple secret keys and other parameters on the token, securely transmitting an n-secret key table from the token to the storage system and retrieving the secret key from n-secret key table in the storage system specific to a sector.
[0028] Referring now to Figure 1, a schematic block diagram of a token-based security system (100) is shown in accordance with an embodiment of the present invention. The token-based security system (100) includes a token (101) with a built-in keypad (102). The token-based security system (100) further includes a storage system (103) having a processor (104) and a memory (105) such as a hard disk drive (HDD) (105). The keypad (102) is used to enter a password into the token (101). The token (101) stores an n-secret key table.
[0029] Securing data stored on the storage system (103) includes use of multiple secret keys. The secret keys are stored on the token (101). The secret key is one of the keys from the n-secret key table accessed using index generated from an index generator based on a system ID and a sector address on the storage system (103). The secret key is used to encrypt or decrypt the data to be stored on the specific sector. The n-secret key table consists of n secret keys is generated and stored on the token (101). Thereafter, a key is derived from a user ID and a password on the token (101). The token (101) is a specific hardware token. The n-secret key table along with a token ID is stored on the token (101) in an encrypted format, where encryption is performed using derived key. The user ID in plain format and a hash value of the password is stored on the token (101). Once the token (101) is connected to the storage system (103), a user enters the password on the token (101). The token (101) calculates the hash value of the entered password. The token (101) compares the calculated hash value with the stored hash value on the token (101). If the comparison fails, the token (101) waits for another password from the user. If the comparison succeeds, the token (101) derives the key from the user ID and the password for which the comparison succeeded. The token (101) decrypts the n-secret key table and token ID from the derived key. The token (101) exchanges a symmetric key with the storage system (103) using a symmetric key exchange protocol. The token (101) encrypts the n-secret key table along with the token ID and transmits to the storage system (103). The storage system (103) receives the n-secret key table and stores it in volatile memory after decryption and verification with the token ID.
[0030] Referring now to Figure 2, a secure storage system protocol architecture is shown in accordance with an embodiment of the present invention.
[0031] At 201, the data is stored on the token (101). At 202, the token (101) is authenticated and n-secret key table and token ID is retrieved. At 203, the n-secret key table is securely transmitted from the token (101) to storage system (103). At step 204, the token (101) is verified at the storage system (103) and the secret key is retrieved from the n-secret key table for any sector data encryption/decryption. During setup of the token (101), the token (101) generates the n-secret keys, converts the n-secret keys into the table format and names the table as the n-secret key table. The token (101) has the user ID, the token ID and the user-defined password. The token (101) encrypts the n-secret key table and the token ID using a derived key, which is derived from the user ID and the password. The token (101) stores the encrypted n-secret key table and the token ID. The token (101) calculates the hash value of the password and stores the hash value of the password. The token (101) also stores the user ID in plain format.
[0032] Referring now to Figure 3, a flowchart of a method for token authentication and an n-secret key table retrieval is shown in accordance with an embodiment of the present invention.
[0033] At 301, the user connects the token (101) to the storage system (103). At 302, the user enters the password on the token (101). At 303, once the password is entered, the token (101) calculates the hash value of the entered password. At 304, the token (101) compares the calculated hash value with the stored hash value of the password. If at step 304, the token (101) determines that the calculated hash value is same as the stored hash value, step 305 is executed. At 305, the token (101) sets a password counter value to zero and gets enumerated into the storage system (103). At 306, the token (101) derives a key from the user ID and the password. At 307, the token (101) decrypts the stored n-secret key table and the token ID. If at step 304, the token (101) determines that the calculated hash value is not same as the stored hash value, step 302 is executed. At 302, the password counter is increased by one. The token (101) checks the value of the password counter. If the value of the password counter exceeds six, the token (101) will be locked. If the value of the password counter does not exceed six, the token (101) allows the user to enter the password again.
[0034] Referring now to Figure 4, a flowchart of a method for an n-secret key table transfer from the token (101) to the storage system (103) is shown in accordance with an embodiment of the present invention.
[0035] At 401, when the token (101) gets enumerated with the storage system (103), the token (101) exchanges securely the symmetric key with the storage system (103). At 402, the token (101) encrypts the n-secret key table and the token ID using an agreed symmetric key and transmits the encrypted n-secret key table along with token ID to the storage system (103). At 403, the storage system (103) receives the encrypted n-secret key table, the token ID and decrypts these with the agreed symmetric key. At 404, the storage system (103) verifies the received token ID. If the verification fails, the storage system (103), at 405, aborts the process. If the verification succeeds, the storage system (103), at 406, stores the n-secret key table into its volatile memory.
[0036] Figure 5 illustrates a flowchart of a method for retrieval of a secret key from an n-secret key table for every sector in the storage system (103) in accordance with an embodiment of the present invention.
[0037] The storage system (103) comprises an index-generator implemented by processor (104). At 501, the index-generator generates log n-bit (base 2) index based on input of a sector address and a system ID. At 502, when a sector data must be encrypted or decrypted by the storage system, the storage system provides the system ID and sector address to the index-generator. The index-generator generates the log n-bit (base 2) index specific to sector address. Based on the index, the storage system (103) selects a secret key from the n-secret key table. At 503, the secret key is used to encrypt/decrypt the sector data. The secret key for each sector is selected using index from the larger key space of the n-secret key table.
[0038] In operation, the n-secret key table and the token ID is cryptographically stored in the token (101). the token (101) retrieves the user ID and the password. The token (101) computes the hash value of the received password. The token (101) matches the hash value with the stored hash value. The token (101) validates the received password when the computed hash value matches the stored hash value. The token (101) generates the key based on the validated password and user ID. The token (101) decrypts the n-secret key table and the token ID based on the generated key. The token (101) exchanges securely the symmetric key with the storage system (103). The token (101) encrypts the n-secret key table and the token ID based on the exchanged symmetric key. The token (101) transmits the encrypted n-secret key table and the encrypted token ID to the storage system (103). The storage system (103) decrypts the n-secret key table and the token ID based on the symmetric key. The storage system (103) verifies the decrypted token ID. The storage system (103) generates the index corresponding to the storage sector using the index generator. The index generator generates the index based on the system ID corresponding to the storage system (103) and the sector address corresponding to the storage sector. The index is the logn-bit (base2) value. The storage system (103) selects the secret key form the n-secret key table for said sector based on the generated index.
[0039] Advantageously, the token-based security system and the token-based method for securing a storage system of the present disclosure provides end-to-end security of the secret key and ensures the authenticity of the token, secure generation of multiple secret keys, and secure storage of the secret keys on the token.
[0040] Advantageously, the token-based security system of the present invention ensures the authenticity of the token, securely stores the multiple keys on the token and provides usage of different keys at different sector location in most cases. Instead of using one secret key for entire sector locations, the usage of multiple secret keys based on sector locations provides enhanced security to the storage system.
[0041] The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the invention.

,CLAIMS:We Claim:
1. A token-based method for securing a storage system (103), said method comprising:
receiving, by a token (101), a password;
validating, by the token (101), the received password;
generating, by the token (101), a key based on the validated password and a stored user ID;
decrypting, by the token (101), an n-secret key table and a token ID based on the generated key;
exchanging securely a symmetric key between the token (101) and the storage system (103);
encrypting, by the token (101), the n-secret key table and the token ID based on the exchanged symmetric key; and
transmitting, by the token (101), the encrypted n-secret key table and the encrypted token ID to the storage system (103).

2. The method as claimed in claim 1, comprising:
decrypting, by the storage system (103), the n-secret key table and the token ID based on the symmetric key;
verifying, by the storage system (103), the decrypted token ID;
generating, by the storage system (103), an index corresponding to a storage sector using an index generator; and
selecting, by the storage system (103), a secret key from the n-secret key table for said sector based on the generated index.

3. The method as claimed in claim 1, comprising:
computing, by the token (101), a hash value of the received password;
matching, by the token (101), the hash value with a stored hash value;
validating, by the token (101), the received password when the computed hash value matches the stored hash value.

4. The method as claimed in claim 2, comprising generating, by the index generator, the index based on a system ID corresponding to the storage system (103) and a sector address corresponding to the storage sector, wherein the index is a logn-bit value.

5. The method as claimed in claim 1, wherein the n-secret key table and the token ID is cryptographically stored in the token (101).

6. A token-based security system (100) comprising:
a storage system (103); and
a token (101) configured to:
receive a password,
validate the received password,
generate a key based on the validated password and a stored user ID,
decrypt an n-secret key table and a token ID based on the generated key,
exchange securely a symmetric key with the storage system (103),
encrypt the n-secret key table and the token ID based on the exchanged symmetric key, and
transmit the encrypted n-secret key table and the encrypted token ID to the storage system (103).

7. The token-based security system (100) as claimed in claim 6, wherein the storage system (103) is configured to:
decrypt the n-secret key table and the token ID based on the symmetric key,
verify the decrypted token ID,
generate an index corresponding to a storage sector using an index generator, and
select a secret key form the n-secret key table for said sector based on the generated index.

8. The token-based security system (100) as claimed in claim 6, wherein the token is configured to:
compute a hash value of the received password,
match the hash value with a stored hash value, and
validate the received password when the computed hash value matches the stored hash value.

9. The token-based security system (100) as claimed in claim 7, wherein the index generator is configured to generate the index based on a system ID corresponding to the storage system (103) and a sector address corresponding to the storage sector, wherein the index is a logn-bit value.

10. The token-based security system (100) as claimed in claim 6, wherein the n-secret key table and the token ID is cryptographically stored in the token (101).

Dated this 26th day of March, 2020

For BHARAT ELECTRONICS LIMITED,
By their Agent,

D. MANOJ KUMAR (IN/PA-2110)
KRISHNA & SAURASTRI ASSOCIATES LLP