Granted Patent B2

US 12,651,247 · App. 18/747,354 · Granted Jun 9, 2026

Inventors: Vishwas Saxena (Bengaluru, IN); Deepankar Kansal (Bathinda, IN); Rashi Gupta (Rampur, IN)

Assignee: Sandisk Technologies, Inc.

G06Q20/3674H04L9/14H04L9/3242

Abstract

Claims (71)

1 . A method of securely signing a transaction at a hardware wallet, the method comprising:

receiving, from a host application of a host device, a request to sign an unsigned transaction, wherein the request comprises the unsigned transaction and a coin seed associated with a cryptocurrency coin of the unsigned transaction;

generating, at the hardware wallet and responsive to receiving the coin seed, a private key based on:

a root seed stored in a storage medium of the hardware wallet; and

the coin seed;

cryptographically signing the unsigned transaction with the private key to generate a signed transaction; and

sending the signed transaction to the host device, wherein:

the private key has a corresponding public key in a cryptographic private-public key pair; and

the signed transaction is associated with a wallet address derived from the public key.

2 . The method according to claim 1 , wherein generating the private key comprises hierarchical deterministic key generation based on a first cryptographic hash function applied to the coin seed appended, or prepended, with the root seed.

3 . The method according to claim 2 , wherein a cryptographic output of the first cryptographic hash function includes:

a first portion to form the private key; and

a second portion to form a chain key.

4 . The method according to claim 1 , further comprising

receiving, from the host application of the host device, a second request for a second unsigned transaction, wherein the second request comprises the second unsigned transaction and an alternative coin seed associated with a different cryptocurrency coin for the second unsigned transaction; and

generating, at the hardware wallet and responsive to the alternative coin seed, a second private key based on the root seed and the alternative coin seed.

5 . The method according to claim 1 , wherein the coin seed received in the request to sign the unsigned transaction is in hexadecimal format.

6 . The method according to claim 1 , further comprising, in an initialization mode:

generating a mnemonic phrase comprising a plurality of mnemonic words;

generating the root seed based on the mnemonic phrase; and

storing the root seed in the storage medium.

7 . The method according to claim 6 , wherein the step of generating the root seed is based on a password based key derivation function applied to the plurality of mnemonic words in the mnemonic phrase.

8 . The method according to claim 1 , further comprising, in an initialization mode:

receiving, from the host device, a mnemonic phrase to generate the root seed;

generating the root seed based on the mnemonic phrase; and

storing the root seed in the storage medium.

9 . The method according to claim 1 , wherein:

receiving the request to sign the unsigned transaction comprises receiving the unsigned transaction from a card acceptance device associated with the host device; and

sending the signed transaction comprises sending the signed transaction to the card acceptance device associated with the host device.

10 . The method according to claim 1 , wherein the hardware wallet comprises a Java Card enabled smart card configured to operate a Java-based application to perform the method.

11 . A hardware wallet comprising:

a storage medium configured to store a root seed;

one or more processors configured, individually or in combination, to:

receive, from a host application of a host device, a request to sign an unsigned transaction, wherein the request comprises the unsigned transaction and a coin seed associated with a cryptocurrency coin of the unsigned transaction;

generate, responsive to receiving the coin seed, a private key based on:

the root seed; and

the coin seed;

cryptographically sign the unsigned transaction with the private key to generate a signed transaction; and

send the signed transaction to the host device, wherein:

the private key has a corresponding public key in a cryptographic private-public key pair; and

the signed transaction is associated with a wallet address derived from the public key.

12 . The hardware wallet according to claim 11 , wherein the one or more processors are further configured, individually or in combination, to generate the private key with hierarchical deterministic key generation based on a first cryptographic hash function applied to the coin seed appended, or prepended, with the root seed.

13 . The hardware wallet according to claim 12 , wherein the one or more processors are further configured, individually or in combination, to generate a cryptographic output of the first cryptographic hash function that includes:

a first portion to form the private key; and

a second portion to form a chain key.

14 . The hardware wallet according to claim 11 , wherein the one or more processors are further configured, individually or in combination, to;

receive, from the host application of the host device, a second request for a second unsigned transaction, wherein the second request comprises the second unsigned transaction and an alternative coin seed associated with a different cryptocurrency coin for the second unsigned transaction; and

generate, responsive to the alternative coin seed, a second private key based on the root seed and the alternative coin seed.

15 . The hardware wallet according to claim 11 , wherein, in an initialization mode, the one or more processors are further configured, individually or in combination, to:

generate a mnemonic phrase comprising a plurality of mnemonic words;

generate the root seed based on the mnemonic phrase; and

store the root seed in the storage medium.

16 . The hardware wallet according to claim 15 , wherein the one or more processors are further configured, individually or in combination, to generate the root seed based on a password based key derivation function applied to the plurality of mnemonic words in the mnemonic phrase.

17 . The hardware wallet according to claim 11 , wherein, in an initialization mode, the one or more processors are further configured, individually or in combination, to:

receive, from the host device, a mnemonic phrase to generate the root seed;

generate the root seed based on the mnemonic phrase; and

store the root seed in the storage medium.

18 . The hardware wallet according to claim 11 , further comprising:

a communication interface configured to communicate with a card acceptance device associated with the host device, wherein the one or more processors are further configured, individually or in combination, to:

receive the unsigned transaction via the communication interface and the card acceptance device; and

send the signed transaction via the communication interface and the card acceptance device.

19 . The hardware wallet according to claim 11 , further comprising:

a Java Card enabled smart card configured to operate a Java-based application using the one or more processors.

20 . A data storage device comprising:

means for storing data to store a root seed;

means for receiving, from a host application of a host device, a request to sign an unsigned transaction, wherein the request comprises the unsigned transaction and a coin seed associated with a cryptocurrency coin of the unsigned transaction;

means for generating, responsive to receiving the coin seed, a private key based on:

the root seed; and

the coin seed;

means for cryptographically signing the unsigned transaction with the private key to generate a signed transaction; and

means for sending the signed transaction to the host device, wherein the private key has a corresponding public key in a cryptographic private-public key pair and the signed transaction is associated with a wallet address derived from the public key.

Assignments (4)

Continuity (1)

References Cited (12)