# US 10,375,575 B2 · Mobile device locking > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,375,575 B2 - Document ID: US10375575B2 - Status: Granted - Kind: B2 - Application number: 16/161,554 - Filed: 2018-10-16 - Published: 2019-02-14 - Granted: 2019-08-06 - Earliest claimed: 2017-04-24 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Lisa M. W. Bradley; Jonathan Dunne; Liam Harpur; Asima Silva - Web page: https://patentgrep.com/patent/US10375575B2 ## CPC - H04W 12/08: Access security - H04W 12/06: Authentication - H04W 12/12: Detection or prevention of fraud - H04W 12/126: Anti-theft arrangements, e.g. protection against subscriber identity module [SIM] cloning - H04W 56/002: {Mutual synchronization} - H04W 76/14: Direct-mode setup - H04W 12/65: Environment-dependent, e.g. using captured environmental data - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Systems and methods for securing access to a mobile device are disclosed. A method includes: synchronizing, by a first mobile computer device, with a remote mobile computer device; transmitting, by the first mobile computer device, a tone to a surface of an object; receiving, by the first mobile computer device, a compound resonance frequency from the object based on the transmitted tone; determining, by the first mobile computer device, the received compound resonance frequency conforms to a stored compound resonance frequency; unlocking, by the first mobile computer device, the first computer device based on the determining; and establishing, by the first mobile computer device, a group connection with the remote mobile computer device based on the unlocking. ## Claims ### Claim 1 A computer implemented method, comprising: synchronizing, by a first mobile computer device, with a remote mobile computer device; transmitting, by the first mobile computer device, a tone to a surface of an object; receiving, by the first mobile computer device, a compound resonance frequency from the object based on the transmitted tone; determining, by the first mobile computer device, the received compound resonance frequency conforms to a stored compound resonance frequency; unlocking, by the first mobile computer device, the first mobile computer device based on the determining; and establishing, by the first mobile computer device, a group connection with the remote mobile computer device based on the unlocking. ### Claim 2 (depends on 1) The method of claim 1, wherein the synchronizing comprises: transmitting synchronization information to the remote mobile computer device; and receiving synchronization response data from the remote mobile computer device based on transmitting the synchronization information. ### Claim 3 (depends on 1) The method of claim 1, wherein the synchronizing comprises: transmitting synchronization information including timing data of a time to transmit a tone to a surface of an object; and receiving synchronization response data based on the transmitting synchronization information. ### Claim 4 (depends on 1) The method of claim 1, wherein the compound resonance frequency comprises a temporal period, a transmissibility, and a damping coefficient of the surface of the object. ### Claim 5 (depends on 1) The method of claim 1, further comprising locking, by the first mobile computer device, the first mobile computer device based on determining the received compound resonance frequency does not conform to the stored compound resonance frequency. ### Claim 6 (depends on 1) The method of claim 1, wherein the tone comprises one of a pulse of white noise and a pulse of a particular frequency. ### Claim 7 (depends on 1) The method of claim 1, wherein a speaker on the first mobile computer device transmits the tone. ### Claim 8 (depends on 1) The method of claim 1, wherein a microphone on the first mobile computer device receives the compound resonance signal. ### Claim 9 (depends on 1) The method of claim 1, wherein the stored compound resonance frequency is a stored compound resonance frequency of a trusted object. ### Claim 10 (depends on 9) The method of claim 9, wherein the determining comprises comparing a resonance frequency, temporal period, transmissibility, and damping coefficient of the received compound resonance frequency from the object to the stored resonance frequency, temporal period, transmissibility, and damping coefficient of the trusted object. ### Claim 11 (depends on 1) The method of claim 1, wherein the unlocking is based on the compound resonance frequency from the object conforming to the stored compound resonance frequency of a trusted object. ### Claim 12 A computer implemented method, comprising: synchronizing, by a first mobile computer device, with a remote mobile computer device; transmitting, by the first mobile computer device, a tone to a surface of an object; receiving, by the first mobile computer device, a compound resonance frequency from the object, wherein the compound resonance frequency is a frequency response of the object when the object is driven by the first mobile computer device and the remote mobile computer device; determining, by the first mobile computer device, the received compound resonance frequency conforms to a stored compound resonance frequency; and unlocking, by the first mobile computer device, the first mobile computer device based on the determining. ### Claim 13 (depends on 12) The method of claim 12, further comprising transmitting, by the first mobile computer device and based on the unlocking, a request to establish a group connection with the remote mobile computer device.