# US 9,438,427 B2 · Method and system for providing a plurality of tamperproof digital certificates for a plurality of public keys of a device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,438,427 B2 - Document ID: US9438427B2 - Status: Granted - Kind: B2 - Application number: 14/515,777 - Filed: 2014-10-16 - Published: 2015-04-23 - Granted: 2016-09-06 - Earliest claimed: 2013-10-17 - Assignees: Siemens Aktiengesellschaft - Applicants: Siemens Aktiengesellschaft - Inventors: Jens-Uwe Busser - Web page: https://patentgrep.com/patent/US9438427B2 ## CPC - H04L 9/3247: {involving digital signatures} - G06F 21/64: Protecting data integrity, e.g. using checksums, certificates or signatures - H04L 9/30: Public key, i.e. encryption algorithm being computationally infeasible to invert or user's encryption keys not requiring secrecy - H04L 9/3263: {involving certificates, e.g. public key certificate [PKC] or attribute certificate [AC]; Public key infrastructure [PKI] arrangements (network architectures or network communication protocols for supporting authentication of entities using certificates in a packet data network H04L63/0823)} - H04L 63/0823: {using certificates (cryptographic mechanisms or cryptographic arrangements for entity authentication involving certificates H04L9/3263)} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract A method and system for providing a plurality of tamperproof digital certificates for a plurality of public keys of a device by a certification authority wherein a respective signing request for requesting a digital certificate is initially created for each of a plurality of public keys, where the signing request for the ith public key is signed using the jth private key in accordance with a signing rule, the jth private key being dissimilar to the ith private key belonging to the ith public key, and wherein all signing requests are transmitted to the same certification authority in each case, and each signing request is verified in the certification authority, in which case a check is performed to determine whether the ith signing request has been signed using the jth private key in accordance with the signing rule. ## Claims ### Claim 1 A method for providing a plurality of tamperproof digital certificates for a plurality of public keys of a device by a certification authority, comprising: creating a respective signing request for requesting a digital certificate for each of a plurality of public keys; signing the signing request for the ith public key using the jth private key for all M public keys in accordance with a signing rule, the jth private key being dissimilar to the ith private key belonging to the ith public key; transmitting all signing requests to the same certification authority in each case; verifying each signing request in the certification authority, in which case a check is performed to determine whether each signing request has been signed in accordance with the signing rule; and issuing a respective digital certificate for all of the plurality of public keys if all signing requests have been positively verified. ### Claim 2 (depends on 1) The method as claimed in claim 1, wherein the ith signing request is respectively signed cyclically, anticyclically or interchanged in another manner using the jth private key as the signing rule. ### Claim 3 (depends on 1) The method as claimed in claim 1, wherein the signing requests are each sent to the certification authority in a manner spaced apart from one another by a random waiting time. ### Claim 4 (depends on 1) The method as claimed in claim 1, wherein the signing requests are each sent to the certification authority on different communication paths. ### Claim 5 (depends on 1) The method as claimed in claim 1, wherein the certification authority transmits the requested certificates to the device in a common message. ### Claim 6 (depends on 1) The method as claimed in claim 1, wherein the certification authority transmits the requested certificates to the device separately in a plurality of messages. ### Claim 7 (depends on 1) The method as claimed in claim 1, wherein a number of signing requests transmitted by a single device is at least one of (i) known to the certification authority and (ii) communicated to the certification authority. ### Claim 8 (depends on 1) The method as claimed in claim 1, wherein the signing rule utilized is at least one of (i) known to the certification authority and (ii) communicated to the certification authority. ### Claim 9 (depends on 7) The method as claimed in claim 7, wherein at least one of (i) a number of signing requests and (ii) the signing rule is transmitted to the certification authority in at least one of the signing requests from the device. ### Claim 10 (depends on 7) The method as claimed in claim 7, wherein at least one of (i) a number of signing requests and (ii) the signing rule is transmitted to the certification authority in at least one of the signing requests from the device. ### Claim 11 (depends on 1) The method as claimed in claim 1, wherein the certification authority triggers an alarm if at least one signing request is not positively verified. ### Claim 12 (depends on 1) The method as claimed in claim 1, wherein issue of at least the associated digital certificate is refused by the certification authority in an event of a negatively verified signing request. ### Claim 13 (depends on 1) The method as claimed in claim 1, wherein the certification authority refuses the issue of all digital certificates if at least one signing request is negatively verified. ### Claim 14 A device for providing a plurality of tamperproof digital certificates for a plurality of public keys, comprising: a storage unit configured to store a plurality of key pairs each with a public key and an associated private key; a requesting unit configured to respectively create a signing request for requesting a digital certificate for each of a plurality of public keys and to sign a signing request for the ith public key using a jth private key for all public keys in accordance with a signing rule, the jth private key being dissimilar to an ith private key belonging to an ith public key; and a transmitting unit configured to transmit all signing requests to the same certification authority in each case; wherein a respective digital certificate for all of the plurality of public keys is received by the device if all signing requests have been positively verified. ### Claim 15 (depends on 12) The device as claimed in claim 12, wherein, via the storage unit, the requesting unit and the transmitting unit, the ith signing request is respectively signed cyclically, anticyclically or interchanged in another manner using the jth private key as the signing rule. ### Claim 16 (depends on 1) The device as claimed in claim 1, wherein, via the storage unit, the requesting unit and the transmitting unit, the signing requests are each sent to the certification authority in a manner spaced apart from one another by a random waiting time. ### Claim 17 (depends on 1) The device as claimed in claim 1, wherein the signing requests are each sent to the certification authority on different communication paths. ### Claim 18 (depends on 1) The device as claimed in claim 1, wherein, via the storage unit, the requesting unit and the transmitting unit, the certification authority transmits the requested certificates to the device in a common message. ### Claim 19 (depends on 1) The device as claimed in claim 1, wherein, via the storage unit, the requesting unit and the transmitting unit, the certification authority transmits the requested certificates to the device separately in a plurality of messages. ### Claim 20 (depends on 1) The device as claimed in claim 1, wherein, via the storage unit, the requesting unit and the transmitting unit, a number of signing requests transmitted by a single device is at least one of (i) known to the certification authority and (ii) communicated to the certification authority. ### Claim 21 (depends on 1) The device as claimed in claim 1, wherein, via the storage unit, the requesting unit and the transmitting unit, the signing rule utilized is at least one of (i) known to the certification authority and (ii) communicated to the certification authority. ### Claim 22 (depends on 20) The device as claimed in claim 20, wherein at least one of (i) a number of signing requests and (ii) the signing rule is transmitted to the certification authority in at least one of the signing requests from the device. ### Claim 23 A certification authority for providing a plurality of tamperproof digital certificates for a plurality of public keys of a device, comprising: a receiving unit configured to respectively receive a signing request for requesting a digital certificate for each of a plurality of public keys from a device; a storage unit configured to store at least one signing rule, the signing rule indicating that a signing request for an ith public key is signed using a jth private key for all M public keys, the jth private key being dissimilar to the ith private key belonging to the ith public key; a certification unit configured to check a signing request message to determine whether it has been signed in accordance with the signing rule; and an issuing unit configured to respectively issue a digital certificate for all of the plurality of public keys if all signing request messages are positively verified. ### Claim 24 (depends on 16) The certification authority as claimed in claim 16, wherein, via the receiving unit, the storage unit, the certification unit and the issuing unit, a respective digital certificate is issued for all of the plurality of public keys if all signing requests have been positively verified. ### Claim 25 (depends on 17) The certification authority as claimed in claim 17, wherein, via the receiving unit, the storage unit, the certification unit and the issuing unit, a respective digital certificate is issued for all of the plurality of public keys if all signing requests have been positively verified. ### Claim 26 A system for providing a plurality of digital certificates for a plurality of public keys of a device, the system comprising: a device for providing a tamperproof plurality of digital certificates for a plurality of public keys, the device comprising: a storage unit configured to store a plurality of key pairs each with a public key and an associated private key; a requesting unit configured to respectively create a signing request for requesting a digital certificate for each of a plurality of public keys and to sign a signing request for the ith public key using a jth private key for all M public keys in accordance with a signing rule, the jth private key being dissimilar to an ith private key belonging to an ith public key; and a transmitting unit configured to transmit all signing requests to the same certification authority in each case; and a certification authority for providing the plurality of tamperproof digital certificates for the plurality of public keys of the device, the certification authority comprising: a receiving unit configured to respectively receive the signing request for requesting the digital certificate for each of the plurality of public keys from the device; a storage unit configured to store at least one signing rule, the signing rule indicating that a signing request for an ith public key is signed using a jth private key for all M public keys, the jth private key being dissimilar to the ith private key belonging to the ith public key; a certification unit configured to check a signing request message to determine whether it has been signed in accordance with the signing rule; and an issuing unit configured to respectively issue a digital certificate for all of the plurality of public keys if all signing request messages are positively verified.