AN235196 INFINEON | Alldatasheet
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Application Note Please read the sections “Important notice” and “Warnings” at the end of this document 002-35196 Rev. ** www.infineon.com page 1 of 11 2022-05-02 AN235196 Provisioning OPTIGA™ Trust Charge for WLC transmitters Application note About this document Scope and purpose This document is intended to provide process information for provisioning OPTIGA™ Trust Charge for wireless charger (WLC) transmitter system authentication functionality. Intended audience Product manufacturers who want to adopt the WLC transmitter reference design for their end product. Table of contents
Application Note 2 of 11 002-35196 Rev. ** 2022-05-02 Provisioning OPTIGA™ Trust Charge for WLC transmitters Application note Introduction
1 Introduction
This document describes the blocks in the WLC system architecture required for the Qi authentication process using OPTIGA™ Trust Charge. The Qi 1.3.x specification mandates authentication for Extended Power Profile (EPP) Power Delivery (PD) of more than 5 W. Qi authentication is a tamper-resistant method to establish and verify the identity of the power transmitter; it enables the power receiver to trust the power transmitter to operate within the bounds of the Qi specification. OPTIGA™ Trust Charge enables the WLC power transmitter’s authentication functionality and thereby ensures that the WLC transmitter system remains compliant with the Qi specification. OPTIGA™ Trust Charge’s main features are:
- Common Criteria EAL 6+ certified secure storage subsystem
- Supports X.509 v3 with DER encoding for the certificate format
- Authentication based on ECDSA
- Cryptography support: NIST P-256, SHA2
- OPTIGA™ Trust Charge meets the security and authentication requirements mandated by the WPC specification
- OPTIGA™ Trust Charge comes with manufacturer certificate service provider (MCSP) services for creating and provisioning the WPC-signed certificate chain issued to the product manufacturer organization − This process creates a new OPTIGA™ Trust Charge sales part number for the customer organization
2 WLC transmitters designed with OPTIGA™ Trust Charge
Figure 1. The WLC transmitter system processor has all the hardware/firmware capabilities to use the OPTIGA™ Trust Charge for Qi authentication functionality without any additional requirements.
31 UART/GPIO7
Application Note 4 of 11 002-35196 Rev. ** 2022-05-02 Provisioning OPTIGA™ Trust Charge for WLC transmitters Application note Public key infrastructure
3 Public key infrastructure
The Qi specification follows the public key infrastructure (PKI), and uses the following cryptographic methods in Qi wireless charger cryptography. Table 1 Qi wireless charger cryptography methods Method Use X.509 v3, ANS.1 DER encoding Certificate format ECDSA using the NIST P256, secp256r1 curve Digital signing of certificates and authentication messages SHA-256 The hash algorithm is used in the ECDSA calculation and in creating digests of certificates and certificate chains WPC public key cryptography (PKC) relies on a public and private key pair to encrypt and decrypt the content. These keys are mathematically related, and the content encrypted by one of the keys can be decrypted by using the other key. The private key is the most sensitive secure credential and must be stored securely. The public key is typically a part of the binary certificate, and this certificate is transmitted to the recipient through a communication medium. The recipient of the public key certificate can do the following:
- Cryptographically verify the authenticity of public key certificate data origin
- Cryptographically verify the challenge which was signed by the “Secure Storage Subsystem” in the power transmitter The X.509 PKI standard identifies the requirements for robust public key certificates. A public key certificate is a digitally signed data structure that binds a public key with the power transmitter device identity. Public key certificates are issued by a certificate authority (CA). A PKI is a set of roles, policies, hardware, software and procedures needed to create, manage, distribute, use, store and revoke digital certificates. WPC defines the PKI process and rules for digitally signed certificate chain creation. See the authentication protocol booklet in the Qi specification and the WPC-PKI web page for more information. The Qi specification mandates the power transmitter to securely host the product unit’s private key for digital signature purposes in a secure storage subsystem. This private key is used to digitally sign the Challenge Authentication response from the power transmitter device.
Application Note 5 of 11 002-35196 Rev. ** 2022-05-02 Provisioning OPTIGA™ Trust Charge for WLC transmitters Application note Provisioning OPTIGA™ Trust Charge
4 Provisioning OPTIGA™ Trust Charge
The WLC transmitter solution is a reference design for the product manufacturer adaptation. The public key certificate data present in the OPTIGA™ Trust Charge of the WLC transmitter reference design contains:
- Infineon Technologies as a power transmitter manufacturer organization
- WLC solution reference design’s Qi logo certificate registration Qi-ID Therefore, the manufacturer certificate data and product unit certificate data must be provisioned in OPTIGA™ Trust Charge to represent the product manufacturer’s end products. The following flow diagram depicts the process flow involved in provisioning OPTIGA™ Trust Charge for the end-product manufacturer organization and end-product logo registration Qi-ID. Product Manufacturer Infineon Technologies Manufacturer Certificate Service Provider Wireless Power Consortium (WPC) Product Manufacturer Join and Sign WPC Membership Agreement (Skip this step if completed before) Request Infineon Technologies To provide MCSP (Manufacturer Certificate Service Provider) Services.
- Infineon Technologies creates new Manufacturer Certificate.
- Request WPC to digital sign Manufacturer Certificate. WPC Provides Root CA Digitally Signed Manufacturer Certificate to Manufacturer Certificate Service Provider Supply OPTIGA Trust Charge engineering sample with the new data Provision
- Infineon Technologies creates final certificate chain for the product.
- OPTIGA Trust Charger is Provisioned with new Certificate chain
- Infineon Technologies setup new OPTIGA Trust Charge Sales Part number for customer Future Orders Place Production Order for Infineon Parts Figure 2 Process for provisioning OPTIGA™ Trust Charge
4.1 Information required in setting up certificate chain data
- WPC membership a) Navigate to https://www.wirelesspowerconsortium.com/members/join-the-wpc and fill all the required fields to create a WPC membership. WPC membership will create a power transmitter manufacturer code (PTMC). b) Qi-ID: Reserve a Qi-ID for the new product. This process involves signing a legal agreement called “Qi Authentication Agreement for a Manufacturer” with WPC. 2. Fill out a standard form for assigning “Infineon Technologies” as your manufacturer CA service provider.
Application Note 6 of 11 002-35196 Rev. ** 2022-05-02 Provisioning OPTIGA™ Trust Charge for WLC transmitters Application note Provisioning OPTIGA™ Trust Charge Note: Infineon Technologies is one of the WPC-approved manufacturer CA service providers. Product manufacturers should contact Infineon Technologies to receive manufacturer CA service provider services.
4.2 WPC-compliant certificate chain data
The WPC-compliant certificate chain is provisioned in OPTIGA™ Trust Charge, as shown in the following figure. WPC Root Key Pair (Maintained by WPC) Public Key Private Key Manufacturer Certificate Key Pair (Created and Maintained by Manufacturer CA ) Public Key Private Key Product Certificate Key Pair (Created and Maintained by Manufacturer CA ) Public Key Private Key Wireless Transmitter Certificate Chain WPC Root Certificate Digest/Hash Manufacturer Certificate Digital Signed by WPC Root key Product Unit Certificate Digital Signed by Private key associated to Manufacturer Certificate Certificate Chain Length OPTIGA Trust Charger Secure Storage Product Unit Private Key Digital Sign Digital Sign OPTIGA Trust Charge Device Data Store Manufacturer CA Figure 3 Certificate chain data in OPTIGA™ Trust Charge
Application Note 7 of 11 002-35196 Rev. ** 2022-05-02 Provisioning OPTIGA™ Trust Charge for WLC transmitters Application note WPC compliance mandate
5 WPC compliance mandate
WPC compliance in the Qi 1.3.x specification mandates the need for public key authentication for all the EPP PD of more than 5 W. Product manufacturers can benefit by reusing the reference design logo certification to achieve end-product logo compliance. There are two possible routes:
- Substantially similar product
- Fresh product registration compliance certification
5.1 Substantially similar product
A substantially similar product is identical to a previously registered product, except for the properties that do not influence the wireless power functionality. For example, a different color, or a different brand name. Products that have different components, coils, shielding or even different metal parts in their housing do not qualify as substantially similar. The criteria for determining substantial similarity are described in “Annex D of the Wireless Power Logo License Agreement”.
5.2 Fresh product registration compliance certification
This fresh product registration process is required for those adaptations where the product manufacturer has made changes to the bill of materials (BOM) and/or for those designs that do not satisfy Annex D of the logo license agreement. Refer to the WPC website for a suitable workflow option.
Application Note 8 of 11 002-35196 Rev. ** 2022-05-02 Provisioning OPTIGA™ Trust Charge for WLC transmitters Application note Abbreviations
6 Abbreviations
ASN Abstract syntax notation CA Certificate authority DER Distinguish encoding rule PKI Public key infrastructure MCSP Manufacturer certificate service provider WPC Wireless Power Consortium
Application Note 9 of 11 002-35196 Rev. ** 2022-05-02 Provisioning OPTIGA™ Trust Charge for WLC transmitters Application note References References [1] Qi 1.3.x authentication specification [2] OPTIGA™ Trust Charge product datasheet and product brief [3] X.509 public key infrastructure certificate
Application Note 10 of 11 002-35196 Rev. ** 2022-05-02 Provisioning OPTIGA™ Trust Charge for WLC transmitters Application note
Revision history
Date of release Description of changes ** 2022-05-02 Initial release
81726 Munich, Germany
© 2022 Infineon Technologies AG. All Rights Reserved. Do you have a question about this document? Email: www.infineon.com/support Document reference 002-35196 Rev. ** IMPORTANT NOTICE The information contained in this application note is given as a hint for the implementation of the product only and shall in no event be regarded as a description or warranty of a certain functionality, condition or quality of the product . Before implementation of the product, the recipient of this application note must verify any function and other technical information given herein in the real application. Infineon Technologies hereby disclaims any and all warranties and liabilities of a ny kind (including without limitation warranties of non - infringement of intellectual property rights of any third party) with respect to any and all information given in this application note. The data contained in this document is exclusively intended f or technically trained staff. It is the responsibility of customer’s technical departments to evaluate the suitability of the product for the intended application and the completeness of the product information given in this document with respect to such application. For further information on the product, technology, delivery terms and conditions and prices please contact your nearest Infineon Technologies office (www.infineon.com). WARNINGS Due to technical requirements products may contain dangerous substances. For information on the types in question please contact your nearest Infineon Technologies office. Except as otherwise explicitly approved by Infineon Technologies in a written document signed by authorized representatives of Infineon Technologies, Infineon Technologies’ products may not be used in any applications where a failure of the product or any consequences of the use thereof can reasonably be expected to result in personal injury. Trademarks All referenced product or service names and trademarks are the property of their respective owners.