# US 2014/0157385 A1 · Method for authentication, RF chip document, RF chip reader and computer program products > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0157385 A1 - Document ID: US20140157385A1 - Status: Published application - Kind: A1 - Application number: 14/003,721 - Filed: 2012-03-09 - Published: 2014-06-05 - Earliest claimed: 2011-03-10 - Assignees: Federal Republic of Germany Represented By Federal Ministry of the Interior Represented By Bundesamt Fuer Sicherheit In Der Informationstechnik (Bsi) - Inventors: Dennis Kuegler; Jens Bender - Web page: https://patentgrep.com/patent/US20140157385A1 ## CPC - H04L 63/0823: {using certificates (cryptographic mechanisms or cryptographic arrangements for entity authentication involving certificates H04L9/3263)} - H04L 9/0844: {with user authentication or key authentication, e.g. ElGamal, MTI, MQV-Menezes-Qu-Vanstone protocol or Diffie-Hellman protocols using implicitly-certified keys} - H04L 9/3226: {using a predetermined code, e.g. password, passphrase or PIN (network architectures or network communication protocols for supporting authentication of entities using passwords in a packet data network H04L63/083)} - 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 63/083: {using passwords (cryptographic mechanisms or cryptographic arrangements for entity authentication using a predetermined code H04L9/3226)} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract An authentication method for trusted communication between a first party (A) and a second party (B) is intended to be efficient and secure. For this purpose, provision is made to combine password-based authentication and certificate-based authentication. For certificate-based authentication, the first party (A) has a static key pair consisting of a private static key and a public static key and a certificate for the public static key issued by a certification body (C). The certification body (C) is assigned a public key which is known by the second party (B). During the certificate-based authentication, the party A calculates a transformation between its own ephemeral key pair from the password-based authentication and its own static key pair from the certificate-based authentication so as to obtain a transformation parameter for carrying out the transformation. The practice of reusing the party's own ephemeral key pair from the password-based authentication in the certificate-based authentication reduces the overall calculation and communication complexity, on the one hand, and links the two protocols, on the other hand, thus ensuring that both protocols are executed by the same party. This increases the security while simultaneously reducing the complexity. The novel method is suitable for authenticating electronic passports. ## Claims ### Claim 1 An authentication method for trusted communication between a first party (A) and a second party (B) by combining password-based authentication and certificate-based authentication in such a manner that, for the certificate-based authentication, the first party (A) has a static key pair consisting of a private static key and a public static key and a certificate for the public static key issued by a certification body (C), and the certification body (C) is assigned a public key which is known by the second party (B) in such a manner that password-based authentication is first of all carried out with the following steps: the first party (A) and the second party (B) a) each generate an ephemeral key pair consisting of a private ephemeral key and a public ephemeral key, b) each interchange the public ephemeral key and validate the latter using a common password, c) generate and then validate a session key, on the basis of which a secure communication channel is established, that certificate-based authentication is then carried out with the following steps: d) the first party (A) calculates a transformation between its own ephemeral key pair from the password-based authentication and its own static key pair from the certificate-based authentication so as to obtain a transformation parameter, e) the first party (A) transmits the transformation parameter, together with the certificate issued by the certification body (C), to the second party (B) via the secure communication channel, f) the second party (B) applies the received transformation parameter to the public ephemeral key and/or the public static key associated with the first party (A) and in the process obtains at least one transformed public key, the correctness of which is checked, and g) the second party (B) validates the certificate received from the first party (A) using the public key associated with the certification body (C). ### Claim 2 (depends on 1) The method as claimed in claim 1 in such a manner that, in step d) the private static key is mapped to the private ephemeral key in order to calculate the transformation parameter. ### Claim 3 (depends on 1) The method as claimed in claim 1 in such a manner that, in step d) an additional random number which cannot be influenced by the first party (A) is used to calculate the transformation parameter. ### Claim 4 (depends on 1) The method as claimed in claim 1, in which, with respect to step f) the second party (B) applies the received transformation parameter only to one of the two public keys associated with the first party (A) and checks the correctness of the obtained transformed public key by checking for equivalence between the transformed key and the other public key associated with the first party (A). ### Claim 5 (depends on 1) The RF chip document as claimed in claim 1 having a microcomputer with a microcomputer memory in such a manner that the microcomputer memory stores a first computer program which is designed in such a manner that the method can be carried out with respect to the first party (A). ### Claim 6 (depends on 5) The first computer program product as claimed in claim 5 which has a computer-readable medium, comprising a program code for implementing the first computer program in the microcomputer memory. ### Claim 7 (depends on 1) The RF chip reader as claimed in claim 1, having a computer with a computer memory in such a manner that the computer memory stores a second computer program which is designed in such a manner that the method can be carried out with respect to the second party (B). ### Claim 8 (depends on 7) The second computer program product as claimed in claim 7 which has a computer-readable medium, comprising a program code for implementing the second computer program in the computer memory.