EP1709764A1 - Circuit arrangement and method for securing communication within communication networks - Google Patents

Abstract

The invention relates to a circuit arrangement and associated method for the authentication of a network subscriber. A digital certificate is stored as a resource in the P2P network. The advantage thereof is that data can be also be provided for the other network subscribers, when the network subscriber(s) are offline or can not be reached for other reasons. It is also possible to encode data which is specific for other network units and file said data in a protective manner for the P2P network.

Description

 description

Circuit arrangement and method for communication security within communication networks

Communication security is becoming increasingly important in modern communication networks. Important aspects of communication security are the authenticity of the participants and the confidentiality of messages. Authorization may also be required to participate in communication within networks. This communication security is usually achieved with pre-administered shared secrets such as shared secrets. Furthermore, communication security can also be guaranteed with digital signatures / certificates. Every network subscriber authorized for secure communication receives their own digital certificate from a trustworthy central entity. These certificates bind a public key to the identity of its owner. These certificates can be checked with _“ the public key of the central instance, which is contained in the so-called root certificate of the central instance, which must be distributed to all network participants in an unadulterated manner. A network subscriber can now use his secret private key to generate a signed message, the authenticity of which can be checked by any recipient using the public key from the certificate of the network subscriber. The recipient of the network subscriber receives the certificate either from the network subscriber himself or from a central server. For the confidential transmission of messages, they are encrypted with the public key from the recipient's certificate, so that only the recipient can decrypt the message. Security functions such as authentication, authorization and encryption / decryption are also used in a peer-to-peer network, hereinafter abbreviated to P2P network. Who- who then needs information from the certificate of a network subscriber, the certificate can be requested from this network unit itself or, if available, from an external storage unit.

However, the previously described authentication of data or messages from a network unit in a P2P network has the disadvantage that a certificate server must be available for the participants in the P2P network and / or the network participants must be constantly online. In addition, no confidential messages for network subscribers in general or for certain network subscribers can be stored if the above-mentioned network and network subscriber conditions exist.

The invention has for its object to provide a circuit arrangement and an associated method for securing the communication of network participants.

The object is solved by the features of claims 1 and 4.

The invention has the advantage that an authenticity check can also be carried out when the network subscriber is operating offline.

The invention has the advantage that an authorization check can be carried out using the certificate of the network subscriber even when the network subscriber is operating offline.

The invention has the advantage that confidential information can also be stored in an offline mode of the network subscriber in the P2P network.

The invention has the advantage that servers for the provision of created and stored certificates ten are not required during operation.

Further special features of the invention can be seen from the following detailed explanations of the figures of an exemplary embodiment.

Show it:

FIG. 1 shows a P2P network within an IP network,

FIG. 2 shows an allocation of a certificate for a new network subscriber and its distribution in the P2P network,

FIG. 3 shows a schematic illustration of the authentication of the message from a network subscriber,

Figure 4 shows a structure of circuit modules within a

Peers, Figure 5 is a flow diagram of a certificate distribution,

Figure 6 is a flowchart of an authenticity check and Figure 7 is a flowchart of an encrypted deposit.

Using a circuit arrangement and the associated method for authenticating a network subscriber, a digital certificate is stored as a resource in the P2P network. This has the advantage that data can be made available to the other network participants even if the network participant or the network participant cannot be reached offline or for other reasons in the operating mode. Furthermore, it is also possible to encrypt data intended for network units and thus protect them in the P2P network.

Figure 1 shows a P2P network within a network designated IP.

The data transfer to the transport layer takes place via common protocols, for example the Internet protocol. Between this transport layer and the application layer, the layer of is located as an additional layer P2P protocol, which assigns identification ID to other subscribers and data recorders, regulates storage, extraction and replication of data records, etc. The elements called peer A, peer B, ..., peer N of the P2P network are, for example independent computers that are connected to each other, for example, both via IP protocol and via P2P protocol. The technology of a P2P network required here is, for example, from a thesis by Thomas Friese on the

Philipps University of Marburg on the topic - Self-Organizing Peer-to-Peer Networks from March 2002 known. A server or certificate server, for example of a service provider, can also be arranged within the IP network.

The subject matter of the inventions is illustrated by the following description of the figures. A network element denoted by Peer X should, for example, have access to network subscribers of a network denoted P2P.

The access of the network subscriber Peer X to the P2P network is explained schematically in FIG. In a first method step, the network subscriber Peer X, which can be a computer, for example, requests or applies for a certificate ZX from a provider FIRM. The provider FIRM sends the applicant Peer X the assigned certificate, which is also stored in the certificate server CA. This certificate ZX created by the certificate server for the network subscriber Peer X consists, for example, of various categories such as the name of the provider, the company or the trust center that issues the certificate, a serial number of the certificate, a public key of Peer X, a validity period, a name, who the key (Peer X) belongs and a signature that is generated by the provider or trust center.

The signature ensures that the data stored in the certificate is only from the trust center or the Company or provider. In a second step, this certificate ZX is sent to the new network subscriber Peer X of the P2P network. The certificate server CA, which looks at the P2P network as a whole, also sends the certificate ZX to the P2P network. For example, the certificate server CA sends the certificate ZX to peer A. For this purpose, peer A can assume a gateway function. The certificate ZX is then stored as a resource within the P2P network, for example in the peer M.

With the storage of the digital certificate as a resource in the P2P network, the information of the digital certificate is also available to the network subscribers of the P2P network if the network unit Peer X is not accessible in offline mode or for other reasons. The validity period of this resource corresponds to the validity period of the certificate. It is thus possible to access a public key, which is stored in the certificate, in order to check the authenticity of the information stored and signed in a network unit in the P2P network. The authorization of the certificate user results from the possession of a valid certificate, which was issued by the provider FIRM. Furthermore, it is also possible to encrypt certain information for a network subscriber and thus store it in the P2P network in a protected manner. This could be used to implement a confidential answering machine function, for example.

FIG. 3 schematically shows how the network subscriber Peer C receives a message from network subscriber Peer X, the authenticity of which is to be checked by Peer C. For this, Peer C requires the ZX certificate from Peer X. This certificate ZX extracts Peer C from the P2P network and loads it into its memory: For this purpose, Peer C determines the identification ID of the ZX certificate, using the method defined in the P2P algorithm used, and searches then with the im P2P algorithm used method according to a peer, the identification of which matches the ID of the certificate as closely as possible, and in whose memory the certificate ZX was therefore stored. After the certificate ZX has been found in the resource of the network subscriber Peer M, the certificate ZX is sent to the searching network subscriber Peer C. The latter now first checks the validity of the ZX certificate using the public key QCA from the root certificate ZCA; he then checks the authenticity of the message using the public key QX, which is contained in the certificate ZX. If the authenticity is confirmed, the message is processed; otherwise it will be ignored.

The structure of a network subscriber is shown schematically in FIG

Peer A described. To understand the invention, a network module NWM, a first memory module SMPA, SMCA, SMA, .. and a second memory module SMX, SMY, ..., a crypto module KRM and a processor P connected to these modules are included in the illustration , The network module NWM with network card and associated software etc. regulates communication with all external devices, eg between peers in the P2P network and on the Internet protocol-based IP level. A private key PA from peer A is stored in the memory module SMPA; this must be kept secret by peer A. In the SMA memory module there is a certificate from Peer A with a public key QA and in the memory module SMCA there is a certificate from Server CA with a public key QCA. These first 3 records are always present in every peer. Certificates from other peers X, Y, ... are stored in a second memory module; these are fetched from the P2P network if required. The crypto module KRW, which is designed for software and / or hardware, has functions such as: Generation of a digital signature using the private key PA. Authenticity check of the digital signature of any peer X using its public key QX, which is included in the certificate kat of X is included. Validity check of a digital certificate via the authenticity check of its digital signature, created by the server CA using its public key QCA, which is contained in the (root) certificate of CA. Encryption of a confidential message to Peer X using the public key QX from Peer X's certificate. Decryption of a confidential message from Peer X to Peer A using the private key PA from Peer A.

FIG. 5 shows a program flow of a certificate distribution as shown schematically in FIG. With regard to the distribution of certificates, a preliminary remark should be made that all network participants in the P2P network have a self-signed certificate of the certificate generation server CA firmly integrated. Each network subscriber thus has a public key QCA of the certificate product server CA. All peers A, B, ... N also have an identification ID, this identification ID is, for example, the network address in the P2P network mentioned. The certificate generation server CA has generated the certificate ZX for the network subscriber Peer X of the P2P network, i.e. signed with the server's private key PCA. This certificate binds a public key QX to its identity X.

The certificate is then distributed according to the following procedural steps: The server sends a certificate to a specific peer. In the present example, this is peer A in the P2P network. The signature of the certificate ZX can be checked in peer A using the public key QCA known to it. If the signature is found to be invalid, the certificate is not forwarded but deleted. It is also possible that the certificate server itself is such a network participant in the P2P network.

In peer A the identification ID, which determines on which peers a resource is stored in the P2P network, is the Certificates ZX determined according to a method common in P2P networks, which depends on the P2P algorithm / protocol used. For P2P algorithms / protocols see for example Petar Maymounkov, David Mazieres, New York University, Kademia: A Peer to Peer Information System Based on XOR Metric, 2001 or Stoica, Morris, Karger, Kaashoek, Balakrishnan, MIT Laboratory for Computer Science: Chord: A Scalable Peer-to-peer Lookup Service for Internet Applications, August 2001. For example, the peer A calculates this ID of the certificate in such a way that it emerges from a unique identification by the peer X, so that the certificate is only known when this identification is known in the P2P network can be found and extracted.

Peer, A looks for peer M within the P2P network, whose identification ID best matches the ID of the certificate. The match relates to a metric of the P2P network system.

Peer A sends the ZX certificate to Peer M.

In the Peer M computer, the signature of the certificate can also be checked using the public key QCA. If this is ok, he saves the certificate, otherwise the certificate is deleted.

The Peer X certificate is available as a resource in the P2P network as described above, i.e. it can be searched and extracted by any peer A, B, ... N who needs it in the P2P network. The invention thus has the advantage that the ZX certificate is still available even when the server and Peer X are not available.

A flowchart of an authenticity check is shown schematically in FIG. For authenticity check noted that all peers in the P2P network have firmly integrated self-signed certificates of the certificate generation server CA. Each peer A, B, ... N, thus has a public key QCA of the certificate generation server CA. All peers A, B, ..., N, have an identification ID that serves as the network address in the P2P network. The certificate for Peer X is a resource in the P2P network. For example, a data record such as a data file, service request or message ..., signed by the peer X with its private key PX and sent to peer C or in the P2P network in another computer Peer M, ..., Peer N, are filed. Peer C receives this data record from Peer X or from a third computer Peer M.

Peer C now needs to authenticate, that is

Check that the data record really comes from Peer X, whose certificate is ZX.

Peer C determines e.g. from a unique identification of Peer X the identification ID of the certificate of Peer X.

In a subsequent process section, Peer C uses this ID to search for a network subscriber on which the certificate is stored and receives Peer M as the destination.

The computer Peer C causes Peer M to send it the certificate. Peer C now checks the validity of the ZX certificate and then checks the authenticity of the data record received from Peer X. If the certificate and authenticity are ok. Peer C processes the data record that was sent by Peer X. This also enables access control of the P2P network: only participants who have received a certificate from the certificate generation server CA are authorized to generate data records for processing by other participants.

Due to the deposit of the certificate in the resources of the P2P network, each peer A, B, ..N can now check the authenticity of data records in the network in the P2P network. The check can still be carried out even if the server and the Peer X subscriber are not available.

The sequence of an encrypted deposit is shown schematically in FIG. The subsequent process of an encrypted deposit is similar to the authenticity check described above. Based on peer C, an encrypted message to peer X is to be stored in the network. The computer peer C determines e.g. from a unique identification of Peer X the ID of the certificate of Peer X. The computer Peer C searches with this ID for a peer on which the certificate is stored and receives Peer M as the destination. The computer Peer C causes Peer M to send it the certificate. Peer C checks the validity of the Peer X certificate. In Peer C the message is encrypted with the public key QX from the Peer X certificate. The peer C can now store the encrypted message in the P2P network.

When Peer X receives the encrypted message, only Peer X can decrypt the Peer C message addressed to it with its private key PX.

With this process of encrypted storage, each peer A, B, .. Peer N, can send or store encrypted messages to other participants in the P2P network. This sending or storing of messages to other participants in the P2P network can take place independently of a server or the accessibility of the target peer.

Process for the safe communication of devices or network participants in P2P networks. In these networks, certification information about devices and users is required in order to check the authenticity of information signed by them and to send confidential information to them. keys to transfer. Anyone who needs this certification information can request it from the network participant himself or from external servers. According to the invention, this information is additionally stored as a resource in the P2P network. This has the advantage that the information is also available when the device or the user cannot be reached and no server is available. This also has the further advantage that the authenticity check is permanently guaranteed and information is also stored confidentially even when the device and user are temporarily unavailable.

Claims

claims 1. Circuit arrangement for communication security between network subscribers belonging to a peer-to-peer network, with a network module for communication with the other network subscribers and external communication devices (servers) not belonging to the peer-to-peer network, a crypto module for handling cryptographic tasks. ben, a first partial memory modules having memory module (SM1) in which membership characteristics (PA, ZA, ZCA) are stored to a first network subscriber, characterized in that a second memory module (SM2) is provided, the second memory module (SM2) partial memory modules (SMX . SMY, ...) for the intermediate storage of certificates (ZX, ZY, ..) of further network participants (Peer X, Peer Y,) and the certificates of these further network participants from all other network participants (Peer N, Peer M, ... .) can be requested. 2. Circuit arrangement according to claim 1, characterized in that the external communication device is designed in such a way that digital certificates can be produced and stored in the second memory module (SM2). 3. Circuit arrangement according to one of the preceding claims, characterized in that it is arranged in the first network subscriber. 4. Method for communication security between network subscribers belonging to a peer-to-peer network, with a network module for communication with the other network subscribers and external networks that are not part of the peer-to-peer network. listening communication devices (servers), a crypto module for handling cryptographic tasks, a memory module (SM1) having first partial memory modules, in which features belonging to a first network subscriber are stored, characterized in that a second memory module (SM2) in partial memory modules (SMX, SMY , ...) for the temporary storage of certificates (ZX, ZY, ..) others _. r network participants (Peer X, Peer Y,) is divided and the certificates of these other network participants can be requested from all other network participants (Peer N, Peer M, ....). 5. The method according to claim 4, characterized in that digital certificates are created in the external communication device and can be stored in the second memory module (SM2).