Patent Grant
7398551
The present invention is generally directed to telephony and multimedia communications carried by a distributed computer network, such as the global Internet. More specifically, the present invention relates to the secure enrollment of devices with a clearinghouse server so that communication can be routed between an originating device and a terminating device via the Internet.
Telecommunications networks are experiencing a drastic technology shift—from a circuit-switched architecture (such as the current voice phone network) to a packet-switched architecture (such as the global Internet). Worldwide, the capacity of deployed packet-switched networks is doubling every year while circuit-switched capacity is only increasing at an annual rate of around 6%. In many developed regions, packet-switched capacity already exceeds circuit-switched capacity. Recognizing this trend, telecommunications providers have begun to optimize their networks for the technology that is expected to dominate future growth: packet-switching. As they deploy packet-switched technology, these providers must still support traditional circuit-switched applications such as voice and facsimile. Instead of operating parallel network infrastructures, however, clearinghouse service providers seek to support those applications over a packet-switched network. This approach offers several advantages: greater efficiency through the use of a single, common, network infrastructure; lower cost through a reliance on packet-switching equipment; and better support of innovative new services through an open architecture.
As circuit-switched applications move to a packet-switched network, service providers need a way to identify systems on the packet-switched network that are associated with addresses (typically telephone numbers) common to the circuit-switched world. Providers must also have a means to authorize communications, and to ensure that unauthorized communications do not consume bandwidth. For example, the provisioning of a physical, circuit-switched, connection between two providers typically serves as authorization for the providers to share traffic. In a packet-switched environment, however, communicating parties need not share a physical connection and some other means of authorizing traffic is required. Finally, providers must have a reliable way to collect information from packet-switched devices to account for customer usage (e.g., for billing).
There remains a need in the art for a convenient, centralized application to provide authorization, or enrollment, for circuit-switched applications in a packet-switched network environment. Enrollment is the process of taking a device and exchanging sufficient cryptographic information with the clearinghouse server so that later communications with that device can be secured.
The conventional art does not provide an effective, secure way to enroll a device with a clearinghouse server. In particular, the identity of the clearinghouse server is verified by a telephone call. This verification has many drawbacks. Telephone calls are not automated, and require contact with people. As people have certain work hours, and cannot be relied upon to always be available, the telephone call verification is impractical, and time consuming. In addition, as packet-switched architecture becomes more and more popular, this problem will become more pronounced.
The present invention provides for the secure enrollment of a device for operation with a clearinghouse server, also described as a clearinghouse enrollment server, so that telephony and multimedia communications can be routed between an originating device and a terminating device via the Internet. The enrollment process is typically completed by a network device (such as a router, gateway, gatekeeper, etc.) and the clearinghouse server. This source device and the clearinghouse server can exchange encrypted information, so that later communications with that device can be secured. Once this verification process is finished, the device can have a public key certificate that is valid for a certain length of time (such as one year). Once this length of time has passed, however, the certificate can expire and the device must re-enroll. The enrollment process can also provide the device with a certificate authority's (CA) public key certificate. The device can use the CA's certificate to authenticate subsequent communications from other clearinghouse servers.
To enroll, the device can tell the clearinghouse server its public key. Then the device can prove that it possesses the private key that corresponds to the public key. This can be done by taking information provided by the clearinghouse enrollment server, and having the device encrypt it with the private key. The device can then send this information to the clearinghouse enrollment server. If the clearinghouse enrollment server can then decrypt the information, the clearinghouse enrollment server can verify that the device possesses the private key.
When the device tells the clearinghouse enrollment server its public key, a security issue arises. If an illegitimate user successfully intercepts, redirects, or captures the public key when it is sent to the clearinghouse enrollment server, the illegitimate user could take the place of the legitimate clearinghouse server. The illegitimate user could then be able to decrypt the encrypted message that the device sends, and would seem to be a legitimate clearinghouse enrollment server. Thus, the identity of the clearinghouse enrollment server must be verified.
Rather than using the conventional telephone call to verify the clearinghouse enrollment server's identity, the present invention can rely on the Web infrastructure to securely identify the clearinghouse enrollment server. The present invention does this by having the device pre-configured with a third party CA certificate. The clearinghouse enrollment server obtains a public key certificate under the authority of this CA certificate, and it provides that certificate, along with proof of possession of the corresponding private key, in the initial communications with the device.
In view of the foregoing, it will be appreciated that the present invention provides a method for secure enrollment of a device with services of a clearinghouse enrollment server to supporting communications carried by an Internet telephony system. A device can initiate a request to enroll for the services of the clearinghouse enrollment server. In turn, the identity of the clearinghouse enrollment server is verified a communication exchange between the device and the clearinghouse enrollment server. This exchange is supported by use of a security infrastructure comprising the Secure Sockets Layer (SSL) and a public key infrastructure. In response to verifying the identity of the clearinghouse enrollment server, enrollment of the device is completed at the clearinghouse enrollment server to all the device to access the communication services of the Internet telephony network.
More specifically, the present invention provides a for secure enrollment of a device with services of a clearinghouse server for an Internet telephony system. In response to obtaining an identity of the clearinghouse server, the device issues a CA certificate request to the clearinghouse server using that obtained identity. In response to the CA certificate request, the clearinghouse server transmits a CA certificate to the device. The device next determines whether the clearinghouse is a valid and secure service provider by verifying the CA certificate. Responsive to verification of the CA certificate, the device generates a combination of a private key and a public key and issues to the clearinghouse server a request for enrollment comprising the public key. In turn, the clearinghouse server generates a public key certificate and transmits the public key certificate to the device. This enables the device to securely verify the identity of the clearinghouse server and to complete device enrollment at the clearinghouse server.
These and other aspects of the present invention will be shown in the attached drawing set and following detailed description.
The present invention provides a clearinghouse solution for routing multi-media communications, including telephony calls, between a source device and a destination device via a distributed computer network, such as the global Internet. The present invention also authorizes the completion of a communication from a source device to a destination device and collects usage-related information for the completed communication. The clearinghouse server constructed in accordance with the inventive concept can identify one or more available destination devices available to accept a communication from an authorized source device based upon the source of that communication. An exemplary embodiment of the clearinghouse server can operate in either a “WINDOWS” or “SOLARIS” operating system environment in support of Web-based communications in a distributed computer network.
Turning now to the drawings, in which like reference numbers identify like elements of exemplary embodiments of the present invention,
To initiate a communication supported by the communication system 100, a calling party 105 sends an outgoing call having a called telephone number to the source device 110. For this representative example, the calling party 105 has an established a relationship with the source device 110, such as a subscription to call origination services provided by that source device. To be an authorized user of the clearinghouse services provided by the clearinghouse server 125, the gateway operators 111 or 121 can enroll source device 110 and destination device 120 for operation with the clearinghouse server 125. The enrollment process involves the exchange of information between the gateway operators 111 or 121, the clearinghouse server 125, and the third party server 125. (not affiliated with either the operators or clearinghouse server). This enrollment process is the subject of the present invention. Following the enrollment process, the source device 110 sends an authorization request message to the clearinghouse server 125 via the IP network 130 to request the completion of the outgoing call with an available designation device 120. The authorization request typically comprises the called telephone number, otherwise described as the dialed number, a call identifier to uniquely identify the outgoing call and, for certain applications, the telephone number for the calling party 105 and payment authorization, such as a calling card number and a personal identification number (PIN).
If the clearinghouse server 125 determines that the source device 110 is an authorized user of clearinghouse services, the clearinghouse server 125 can identify one or more destination devices for handling the outgoing call. The source device 110 can use the information provided by the clearinghouse server 125 in the authorization response to contact a selected destination device 120 and to complete the incoming call via the IP network 130. In turn, the selected destination device 120 can communicate the outgoing call to a called party 115, typically via the Public Switched Telephone Network (PSTN). In this manner, the outgoing call is connected between the calling party 105 and the called party 115 by a combination of a distributed computer network and the PSTN.
The platform of the clearinghouse server 125 is provided by the operating system 205, which is preferably implemented by Microsoft Corporation's “WINDOWS 2000” or Sun Microsystem's “SOLARIS” operating systems. Although the “WINDOWS” and the “UNIX” platforms represent preferred platforms, it will be appreciated that the inventive concept of a clearinghouse server 125 can be supported by other operating systems and is not limited to those described herein. The operating system 205 communicates with the Web server 210.
The Web server 210 supports Web-based communications with client computers in a Web-enabled computing environment, including the source devices illustrated in
The clearinghouse engine 220 supports the processing of clearinghouse transactions and communicates with the operating system 205, the Web server 210, and the user interface 225. APIs can be used to access functions supported by the clearinghouse engine 220. The clearinghouse engine 220 also can access configuration files maintained by the configuration database 230 in support of clearinghouse transactions. The configuration files typically contain descriptive information identifying characteristics of enrolled source devices and clearinghouse transaction records, including transaction identifiers assigned to transactions by the clearinghouse server 125.
The user interface 225 provides a mechanism for a user, such as an assistant administrator, to input information about the clearinghouse environment, including details about enrolled source devices and destination devices. The user interface 225 also can present the user with information related to clearinghouse transaction records stored by the clearinghouse server 125.
Secure Enrollment
Referring again to
This invention works for any type of service or device 110 that requires secured communications. This includes devices 110 under the direct control of human users (like a personal computer or a IP-based telephone) and those that are automated and not under the direct control of human users.
Exemplary Encryption Environment
In light of the discussion of public keys and private keys, a general discussion of an exemplary encryption environment may prove beneficial for understanding the present invention. Encryption is the process of encoding data to prevent unauthorized access, especially during transmission. Encryption is usually based on one or more keys, or codes, that are essential for decoding, or returning the data to readable form. An encryption key is a sequence of data that is used to encrypt other data and that, consequently, must be used for the data's decryption. Decryption is the process of restoring encrypted data to its original form.
Public key encryption is a process that uses a pair of keys for encryption: a private (secret) key and a public key. The private key can encrypt messages and can create a unique electronic number (called a digital signature) that can be read by anyone possessing the corresponding public key. The private key can also be used to decrypt messages encrypted with the public key. The public key can be used for encrypting messages to be sent to the user and for decrypting the user's digital signature.
A certification authority (“CA”) is an organization that assigns digital certificates. A CA may be an external issuing company (such as VeriSign) or an internal company authority that has installed its own certificate server 125 (such as a Microsoft Certificate Server) for issuing and verifying certificates. A CA is responsible for verifying the identity of a party and, if that identity is accepted, digitally signing that party's public key certificate. Other parties (that possess and trust the CA's public key, can then verify the applicant's identity merely by verifying the CA's signature of the public key certificate.
A CA certificate (sometimes called a digital certificate) is a user identity card for cyberspace. Issued by a CA, a CA certificate is an electronic credential that demonstrates that a user or site is trusted for the purpose of security and computer authentication.
Overview of Exemplary Enrollment Process
The enrollment process begins when the device generates a public/private key pair. It then establishes a secure communication channel with the clearinghouse enrollment server using the Secure Sockets Layer (SSL) protocol. The SSL exchange provides the device with a public key certificate for the enrollment server. That certificate is digitally signed by the third party certificate authority, who, therefore, vouchsafes for the enrollment server's identity.
Once the secure communications path is established, the enrollment server sends the device CA certificates of a (potentially different) certificate authority. Certificates certified by this additional CA will be used in subsequent communications with the clearinghouse. The additional CA may be the same CA as is authenticating the enrollment server, but it need not be so. By permitting them to differ, the present invention allows for different public key infrastructures for enrollment and for operational clearinghouse communications (e.g. routing telephone calls).
After receiving the CA certificate, the device then sends the enrollment server the previously generated public key. The enrollment server receives this public key and, either immediately or at a later time (e.g. after an administrator has verified that the customer intended to enroll the device in question), the enrollment server issues the device a certificate containing the device's public key.
Message Formats
All messages sent to the clearinghouse enrollment server are carried in HTTP (version 1.1) POST messages. All replies are returned in responses to the POST. Each POST request contains a series of ASCII variable=value pairs, encoded as given in RFC 1738. Any response also consists of variable/value pairs. The following Table 1 lists the variables that can be included in a message. Note that non-alphanumeric characters are encoded as a “%” and their corresponding two hexadecimal digits (as specified in RFC 1738.)
The following example in Table 2 shows a sample CA certificate request message. In it, the device asks for the enrollment server's CA certificate in cleartext:
The response received from the enrollment server might look like the example shown in Table 3:
Once the CA certificate is retrieved, the certificate request is encrypted and transmitted to the enrollment server for approval. The initial request (before it is encrypted) looks like the representative example shown in Table 4:
The retrieve function only differs in the “operation” parameter, in which the “request” value is replaced by “retrieve”. Otherwise, all parameters have the same names and values.
If the enrollment request is pending further approval, then the enrollment server is only required to send the status of the certificate request. It may send a nonce along with the response, but this value is not guaranteed. The response should look like the representative example shown in Table 5:
If the enrollment request has been processed and accepted by the server, it will return a response such as the following in Table 6. Note that a status of 0 indicates that the certificate is now ready for retrieval.
In step 310, commands are issued at the source device to complete an enrollment request for transmission to the clearinghouse server. These commands are typically device dependent and often require support by an administrator to select the appropriate enrollment instructions. Representative enrollment request tasks completed by the source device for step 310 are shown in the logical flow chart diagram of
Turning briefly to
Returning now to
Each line in a configuration file (other than comments or blank lines) contains a single configuration item. The first word on the line identifies that item. The possible values for this word are listed below in Table 8.
The same configuration item may be included multiple times in this file. In such cases, the clearinghouse server's behavior depends on the specific item. In most cases, later occurrences of an item will override an earlier value. For example, if multiple “license” lines are included in the file, only the last line will actually be used by the server. In the case of “group”, “device”, and “route”, multiple occurrences define additional groups, devices, or routes. Note, however, that it is not possible to define multiple groups with the same name, multiple devices with the same name, or multiple routes with the same group and called number. If the configuration file attempts to define duplicates, the server will generate an error when attempting to read and parse the file.
License “Software License Key”
The content following the license keyword should be a software license key enclosed in double quotation marks. If this parameter is absent from the file, or if the included license key is invalid, the underlying software supporting operations of the clearinghouse server will revert to a trial version. New software license keys may be obtained from a licensor of the clearinghouse server software. They can either be added to the configuration file manually or imported into the server through the user interface. Imported license keys are stored in configuration backups. Unlike other configuration items, old values of the license key are kept in the configuration file, allowing a straightforward reversion to an earlier license (by deleting the newest license keys), as well as problem diagnosis and auditing.
Crypto “Cryptographic Parameters”
The content following the crypto keyword should be cryptographic parameters for the clearinghouse server enclosed in double quotation marks. If this parameter is absent, the clearinghouse server will automatically generate new cryptographic parameters. If this occurs, though, all enrolled devices will have to re-enroll with the server to refresh their cryptographic knowledge.
Enroll {Enabled|Disabled}
The content following the enroll keyword should be a single word, either “enabled” or “disabled” (without the quotation marks), whichever is appropriate. If this parameter is not present, device enrollment will be disabled.
Routing {Enabled|Disabled}
The content following the routing keyword should be a single word, either “enabled” or “disabled” (without the quotation marks), whichever is appropriate. If this parameter is not present, call routing will be disabled.
Cdrs {Enabled|Disabled}
The content following the call details records) (cdrs) keyword should be a single word, either “enabled” or “disabled” (without the quotation marks), whichever is appropriate. If this parameter is not present, CDR collection will be disabled.
Ssl {Enabled|Disabled}
The content following the ssl keyword should be a single word, either “enabled” or “disabled” (without the quotation marks), whichever is appropriate.
Group Name
The content following the group keyword should be the name of the group. If the name consists of more than one word, the entire name should be enclosed in double quotation marks.
Device Name Group {Enabled|Disabled}[Enrolled]
The content following the device keyword should be the DNS name of the device, the name of the group to which the device belongs (enclosed in quotation marks if the name is more than one word), the word “enabled” or “disabled” (without the quotation marks), and, optionally, the word “enrolled” (also without quotation marks).
Route Group Number (Device Weight)
The content following the route keyword should be the name of the group to which the route applies (enclosed in quotation marks if the name is more than one word), the called number prefix for the routes (enclosed in quotation marks if the number includes spaces) and then a series of one or more device weight pairs, where device is the DNS name of the destination device, and weight is the weighting factor for that device.
It should be understood that the foregoing relates only to illustrative embodiments of the present invention, and numerous changes may be made therein without departing from the spirit and scope of the invention as defined by the following claims.
This application is a continuation of and claims priority to application Ser. No. 09/747,365 filed Dec. 22, 2000, now U.S. Pat. No. 7,203,956 entitled “System and Method for Secure Enrollment of Devices with a Clearinghouse Server for Internet Telephony and Multimedia Communications,” the entire contents of which are incorporated by reference.
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