Lenovo ThinkCentre M50 IDC white paper titled "The Coming of Age of Clien - Page 13

cryptographic operations through the chip. Cryptographic middleware automatically routes function calls to the hardware. The chip is compliant with Microsoft's CAPI and PKCS #11, industry-standard interfaces, which many of the PKI providers, such as Entrust, Baltimore, and Microsoft itself, use for applications such as email (e.g., Outlook and Notes), VPN clients (e.g., Cisco, SonicWALL, and L2TP), or network log-on clients (e.g., NetWare). The chip library supports 512-, 1024-, and 2,048-bit key generation; encryption; decryption; and digital signature operations as well as 256-bit decryption for symmetric key operations. All private key operations take place within the protected environment of the chip. The keys, which are generated internally and stored on the chip, never appear in main memory. So there is no way a Trojan horse can sniff it. When a system with the a hardware security chip is first booted up, the chip must be enabled with a BIOS setting (the BIOS itself is protected by an integrity procedure). No one can give a user his or her identity. Each system owner configures his or her own personalized subsystem identity by initializing it. This subsystem identity key pair is called the "hardware key pair." Once inside, the private key is used only to hide other keys and never to identify the system or owner. In its most recent implementation, the security chip has been paired with external hardware, such as a PC Card-slot or USB-attached fingerprint reader from Targus, a USB-connected proximity badge from Ensure Technologies, or even a smart card. IBM's focus has shifted from providing fully authenticated PKI communications and guaranteed ebusiness transactions to the more straightforward tasks of making sure that the individual logging on to a particular client node is the authorized user and that his or her local data is protected from intruders. A HIERARCHY OF KEYS One of the greatest strengths of hardware security architecture is the hierarchical nature of its key-management system. The first key pair generated is used to protect another key pair, called the "platform identity key pair." This key pair is created under the system owner's control and can be used by the system owner to definitively identify the PC. As part of the subsystem initialization, the owner of the system can make an archive copy of the platform private key. The platform private key is encrypted with the administrative public key. The corresponding administrative private key can be split into up to five parts, allowing the restoration responsibility to be secured among multiple administrators. This archive data, including the administrative private key, can be stored on external removable media or on a network server. If the system, chip, or motherboard dies, or the system needs to be upgraded, the owner has the ability to securely migrate all of his or her key information from the old system to the new system. The security administrator might or might not want to use this sort of backup scheme, which represents a back door to the system, but it is there for corporate implementations. Without it, the whole system could become inaccessible. With it, as with any archive system, a potential security exposure exists if the administrator's private key is ever compromised. Each firm has to assess its circumstances and risk profile. Next, a "user key pair" is created. The private key of the user pair is encrypted with the public key of the platform pair. Before encrypting the private key of the user pair, a "passphrase" (up to 128 characters) is associated with it. Then the private key and passphrase are encrypted with the public key of the platform pair. As another level of protection, the chip will not execute any operations if it doesn't receive the correct passphrase for that key. ©2003 IDC #3577 13