These supplement JG's post on CAPSTONE -- which is itself available with related crypto papers at csrc.ncsl.gov: ------------------ URL: http://csrc.ncsl.nist.gov/nistgen/clip.txt CLIPPER CHIP TECHNOLOGY CLIPPER is an NSA developed, hardware oriented, cryptographic device that implements a symmetric encryption/decryption algorithm and a law enforcement satisfying key escrow system. While the escrow management system design is not completely designed, the cryptographic algorithm (SKIPJACK) is completely specified (and classified SECRET). The cryptographic algorithm (called CA in this paper) has the following characteristics: 1. Symmetric, 80-bit key encryption/decryption algorithm; 2. Similar in function to DES (i.e., basically a 64-bit code book transformation that can be used in the same four modes of operation as specified for DES in FIPS 81); 3. 32 rounds of processing per single encrypt/decrypt operation; 4. Design started by NSA in 1985; evaluation completed in 1990. The CLIPPER CHIP is just one implementation of the CA. The CLIPPER CHIP designed for the AT&T commercial secure voice products has the following characteristics: 1. Functions specified by NSA; logic designed by MYKOTRONX; chip fabricated by VLSI, Inc.: manufactured chip programmed (made unique) by MYKOTRONX to security equipment manufacturers willing to follow proper security procedures for handling and storage of the programmed chip; equipment sold to customers; 2. Resistant to reverse engineering against a very sophisticated, well funded adversary; 3. 15-20 MB/S encryption/decryption constant throughout once cryptographic synchronization is established with distant CLIPPER Chip; 4. The chip programming equipment writes (one time) the following information into a special memory (called VROM or VIA-Link) on the chip: a. (unique) serial number b. (unique) unit key c. family key d. specialized control software 5. Upon generation (or entry) of a session key in the chip, the chip performs the following actions: a. Encrypts the 80-bit session key under the unit key producing an 80-bit intermediate result; b. Concatenates the 80-bit result with the 25-bit serial number and a 23-bit authentication pattern (total of 128 bits); c. Enciphers this 128 bits with family key to produce a 128-bit cipher block chain called the Law Enforcement Field (LEF); d. Transmits the LEF at least once to the intended receiving CLIPPER chip; e. The two communicating CLIPPER chips use this field together with a random IV to establish Cryptographic Synchronization. 6. Once synchronized, the CLIPPER chips use the session key to encrypt/decrypt data in both directions; 7. The chips can be programmed to not enter secure mode if the LEF field has been tampered with (e.g., modified, superencrypted, replaced); 8. CLIPPER chips will be available from a second source in the future; 9. CLIPPER chips will be modified and upgraded in the future; 10. CLIPPER chips presently cost $16.00 (unprogrammed) and $26.00 (programmed). 4/30/93 ------------------- URL: http://csrc.ncsl.nist.gov/nistnews/esc_key2.txt February 4, 1994 AUTHORIZATION PROCEDURES FOR RELEASE OF ENCRYPTION KEY COMPONENTS IN CONJUNCTION WITH INTERCEPTS PURSUANT TO FISA The following are the procedures for the release of escrowed key components in conjunction with lawfully authorized interception of communications encrypted with a key-escrow encryption method. These procedures cover all electronic surveillance conducted pursuant to the Foreign Intelligence Surveillance Act (FISA), Pub. L. 95-511, which appears at Title 50, U.S. Code, Section 1801 et seq. 1) In each case there shall be a legal authorization for the interception of wire and/or electronic communications. 2) In the event that federal authorities discover during the course of any lawfully authorized interception that communications encrypted with a key-escrow encryption method are being utilized, they may obtain a certification from an agency authorized to participate in the conduct of the interception, or from the Attorney General of the United States or designee thereof. Such certification shall (a) identify the agency participating in the conduct of the interception and the person providing the certification; (b) certify that necessary legal authorization has been obtained to conduct electronic surveillance regarding these communications; (c) specify the termination date of the period for which interception has been authorized; (d) identify by docket number or other suitable method of specification the source of the authorization; (e) certify that communications covered by that authorization are being encrypted with a key-escrow encryption method; (f) specify the identifier (ID) number of the key-escrow encryption chip providing such encryption; and (g) specify the serial (ID) number of the key-escrow decryption device that will be used by the agency participating in the conduct of the interception for decryption of the intercepted communications. 4) This certification shall be submitted to each of the designated key component escrow agents. If the certification has been provided by an agency authorized to participate in the conduct of the interception, a copy shall be provided to the Department of Justice, Office of Intelligence Policy and Review. As soon as possible, an attorney associated with that office shall provide each of the key component escrow agents with written confirmation of the certification. 5) Upon receiving the certification, each key component escrow agent shall release the necessary key component to the agency participating in the conduct of the interception. The key components shall be provided in a manner that assures they cannot be used other than in conjunction with the lawfully authorized electronic surveillance for which they were requested. 6) Each of the key component escrow agents shall retain a copy of the certification, as well as the subsequent written confirmation of the Department of Justice, Office of Intelligence Policy and Review. 7) Upon, or prior to, completion of the electronic surveillance phase of the investigation, the ability of the agency participating in the conduct of the interception to decrypt intercepted communications shall terminate, and such agency may not retain the key components. 8) The Department of Justice shall, in each such case, (a) ascertain the existence of authorizations for electronic surveillance in cases for which escrowed key components have been released; (b) ascertain that key components for a particular key-escrow encryption chip are being used only by an agency authorized to participate in the conduct of the interception of communications encrypted with that chip; and (c) ascertain that, no later than the completion of the electronic surveillance phase of the investigation, the ability of the agency participating in the conduct of the interception to decrypt intercepted communications is terminated. 9) Reports to the House Permanent Select Committee on Intelligence and the Senate Select Committee on Intelligence, pursuant to Section 108 of FISA, shall, with respect to any order for authorized electronic surveillance for which escrowed encryption components were released and used for decryption, specifically note that fact. These procedures do not create, and are not intended to create, any substantive rights for individuals intercepted through electronic surveillance, and noncompliance with these procedures shall not provide the basis for any motion to suppress or other objection to the introduction of electronic surveillance evidence lawfully acquired. ------------------