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WO2004010637A1 - Distribution de cle cryptographique au moyen du doublage de cles - Google Patents

Distribution de cle cryptographique au moyen du doublage de cles Download PDF

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Publication number
WO2004010637A1
WO2004010637A1 PCT/US2003/022648 US0322648W WO2004010637A1 WO 2004010637 A1 WO2004010637 A1 WO 2004010637A1 US 0322648 W US0322648 W US 0322648W WO 2004010637 A1 WO2004010637 A1 WO 2004010637A1
Authority
WO
WIPO (PCT)
Prior art keywords
key
transport
party
cryptographic
encrypting
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2003/022648
Other languages
English (en)
Inventor
Wolfgang S. Hammersmith
Lance R. Gaines
Rod G. Nicholls
Byron T. Shank
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vadium Tech Inc
Original Assignee
Vadium Tech Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Vadium Tech Inc filed Critical Vadium Tech Inc
Priority to AU2003252071A priority Critical patent/AU2003252071A1/en
Publication of WO2004010637A1 publication Critical patent/WO2004010637A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
    • H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
    • H04L9/0819—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s)
    • H04L9/0822—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s) using key encryption key
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L2209/00—Additional information or applications relating to cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
    • H04L2209/30—Compression, e.g. Merkle-Damgard construction

Definitions

  • This invention pertains to the field of secure distribution (including distribution over insecure electronic means) of cryptographic keys, such as encryption keys for a One-Time Pad cipher system.
  • the encryption method is referred to as a "repeating key" encryption method.
  • the use of the OTP encryption method for any but the shortest of messages was extremely difficult and time consuming, due to the sheer size and volume of the necessary encryption keys needed. For example, for a person to encrypt a one megabyte computer file, the OTP cipher requires a one megabyte encryption key that cannot be reused. This system requirement made the implementation of an OTP cipher system very difficult and nearly impractical, prior to the advent of computers.
  • a popular repeating key method known as public key encryption uses different but related public and private keys for encryption and decryption.
  • computers that include fast, easy to use, and removable data storage media (like flash RAM memory devices using universal serial bus (USB) interfaces capable of secure storage and management of the very large encryption keys needed for practical OTP deployment)
  • USB universal serial bus
  • OTP encryption for data communication and storage has become practical.
  • repeating key encryption methods previously thought to provide adequate security have been broken, and are being broken at an increasing rate. Given a large enough sample of encrypted messages and a fast enough computer with a large enough memory, any repeating key encryption scheme can be broken.
  • the only known encryption method that is provably unbreakable and immune to these advances in computer processing power and speed is the One-Time Pad cipher.
  • One of the primary challenges to encrypted communications is the need to distribute, update, and replace encryption keys. Although this need applies to all cipher systems, it is especially acute with the One-Time Pad cipher.
  • Prior to this invention there was no secure way to distribute, update, and replace keys by any means other than to physically deliver said keys to each participant in the communications channel.
  • OTP and other encryption keys can be distributed in a secure manner even over insecure electronic means like the Internet, rather than through physical distribution methods.
  • the present invention geometrically increases the use, scalability, encryption volume, surge capabilities, and efficiency of the OTP and other cipher systems.
  • a method embodiment of the present invention comprises the steps of combining (steps 1 and 2) the cryptographic key (C) with a transport key (T) to form a key set; encrypting (step 7) the key set to form an encrypted key set; distributing (step 8) the encrypted key set across a medium (3) ; and decrypting (step 9) the encrypted key set to reconstitute the cryptographic key (C) and the transport key (T) .
  • Figure 1 is a state diagram illustrating operation of the present invention, with method steps shown as lines connecting the states .
  • OTP One-Time Pad Cipher
  • Key is any sequence of symbols of any length that is used to encrypt and/or decrypt information in any form.
  • compression is an algorithm or the product of an algorithm used for the reduction of the volume of binary data.
  • Key folding is a process of compressing a key so that the total volume, represented by the number of bits or bytes in the key, is one half of the original volume of the key before compression.
  • LSB means "least significant bit” or "least significant bits”, i.e., the rightmost bit or bits of an ordered sequence of bits .
  • MSB means "most significant bit” or “most significant bits”, i.e., the leftmost bit or bits of an ordered sequence of bits .
  • the invention will be illustrated for a computer system having words that are 8 bits (one byte) long.
  • the word length in bits is any power of two, i.e., 16 bits, 32 bits, 64 bits, etc.
  • the invention is illustrated primarily with respect to a One-Time Pad cipher system.
  • the method can be used to distribute any type of cryptographic key, such as a private (secret) key in a public key cryptosystem, or a symmetric key in a symmetric cryptosystem such as RC .
  • the illustrated method has 10 steps, and can be executed an arbitrarily large number of iterations (assuming that no key is lost, stolen, or corrupted), even when the keys C being distributed are OTP keys, when the compression performed in step six is 50% compression (key folding) or greater than 50% compression.
  • Two iterations of the method, plus an initialization, are illustrated in Figure 1. For each successive iteration, the subscripts on all the keys are incremented by one, as can be seen by examining Figure 1.
  • the communications keys C each have a volume of 5 (arbitrary) units
  • the transport keys T each have a volume of 10 units, i.e., 50% compression is performed at step 6.
  • An exception to the general rule is that the first communications key C 0 does not have to have a volume of 10 units, and in this case is shown as having 50 units.
  • the boxes and lines connecting boxes that are illustrated in Figure 1 can be implemented using software, firmware, hardware, or any combination thereof, e.g., one or more application specific integrated circuits (ASICs) can be used.
  • the method steps can be embodied in software resident on any computer-readable medium or media, such as a hard disk, floppy disk, CD, DVD, etc.
  • one computer-readable medium may contain software for executing the steps performed by party A
  • a second computer-readable medium may contain software for executing the steps performed by party B.
  • TRNG 1 is a cryptographically approved non-deterministic random number generator, i.e., one having no repeat period and an output rated for unbreakable cryptography.
  • An example of TRNG 1 is Model SG100 made by Protego of Sweden.
  • Secure distribution path 2 can comprise a trusted courier, a face-to-face meeting between party A and party B, biometric verification, or any other means deemed by party A and party B to be secure enough for the communications that the two parties wish to undertake.
  • Network 3 can comprise any electronic or non-electronic network or signal path, such as the public switched telephone network (PSTN) , a computer network, a wired or wireless LAN (Local Area Network) , a wired or wireless WAN (Wide Area Network) , a terrestrial microwave link, a satellite communications network, a telegraph over which the parties communicate using Morse code, a semaphore signaling system, or any combination of any of the above.
  • Network 3 may comprise a secure network or an inherently insecure network such as the Internet .
  • a transport key T is created.
  • T is created by using TRNG 1 to create a random sequence of bytes from any subset of bytes in which the first four MSB in each byte are identical.
  • TRNG 1 One example of a suitable range of bytes satisfying this criterion consists of those 16 consecutive bytes from the ASCII character set 64 (decimal) through 79 (decimal) . This corresponds to the ASCII characters @ through 0.
  • This set of 16 bytes is illustrated in Table 1 as follows :
  • Such a transport key T can be achieved by using a table lookup (e.g., a MIME type of table lookup), mathematical formula, or any other process to convert a random binary string or random byte sequence into a random byte sequence of 16 serial ASCII values having uniform MSB.
  • a table lookup e.g., a MIME type of table lookup
  • mathematical formula or any other process to convert a random binary string or random byte sequence into a random byte sequence of 16 serial ASCII values having uniform MSB.
  • One example of such a process is an expansion by a factor of two of a key randomly generated by TRNG 1 by means of concatenating a common MSB sequence at uniform four bit intervals throughout the length of the key.
  • the volume (size) of the transport key T must be greater than or equal to the combined sizes of the communications key C to be distributed in the next iteration plus the size of the compressed transport key FT to be used in the next iteration.
  • the size of T 0 must be greater than or equal to the combined sizes of Ci plus FTi; the size of Ti must be greater than or equal to the combined sizes of C 2 plus FT 2 ; etc.
  • Step 1 is one of the few steps that is performed during the initialization, as can be seen by examining Figure 1.
  • the initial transport key T 0 is created in step 1, then distributed from party A to party B via secure distribution path 2 in a special step 4 that is performed only during initialization.
  • T 0 can be generated by party B and then distributed to party A across secure distribution path 2.
  • Step 2 is the creation of a communications key C.
  • C is created by tasking TRNG 1 to create a random sequence from the full range of the ASCII character set 0 (decimal) trough 255 (decimal) .
  • Step 2 is another one of the few steps that is performed during the initialization.
  • the initial communications key C 0 created during initialization can be any size, as long as C 0 is larger than the conversion key K (see step 3 below) .
  • C 0 need not be created in proportion relative to any transport key, because the main purpose of C 0 is to generate K.
  • C 0 is sent from party A to party B via secure distribution path 2, and is subsequently used by party B for use as a cryptographic key in encrypting and decrypting messages sent between party B and other parties, such as party A.
  • the only C that needs to be distributed from party A to party B by secure means is C 0 -- all the subsequent C's can be distributed over network 3, which can be insecure.
  • a new communications key C replaces a previous communications key C when the previous communications key C reaches or nears the end of its useful life.
  • Ci replaces Co
  • C 2 replaces C l7 etc.
  • Each communications key C is created by tasking TRNG 1 to create a random sequence from the full range of the ASCII character set 0 (decimal) through 255 (decimal) .
  • the method can be repeatable an arbitrarily large number of iterations, even in an OTP cipher system.
  • C has a volume 50% of the volume of the initially distributed transport key T 0 , as illustrated in Figure 1.
  • Step 3 is the creation of a conversion key K.
  • step 3 is performed just during initialization.
  • step 3 is performed during each iteration of the method, to enhance security.
  • K as it appears on Figure 1 can be replaced by K 0/ Ki, K 2 , etc.
  • K can be regenerated upon the occurrence of a preselected event, e.g., the expiration of a preselected period of time.
  • K can be regenerated when it expires or is about to expire.
  • K has a size of 30 and each T has a size of 10.
  • K may be used in the XORing process of step 5 to convert three different T's, after which K is regenerated.
  • K can be encrypted and sent across network 3 from party A to party B for subsequent use by party B.
  • party B can generate K from its corresponding C assuming that party B has knowledge as to how party A generated K from C.
  • This knowledge (as well as other items of knowledge, such as the encryption algorithm used in step 7, the folding algorithm used in step 6, and the folding range used in step 6) can be sent from party A to party B by secure means prior to execution of the method iterations.
  • K comprises the removed bytes that are created by removing a continuous sequence of bytes from communications key C.
  • K typically has a size between 100KB and 1MB. This implies that the size of the communications key C from which K is extracted should be considerably greater than 1MB, e.g., at least 20MB. Since the sequence of bytes that is removed from C is continuous, the bytes in K exhibit the same cryptographically approved qualities of C, and are likewise from the range of the full ASCII character set 0 (decimal) through 255 (decimal) .
  • K is generated by TRNG 1 and comprises a random sequence from the full range of the ASCII character set 0 (decimal) through 255 (decimal) .
  • a given K can be smaller than its corresponding T, e.g., K 0 can be smaller than T 0 , in which case K is a repeating key.
  • Step 4 is performed only during initialization, as described previously. At step 4, K and T 0 are distributed from party A to party B across secure distribution path 2.
  • Step 5 is the conversion of a transport key T into a key whose bytes are from the full range of ASCII values, without compromising the random properties of the transport key T.
  • a new K may be generated during each iteration, whether by carving K out of C or by tasking TRNG 1 to create K. In this case, step 5 is also performed once per iteration.
  • the conversion of T is accomplished by exclusive OR-ing
  • Step 6 comprises compressing the transport key T. If it is desired for the method to be continuable indefinitely in certain cipher systems including an OTP cipher system, the compression must entail key folding (i.e., compression by 50%), or compression by more than 50%. For distribution of certain types of non-OTP keys, step 6 may not be needed at all.
  • the compression performed in step 6 can be performed by any suitable technique, including one, or a combination of, the following techniques: advanced matrix arithmetic compression, vector based compression, quantum compression, sliding window compression, or key folding using bit swapping.
  • the compression can be applied to individual bits, whole bytes, or partial bytes.
  • the compression technique that will now be described is key folding using bit swapping. This technique is accomplished by discarding the four MSB of each byte in T, and using these vacated positions to temporarily store the four LSB from half of the bytes of T.
  • the four MSB of the ASCII values 64 (decimal) through 79 (decimal) are 0100 for each byte in T, as can be seen from Table 1. These bits are discarded during folding, and reassembled later (in step 10) upon receipt by party B to recreate the original form of T.
  • Table 2 illustrates key folding using bit swapping, as follows :
  • the four LSB in byte 1 of T have been shifted to become the four MSB in byte 1 of FT
  • the four LSB in byte 2 of T are now the four LSB in byte 1 of FT
  • the four LSB in byte 3 of T are now the four MSB of byte 2 of FT
  • the four LSB of byte 4 of T are now the four LSB in byte 2 of FT.
  • the folded transport key FT is 50% of its original size, because each folded byte in FT contains the information from two of the original bytes of T.
  • step 7 for an OTP cipher system, an exclusive OR (XOR) is performed between the random converted transport key KT from the previous iteration of the method and a new (for that iteration) key set comprising a communications key C and a compressed transport key FT.
  • the result of step 7 is transmittable ciphertext comprising an encrypted communications key EC plus an encrypted compressed transport key EFT.
  • the encryption performed in step 7 must be true OTP encryption, to preserve security. If the communications key C is a key for a weaker non-OTP cryptosystem, this requirement can be relaxed -- the encryption in step 7 does not have to be OTP encryption, and XORing does not have to be used.
  • Step 8 is the distribution of EC and EFT from party A to party B via network 3.
  • steps 9 and 10 are performed by party B.
  • party B decrypts EC and EFT using KT from the previous iteration.
  • the decryption key used in step 9 must be the same as the encryption key used in step 7 for that iteration, and the decryption algorithm must be consistent with the encryption algorithm.
  • the result of step 9 is C plus FT.
  • FT is uncompressed (unfolded in the illustrated embodiment) .
  • the unfolding process is exactly the reverse of the folding process described in step 6 above.
  • FT is unfolded by splitting each byte of FT into two new bytes, moving the four MSB of each old FT byte into four LSB of a new T byte, and padding 0100 into the four MSB for each new T byte. It is assumed that party B doing the unfolding in step 10 knows the folding range and folding algorithm used by party A in step 6.
  • transport key T sizes remain uniform, because 50% compression is achieved.
  • key C upgrades can be performed to infinity, i.e., there can be an infinite number of iterations, even in an OTP cipher system.
  • the encryption is secure, because fresh communications keys C and transport keys T are being created for each iteration. If less than 50% compression is achieved in step 6, each successive iteration's communications key C will have a smaller and smaller size in many cipher systems, including the OTP cipher system, until the size of the communications key C becomes zero. Thus, the number of iterations is finite when less than 50% compression is utilized in these cipher systems .
  • the transport key T retrieved by party B is stored in a secure area within the purview of party B, awaiting the next iteration of the method.
  • the communications key C retrieved by party B is placed into service. This can entail using C for encrypted communications between party A and party B, or using C to communicate in a secure fashion with a third party. In the ' case of a One-Time Pad cipher system, the communications key C must be used just once if security is to be preserved. However, portions of a communications key C can be used for one communication, then subsequent portions of key C can be used for subsequent communications. Thus, party B can use a portion of a newly distributed communications key C to communicate with party A and another portion of the newly distributed communications key C to communicate with a third party.
  • party B can communicate to party A that it is time for a new iteration of the method to take place, so that party B can receive a new communications key C.
  • This message from party B to party A can be done automatically, and can be done via computer means, e.g., over network 3.
  • a monitoring device monitors the degree to which a given communications key C is being exhausted ⁇ This information can be displayed in graphical form to party B via a graphical user interface (GUI) .
  • GUI graphical user interface
  • the repetition of the method steps can be terminated after a preselected event has occurred. For example, the method can be aborted every week, at which time the method is reinitialized. This may be done to enhance security.

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  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Storage Device Security (AREA)

Abstract

La présente invention concerne des procédés, des supports lisibles par ordinateur et des appareils permettant de distribuer en toute sécurité une clé cryptographique (C) entre au moins une première partie et au moins une deuxième partie. Une forme de réalisation du procédé selon l'invention comprend les étapes qui consistent à combiner (étapes 1 et 2) la clé cryptographique et une clé de transport (T) pour former un ensemble clé; à chiffrer (étape 7) l'ensemble clé pour former un ensemble clé chiffré; à distribuer (étape 8) l'ensemble clé chiffré sur un support (3); et à déchiffrer (étape 9) l'ensemble clé chiffré pour reconstituer la clé cryptographique (C) et la clé de transport (T).
PCT/US2003/022648 2002-07-19 2003-07-18 Distribution de cle cryptographique au moyen du doublage de cles Ceased WO2004010637A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2003252071A AU2003252071A1 (en) 2002-07-19 2003-07-18 Cryptographic key distribution using key folding

Applications Claiming Priority (2)

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US39711302P 2002-07-19 2002-07-19
US60/397,113 2002-07-19

Publications (1)

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WO2004010637A1 true WO2004010637A1 (fr) 2004-01-29

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US12294645B2 (en) 2021-10-04 2025-05-06 QDS Holdings Inc. Systems and methods for securing a quantum-safe digital network environment

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5937066A (en) * 1996-10-02 1999-08-10 International Business Machines Corporation Two-phase cryptographic key recovery system
US6052468A (en) * 1998-01-15 2000-04-18 Dew Engineering And Development Limited Method of securing a cryptographic key
US6058188A (en) * 1997-07-24 2000-05-02 International Business Machines Corporation Method and apparatus for interoperable validation of key recovery information in a cryptographic system
US6266421B1 (en) * 1997-07-07 2001-07-24 Hitachi, Ltd Key recovery system and key recovery method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5937066A (en) * 1996-10-02 1999-08-10 International Business Machines Corporation Two-phase cryptographic key recovery system
US6266421B1 (en) * 1997-07-07 2001-07-24 Hitachi, Ltd Key recovery system and key recovery method
US6058188A (en) * 1997-07-24 2000-05-02 International Business Machines Corporation Method and apparatus for interoperable validation of key recovery information in a cryptographic system
US6052468A (en) * 1998-01-15 2000-04-18 Dew Engineering And Development Limited Method of securing a cryptographic key

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US12294645B2 (en) 2021-10-04 2025-05-06 QDS Holdings Inc. Systems and methods for securing a quantum-safe digital network environment

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