session_01_classic_cryptography_and_ia_082508

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Unformatted text preview: Cryptography and Network Security TECH 6350 Session 1 Classic Cryptography and Information Assurance Manuel Mogollon [email protected] Graduate School of Management Information Assurance University of Dallas 0 Session 1 – Contents • Classic Cryptography — Classic Cipher Techniques — Early Cipher Machines — The Rotor Crypto Machines • Information Assurance — OSI and TCP/IP Stack — Crypto Terminology — Security Services and Security Mechanisms Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 1 M. Mogollon – 01/08 - 1 1 Introduction • Scribes in the Egyptian civilization used unusual hieroglyphics to tell the story of their masters' lives. — The inscriptions were not secret writing, but incorporated one of the essential elements of cryptography: an intentional transformation of writing so that only certain people could read it • The Spartans were probably the first to use cryptography for military purposes. — Their crypto device was called the scytale (stick). We need to proceed with the plan Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 2 M. Mogollon – 01/08 - 2 • The Spartans were probably the first to use cryptography for military purposes. Their crypto device, called the scytale (stick), consisted of a wooden stick around which a narrow piece of papyrus, leather, or parchment was wrapped in a spiral. The secret message was inscribed on the parchment over the whole length of the shaft, and the ribbon was then sent to its destination. The ribbon alone was useless to all but the recipient, who had a cylinder of the same diameter as the sender. The diameter of the cylinder determined the key. 2 Crypto Analysis Rules • The Arab civilization, with its advanced mathematics, was the first to establish specific rules to cryptanalyze written messages. These rules were the following: — The cryptanalyst must know the language in which the crypto message is written and its linguistic characteristics. — In every language, there are letters that are never found together in one word, letters that rarely come together in a word, and combinations of letters that are not possible. — All letters are not used equally in any language, and the proportions in which the letters occur remain constant. Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 3 M. Mogollon – 01/08 - 3 3 Classical Cipher Techniques • Too weak for serious applications; however, many of their basic principles are still used in modern cryptography. • Substitution Ciphers Plain Cipher abcdefghijklmnopqrstuvwxyz defghijklmnopqrstuvwxyzabc • Monoalphabetic Substitution Plain Cipher abcdefghijklmnopqrstuvwxyz hosbrgvkwcyfpjtazmxiqdluen — The number of possible substitutions is 26! or 4.0329 x 1026. — It is a very weak cipher; in any language there are some letters that occur more often than others. Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 4 M. Mogollon – 01/08 - 4 • Many of the techniques employed over the centuries to attempt to code information were not very sophisticated. By today's standards, most of these techniques are considered too weak for serious applications; however, many of their basic principles are still used in modern cryptography and, therefore, it is worthwhile to review them. 4 Polyalphabetic Substitution • Introduced by Blaise de Vigenere in the 16th century. • Uses one alphabet for each of the plain letters. • Has several key methods, such as words, phrases, and a running key in which the message itself is its own key —the so-called autokey. Key Plain Cipher DNOWISTHETIM NOWISTHETIME QBKEALALXBUQ Cipher Key Plain QBKEALALXBUQ DNOWISTHETIM NOWISTHETIME Classic Cryptography Rotor Crypto Machines The Vigenere Tableau (Plain Text) ABCDEFGHIJKLMNOPQRSTUVWXYZ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z a b c d e f g h i j k l m n o p q r s t u v w x y z b c d e f g h i j k l m n o p q r s t u v w x y z a c d e f g h i j k l m n o p q r s t u v w x y z a b d e f g h i j k l m n o p q r s t u v w x y z a b c e f g h i j k l m n o p q r s t u v w x y z a b c d OSI/TCP Stack f g h i j k l m n o p q r s t u v w x y z a b c d e g h i j k l m n o p q r s t u v w x y z a b c d e f h i j k l m n o p q r s t u v w x y z a b c d e f g i j k l m n o p q r s t u v w x y z a b c d e f g h j k l m n o p q r s t u v w x y z a b c d e f g h i k l m n o p q r s t u v w x y z a b c d e f g h i j l m n o p q r s t u v w x y z a b c d e f g h i j k m n o p q r s t u v w x y z a b c d e f g h i j k l Crypto Terminology n o p q r s t u v w x y z a b c d e f g h i j k l m o p q r s t u v w x y z a b c d e f g h i j k l m n p q r s t u v w x y z a b c d e f g h i j k l m n o q r s t u v w x y z a b c d e f g h i j k l m n o p r s t u v w x y z a b c d e f g h i j k l m n o p q s t u v w x y z a b c d e f g h i j k l m n o p q r t u v w x y z a b c d e f g h i j k l m n o p q r s u v w x y z a b c d e f g h i j k l m n o p q r s t v w x y z a b c d e f g h i j k l m n o p q r s t u w x y z a b c d e f g h i j k l m n o p q r s t u v x y z a b c d e f g h i j k l m n o p q r s t u v w y z a b c d e f g h i j k l m n o p q r s t u v w x z a b c d e f g h i j k l m n o p q r s t u v w x y Security Services & Mechanisms 5 M. Mogollon – 01/08 - 5 • In the 16th century, the Frenchman Blaise de Vigenere wrote the book, Traite des Chiffres, which described cryptology up to his day, and introduced a polyalphabetic substitution using one alphabet for each of the plain letters. Using Caesar’s basic idea, he formed a square, the Vigenere Table, consisting of 25 horizontal alphabets, one below the other, with each shifted to the right by one letter. A vertical alphabet was used to define the key and, at the top, an additional alphabet was used for the plaintext letters. • The Vigenere encryption could also be expressed as a modulo-26 addition of the letters of the key word, repeated as many times as necessary into the plaintext. 5 Transposition Ciphers • Successive letters of the plaintext are arranged according to the key. • The key is a group of sequential numbers arranged at random. • The plaintext is separated into groups of letters in which each group has the same number of letters as the number chosen as a key. Plaintext Key Ciphertext Classic Cryptography Rotor Crypto Machines nowis/theti/mefor/allxx/ 51342 snwio iteth rmfoe xalxl snwioitethrmfoexalxl OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 6 M. Mogollon – 01/08 - 6 6 Early Cipher Machines • The Saint Cyr Slide A ABCDEFGHIJKLMNOPQRSTUVWXYZ DEFGHIJKLMNOPQRSTUVWXYZABC GHIJHLMNOPQRSTUVWXYZ • 18th Century Wheel Cipher Picture from: http://www.nsa.gov/museum/wheel.html Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 7 M. Mogollon – 01/08 - 7 • The construction, compilation, and use of complete enciphered tables in the polyalphabetic cipher system were inconvenient. This problem disappeared with a device called the SaintCyr Slide, invented by Kerckhoffs and named after the French military academy With this device, the process of modulo-26 addition could be conducted conveniently. • In the 1790s, Thomas Jefferson developed a device for polyalphabetic substitution that consisted of thirty-six discs or cylinders with their peripheries divided into 26 equal parts (Khan, 1976, pp. 192-195). Each of the discs was numbered and carried in its peripheral an alphabet with the letters placed, not alphabetically, but randomly. The discs were mounted on a shaft, and the order was specified and agreed to between the correspondents. The discs' order constituted the key, and the number of possibilities was 36! or 3.72 x 1041. • The message was enciphered by rotating the discs until the message letters stood in the same row. The ciphertext was any of the other 26 positions around the cylinder in which the letters appeared jumbled and meaningless. To decipher the message, the correspondent set the discs in the same specified order and rotated them to present a row with the same ciphertext; the correspondent then moved the wheel cipher device around until a meaningful row of letters was found. 7 Early Cipher Machines • The Vernam Cipher was designed in 1917 by Gilbert Vernam • Is a bit-by-bit combination of random characters (keystream) with characters of plaintext using modulo-2 addition (the XOR function) 1+0=1 1+1=0 0+1=1 0+0=0 Enciphering Deciphering Plaintext 10011000101000110 Ciphertext 00101011001100101 Keystream 10110011100100011 ──────────────────── Keystream 10110011100100011 ──────────────────── Ciphertext 00101011001100101 Plaintext 10011000101000110 Key Stream Key Stream Plaintext + Ciphertext Encryption Algorithm Modulo 2 Adder Encipher Classic Cryptography Rotor Crypto Machines + Plaintext Decryption Algorithm Modulo 2 Adder Decipher OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 8 M. Mogollon – 01/08 - 8 • In 1917, Gilbert Vernam, an employee of AT&T, designed a security device for telegraphic communications that revolutionized modern cryptography: the bit-by-bit combination of random characters (keystream) with characters of plaintext using modulo-2 addition (the XOR function) —the stream cipher. Vernam's system, based upon the Baudot code, required punching a tape of random characters (chosen by picking numbers out of a hat) and electronically adding them to the plaintext characters. • A new tape, the ciphertext, was thus produced in a simple and reversible operation; all that was necessary to obtain the message was to subtract the ciphertext pulses from the keystream pulses. 8 The Rotor Crypto Machines • Rotor Crypto Machines implement polyalphabetic substitution ciphers with long periods. • These machines consist of several “t” rotary discs, each one with 26 electrical contacts called studs. • Each stud is connected at random by wire to another stud on the other side of the disc. • After each letter is enciphered, one or more of the rotors are rotated one step. • A machine with “t” rotors does not return to its starting position until after 26t successive steps. • A five-rotor machine has a period of 265 = 11,881,376 different alphabets before it repeats itself. A B C D E F Plaintext G H I A B Ciphertext C D E F G H I Encryption A B Ciphertext C D E F G H I A B C D E F Plaintext G H I Decryption Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 9 M. Mogollon – 01/08 - 9 • Rotor machines implemented polyalphabetic substitution ciphers with long periods. The body of the machine consisted of several t rotary discs made of insulated material, normally two to four inches in diameter, and half an inch thick. On each side of each disc were 26 electrical contacts in the form of metal studs. Each stud on one side of the disc was connected by wire to another stud on the other side of the disc. The wire did not go directly from one stud to the immediate opposite stud, but to a stud at random. For example, the stud from the letter G was connected internally not to G, but to another letter. • If the discs were immovable, an alphabet could be changed only to another alphabet. However, if after each letter were enciphered, one or more of the rotors were rotated one step, a new alphabet would be created to encipher each letter with a different ciphertext alphabet. A machine with t rotors would not return to its starting position until after 26t successive steps; a three-rotor machine would go through 263 = 17,576 different alphabets before repeating itself; a five-rotor machine has a period of 265 = 11,881,376 different alphabets before repeating itself. • After World War I, four men, all from different countries, independently created a crypto machine based on the wired code wheel, the rotor. The inventor of the first rotor machine in the United States was Edward Hugh Herbert who, in the 1920’s, founded the Herbert Electric Code, the first cipher machine company in the U.S. By 1923, the firm had defaulted after selling only 12 machines. 9 The M 209 The Enigma • Used by the U.S. Army until the early 1950s. • Polyalphabetic ciphertext with a period of 26 x 25 x 23 x 21 x 19 x 17 = 101,405,850, nearly ten times greater than a fiverotor machine. Picture from http://www.nsa.gov/museum/enigma.html Picture from http://www.maritime.org/csp1500.htm Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 10 M. Mogollon – 01/08 - 10 • The M-209 has six rotors, but not all the rotors have the complete alphabet. The following sequences of letters are engraved around the rotors’ circumference: • Rotor I or ABCDEFGHIJKLMNOPQRSTUVWXYZ "26 wheel": • Rotor II or ABCDEFGHIJKLMNOPQRSTUVXYZ "25 wheel": • Rotor III or ABCDEFGHIJKLMNOPQRSTUVX "23 wheel": • Rotor IV or ABCDEFGHIJKLMNOPQRSTU "21 wheel": • Rotor V or ABCDEFGHIJKLMNOPQRS "19 wheel": • Rotor VI ABCDEFGHIJKLMNOPQ "17 wheel": or • The six M-209 rotors produce the following individual periods: 26 25, 23, 21, 19 and 17. Therefore, the ciphertext that the M-209 produces is polyalphabetic with a period of 26 x 25 x 23 x 21 x 19 x 17 = 101,405,850, nearly ten times greater than a five-rotor machine. 10 OSI and TCP/IP Stacks Layer 7 Application Layer 6 Presentation Layer 5 Session Layer 4 Transport Transport Layer TCP Layer 3 Network Network Layer IP Layer 2 Data Link Layer 1 Physical Application Layer Classic Cryptography Rotor Crypto Machines UDP ARP RARP Ethernet, Token-Ring, FDDI, X.25, Wireless, Async, ATM, SNA...Data Layer Data Layer OSI Stack SMTP, Telnet, FTP, Gopher TCP/IP Stack OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 11 M. Mogollon – 01/08 - 11 • As an international organization dedicated to the writing and dissemination of technical standards for industry and trade, the International Standards Organization (ISO) has formulated a network structure for Open System Interconnection (OSI): the ISO IEC 74983: 1997 — Basic Reference Model. • The OSI divides communications into seven layers, each providing a specific set of services from a lower level, or physical layer, up to the top, or application layer. This division of the communication services allows for interoperability and flexibility. By defining standards for each layer, OSI attempts to ensure that a vendor providing a protocol at a certain layer can interoperate with a different vendor providing the same protocol at that layer. • The following are the seven layers in which the OSI model is divided: 1. Physical Layer 2. Data Link Layer 3. Network Layer 4. Transport Layer 5. Session Layer 6. Presentation Layer 7. Application Layer • The OSI was developed in the mid 80’s, but the basics for the ARPANET Model (used by the Department of Defense and in today’s IP networks) were already developed and implemented by that time. That is why the Transmission Control Protocol/Internet Protocol has it is own model. 11 TCP/IP • • • TCP/IP — Transmission Control Protocol/Internet Protocol. • TCP/IP has two parts, TCP and IP. TCP/IP is the protocol suite used by the Internet. TCP/IP is based on a connectionless networking. Eliminates the need for the network to support signaling and maintain connections (and thus state information). All aspects of a reliable connection are moved to Layer 4 and supported in the endpoints. — TCP perform the functions of the transport layer in the OSI model (e.g., breaking the data into smaller packets, numbering them, ensuring each packet is reliably delivered and putting them in the proper order). — IP performs the role of the network layer in the OSI model (e.g., routing and addressing). • Some of the protocols used in the TCP/IP suite are: — — — — Data Layer: Frame Relay, ATM, IEEE 802.3, PPP PPP EAP (among others) Network Layer: IP Transport Layer: User Data Protocol (UDP), Transmission Control Protocol (TCP) Applications Layer Applications: HTTP, FTP, SMTP, SNMP Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 12 M. Mogollon – 01/08 - 12 • TCP/IP, Transmission Control Protocol/Internet Protocol, is the protocol suite on which the Internet and most commercial networks run. • TCP/IP, like most networking software, is modeled in layers, but these layers are not functionally the same as the layers in the Systems Network Architecture (SNA) or in the Open System Interconnection (OSI) model. • TCP/IP, also called the Internet Protocol, consist of two parts, TCP and IP. TCP perform the functions of the transport layer in the OSI model (e.g., breaking the data into smaller packets, numbering them, ensuring each packet is reliably delivered and putting them in the proper order). IP performs the role of the network layer in the OSI model (e.g., routing and addressing). • The TCP/IP protocol stack consists of four layers: Applications Layer, Transport Layer, Network Layer, and Data Layer. 12 TCP/IP Protocol Stack Data Application Layer Transport Layer TH NH DH Payload Application Layer Transport Layer Network Layer Payload Data Layer NH DH Payload Data TH Network Layer Data Layer NH DH Payload Payload Router • Application Layer: Provides services for a user to send and received data over the network, such as web browsers (HTTP), FTP, SMTP, SNMP, and emails. • • • Transport Layer: Provides connection, error and flow control (TCP or UDP), and security. Network Layer: Responsible for addressing (IP) and routing the packets. Data Link Layer: Defines the electrical, mechanical, and physical interfaces to the network. It frames the packets for transmission over the physical media, such as Ethernet, Token Ring, Frame Relay, Asynchronous Transfer Mode (ATM). Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 13 M. Mogollon – 01/08 - 13 • The TCP/IP protocol stack consists of 4 layers. The highest layer in the stack is the Application Layer. Applications run at this layer. Applications communicate with each other over the network by using the data communication services of the Transport Layer. Applications access the Transport Layer via uniquely assigned ports and communicate with each other via different transport protocols depending on their needs. These protocols are the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP). TCP provides reliable connections via error correction, flow control, in-sequence delivery of data, and retransmission of lost data; it is called the reliable protocol. UDP implements connectionless sessions via “best effort” delivery mechanisms. UDP is called the unreliable protocol. • The Transport Layer needs to determine the routes between endpoints, so the Network Layer provides the network routing services or IP addresses. The protocol used to provide these services over the Internet is the Internet Protocol. • Once the network route has been specified and the network headers added, the Network Layer relies on the Data Link interface to provide the device drivers to interface the data to the hardware components, such as Ethernet, Frame Relay, ATM, etc. Some of the protocols used in the TCP/IP suite are: • Data Layer: Any physical layer, at any rate. PPP, Frame Relay, ATM, IEEE 802.3 (among others) • Network Layer: IP • Transport Layer: User Data Protocol (UDP), Transmission Control Protocol (TCP) • Applications Layer: Applications: HTTP, FTP, SMTP, SNMP. 13 TCP/IP Stack and Security Related Protocols Application Layer Transport Layer Network Layer SMTP, Telnet, FTP, Gopher TCP IP • SOCKS V5 • SSL, TLS UDP ARP • S/MIME • S-HTTP • PGP • SET • IPSec (ISAKMP) RARP • IPSec (AH, ESP) • Packet filtering • Tunneling Protocols Ethernet, Token-Ring, FDDI, X.25, Wireless, Async, ATM, SNA...Data Layer PPP-EAP, IEEE 802.1X, CHAP, PAP, MS-CHAP The Data Layer is also called Network Interface Layer, Link Layer, or Data-Link Layer. Data Layer Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 14 M. Mogollon – 01/08 - 14 • This slide shows the security protocols that we will discuss in this course and the stack layer were they are implemented. • Secure mail, S/MIME and PGP, IPSec, and S-HTTP are implemented in the Application Layer. • TLS / SSL in the transport layer. • IPsec (AH and ESP) and tunneling protocols in the network layer. • Password and authentication protocols are implemented in the data layer. 14 NSA Terminology COMSEC / (1960s) Communications security which provided protection against disclosure to unauthorized parties when information was transmitted or broadcasted from point-to-point. COMPUSEC / (Late 1970s) Computer security which provided protection against unauthorized disclosure of information, injection of malicious code, or the theft of data on magnetic media. INFOSEC / (Early 1980s) Information security which was the result of the convergence of COMSEC and COMPUSEC. IA / (Late 1990s) Information Assurance which deals with providing protection against unauthorized disclosure of information (confidentiality), modification of information (integrity), denial of service (availability), authenticity, and non-repudiation. Definitions taken from Daniel G. Wolf, NSA Director of Information Assurance statement before the House Select Committee of Homeland Security on July 22, 2003, pages 4 and 5. Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 15 M. Mogollon – 01/08 - 15 • The National Security Agency has been using several words to describe the type of information the it is protected. • In the 1960s, COMSEC, Communications Security, was used to indicate protection against disclosure to unauthorized parties when information was transmitted or broadcasted from point-to-point. • In the late 1970s, COMPUSEC, Computer security, was used to indicate protection against unauthorized disclosure of information, injection of malicious code, or the theft of data on magnetic media. • In the early 1980s, Information Security was used as the result of the convergence of COMSEC and COMPUSEC. • Starting the late 1990s, IA, Information Assurance, has been used to indicate protection against unauthorized disclosure of information (confidentiality), modification of information (integrity), denial of service (availability), authenticity, and non-repudiation. • Definitions taken from Daniel G. Wolf, NSA Director of Information Assurance statement to House committee of Homeland security on July 22, 2003, pages 4 and 5. • http://www.nsa.gov/isso/Wolf_SFR_22July2003_final.pdf 15 What is Cryptography? • cryptography / The art or science that treats of the principles, means, and methods to render information unintelligible to all but the intended receiver. The sender enciphers a message into an unintelligible form, and the receiver deciphers it into intelligible form. The word "cryptology" is derived from the Greek “kryptos” (hidden) and “logos” (word). Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 16 M. Mogollon – 01/08 - 16 16 What is Cryptology? • cryptology / The scientific study of cryptography and cryptanalysis. • cryptanalysis / The process of deducting the plaintext from the ciphertext (breaking a code) without being in possession of the key or the system (code breaking). Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 17 M. Mogollon – 01/08 - 17 17 Crypto Terminology Cryptographic Variables (CV), Secret Keys, Private Keys Key Generator Synchronization Key Stream Key Stream Message Plaintext As the market requirements for secure products has exponentially increased, our strategy will be to …. Encryption Algorithm Encipher Key Generator Cryptographic Variables (CV), Secret Keys, Public Keys Ciphertext Asdfe8i4*(74mjsd( 9&*nng654mKhna mshy75*72mnasja dif3%j*j^3cdf(#421 5kndh_!8g,kla/”2a cd:{qien*38mnap4 *h&fk>0820&ma01 2M Encryption Algorithm Decipher Plaintext Message As the market requirements for secure products has exponentially increased, our strategy will be to …. Security is based on the crypto variable, not on the encryption algorithm. Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 18 M. Mogollon – 01/08 - 18 • Any field has its own language, and cryptography is not an exception. The following are some of the common terms used in cryptography. • Plaintext: Information that will be put into secret form, or the original intelligible information that emerges from deciphering a ciphertext. • Encipher: A method of transforming information in order to conceal its meaning. The information to be protected is broken down to the smallest possible element (usually a bit or a block of bits) and each element is enciphered independently. • Ciphertext: Plaintext that has been enciphered. • Decipher: The process translating the ciphertext back to intelligible information (it can be read). • Cleartext: Information that has not been enciphered for transmission. It is transmitted in clear. • Cryptographic Variables: Also called crypto keys or keys. Any of the randomly generated variables that the user can change frequently to control the operation of the cipher algorithm to encipher or decipher information. The crypto variables are loaded into the keystream generator to change its output. • Keystream Generator: Device that produces keystream. Also called key generator. • Keystream: Pseudorandom stream of bits used by the ciphering algorithm to combine with the plaintext to form the ciphertext. Also called running key. • Encryption Algorithm: Set of rules implemented in software or hardware and used in conjunction with the cryptographic variables to encipher plaintext and decipher ciphertext. 18 Crypto Terminology Cryptographic Variables (CV), Secret Keys, Private Keys Message Plaintext As the market requirements for secure products has exponentially increased, our strategy will be to …. Classic Cryptography Cryptographic Variables (CV), Secret Keys, Public Keys Synchronization Encryption Algorithm (Block Cipher) Encipher Rotor Crypto Machines Ciphertext Asdfe8i4*(74mjsd( 9&*nng654mKhna mshy75*72mnasja dif3%j*j^3cdf(#421 5kndh_!8g,kla/”2a cd:{qien*38mnap4 *h&fk>0820&ma01 2M OSI/TCP Stack Encryption Algorithm (Block Cipher) Decipher Crypto Terminology Plaintext Message As the market requirements for secure products has exponentially increased, our strategy will be to …. Security Services & Mechanisms 19 M. Mogollon – 01/08 - 19 • When a block cipher is used, the inputs are the crypto variables or keys and the plaintext and the output is the cipher text. Note for any encryption algorithm, the keys should be the same for enciphering and deciphering processes. 19 Security Services Security Mechanisms Confidentiality Encryption Integrity Hash Functions Authentication Digital Signatures Access Security Tokens Non-Repudiation Digital Signatures Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 20 M. Mogollon – 01/08 - 20 • Security Policies is a document or set of documents that states an organization’s intentions and decisions on what and how electronic information should be secured. A security policy is implemented using security mechanisms to provide security services. • The RFC 4949, “Internet Security Glossary” (Shirey, 2007), provides the following definitions for security policy, security services, and security mechanisms: • Security Policy: (1) A set of rules and practices that specify or regulate how a system or organization provides security services to protect sensitive and critical system resources. (2) The set of rules laid down by the security authority governing the use and provision of security services and facilities. • Security Services: A processing or communication service that is provided by a system to give a specific kind of protection to system resources. • Security Mechanisms: A process (or a device incorporating such a process) that can be used in a system to implement a security service that is provided by or within the system. • The standards ISO 7498-2 (1989), Reference Model for Security Architecture and ITU-T X800, Security Architecture for Open System Interconnection, define the general securityrelated architectural elements that can be applied appropriately when communications between open systems needs to be protected. Both standards divide security services into five categories: authentication, access control, confidentiality, integrity, and non-repudiation. • This slide shows a one-to-one link between security services and a specific security mechanism. In some cases more than one security mechanism can be used to achieve a security service. Some organizations do not require all five security services in IA, and the security policy of such an organization should specify which security services are required. 20 Typical Protections - Need Many Tools Used in Concert • Physical Security — — — • Information Assurance — — — — • Management tools (sniffers, scanners, profilers, honey pots, shunts, program registers, etc.) Database security Disaster Recovery Planning — — • • Access controls authentication (firewalls, passwords, biometrics, etc.) Virus protection tools Operation system protection (Windows, Unix, Linux) Network Security — — • Confidentiality (symmetric and asymmetric encryption) Integrity (hash functions) Authentication (digital certificates, tokens, digital signatures, passwords, biometrics, etc.) Non-Repudiation (public key encryption, digital signatures, System Security — — — • Physical access (guards, fences, alarms, locks,, etc.) Environment risk security (power Filtering and UPS devices surge protectors Fire and flooding protection Contingency plans Security policies. EMI/RFI Shielding Training and Education Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 21 M. Mogollon – 01/08 - 21 • Information Assurance is only one aspect of the overall security. Other aspects of the security are physical security, system security, network security, disaster recovery planning, EMI/RFI shielding, and training and education. 21 Security Services • Confidentiality — Protection against unauthorized individuals reading information that is supposed to be kept private. • Data Integrity — Assurance that a message was not accidentally or deliberately modified in transit by replacement, insertion, or deletion. • Authentication — Assurance that the message is coming from the source from which it claims to come. • Non-Repudiation of Origin — Protection against an individual denying sending or receiving a message. • Access Control — The prevention of the unauthorized use of a resource by identifying or verifying the eligibility of a station, originator or individual to access specific categories of information. A security policy is implemented using security mechanisms to provide provide security services. Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 22 M. Mogollon – 01/08 - 22 • The following are the security services that we will discuss in this course: • Confidentiality: Protection against unauthorized individuals reading information that is supposed to be kept private. • Data Integrity: Assurance that a message was not accidentally or deliberately modified in transit by replacement, insertion, or deletion. • Authentication: Assurance that the message is coming from the source from which it claims to come. • Non-Repudiation of Origin: Protection against an individual denying sending or receiving a message. • Access Control: The prevention of the unauthorized use of a resource by identifying or verifying the eligibility of a station, originator or individual to access specific categories of information. 22 IA Security Policy When is the Electronic Information Collected, Used, Processed, Transmitted, or Stored, provide Security Mechanisms Confidentiality, Integrity, Availability, Authenticity, Non-repudiation. Security Mechanisms must be: Comprehensive, Coordinated, Scaleable, & Technology Agnostic Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 23 M. Mogollon – 01/08 - 23 • IT personnel in charge of security should remember that when electronic information is collected, used, processed, transmitted, or stored, they should used security mechanisms that provides confidentiality, integrity, availability, authenticity, and non-repudiation. 23 Confidentiality and its Security Mechanisms Confidentiality Protection of data from unauthorized disclosure Encryption Algorithms Symmetric Asymmetric Stream Ciphers Block Cipher Public-Key DES MARS RC5 CAST Pohlig Hellman Blowfish IDEA OFB SelfSynchronous AES 3DES Synchronous RSA CFB ElGamal Schnorr ECC RC4 Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 24 M. Mogollon – 01/08 - 24 • Confidentiality is the assurance that information is not made available or disclosed to unauthorized individuals, entities, or processes. The confidentiality services are the following: 1. Connection confidentiality, which provides protection to all users in all connections. 2. Connectionless confidentiality, which provides protection to all users in a single connectionless sessions. 3. Selective field confidentiality, which provides protection to selected fields for n users on m connections or a single connectionless session. 4. Traffic-flow confidentiality, which provides protection for information against wire tappers monitoring the traffic flow through passive wiretapping or eavesdropping. • In this course, the term confidentiality is used to refer to traffic-flow confidentiality. 24 Integrity and its Security Mechanisms Assurance that a message was not accidentally or deliberately modified in transit by replacement, insertion, or deletion. Integrity Hash Functions SHA MD5 Digital Signature MAC Encryption HMAC SHA-1 SHA-384 DES CBC HMAC-SHA-1-96 SHA-256 SHA-512 AES-XCBCMAC-96 HMAC-MD5-96 Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 25 M. Mogollon – 01/08 - 25 • Integrity is the assurance that data is not accidentally or deliberately modified in transit by replacement, insertion, or deletion 25 Authentication and its Security Mechanisms Authentication Digital Signatures MD5 ElGamal RSA Assurance that the message is coming from the source from which it claims to be. Digital Signatures provide authentication, nonrepudiation, and integrity. DSA RSA Hash Functions SHA SHA DSA ECDSA A Digital Signature is created by taking the message’s hash and encrypting it with the sender’s private key. Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 26 M. Mogollon – 01/08 - 26 • Authentication is the assurance that a message is coming from the source from which it claims to come. Authentication is an automatic feature of encryption; if nobody else has the encrypting key, the ability to communicate with a peer implies possession of the key and, therefore, proper authentication. • Authentication services include the following: • Peer Entity Authentication is the corroboration (proof) of the sender's identity and authenticity —that the sender is who he claims to be. The service is provided for use when the connection is established, or during the data transfer phase, to confirm the identities of the entities connected. • Data Origin Authentication is the corroboration of the original content of the data (data integrity) and that the source of data received is as claimed (authenticity). The data origin authentication service also provides the sender with proof of delivery of data to the receiver. This is also called a non-repudiation service. Digital signatures can be used for non-repudiation purposes. 26 Access Authentication Access Authentication Protocol The prevention of the unauthorized use of a resource. EAP Method IEEE 802.1X Mechanism EAP-TLS EAP-SIM CHAP OTP EAP-TTLS EAP-AKA GTC MS-CHAP v2 EAP-PEAP EAP-PSK Digital Certificates IEEE 802.1X: Port-based Access Control Protocol PEAP: Protected EAP EAP: Extensible Authentication Protocol TLS: Transport Layer Security CHAP: Challenge-Handshake Authentication Protocol OTP: One-Time Password TTLS: Tunneled Transport Layer Security GTC: Generic Token Card Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 27 M. Mogollon – 01/08 - 27 • Access control provides protection against the unauthorized use of resources. It includes the prevention of the use of a resource in an unauthorized manner by identifying or verifying the eligibility of a station, originator, or individual to access specific categories of information 27 Non-Repudiation and its Security Mechanisms NonRepudiation Public-Key Schnorr ElGamal Protection against an individual denying sending a message. Digital Signature RSA Encryption ECC Sender enciphers the message with his private key and recipient deciphers the message with sender’s public key. Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 28 M. Mogollon – 01/08 - 28 • Repudiation means denial by one of the entities involved in a communication of having participated in all or part of the communication. Non-repudiation refers to protection against an individual denying sending or receiving a message. The non-repudiation service may take one or two forms: 1. Non-Repudiation with proof of origin – The recipient of the data is provided with a proof of the origin of data. This proof will protect the recipient against any attempt by the sender to falsely deny sending the data or its original content. The sender cannot deny that he sent the message, nor can he deny its original content. 2. Non-repudiation with proof of delivery – The sender of data is provided with proof of delivery of data. This proof will protect the sender against any subsequent attempt by the recipient to falsely deny receiving the data or its original content. 28 Example: Ecommerce – SSL Application Intranet or DMZ • Firewall • SSL Accelerator Web Servers Internet Buyer • • • • Seller Authenticates seller. Enciphers information. Clientless Access from any computer Classic Cryptography Rotor Crypto Machines SSL Accelerator • SSL traffic is encrypted • Offloads expensive public key operation from backend servers • Normally, 250,000 transactions/sec OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 29 M. Mogollon – 01/08 - 29 • Secure Sockets Layer (SSL) protocol, built into most browsers and Web servers, is used to protect communications to and from Web applications. Unfortunately, SSL processing is very compute-intensive and significantly reduces server performance. This results in increased cost and operational complexity when it comes time to scale secure transaction processing. SSL Accelerators offload SSL processing from local servers without imposing delays on other traffic in the same data path, and offer a simpler way to deploy and maintain the Public Key Infrastructure (PKI) required for electronic transactions. 29 Example: Remote Access Application – VPNs VoIP VPN Gateway Home office Authentication Server Internet Intranet Firewall • Firewall • VPN Gateway • Classic Cryptography • Creates tunnel for VPN connection • Remote End Authenticates remote access user. Enciphers communications using IPSec. Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 30 M. Mogollon – 01/08 - 30 • Encryption can be achieved with VPN techniques using IPSec, with Authentication Header (AH) and Encapsulating Security Payload (ESP), tunneling through the use of Layer 2 Tunneling Protocol (L2TP), key management based on Internet Key Exchange (IKE), and certificate management based on Public Key Infrastructure X.509 (PKIX), Certificate Management Protocol (CMP), Online Certificate Status Protocol (OCSP), and Simple Certificate Validation Protocol (SCVP). SSL and Transport Layer Security (TLS) protect communications at the application layer. • Standards-based encryption algorithms such as DES, 3DES, AES are used for encryption; RSA and DSA for digital signature; MD5 and SHA hash functions are used for message integrity, and Diffie-Hellman and RSA for key exchange. 30 Example: Remote Wireless Access Application – VPNs VoIP Authentication Server VPN Gateway Internet Home office Intranet Firewall Remote End Wireless Point Security Wireless Security Switch WifiVoIP Classic Cryptography • Firewall • VPN Gateway Rotor Crypto Machines • • • • Authenticate wireless remote access user. Create tunnel for VPN connection Encipher communications using IPSec. Access to all applications through client desktop software. OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 31 M. Mogollon – 01/08 - 31 • WLANs (WiFi) are normally privately owned networks that companies or individuals set up for the use of their employees or their own use. • Wireless security was implemented using the optional wired equivalent privacy (WEP), and later on by using Wi-Fi protected access (WPA). WPA2 includes all elements of the WPA standard but uses the government Advanced Encryption Standard (AES) encryption algorithm. 31 Remote Wireless/Wireline Access Application – SSL VPNs VoIP Authentication Server Home office Internet Intranet Router • Firewall • SSL VPN Router Remote End Wireless Point Security • • • • Classic Cryptography Authenticate wireless/wireline remote access user. Secure communications using SSL IPSec. Access to selected applications through a web portal. Erase any connection information in the access point after log-out. Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 32 M. Mogollon – 01/08 - 32 • This is an example of access authentication. Any of the devices on the left side of the diagram needs to be authenticated by the authentication server in the right side to be able to have access to the servers and services offered by the network. • Note that the network is using the Internet as its wide area network, WAN. 32 Authentication Authentication Server Radius, Kerberos, PKI, OTP, Token EAP over Internet EAP Method Password Authentication Database Authenticator Token Authentication Database X.509 Directory Kerberos Ticket Granting Server Supplicants Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 33 M. Mogollon – 01/08 - 33 • Authentication is initiated by an authentication client (supplicant) in a PC or gateway device and positively verifies the identity of a user as a prerequisite to allowing access. • Authorization determines which system resources are the authenticated user allowed to access. 33 Placeholder Names Used in Cryptography Alice Participant in all protocols Bob Participant in two-, three-, and four-party protocols. Carol Participant in three- and four-party protocols Dave Participant in four-party protocols Eve Passive eavesdropper. While she can listen in on messages between Alice and Bob, she cannot modify them. Mallet Malicious active attacker. Mallet, also called Mallory, can modify messages, substitute his own messages, replay old messages, and so on. The problem of securing a system against Mallory is much greater than against Eve. Peggy Prover Victor Verifier . Victor, a verifier, and Peggy, a prover, must interact in some way to show that the intended transaction between Alice and Bob has actually taken place. Trent Trusted arbitrator Trudy Intruder. Trudy can modify messages in transit, therefore, she is more dangerous than Eve. Bob and Alice ideally should use some integrity protocols to be able to detect any such modification and either ignore the changed message, or retrieve the correct message despite the intrusion. Walter Warden. He guards Alice and Bob in some protocols. Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 34 M. Mogollon – 01/08 - 34 • In the past, when describing an encryption protocol, writers would often say something like this: A sends an encrypted message to B, which has been signed with A’s private key and encrypted with B’s public key. Because the use of letters alone can be confusing, Ron Rivest used the names “Alice” and “Bob” when he presented his RSA cryptosystem article at the 1978 Communications of the ACM conference. He reasoned that using names instead of the letters A and B would make a complex subject easier to explain. • Bruce Schneider (1996) added some other names to indicate the role of other parts in a protocol. The roles of the different names used as placeholders are described in a table that he called dramatis personae” –the characters in a play. • In cryptography and computer security, these placeholders are names widely used by writers in discussions about various security protocols. It is understood that in the protocol implementations where these placeholders are used, they do not refer to human parties, but rather to automated agents such as computer programs. 34 IETF, RFCs, FIPS • The Internet Engineering Task Force (IETF) is a group of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet. http://www.ietf.org/ • The Request for Comments (RFC) consist of the IETF working documents of approved standards and protocols for the Internet. This web site is the RFC repository and it lists all the RFCs. http://www.ietf.org/rfc.html • The Computer Security Resource Center of the National Institute of Standards and Technology, develops standards and metrics to test and validate computer security. http://csrc.nist.gov/ • Federal Information Processing Standards Publications (FIPS PUBS) home web page. http://www.itl.nist.gov/fipspubs/ • Federal Information Processing Standards Publications (FIPS PUBS) web page associated with Computer Security. http://csrc.nist.gov/publications/fips/ • Internet Security Glosary, RFC 4949 http://www.ietf.org/rfc/rfc4949.txt?number=4949 Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 35 M. Mogollon – 01/08 - 35 35 References Classic Cryptography • Bamford, J. (1982). The Puzzle Palace, A Report on NSA America's Most Secret Agency (p 35). Boston: Houghton, Mifflin Co. • • Lexicon Universal Encyclopedia, Volume 5. (1987) (p 371). New York: Lexicon Publications Inc. • Way, P (1977). The Encyclopedia of Espionage, Codes and Ciphers (pp 62 - 92). London: The Danbury Press, Published by Aldus Book. Khan, D. (1967). The Codebreakers (pp. 394 - 398, 411 - 426). New York: Macmillan Publishing Co., Inc. Information Assurance • Abbruscato, C.R. Data Encryption Equipment, IEEE Communications Magazine, Volumen 22, No. 9 (September 1984) • • • International Standards Organization (ISO), ISO 7498-2-1988 (E) Security Architecture. • • • Tanenbaum, A. (1981). Computer Networks.., Englewood Cliffs, New Jersey : Prentice-Hall, Inc. Muftic, S. (1989). Security Mechanisms for Computer Networks. New York: John Wiley & Sons. National Bureau of Standard, Federal Information Processing Standards (FIPS), Publication 113, Computer Data Authentication. Tanenbaum, A. (1981) Networks Protocols. Computing Surveys, Vol. 13, No. 4. Wolf, D (2003). Cybersecurity Getting it Right. Statement by the Director of Information Assurance National Security Agency Before The House Select Committee on Homeland Security Subcommittee on Cybersecurity, Science and Research & Development hearing on July 22, 2003 to the House of Representatives Select Committee on Homeland Security. Classic Cryptography Rotor Crypto Machines OSI/TCP Stack Crypto Terminology Security Services & Mechanisms 36 M. Mogollon – 01/08 - 36 36 ...
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This note was uploaded on 05/26/2010 for the course TECH 6350 taught by Professor Mogollon during the Spring '10 term at University of Arkansas for Medical Sciences.

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