Diese Präsentation wurde erfolgreich gemeldet.
Wir verwenden Ihre LinkedIn Profilangaben und Informationen zu Ihren Aktivitäten, um Anzeigen zu personalisieren und Ihnen relevantere Inhalte anzuzeigen. Sie können Ihre Anzeigeneinstellungen jederzeit ändern.

Security technologies

Information Technology & Management Program

Ähnliche Bücher

Kostenlos mit einer 30-tägigen Testversion von Scribd

Alle anzeigen
  • Als Erste(r) kommentieren

Security technologies

  1. 1. TransformingLives. InventingtheFuture. www.iit.edu I ELLINOIS T UINS TI T OF TECHNOLOGY ITM 578 1 Security Technologies Ray Trygstad ITM 478/578 Spring 2004 Master of Information Technology & Management Program CenterforProfessional Development Slides based on Whitman, M. and Mattord, H., Principles of InformationSecurity; Thomson Course Technology 2003
  2. 2. ITM 578 2 ILLINOIS INSTITUTE OF TECHNOLOGY Learning Objectives: Upon completion of this lesson the student should be able to: – Define and identify the various types of firewalls. – Discuss the approaches to firewall implementation. – Discuss the approaches to dial-up access and protection. – Identify and describe the two categories of intrusion detection systems. – Discuss the two strategies behind intrusion detection systems.
  3. 3. ITM 578 3 ILLINOIS INSTITUTE OF TECHNOLOGY Learning Objectives: Upon completion of this lesson the student should be able to: – Discuss scanning, analysis tools, and content filters. – Understand trap and trace technologies. – Discuss the process of encryption and define key terms. – Identify and discuss common approaches to cryptography. – Compare and contrast symmetric and asymmetric encryption. – Discuss various approaches to biometric access control.
  4. 4. ITM 578 4 ILLINOIS INSTITUTE OF TECHNOLOGY Introduction  Information security: a discipline relying on the synthesis of people, policy, education, training, awareness, procedures, and technology to improve protection of an organization’s information assets  Technical solutions can maintain – Confidentiality, Integrity & Availability of information – In each of its three states • Storage • Transmission • processing
  5. 5. ITM 578 5 ILLINOIS INSTITUTE OF TECHNOLOGY Physical Design of the SecSDLC The physical design phase of the SecSDLC is made up of two parts: – security technologies – physical security Physical design takes the logical design, expressed by the information security blueprint and the contingency planning elements and extends the design to the next level
  6. 6. ITM 578 6 ILLINOIS INSTITUTE OF TECHNOLOGY Physical Design of the SecSDLC Analyze Physical Design: Security Technologies Chapter 8 Physical Design: Physical Security Chapter 9 Logical Design Implement Maintain FIG URE 8-1 Physical Design within the SecSDLCPhysical Design within the SecSDLC
  7. 7. ITM 578 7 ILLINOIS INSTITUTE OF TECHNOLOGY Physical Design of the SecSDLC  The physical design phase encompasses the selection of technologies and processes to manage risk  At the end of the physical design phase you have: – Selected technologies needed to support the information security blueprint – Defined what the successful solution for a secured environment will encompass – Designed physical security measures that support the technical solutions – Prepared to create project plans in the implementation phase to follow
  8. 8. ITM 578 8 ILLINOIS INSTITUTE OF TECHNOLOGY Firewalls  A firewall is any device that prevents a specific type of information from moving between the untrusted network outside and the trusted network inside  There are five recognized generations of firewalls  The firewall may be: – a separate computer system – a service running on an existing router or server – a separate network containing a number of supporting devices
  9. 9. ITM 578 9 ILLINOIS INSTITUTE OF TECHNOLOGY First Generation  Called packet filtering firewalls  Examines every incoming packet header and selectively filters packets based on – address, packet type, port request, and others factors  The restrictions most commonly implemented are based on: – IP source and destination address – Direction (inbound or outbound) – TCP or UDP source and destination port-requests
  10. 10. ITM 578 10 ILLINOIS INSTITUTE OF TECHNOLOGY Packet Filtering Firewall Packet filtering router used as a first generation firewall Trusted network Untrusted Network FilteredFiltered Data PacketsData Packets UnrestrictedUnrestricted Data PacketsData Packets BlockedBlocked Data PacketsData Packets FIGURE 8-2 Packet Filtering Firewall
  11. 11. ITM 578 11 ILLINOIS INSTITUTE OF TECHNOLOGY Second Generation  Called application-level firewall or proxy server  Often a dedicated computer separate from the filtering router  With this configuration the proxy server, rather than the Web server, is exposed to the outside world in the DMZ  Additional filtering routers can be implemented behind the proxy server  The primary disadvantage of application-level firewalls is that they are designed for a specific protocol and cannot easily be reconfigured to protect against attacks on protocols for which they are not designed
  12. 12. ITM 578 12 ILLINOIS INSTITUTE OF TECHNOLOGY Third Generation  Called stateful inspection firewalls  Keeps track of each network connection established between internal and external systems using a state table which tracks the state and context of each packet in the conversation by recording which station sent what packet and when  If the stateful firewall receives an incoming packet that it cannot match in its state table, then it defaults to its ACL to determine whether to allow the packet to pass
  13. 13. ITM 578 13 ILLINOIS INSTITUTE OF TECHNOLOGY Third Generation  The primary disadvantage is the additional processing requirements of managing and verifying packets against the state table which can possibly expose the system to a DoS attack  These firewalls can track connectionless packet traffic such as UDP and remote procedure calls (RPC) traffic
  14. 14. ITM 578 14 ILLINOIS INSTITUTE OF TECHNOLOGY Fourth Generation  A dynamic packet filtering firewall allows only a particular packet with a particular source, destination, and port address to enter through the firewall  Does this by understanding how the protocol functions, and opening and closing “doors” in the firewall, based on the information contained in the packet header  In this manner, dynamic packet filters are an intermediate form, between traditional static packet filters and application proxies
  15. 15. ITM 578 15 ILLINOIS INSTITUTE OF TECHNOLOGY Fifth Generation The final form of firewall is the kernel proxy, a specialized form that works under the Windows NT Executive, which is the kernel of Windows NT It evaluates packets at multiple layers of the protocol stack, by checking security in the kernel as data is passed up and down the stack
  16. 16. ITM 578 16 ILLINOIS INSTITUTE OF TECHNOLOGY Packet-filtering Routers Most organizations with an Internet connection have some form of a router as the interface at the perimeter between the organization’s internal networks and the external service provider Many of these routers can be configured to filter packets that the organization does not allow into the network
  17. 17. ITM 578 17 ILLINOIS INSTITUTE OF TECHNOLOGY Packet-filtering Routers This is a simple but effective means to lower the organization’s risk to external attack The drawback to this type of system includes a lack of auditing and strong authentication The complexity of the access control lists used to filter the packets can grow and degrade network performance
  18. 18. ITM 578 18 ILLINOIS INSTITUTE OF TECHNOLOGY Screened-Host Firewall Systems  Combine the packet-filtering router with a separate, dedicated firewall such as an application proxy server  Allows the router to pre-screen packets to minimize the network traffic and load on the internal proxy  Application proxy examines an application layer protocol, such as HTTP, and performs the proxy services  This separate host often referred to as a bastion- host, as it represents a single, rich target for external attacks, and should be very thoroughly secured
  19. 19. ITM 578 19 ILLINOIS INSTITUTE OF TECHNOLOGY Filtered Data Packets Screened-Host Firewall Trusted network Untrusted Network Unrestricted Data Packets Blocked Data Packets FIGURE 8-3 Screened Host Firewall Bastion-host Application Level Firewall Proxy access
  20. 20. ITM 578 20 ILLINOIS INSTITUTE OF TECHNOLOGY Dual-homed Host Firewalls  The bastion-host contains two NICs (network interface cards)  One NIC connected to the external network, and one connected to the internal network  With two NICs all traffic must physically go through the firewall to move between the internal and external networks  A technology known as network-address translation (NAT) is commonly implemented with this architecture to map from real, valid, external IP addresses to ranges of internal IP addresses that are non-routable
  21. 21. ITM 578 21 ILLINOIS INSTITUTE OF TECHNOLOGY Dual-homed Host Firewall Trusted network Untrusted Network Unrestricted Data Packets Blocked External Data Packets FIGURE 8-4 Dual-homed Host Firewall Dual-homed Host used as a firewall providing Network Address Translation (NAT) External filtering router Internal filtering router Public IP Addresses NAT assigned local addresses Blocked Internal Data Packets Proxy Access
  22. 22. ITM 578 22 ILLINOIS INSTITUTE OF TECHNOLOGY Screened-Subnet Firewalls (with DMZ) Consists of two or more internal bastion-hosts, behind a packet-filtering router, with each host protecting the trusted network The first general model consists of two filtering routers, with one or more dual-homed bastion-host between them
  23. 23. ITM 578 23 ILLINOIS INSTITUTE OF TECHNOLOGY Screened-Subnet Firewalls (with DMZ)  The second general model involves the connection from the outside or untrusted network going through this path: – Through an external filtering router – Into and then out of a routing firewall to the separate network segment known as the DMZ  Connections into the trusted internal network are allowed only from the DMZ bastion-host servers
  24. 24. ITM 578 24 ILLINOIS INSTITUTE OF TECHNOLOGY Screened-Subnet Firewall Trusted network Untrusted Network Blocked Data Packets Proxy access FIGURE 8-5 Screened Subnet (DMZ) External filtering router Internal filtering router Controlled access Demilitarized zone (DMZ) ServersServers
  25. 25. ITM 578 25 ILLINOIS INSTITUTE OF TECHNOLOGY SOCKS Servers  The SOCKS system is a proprietary circuit-level proxy server that places special SOCKS client-side agents on each workstation  Places the filtering requirements on the individual workstation, rather than on a single point of defense (and thus point of failure)  This frees the entry router of filtering responsibilities, but then requires each workstation to be managed as a firewall detection and protection device  A SOCKS system can require additional support and management resources to configure and manage possibly hundreds of individual clients, versus a single device or set of devices
  26. 26. ITM 578 26 ILLINOIS INSTITUTE OF TECHNOLOGY Selecting the Right Firewall  What type of firewall technology offers the right balance of protection features and cost for the needs of the organization?  What features are included in the base price? What features are available at extra cost? Are all cost factors known?  How easy is it to set up and configure the firewall? How accessible are staff technicians with the mastery to do it well?  Can the candidate firewall adapt to the growing network in the target organization?
  27. 27. ITM 578 27 ILLINOIS INSTITUTE OF TECHNOLOGY Configuring and Managing Firewalls  Each firewall device will have its own set of configuration rules that regulate its actions  Simple mistakes can turn the device into a choke point  When security rules conflict with the performance of business, security loses since organizations are much more willing to live with a potential risk than a certain failure
  28. 28. ITM 578 28 ILLINOIS INSTITUTE OF TECHNOLOGY Firewall Recommended Practices  All traffic from the trusted network is allowed out  The firewall device is always inaccessible directly from the public network  Allow Simple Mail Transport Protocol (SMTP) data to pass through your firewall, but insure it is all routed to a well-configured SMTP gateway to filter and route messaging traffic securely  All Internet Control Message Protocol (ICMP) data should be denied  Block telnet (terminal emulation) access to all internal servers from the public networks  When Web services are offered outside the firewall, deny HTTP traffic from reaching your internal networks by using some form of proxy access or DMZ architecture
  29. 29. ITM 578 29 ILLINOIS INSTITUTE OF TECHNOLOGY Dial-Up Protection  While internal network connection via private networks are now less popular due to the high cost of installation, maintenance, and protection, dial-up connections are still quite common  Unsecured, dial-up access represents a substantial exposure to attack – An attacker who suspects that an organization has dial-up lines can use a device called a war- dialer to locate the connection points  For the most part, simple username and password schemes are the only means of authentication
  30. 30. ITM 578 30 ILLINOIS INSTITUTE OF TECHNOLOGY Remote Authentication Dial-in User Service  RADIUS system centralizes management of user authentication by placing the responsibility for authenticating each user in the central RADIUS server Radius serverRemote access server(RAS) 1. Remote worker dials RAS and submits username and password 2. RAS passes username and password to RADIUS server 3. RADIUS server approves or rejects request and provides access authorization 4. RAS provides access to authorized remote worker (1) (2) (3)(4) Tele-worker FIGURE 8-6 RADIUS Configuration
  31. 31. ITM 578 31 ILLINOIS INSTITUTE OF TECHNOLOGY Terminal Access Controller Access Control System TACACS contains a centralized database, such as RADIUS, and validates the user’s credentials at the TACACS server There are three versions of TACACS – TACACS – Extended TACACS – TACACS+
  32. 32. ITM 578 32 ILLINOIS INSTITUTE OF TECHNOLOGY Intrusion Detection Systems (IDSs)  IDSs work like burglar alarms  IDSs require complex configurations to provide the level of detection and response desired  An IDS operates as either network-based, when the technology is focused on protecting network information assets, or host-based, when the technology is focused on protecting server or host information assets  IDSs use one of two detection methods, signature-based or statistical anomaly-based
  33. 33. ITM 578 33 ILLINOIS INSTITUTE OF TECHNOLOGY Intrusion Detection System External Router Host IDS: Examines the data in files stored on host and alerts systems administrators to any any changes Network IDS: Examines packets on network and alerts admin to unusual patterns. Header 0100101011Untrusted Network FIGURE 8-7 Intrusion Detection Systems
  34. 34. ITM 578 34 ILLINOIS INSTITUTE OF TECHNOLOGY Host-based IDSs  Resides on a particular computer or server (known as the host) and monitors activity on that system.  Most work on principle of configuration or change management, in which the systems record the file sizes, locations, and other attributes, and reports when one or more of these attributes changes, when new files are created, and when existing files are deleted.  Can also monitor systems logs for pre- defined events.
  35. 35. ITM 578 35 ILLINOIS INSTITUTE OF TECHNOLOGY Host-based IDSs  Maintains own log files so when hackers successfully modify a systems log the IDS provides independent verification of the attack Once properly configured, host-IDSs are very reliable.  Managed host-based IDS can monitor multiple computers simultaneously. – Stores a client file on each monitored host – Has that host report back to the master console (usually located on the sysadmin’s computer)
  36. 36. ITM 578 36 ILLINOIS INSTITUTE OF TECHNOLOGY Host-based IDS Host-based IDS FIGURE 8-8
  37. 37. ITM 578 37 ILLINOIS INSTITUTE OF TECHNOLOGY Network-based IDSs  Works differently than its host-based counterpart; monitors network traffic  When a pre-defined condition occurs, it responds and notifies the appropriate administrator  Must match known and unknown attack strategies against knowledge base to determine if an attack has occurred  Result in more false positive readings than do host-based IDSs – System is attempting to read into the pattern of activity on the network to determine what is normal and what is not
  38. 38. ITM 578 38 ILLINOIS INSTITUTE OF TECHNOLOGY Network-based IDS Network- based IDS FIGURE 8-8
  39. 39. ITM 578 39 ILLINOIS INSTITUTE OF TECHNOLOGY Signature-based IDSs  AKA knowledge-based IDS; examines data traffic looking for something that matches signatures, which are pre-configured, predetermined attack patterns  Problem: signatures must be continually updated as new attack strategies are identified  Attackers who are slow and methodical may slip undetected through the IDS, as actions may not match the signature that includes factors based on duration of the events
  40. 40. ITM 578 40 ILLINOIS INSTITUTE OF TECHNOLOGY Statistical Anomaly-based IDSs AKA behavior-based IDS Collects data from normal traffic and establishes a baseline Once the baseline is established, periodically samples network activity, based on statistical methods, and compares samples to baseline If activity is outside baseline parameters (known as a clipping level), IDS notifies administrator
  41. 41. ITM 578 41 ILLINOIS INSTITUTE OF TECHNOLOGY Statistical Anomaly-based IDSs  Advantage: system able to detect new types of attacks as it looks for abnormal activity of any type  Unfortunately require much more overhead and processing capacity than signature-based versions, as they must constantly attempt to pattern matched activity to the baseline  Also may not detect minor changes to systems variables can generate many false positives
  42. 42. ITM 578 42 ILLINOIS INSTITUTE OF TECHNOLOGY Scanning And Analysis Tools  Used to collect information needed by an attacker to succeed  One of the preparatory parts of an attack is collection of information about a potential target, a process called footprinting – Organized research of the Internet addresses owned or controlled by a target organization  Attacker uses public Internet data sources to perform keyword searches to identify the network addresses of the organization  This research augmented with browsing organization’s Web pages
  43. 43. ITM 578 43 ILLINOIS INSTITUTE OF TECHNOLOGY Scanning And Analysis Tools Next phase of the pre-attack data gathering process: fingerprinting Systematic examination of all Internet addresses of the organization (collected during the footprinting) Accomplished with tools discussed in the next section, fingerprinting reveals useful information for the anticipated attack
  44. 44. ITM 578 44 ILLINOIS INSTITUTE OF TECHNOLOGY Scanning And Analysis Tools Scanners, sniffers, and other analysis tools are invaluable to security administrators; enables them to see what the attacker sees Can find vulnerabilities in systems, holes in security components, and unsecured aspects of the network – Unfortunately, they cannot detect the unpredictable behavior of people.
  45. 45. ITM 578 45 ILLINOIS INSTITUTE OF TECHNOLOGY Scanning And Analysis Tools Many of these tools have distinct signatures & some Internet service providers (ISPs) scan for these signatures. – If an ISP discovers someone using “hacker tools” it can pull access privileges – Best to establish working relationship with the ISP & notify them of the purpose and extent of the signatures.
  46. 46. ITM 578 46 ILLINOIS INSTITUTE OF TECHNOLOGY Port Scanners  Port scanners fingerprint networks to find ports and services and other useful information  Why secure open ports? – An open port can be used to send commands to a computer, gain access to a server, and exert control over a networking device – The general rule of thumb is to remove from service or secure any port not absolutely necessary for the conduct of business
  47. 47. ITM 578 47 ILLINOIS INSTITUTE OF TECHNOLOGY Well-known Port Numbers Port numbers Description 20 and 21 File Transfer Protocol (FTP) 25 Simple Mail Transfer Protocol (SMTP) 53 Domain Name Services (DNS) 67 and 68 Dynamic Host Configuration Protocol (DHCP) 80 Hypertext Transfer Protocol (HTTP) 110 Post Office Protocol (POP3) 161 Simple Network Management Protocol (SNMP) 194 IRC Chat port (used for device sharing) 443 HTTP over SSL 8080 Used for proxy services Table 8-2 Well-known Port Numbers
  48. 48. ITM 578 48 ILLINOIS INSTITUTE OF TECHNOLOGY Source:http://support.gfi.com/manuals/en/lanscan2/analyzingthescanresults.htm FIGURE 8-11 LANGuard Network Scanner LANguard Network Scanner
  49. 49. ITM 578 49 ILLINOIS INSTITUTE OF TECHNOLOGY Vulnerability Scanners Vulnerability scanners are capable of scanning networks for very detailed information As a class, they identify exposed usernames and groups, show open network shares, expose configuration problems, and other vulnerabilities in servers
  50. 50. ITM 578 50 ILLINOIS INSTITUTE OF TECHNOLOGY Source:http://www.insecure.org/nmap/images/nmapfe.gif Nmap Vulnerability Scanner FIGURE 8-12 Nmap Vulnerability Scanner
  51. 51. ITM 578 51 ILLINOIS INSTITUTE OF TECHNOLOGY Packet Sniffers  A network tool that collects copies of packets from the network and analyzes them  Can be used to eavesdrop on the network traffic  To use a packet sniffer legally, you must be: – on a network that the organization owns – under direct authorization of the owners of the network – have knowledge and consent of the content creators (users)
  52. 52. ITM 578 52 ILLINOIS INSTITUTE OF TECHNOLOGY Source http://www.ethereal.com/docs/user-guide/x885.html Ethereal Sample Screen FIGURE 8-13 Ethereal Sample Screen
  53. 53. ITM 578 53 ILLINOIS INSTITUTE OF TECHNOLOGY Content Filters Although technically not a firewall, a content filter is a software filter that allows administrators to restrict accessible content from within a network The content filtering restricts Web sites with inappropriate content
  54. 54. ITM 578 54 ILLINOIS INSTITUTE OF TECHNOLOGY Trap and Trace  Software designed to entice individuals illegally perusing the internal areas of a network  Better known as honey pots, they distract the attacker while notifying the administrator  Trace: attempt to determine the identity of someone using unauthorized access – Main purpose: capture system abusers internal to the network
  55. 55. ITM 578 55 ILLINOIS INSTITUTE OF TECHNOLOGY Cryptography and Encryption Sophisticated approach to security Many security-related tools use embedded encryption technologies Encryption is the process of converting an original message into a form that is unreadable by unauthorized individuals The science of encryption, known as cryptology, encompasses cryptography and cryptanalysis
  56. 56. ITM 578 56 ILLINOIS INSTITUTE OF TECHNOLOGY Encryption Definitions  Algorithm: the mathematical formula used to convert an unencrypted message into an encrypted message.  Cipher: the transformation of the individual components (characters, bytes, or bits) of an unencrypted message into encrypted components.  Ciphertext or cryptogram: the unintelligible encrypted or encoded message resulting from an encryption.  Code: the transformation of the larger components (words or phrases) of an unencrypted message into encrypted components.
  57. 57. ITM 578 57 ILLINOIS INSTITUTE OF TECHNOLOGY Encryption Definitions  Cryptosystem: the set of transformations necessary to convert an unencrypted message into an encrypted message.  Decipher: to decrypt or convert ciphertext to plaintext.  Encipher: to encrypt or convert plaintext to ciphertext.  Key or cryptovariable: the information used in conjunction with the algorithm to create ciphertext from plaintext.  Keyspace: the entire range of values that can possibly be used to construct an individual key.
  58. 58. ITM 578 58 ILLINOIS INSTITUTE OF TECHNOLOGY Encryption Definitions  Link encryption: a series of encryptions and decryptions between a number of systems, whereby each node decrypts the message sent to it and then re-encrypts it using different keys and sends it to the next neighbor, until it reaches the final destination.  Plaintext: the original unencrypted message that is encrypted and results from successful decryption.  Steganography: the process of hiding messages in a picture or graphic.  Work factor: the amount of effort (usually in hours) required to perform cryptanalysis on an encoded message.
  59. 59. ITM 578 59 ILLINOIS INSTITUTE OF TECHNOLOGY Cryptography & Encryption-Based Solutions  Simple forms of encryption are based on two concepts: the block cipher and the exclusive OR operation  With the block cipher method – the message is divided into blocks, i.e., 8 or 16 bit – and then each block is transformed using the algorithm and key  The “exclusive or operation” (XOR) is a function of Boolean algebra
  60. 60. ITM 578 60 ILLINOIS INSTITUTE OF TECHNOLOGY Exclusive OR Operations Bit 1 Bit 2 Exclusive OR result 0 0 0 0 1 1 1 0 1 1 1 0 Exclusive OR OperationsTABLE 8-3
  61. 61. ITM 578 61 ILLINOIS INSTITUTE OF TECHNOLOGY Encryption Algorithms  In encryption the most commonly used algorithms include two functions: substitution and transposition  In a substitution cipher, you substitute one value for another  This type of substitution is based on a monoalphabetic substitution, since it only uses one alphabet  More advanced substitution ciphers use two or more alphabets, and are referred to as polyalphabetic substitutions
  62. 62. ITM 578 62 ILLINOIS INSTITUTE OF TECHNOLOGY Encryption Operations  Just like the substitution operation, the transposition cipher is simple to understand but can be complex to decipher if properly used  Unlike the substitution cipher, the transposition cipher (or permutation cipher) simply rearranges the values within a block to create the ciphertext  This can be done at the bit level or at the byte (character) level - transposition ciphers move these bits or bytes to another location in the block, so that bit 1 becomes bit 4, bit 2 becomes bit 7 etc
  63. 63. ITM 578 63 ILLINOIS INSTITUTE OF TECHNOLOGY Vernam Cipher  Also known as the one-time pad, the Vernam cipher was developed at AT&T and uses a one-use set of characters, the value of which is added to the block of text  The resulting sum is then converted to text  When the two are added, if the values exceed 26, 26 is subtracted from the total (Modulo 26) - the corresponding results are then converted back to text
  64. 64. ITM 578 64 ILLINOIS INSTITUTE OF TECHNOLOGY Book or Running Key Cipher  Another method, made popular by spy movies, is the use of text in a book as the algorithm to decrypt a message  The key consists of – knowing which book to use – a list of codes representing the page number, line number, and word number of the plaintext word  Dictionaries and thesauruses make the most popular sources as they guarantee every word needed, although almost any book will suffice
  65. 65. ITM 578 65 ILLINOIS INSTITUTE OF TECHNOLOGY Symmetric Encryption  The same key, also known as a secret key used to conduct both encryption and decryption of the message  Can be extremely efficient, requiring minimal processing to either encrypt or decrypt the message  Problem: both sender & receiver must own the encryption key – If either copy of the key is compromised, an intermediate can decrypt and read the messages  Challenges: get copy of the key to the receiver, a process that must be conducted out-of-band to avoid interception
  66. 66. ITM 578 66 ILLINOIS INSTITUTE OF TECHNOLOGY Symmetric Encryption
  67. 67. ITM 578 67 ILLINOIS INSTITUTE OF TECHNOLOGY Data Encryption Standard (DES) Developed in 1977 by IBM Based on the Data Encryption Algorithm (DEA) Uses a 64-bit block size and a 56-bit key With a 56-bit key, the algorithm has 256 possible keys to choose from (over 72 quadrillion)
  68. 68. ITM 578 68 ILLINOIS INSTITUTE OF TECHNOLOGY Data Encryption Standard (DES)  DES is a federally approved standard for non classified data  RSA put a bounty on the algorithm offering $10,000 to the team to crack the algorithm  Fourteen thousand users collaborated over the Internet to finally break the encryption  On 19 October 1997 at 1325 UTC, the 56 bit DES algorithm was cracked by a distributed processing system coordinated by a computer in my lab at IIT’s Main Campus
  69. 69. ITM 578 69 ILLINOIS INSTITUTE OF TECHNOLOGY Triple DES (3DES)  Developed as an improvement to DES  Uses up to three keys in succession and also performs three different encryption operations: – 3DES encrypts the message three times with three different keys, the most secure level of encryption possible with 3DES  In 1998, it took a dedicated computer designed by the Electronic Freedom Frontier (www.eff.org) over 56 hours to crack DES
  70. 70. ITM 578 70 ILLINOIS INSTITUTE OF TECHNOLOGY Advanced Encryption Standard (AES) The successor to 3DES is Advanced Encryption Standard (AES), based on the Rijndael Block Cipher, a block cipher with a variable block length and a key length of either128, 192, or 256 bits It would take the same computer approximately 4,698,864 quintillion years to crack AES
  71. 71. ITM 578 71 ILLINOIS INSTITUTE OF TECHNOLOGY Asymmetric Encryption  Best known as public key encryption  Uses two different keys  Either key can be used to encrypt or decrypt the message, however, if Key A is used to encrypt the message, only Key B can decrypt, and if Key B is used to encrypt a message, only Key A can decrypt it.  Public key is stored in a public location, where anyone can use it  Private key is a secret known only to the owner of the key pair
  72. 72. ITM 578 72 ILLINOIS INSTITUTE OF TECHNOLOGY Using Public Keys
  73. 73. ITM 578 73 ILLINOIS INSTITUTE OF TECHNOLOGY Digital Signatures  An interesting thing happens when the asymmetric process is reversed, that is the private key is used to encrypt a short message  The public key can be used to decrypt it, and the fact that the message was sent by the organization that owns the private key cannot be refuted  This is known as nonrepudiation, which is the foundation of digital signatures  Digital Signatures are encrypted messages that are independently verified by a central facility (registry) as authentic
  74. 74. ITM 578 74 ILLINOIS INSTITUTE OF TECHNOLOGY RSA  One of the most popular public key cryptosystems  Stands for Rivest-Shamir-Aldeman, its developers  First public key encryption algorithm developed and published for commercial use  Part of Web browsers from both Microsoft and Netscape  56 bit version is not secure; 128 bit version is acceptable
  75. 75. ITM 578 75 ILLINOIS INSTITUTE OF TECHNOLOGY PKI or Public Key Infrastructure  Public Key Infrastructure is the entire set of hardware, software, and cryptosystems necessary to implement public key encryption  PKI systems are based on public-key cryptosystems and include digital certificates and certificate authorities (CAs) and can: – Issue digital certificates – Issue crypto keys – Provide tools to use crypto to secure information – Provide verification and return of certificates
  76. 76. ITM 578 76 ILLINOIS INSTITUTE OF TECHNOLOGY PKI Benefits PKI protects information assets in several ways: – Authentication – Integrity – Privacy – Authorization – Nonrepudiation
  77. 77. ITM 578 77 ILLINOIS INSTITUTE OF TECHNOLOGY Digital Certificates & Certificate Authorities  A digital certificate is an electronic document, similar to a digital signature, attached to a file certifying that this file is from the organization it claims to be from and has not been modified from the original format  A Certificate Authority is an agency that manages the issuance of certificates and serves as the electronic notary public to verify their worth and integrity
  78. 78. ITM 578 78 ILLINOIS INSTITUTE OF TECHNOLOGY Hybrid Systems  In practice, pure asymmetric key encryption not widely used except in the area of certificates  More often used in conjunction with symmetric key encryption creating a hybrid system  Use the Diffie-Hellman Key Exchange method that uses asymmetric techniques to exchange symmetric keys to enable efficient, secure communications based on symmetric keys  Diffie-Hellman provided the foundation for subsequent developments in public key encryption
  79. 79. ITM 578 79 ILLINOIS INSTITUTE OF TECHNOLOGY Hybrid Encryption Example
  80. 80. ITM 578 80 ILLINOIS INSTITUTE OF TECHNOLOGY Securing E-mail  Encryption cryptosystems have been adapted to inject some degree of security into e-mail: – S/MIME builds on the Multipurpose Internet Mail Extensions (MIME) encoding format by adding encryption and authentication – Privacy Enhanced Mail (PEM) was proposed by the Internet Engineering Task Force (IETF) as a standard to function with the public key cryptosystems – PEM uses 3DES symmetric key encryption and RSA for key exchanges and digital signatures – Pretty Good Privacy (PGP), developed by Phil Zimmerman, uses the IDEA Cipher along with RSA for key exchange
  81. 81. ITM 578 81 ILLINOIS INSTITUTE OF TECHNOLOGY Securing the Web Secure Electronic Transactions (SET) Secure Socket Layer (SSL) Secure Hypertext Transfer Protocol (SHTTP) Secure Shell (SSH) IPSec
  82. 82. ITM 578 82 ILLINOIS INSTITUTE OF TECHNOLOGY IPSec  IP Security (IPSec) is the cryptographic authentication and encryption product of the IETF’s IP Protocol Security Working Group  Defined in RFC 1825, 1826, and 1827  Used to create Virtual Private Networks (VPNs) and is an open framework for security development within the TCP/IP family of protocol standards  Combines several different cryptosystem elements and includes: – the IP Security Protocol itself – the Internet Key Exchange
  83. 83. ITM 578 83 ILLINOIS INSTITUTE OF TECHNOLOGY IPSec Operations  IPSec works in two modes of operation: – In transport mode only the IP data is encrypted, not the IP headers themselves – In tunnel mode, the entire IP packet is encrypted and is then placed as the payload in another IP packet  The implementation of these technologies is very popular through a process known as Virtual Private Networks (VPNs)  In the most common implementation, a VPN allows a user to turn the Internet into a private network between points on the public network
  84. 84. ITM 578 84 ILLINOIS INSTITUTE OF TECHNOLOGY Kerberos Scenario: Initial Login
  85. 85. ITM 578 85 ILLINOIS INSTITUTE OF TECHNOLOGY Kerberos Scenario: Request for Services
  86. 86. ITM 578 86 ILLINOIS INSTITUTE OF TECHNOLOGY Sesame  To solve some of the problems associated with Kerberos, a new project, the Secure European System for Applications in a Multivendor Environment (SESAME), was developed as a European research and development project, partly funded by the European Commission  SESAME is similar in part to Kerberos in that the user is first authenticated to an authentication server to receive a token
  87. 87. ITM 578 87 ILLINOIS INSTITUTE OF TECHNOLOGY Access Control Devices  To insure secure operation, access control needs strong authentication (two-factor authentication)  Consist of the user’s personal password or passphrase but requires at least one other factor to represent strong authentication  Frequently a physical device is used for the second factor  When considering access control you address: – What you know – What you have – Who you are – What you produce
  88. 88. ITM 578 88 ILLINOIS INSTITUTE OF TECHNOLOGY What You Are - Biometrics  Most of the technologies that scan human characteristics convert these images to some form of minutiae  Minutiae are unique points of reference that are digitized and stored in an encrypted format  Each subsequent scan is also digitized and then compared with the encoded value to determine if users are who they claim to be  The problem is that some human characteristics can change over time, due to normal development, injury, or illness
  89. 89. ITM 578 89 ILLINOIS INSTITUTE OF TECHNOLOGY Voice recognition Signature recognition Hand geometry Hand and palm print Fingerprint Iris recognition Retinal Recognition Facial geometry Recognition Characteristics FIGURE 8-20 Recognition Characteristics
  90. 90. ITM 578 90 ILLINOIS INSTITUTE OF TECHNOLOGY Effectiveness of Biometrics Biometric technologies are evaluated on three basic criteria: –False Reject Rate –False Accept Rate –Crossover Error Rate
  91. 91. ITM 578 91 ILLINOIS INSTITUTE OF TECHNOLOGY False Reject Rate (FRR) The percentage or value associated with the rate at which authentic users are denied or prevented access to authorized areas, as a result of a failure in the biometric device Type I error Probably of the least concern to security
  92. 92. ITM 578 92 ILLINOIS INSTITUTE OF TECHNOLOGY False Accept Rate (FAR) The percentage or value associated with the rate at which fraudulent or non-users are allowed access to systems or areas, as a result of a failure in the biometric device Type II error This type of error is unacceptable to security, as it represents a clear breach
  93. 93. ITM 578 93 ILLINOIS INSTITUTE OF TECHNOLOGY Crossover Error Rate (CER) The crossover error rate is the point at which the number of false rejections equals the false acceptances, also known as the equal error rate It is possibly the most common and important overall measure of the accuracy of a biometric system The optimal setting is somewhere near the equal error rate or CER
  94. 94. ITM 578 94 ILLINOIS INSTITUTE OF TECHNOLOGY Acceptability of Biometrics While the use of one authentication area is necessary to access the system, the more devices used the better To obtain strong authentication, the systems must use two or more authentication areas
  95. 95. ITM 578 95 ILLINOIS INSTITUTE OF TECHNOLOGY The End… Questions?