NETWORKContentsSecurity and its breaches…Security Goals and VulnerabilitiesThe people involved…Basic Encryption and DecryptionContd…EncryptionSlide 9Slide 10Encryption Protocols…Symmetric Key X-change W/out ServerSymmetric Key X-change With ServerAsymmetric Key X-change W/out ServerAsymmetric Key X-change With ServerAuthentication in Distributed SystemsContd..How Kerberos withstand Attacks?Why Kerberos is not the perfect Answer?NETWORK SECURITY ISSUESThreatsWire tappingNetwork Security ProtocolsContd...ComparisonsIntrusion DetectionDesirable Characteristic of IDLimitations of Existing IDIntrusion TypesARCHITECTURE TO GENERATE THE STD. FORMATSTANDARD AUDIT TRAIL FORMATSunOS MLS LogsTypical Anomaly Detection SystemAnomaly ID (Statistical Approach)Types of Measure.Typical Misuse Detection SystemMisuse IDSlide 38Model based Intrusion Detection A Pattern Matching approach… ContinuedInferenceA Trivial Bayesian Belief Network modeling Network Intrusion activityConditional ProbabilityWeb Security...Why worry about web security ?The Web Security Problem...Digital Identification TechniquesSlide 48Symmetric Key Digital Signatures with ArbiterAsymmetric Key Digital SignatureCertification Authorities(CA’s)Types of CADifferent kinds of certificatesSlide 54Cryptography and Web SecurityWhat cryptography can’t do ?Working Encryption SystemsContd…Network Layer Security Protocol (IPsec)Authentication Header Protocol (AH)Encapsulation Security Payload Protocol (ESP)What is SSL ?Secure Web ServerWeb server SecurityFirewallsTypes of FirewallsContd …Slide 68Slide 69Comparisons of Firewall typesEncrypting Gateway (Virtual Private Network)ConclusionsReferencesSlide 74NETWORKAuthorsHari ThiruvengadaVarun LalchandaniSECURITY...Contents•Introduction.•Encryption and Protocols.•Kerberos.•Network Security Issues and Protocols.•Intrusion Detection•Web Security.•Digital Identification Techniques.•Cryptography and web Security.•Firewalls.•References.Security and its breaches…Security •a system is secure if it is –Security goals are achieved.–Components behaves as expected on it.Breaches•Interruption - System asset lost , unavailable or unusable.•Interception - Unauthorized party gains access to asset.•Modification - Tampering with the asset.•Fabrication - counterfeit objects on computing system.Security Goals and VulnerabilitiesSecurity Goals•Confidentiality - assets of a computing system accessible only by authorized user.Read only type of access like viewing, printing helps in privacy.•Integrity - modification only by authorized parties.Precise, accurate, consistent assets. •Availability - assets are accessible to authorized parties.Timely response, fair allocation, fault tolerance, usability, controlled concurrency. (Denial of service attacks.)The people involved…•Amateurs - fresh players of the game , disgruntled over a -ve work situation.•Crackers - breaking into unauthorized territory without malicious intent.•Hackers - breaking into unauthorized territory with malicious intent.•Career Criminals - people in the game for money and have predefined targets.Basic Encryption and Decryption•Encryption - process of encoding a message so that its meaning is not obvious.•Decryption - process of decoding the encrypted message.•Cryptography - Hidden writing, which conceals meaningful text.•Cryptanalyst - studies encryption and finds hidden messages.•Cryptanalysis –attempt to break a single message.–Recognize patterns in encrypted messages to break into subproblems by straightforward decryption algorithm.–Find weakness in encryption algorithms.Contd…Encryption with KeysEncryptionEncryptionDecryptionDecryptionPlain TextCipher TextOriginal TextEncryption Key (Ke)(Asymmetric Cryptosystem)Decryption Key (Kd)Encryption with KeysEncryptionEncryptionDecryptionDecryptionPlain TextCipher TextOriginal TextKey(Symmetric Cryptosystem)EncryptionEncryptionDecryptionDecryptionPlain TextCipher TextOriginal TextEncryptionEncryption•Substitutions - one letter x-changed for other.–Monoalphabetic Ciphers.•Caesar CipherExample: Plaintext:ABCDEFGHIJKLMNOPQRSTUVWXYZ Cipher :DEFGHIJKLMNOPQRSTUVWXYZABC–Polyalphabetic Ciphers.•Frequency distribution reflects the underlying letters. Table for Odd PositionsA 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 A D G J M P S V Y B E H K N Q T W Z C F I L O R U XA D G J M P S V Y B E H K N Q T W Z C F I L O R U XTable for Even Positions 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 N S X C H M R W B G L Q V A F K P U Z E J O T Y D IN S X C H M R W B G L Q V A F K P U Z E J O T Y D IContd…Example:F1(x) = (3 * x)mod 26.F2(x) = ((5 * x) +13) mod 26.Encryption for :TREAT YIMPO SSIBL Ewould beFUMNF DYVTF CZYSH HContd…•Transposition - letters of message rearranged.–GOAL - DiffusionExample:C1 C2 C3C4 C5 C6 C7 C8 C9 C10C11 C12 etc.The resulting cipher text will beC1 C2 C3C4 C5 C6 C7 C8 C9 C10C11 C12 etc.Encryption Protocols…ArbiterAABBArbitrated ProtocolAdjudicated ProtocolSelf-Enforcing ProtocolAAAABBBBAdjudicatorYou are cheatingA acted fairlySymmetric Key X-change W/out Server•Small no. of messages.•Less risk of intrusion. •Each user have a copy of symmetric secret encryption key K.•For greater security one can generate a fresh key called KNEW.•Send E(KNEW,K).Symmetric Key X-change With ServerDISTRIBUTION CENTER(DC)ReneePablo1.Give me a key (P, R, Ip )2.Here is the key and E(Ip ,R,KPR,,E((KPR ,P), KR)), KP)3. DC gave me key for Private CommunicationE((KPR ,P), KR )2. E((KPR ,P), KR )Asymmetric Key X-change W/out Server1. EP(DR (K))Renee sends new key2. S (n,K)Pablo sends encrypted random number3. S (n+1,K)Renee returns successor of Random Number ReneePabloAsymmetric Key X-change With ServerDISTRIBUTION CENTER(DC)ReneePablo1.Give me a Renee’s key (P,R)2.Here is the Renee’sKey (DD(ER,R))3. I’ am Pablo, let’s Talk. ER(P, IP)6. Renee here , What’s up ? EP(R, IR )7. Reply with ER(M, IR)5. Here’s Pablo’sKey (DD(EP ,P))4. Please give me Pablo’s public key (R ,P)Authentication in Distributed Systems•KerberosUserUserUUKerberos Kerberos ServerServerTicket Granting Ticket Granting ServerServer1. U’s IdentitySession keySG Ticket TG2. Encrypted under PasswordSession key SG2. Encrypted underKS-TGS KeyInitiating a Kerberos SessionContd..Obtaining