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public key infrastructure

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the basic details and description of public key infrastructure in network cryptography

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public key infrastructure

  1. 1. A Seminar on Public Key Infrastructure Under the guidance of : K. Jeevan Pradeep, M.Tech Assistant professor 1 Presented by: M. Vimal Kumar (11121A0557) SREE VIDYANIKETHAN ENGINEERING COLLEGE (AUTONOMOUS) Sree Sainath Nagar, A.Rangampet-517102 Chittoor Dist, Andhra Pradesh. Department of Computer Science and Engineering
  2. 2. Contents  Introduction to Access Control Policy  Password Authentication  Symmetric and Asymmetric Encryption  Hashing  Digital Signature  Public Key Infrastructure  Certification  Validation  Revocation  Authentication  Keys  Related Technologies  Conclusion  References 2
  3. 3. Introduction to Access Control Policy  To be able to access data and applications from within a company, a user first needs to be authenticated, and then needs to be authorized to perform the operation.  Authentication Procedures perform the former task, and Access Control Decision functions perform the later task.
  4. 4. Password Authentication  When a company has several applications hosted by different systems and servers, there are several ways of identity authentication. Multiple passwords, one for each system/application Same password, replicated in each system  Single sign-on software Directory Server
  5. 5. Symmetric and Asymmetric Encryption  The objective of encryption is to transform a message to a cipher text, ensuring confidentiality  In the symmetric encryption schemes the same key (called the secret key) is used to both encrypt and decrypt the text. Ex :- DES algorithm.  Asymmetric cryptosystems use one key (the public key) to encrypt a message and a different key (the private key) to decrypt it. Ex:- RSA and ECDSA algorithms.
  6. 6. Contd… • Comparison between symmetric and asymmetric encryption
  7. 7. Hashing  Hashing is the method used to obtain a "digital fingerprint" (hash) for a given message.  The hash code has a fixed-length (normally 128 or 160 bits) and it's designed to be unique  Some examples are MD2, MD4, MD5 (128 bits) and SHA1 (Secure Hash Algorithm,160 bits )
  8. 8. Digital Signature  To obtain a secure digital signature,  At first the message is hashed  Creating a digital fingerprint which is encrypted using the receiver's public key  Creating a digital signature. The clear message is combined with the digital signature  The result (an authenticated message) is sent  After the reception, the message is separated from the digital signature  which is decrypted using the receiver's private key  The message is hashed into a "temporary" digital fingerprint  which is used to validate the received fingerprint  If the message has not been modified during the transfer process, it's authenticated.
  9. 9. Mechanism of Digital Signature
  10. 10. Public Key Infrastructure  Three different formats of messages can be used in public- key cryptosystems: Encrypted message, Signed message, Signed and encrypted message.  An infrastructure must be set-up to allow them to be undoubtedly trusted , as they are accessible via unsecured networks (Internet)  PKI entities: -CA ( certification authority ) -RA ( registration authority ) -Subscriber -Relying Party -Repository
  11. 11. PKI basic entities and operations
  12. 12. Certification  Certification is the fundamental function of all PKIs. The certificates provide a secure way of publishing public keys, so that their validity can be trusted.  A certificate contains (at least) the basic information needed to provide a third party entity with the subject's public key: • Subject Identification information • Subject public Key • CA Identification Information • Validity (e.g. time)
  13. 13. Certification contd...  Cross certification :- Not all the entities will trust the same CA to hold their certificates. Cross certification is used to create the certificate between two CAs. If both CAs trust each other, a cross certificate pair is established. In other cases, only one certificate would be created, and not a pair.
  14. 14. Certification contd...  Certification path :- In a universe composed of several different CAs an arbitrary number of CAs must validate each other, until a certificate is obtained. This process is called certification path validation.
  15. 15. Validation  This is the process that ensures that the certificate information is still valid, as it can change over time.  Either the user can ask the CA directly about the validity - every time it's used - or the CA may include a validity period in the certificate. This second alternative is also known as offline validation.
  16. 16. Revocation  This is the process of informing the users when the information in a certificate is not valid.  This is especially interesting in the absence of online validation approaches, and the most common revocation methods consist in publishing Certification Revocation Lists (CRL).  A CRL is a "black" list of revoked certificates that is signed and periodically issued by a CA.
  17. 17. Authentication  In order for the subject to gain access to its private key, it has to possess a smart card or an encrypted key file and know something (PIN or password) or be something (e.g. a particular fingerprint).
  18. 18. Keys  Key pair models :- To increase the security level, different key pairs might exist for different functions, which may be divided into the following categories: • Non-repudiatable message signing (e.g. e-mail). • Encryption/Decryption functions. • Authentication only (e.g. LOG ON functions).
  19. 19. Key Management  These are the main steps performed in a PKI structure to handle the key pairs: •Key Generation •Storage of Private Keys •Revocation of Public Keys •Publication of certificates and CRL •Key Update •Backup / Recovery •Escrow / Recovery
  20. 20. Related Technologies  CMS - Cryptographic Message Syntax  SSL  Secure e-mail / S/MIME  VPN (Virtual Private Network)  PGP (Pretty Good Privacy)
  21. 21. Conclusion  RFC 2822(Internet Security Glossary) defines public-key infrastructure(PKI) as the set of hardware , software , people , policies and procedures needed to revoke digital certificates based on asymmetric cryptography.  The principal objective for developing a PKI is to enable secure , convenient and efficient acquisition of public keys.
  22. 22. References  Wikipedia  www.studymafia.com  Network Security Essentials -by William Stallings 23
  23. 23. QUERIES…???
  24. 24. THANK YOU   

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