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DIGITAL CERTIFICATES

DIGITAL CERTIFICATES. Prof. Ravi Sandhu. PUBLIC-KEY CERTIFICATES. reliable distribution of public-keys public-key encryption sender needs public key of receiver public-key digital signatures receiver needs public key of sender public-key key agreement both need each other’s public keys.

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DIGITAL CERTIFICATES

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  1. DIGITAL CERTIFICATES Prof. Ravi Sandhu

  2. PUBLIC-KEY CERTIFICATES • reliable distribution of public-keys • public-key encryption • sender needs public key of receiver • public-key digital signatures • receiver needs public key of sender • public-key key agreement • both need each other’s public keys

  3. X.509v1 CERTIFICATE VERSION SERIAL NUMBER SIGNATURE ALGORITHM ISSUER VALIDITY SUBJECT SUBJECT PUBLIC KEY INFO SIGNATURE

  4. X.509v1 CERTIFICATE 1 1234567891011121314 RSA+MD5, 512 C=US, S=VA, O=GMU, OU=ISE 9/9/99-1/1/1 C=US, S=VA, O=GMU, OU=ISE, CN=Ravi Sandhu RSA, 1024, xxxxxxxxxxxxxxxxxxxxxxxxx SIGNATURE

  5. CERTIFICATE TRUST • how to acquire public key of the issuer to verify signature • whether or not to trust certificates signed by the issuer for this subject

  6. PEM CERTIFICATION GRAPH Internet Policy Registration Authority IPRA Policy Certification Authorities (PCAs) PERSONA RESIDENTIAL MID-LEVEL ASSURANCE HIGH ASSURANCE Anonymous MITRE GMU Virginia Certification Authorities (CAs) Abrams LEO Fairfax ISSE Subjects Sandhu Sandhu

  7. SECURE ELECTRONIC TRANSACTIONS (SET) CA HIERARCHY Root Brand Brand Brand Geo-Political Bank Acquirer Customer Merchant

  8. CRL FORMAT SIGNATURE ALGORITHM ISSUER LAST UPDATE NEXT UPDATE REVOKED CERTIFICATES SIGNATURE SERIAL NUMBER REVOCATION DATE

  9. X.509 CERTIFICATES • X.509v1 • very basic • X.509v2 • adds unique identifiers to prevent against reuse of X.500 names • X.509v3 • adds many extensions • can be further extended

  10. X.509v3 CERTIFICATE INNOVATIONS • distinguish various certificates • signature, encryption, key-agreement • identification info in addition to X.500 name • internet names: email addresses, host names, URLs • issuer can state policy and usage • good enough for casual email but not for signing checks • limits on use of signature keys for further certification • extensible • proprietary extensions can be defined and registered • attribute certificates • ongoing work

  11. X.509v2 CRL INNOVATIONS • CRL distribution points • indirect CRLs • delta CRLs • revocation reason • push CRLs

  12. GENERAL HIERARCHICAL STRUCTURE Z X Y Q R S T A C E G I K M O a b c d e f g h i j k l m n o p

  13. GENERAL HIERARCHICAL STRUCTURE WITH ADDED LINKS Z X Y Q R S T A C E G I K M O a b c d e f g h i j k l m n o p

  14. TOP-DOWN HIERARCHICAL STRUCTURE Z X Y Q R S T A C E G I K M O a b c d e f g h i j k l m n o p

  15. FOREST OF HIERARCHIES

  16. MULTIPLE ROOT CA’s PLUS INTERMEDIATE CA’s MODEL X S T Q R A C E G I K M O a b c d e f g h i j k l m n o p

  17. THE CERTIFICATE TRIANGLE user X.509 attribute certificate X.509 identity certificate attribute public-key SPKI certificate

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