1. Copyright 2004 MayneStay Consulting Group Ltd. - All Rights Reserved Jan-041 E-mail Security using Encryption Security Features Message Origin Authentication - verifying that the sender is who he or she says they are Content Integrity - verifying that the message was not changed after sender sent it Content Confidentiality - making certain that only the intended recipient reads the message Proof of Delivery - making certain that the message was delivered Continued... 1 2 3 4

2. Copyright 2004 MayneStay Consulting Group Ltd. - All Rights Reserved Jan-042 E-mail Security using Encryption Security Features Message Sequence Integrity - making certain that all messages were delivered in proper order. Non-repudiation of Origin - being able to prove that sender sent a message. Non-repudiation of Delivery - being able to prove that a recipient got a message. Continued... 5 6 7

3. Copyright 2004 MayneStay Consulting Group Ltd. - All Rights Reserved Jan-043 E-mail Security using Encryption Security Features Message Security Labeling - labeling a message with handling instructions. Message Flow Confidentiality - making certain no one knows who you exchange mail with. Secure Access Management - making certain no one uses your e-mail system without being authorized. 8 9 10

4. Copyright 2004 MayneStay Consulting Group Ltd. - All Rights Reserved Jan-044 E-mail Security using Encryption Operation All secure e-mail systems work roughly the same way. –Calculate a message digest of the message. –Encrypt the message digest with sender’s private key. –Encrypt the mail with a session key (random). –Encrypt the session key with receiver’s public key.

5. Copyright 2004 MayneStay Consulting Group Ltd. - All Rights Reserved Jan-045 E-mail Security using Encryption Operation Receiver must: –Decrypt session key with the receiver’s private key. –Decrypt the message with session key. –Decrypt message digest with the sender’s public key. –Calculate a message digest and compare to the one that was sent. Encrypted message digest serves as both signature and integrity check.

6. Copyright 2004 MayneStay Consulting Group Ltd. - All Rights Reserved Jan-046

7. Copyright 2004 MayneStay Consulting Group Ltd. - All Rights Reserved Jan-047