Message integrity protocol

computer network

1. Message integrity protocol & public key distribution x.509 By .. K.Rajalakshmi I-MSC (IT)

2. Synopsis: Message integrity Key management X.509 certificate

3. Message integrity: Message integrity describes the concept of ensuring that the data has not been modified in transit This is typically accomplished with the use of a hashing algorithm The basic premise is a sender wishes to send a message to a receiver and wishes for the integrity of their message to be guaranted

4. The sender will calculate a hash on the message and include the digest with the message On the other side the receiver will independently calculate the hash on just the message and compute the resulting digest which was sent with the message If they are same then the message must have been the same as when it was originally sent

5. If someone intercepted the message changed it and recalculated the digest before sending it along its way the receiver hash calculation would also match the modification message. preventing the receiver knowing message was modified in transit.

6. If the resulting digest matches the one sent with the message then the receiver known two things. The message was definitely not altered in transit The message was definitely sent by someone who had the secret key ideally only the intended sender

7. When using a secret key in conjunction with a message to attain message integrity the resulting digest is known as the message authentication code or mac

8. Key management: In cryptography it is a very tedious task to distribute the public and private key between sender and receiver If the key is known to the third party then the whole security mechanism become worthless so there comes the need to secure the exchange of key There are 2 aspects of key management : Distribution of public keys Use of public key encryption to distribution secret

9. Public key authority: It is similar to directory but, improve security by tightening control over distribution of keys from directory It requires user to knows public key for the directory The key are need a real time access to directory is made by the user to obtain any desired public key securely.

10. x.509 certification: An x.509 certificate is a structured binary record this record consist of several key and value pairs Key represent field name where values may be simple type to more complex structured binary record is done using a standard known as ASN.1