30-04-2011, 02:22 PM
17NWseccrypt.ppt (Size: 1.46 MB / Downloads: 70)
BANKING
SHOPPING
FILING TAX RETURNS
MILIATARY
N/W SECURITY IS LOOMING ON THE HORIZON AS A POTENTIALLY MASSIVE PROBLEM
SECRECY
AUTHENTICATION
NONREPUDIATION
INTEGRITY CONTROL
Encryption: only the authorized party can understand the encrypted message.
Data authentication: Ascertain that information exchanged is indeed the one from the sender.
Signature: allow people to verify the authenticity of the message or authenticate the peer user.
Cryptography
Cryptography
symmetric-key cryptography
public-key cryptography
Used for
authentication,
integrity protection,
encryption,
key management
C=E[P]
P=D[C]
DIFFERENT PUBLIC KEY AND PRIVATE KEY.
Sender A does the following:
Creates a message digest of the information to be sent.
Represents this digest as an integer ‘m’ between 0 and n-1.
Uses her private key(n,d) to compute the signatures=m^d mod n.
Sends this signature s to the recipient B.
Recipient B does the following:
Uses sender A’s public key(n,e) to compute integer v=s^e mod n.
Extracts the message digest from this integer.
Independently computes the message digest of info yhat has been signed.
If both message digests are identical,the signature is valid