Encryption of data
A symmetric algorithm provides better access control.
A symmetric algorithm is a faster process.
A symmetric algorithm provides nonrepudiation of delivery.
A symmetric algorithm is more difficult to implement.
Send a digital signature of the message to the recipient
Encrypt the message with a symmetric algorithm and send it
Encrypt the message with a private key so the recipient can decrypt with the corresponding public key
Create a checksum, append it to the message, encrypt the message, then send to recipient.
Protection of public keys of all users
History of symmetric keys
Proof of nonrepudiation of origin
Validation that a public key is associated with a particular user
Protection and secrecy of keys
Financial records and retention of encrypted data
Formalizing a key hierarchy
The lifespan of key-encrypting keys (KKMs)
Setting new key expiry dates
Updating the certificate revocation list
Removal of the private key from all directories
Notification to all employees of revoked keys
Link encryption encrypts routing information.
Link encryption is often used for Frame Relay or satellite links.
Link encryption is suitable for high-risk environments.
Link encryption provides better traffic flow confidentiality.
Substitution and transposition
Block and stream
Symmetric and asymmetric
DES and AES
All of the above
Here's an interesting quiz for you.