What is the different between digital signature mechanisms and simple encryption?

A.
Digital signatures are generally 128-bit encryption, whereas simple encryption is generally 56 bits

B.
Digital signatures are verified by third parties that vouch for the veracity of the sender and the contents

C.
Digital signatures carry timestamps, whereas standard encryption does not

D.
Standard encryption mechanisms have no provision for traffic padding to thwart password sniffers

Explanation:
A digital signature is verified by a third party, which holds the public encryption keys and other information used to validate the signature. A common know third party is Verisign.
Incorrect Answers:
A: Digital signatures and regular encryption can use any bit length for the keys.
C: A digital signature is not required to carry a timestamp, so not all forms of digitial signatures will have one.
D: This is not true.