Secure Hash Algorithm is the current hashing standard established by the National Institute for Standard and Technology. It uses a 160-bit hash but lately most organizations are moving toward a 256-bit hash.

• Is a 128-bit hash no longer sufficient for integrity checks?
• Explain the likelihood of a collision in a 128-bit hash. You do not need to explain the mathematics.

A digital signature is a technique to validate the integrity and authenticity of a message. The signature provides assurance that the sender is the true sender, and the message has not been changed during transmission.

• What are the similarities between a digital signature and a handwritten signature?
• Differentiate among the three different classes of digital signatures.