# Fundamentals of Encryption

What is a digital signature?

> A piece of encrypted data added to other data to verify the sender

Which of the following uses key sizes equal to 128, 192 and 256 bits?

> AES

Blowfish is an asymmetric stream cipher

> False

Which hashing algorithm do modern Windows systems use?

> NTLM

Secure Multipurpose Internet Mail Extensions (S/MIME) use X.509 certificates to secure e-mail communication

> True

Which encryption algorithm uses a variable length symmetric key?

> Blowfish

Which of the following is a symmetric key system using blocks?

> DES

What is the purpose of a certificate?

> To validate the sender of a digital signature or software

Which of the following is an encryption method developed by three mathematicians?

> RSA

Which of the following encryption algorithms is a block cipher and uses the Rijndael algorithm?

> AES