... is a so-called ''keyed hash'' function.

... is an authentication protocol for key distribution.

... is a tool for email encryption.

... was one of the finalist block ciphers of the AES challenge.

MAC = hash(hash(key||message))

MAC = half of hash(key||message)

MAC = hash(message||key)

MAC = hash(key||message)

username, salt, hash(salt||password)

username, hash(salt||password)

username, salt, hash(password)

username, hash(salt), hash(salt||password)

Someone was able to brute-force its n-bit key in less than 2^(n-1) steps.

Someone found a pre-image to a given image (i.e., the one-wayness has been broken)

Someone found a collision, i.e., two pre-images x<>y that hash to the same image h( x ) = h( y )

Someone was able to find a collision in less than 2^(k/2) steps (for a k-bit hash)

SHA-1 is more computationally expensive than MD5

MD5 does not work on an extremely large input (over 2^64 bits) while SHA-1 does

SHA-1 supports key sizes of up to 160 bits while MD5 only has 128-bit keys

MD5, also called SHA-3, is an updated version of SHA-1

Most modern security protocols use an ECC cipher by default

The security of ECC relies on solving the elliptic curve discrete log problem (ECDLP), which should be hard

According to the NSA, ECC ciphers are more resistant to quantum computer attacks than RSA

ECC keys are significantly shorter than RSA keys for the same level of security

Hashes can be computed without knowing any key

Hashes can be used to provide confidentiality

Hashes can be used to provide authenticity

Hashes can be used to provide integrity

... 150000 bits.

... 1500 bits.

... 15000 bits.

... 150 bits.

The birthday paradox only applies to ciphers operating within GF(2)

The birthday paradox governs how soon one can, statistically, find a collision (any collision) for a hash

The birthday paradox only applies to one particular hash, MD5

The birthday paradox governs how easy it is to break a symmetric cipher

Yes, but only if we use a symmetric cipher such DES or AES

Yes, if there is a known structure in the message (e.g., a certain file format or an error-correcting code)

No, encryption can never provide authenticity

Yes, but only if we use an asymmetric cipher such as RSA or ECC