C836 WGU Review Exam Questions
with 100% Correct Answers.
Protecting data in motion
is vital as well because of the enormous amount of business that is conducted over the
Internet, including financial transactions, medical information, tax filings, and other similarly
sensitive exchanges
Symmetric cryptography
________________ ______, also known as private key cryptography, utilizes a single key for
both encryption of the plaintext and decryption of the ciphertext.
Asymmetric cryptography
______________ , also known as public key cryptography, utilizes two keys: a public key and a
private key. The public key is used to encrypt data sent from the sender to the receiver and
is shared with everyone.
Hash functions:
represent a third cryptography type alongside symmetric and asymmetric cryptography, what we
might call keyless cryptography. _____________ also referred to as message digests, do not use
a key, but instead create a largely unique and fixed-length hash value, commonly referred to as a
,hash, based on the original message, something along the same lines as a fingerprint. Any slight
change to the message will change the hash
Digital signatures:
_____________ allow us to sign a message in order to enable detection of changes to the
message contents, to ensure that the message was legitimately sent by the expected party, and
to prevent the sender from denying that he or she sent the message, known as nonrepudiation.
Certificates:
___________ are created to link a public key to a particular individual and are often used as a
form of electronic identification for that particular person. A certificate is typically formed by
taking the public key and identifying information, such as a name and address, and having
them signed by a certificate authority (CA).
block ciphers and stream ciphers
Symmetric key cryptography makes use of two types of ciphers
Block cipher
takes a predetermined number of bits, known as a block, in the plaintext message and encrypts
that block. Blocks are commonly composed of 64 bits but can be larger or smaller depending
on the particular algorithm being used and the various modes in which the algorithm might be
capable of operating.
Stream cipher
encrypts each bit in the plaintext message, 1 bit at a time.
.
A large majority of the encryption algorithms in use at present are block ciphers. Although
block ciphers are often slower than stream ciphers, they tend to be more efficient. Since block
ciphers operate on larger blocks of the message at a time, they do tend to be more resource
intensive and are more complex to implement in hardware or software
Block ciphers
,____________ are also more sensitive to errors in the encryption process as they are working
with more data. An error in the encryption process of a block cipher may render unusable a
larger segment of data than what we would find in a stream cipher, as the stream cipher
would only be working with 1 particular bit
DES
is a block cipher based on symmetric key cryptography and uses a 56-bit key. Although DES
was considered to be very secure for some period of time, it is no longer considered to be so.
3DES
which is simply DES used to encrypt each block three times, each time with a different key. DES
can operate in several different block modes, including Cipher Block Chaining (CBC),
Electronic CodeBook (ECB), Cipher Feedback (CFB), Output Feedback (OFB), and Counter
Mode (CTR). Each mode changes the way encryption functions and the way errors are handled.
AES
is a set of symmetric block ciphers endorsed by the US government through NIST, and now
used by a variety of other organizations, and is the replacement for DES as the standard
encryption algorithm for the US federal government. AES uses three different ciphers: one with
a 128-bit key, one with a 192-bit key, and one with a 256-bit key, all having a block length of
128 bits. AES shares the same block modes that DES uses and also includes other modes such as
XEX-based Tweaked CodeBook (TCB) mode.
,
There are a large number of other well-known symmetric block ciphers, including Twofish,
Serpent, Blowfish, CAST5, RC6, and IDEA, as well as stream ciphers, such as RC4, ORYX, and
SEAL
Protecting Data at Rest
Data is generally considered to be at rest when it is on a storage device of some kind and is
not moving over a network, through a protocol, and so forth.
Data security
, The primary method we use to protect this type of data is encryption, particularly when we know
that the storage media, or the media and the device in which it is contained, will be potentially
exposed to physical theft, such as on a backup tape or in a laptop.
Physical security
If we make it more difficult for attackers to physically access or steal the storage media on which
our sensitive data is contained, we have solved a large portion of our problem.
.
Physical security should be at the core of all our security planning discussions.
,
The main advantage of asymmetric key cryptography over symmetric key cryptography is the
loss of the need to distribute the key. As we discussed earlier in this lesson, when we use a
symmetric algorithm, we need to distribute the key in some way. We might do this by
exchanging keys in person, sending a key in e-mail, or repeating it verbally over the phone, but
we generally need to communicate the key in an out-of-band manner, meaning that we do not
want to send the key with the message, as this would leave our message easily available to an
eavesdropper. When we use asymmetric key cryptography, we have no need to share a single
key. We simply make our public key easily available, and anyone who needs to send us an
encrypted message makes use of it.
The RSA algorithm
named for its creators Ron Rivest, Adi Shamir, and Leonard Adleman, is an asymmetric
algorithm used all over the world, including in the Secure Sockets Layer (SSL) protocol, which
is used to secure many common transactions such as Web and e-mail traffic. RSA was created in
1977 and is still one of the most widely used algorithms in the world to this day.
Elliptic curve cryptography (ECC)
is a class of cryptographic algorithms, although it is sometimes referred to as though it were
an algorithm in and of itself. ECC is named for the type of mathematical problem on which its
cryptographic functions are based.
with 100% Correct Answers.
Protecting data in motion
is vital as well because of the enormous amount of business that is conducted over the
Internet, including financial transactions, medical information, tax filings, and other similarly
sensitive exchanges
Symmetric cryptography
________________ ______, also known as private key cryptography, utilizes a single key for
both encryption of the plaintext and decryption of the ciphertext.
Asymmetric cryptography
______________ , also known as public key cryptography, utilizes two keys: a public key and a
private key. The public key is used to encrypt data sent from the sender to the receiver and
is shared with everyone.
Hash functions:
represent a third cryptography type alongside symmetric and asymmetric cryptography, what we
might call keyless cryptography. _____________ also referred to as message digests, do not use
a key, but instead create a largely unique and fixed-length hash value, commonly referred to as a
,hash, based on the original message, something along the same lines as a fingerprint. Any slight
change to the message will change the hash
Digital signatures:
_____________ allow us to sign a message in order to enable detection of changes to the
message contents, to ensure that the message was legitimately sent by the expected party, and
to prevent the sender from denying that he or she sent the message, known as nonrepudiation.
Certificates:
___________ are created to link a public key to a particular individual and are often used as a
form of electronic identification for that particular person. A certificate is typically formed by
taking the public key and identifying information, such as a name and address, and having
them signed by a certificate authority (CA).
block ciphers and stream ciphers
Symmetric key cryptography makes use of two types of ciphers
Block cipher
takes a predetermined number of bits, known as a block, in the plaintext message and encrypts
that block. Blocks are commonly composed of 64 bits but can be larger or smaller depending
on the particular algorithm being used and the various modes in which the algorithm might be
capable of operating.
Stream cipher
encrypts each bit in the plaintext message, 1 bit at a time.
.
A large majority of the encryption algorithms in use at present are block ciphers. Although
block ciphers are often slower than stream ciphers, they tend to be more efficient. Since block
ciphers operate on larger blocks of the message at a time, they do tend to be more resource
intensive and are more complex to implement in hardware or software
Block ciphers
,____________ are also more sensitive to errors in the encryption process as they are working
with more data. An error in the encryption process of a block cipher may render unusable a
larger segment of data than what we would find in a stream cipher, as the stream cipher
would only be working with 1 particular bit
DES
is a block cipher based on symmetric key cryptography and uses a 56-bit key. Although DES
was considered to be very secure for some period of time, it is no longer considered to be so.
3DES
which is simply DES used to encrypt each block three times, each time with a different key. DES
can operate in several different block modes, including Cipher Block Chaining (CBC),
Electronic CodeBook (ECB), Cipher Feedback (CFB), Output Feedback (OFB), and Counter
Mode (CTR). Each mode changes the way encryption functions and the way errors are handled.
AES
is a set of symmetric block ciphers endorsed by the US government through NIST, and now
used by a variety of other organizations, and is the replacement for DES as the standard
encryption algorithm for the US federal government. AES uses three different ciphers: one with
a 128-bit key, one with a 192-bit key, and one with a 256-bit key, all having a block length of
128 bits. AES shares the same block modes that DES uses and also includes other modes such as
XEX-based Tweaked CodeBook (TCB) mode.
,
There are a large number of other well-known symmetric block ciphers, including Twofish,
Serpent, Blowfish, CAST5, RC6, and IDEA, as well as stream ciphers, such as RC4, ORYX, and
SEAL
Protecting Data at Rest
Data is generally considered to be at rest when it is on a storage device of some kind and is
not moving over a network, through a protocol, and so forth.
Data security
, The primary method we use to protect this type of data is encryption, particularly when we know
that the storage media, or the media and the device in which it is contained, will be potentially
exposed to physical theft, such as on a backup tape or in a laptop.
Physical security
If we make it more difficult for attackers to physically access or steal the storage media on which
our sensitive data is contained, we have solved a large portion of our problem.
.
Physical security should be at the core of all our security planning discussions.
,
The main advantage of asymmetric key cryptography over symmetric key cryptography is the
loss of the need to distribute the key. As we discussed earlier in this lesson, when we use a
symmetric algorithm, we need to distribute the key in some way. We might do this by
exchanging keys in person, sending a key in e-mail, or repeating it verbally over the phone, but
we generally need to communicate the key in an out-of-band manner, meaning that we do not
want to send the key with the message, as this would leave our message easily available to an
eavesdropper. When we use asymmetric key cryptography, we have no need to share a single
key. We simply make our public key easily available, and anyone who needs to send us an
encrypted message makes use of it.
The RSA algorithm
named for its creators Ron Rivest, Adi Shamir, and Leonard Adleman, is an asymmetric
algorithm used all over the world, including in the Secure Sockets Layer (SSL) protocol, which
is used to secure many common transactions such as Web and e-mail traffic. RSA was created in
1977 and is still one of the most widely used algorithms in the world to this day.
Elliptic curve cryptography (ECC)
is a class of cryptographic algorithms, although it is sometimes referred to as though it were
an algorithm in and of itself. ECC is named for the type of mathematical problem on which its
cryptographic functions are based.
