Information Security 05- Encryption.pdfn

Encryption
• Encryption is a fundamental technique used in information
security
to protect the confidentiality and integrity of data.
• It involves the process of converting plain text or data
into an encoded form called ciphertext, which can only
be accessed and understood by authorized parties with the
corresponding decryption key.

Encryption
cont… Key
Terms
• Cryptography comes from the Greek words kryptos,
meaning “hidden,”
and graphein, meaning “to write,” and involves making and using
codes to secure messages.
• Cryptanalysis involves cracking or breaking encrypted
messages back into their unencrypted origins.
• Cryptography uses mathematical algorithms that are usually known to
all.

Encryption
cont… Key
Terms
• After all, cryptography is not the knowledge of the algorithm
that
protects the encrypted message, it’s the knowledge of the
key, a series of characters or bits injected into the
algorithm along with the original message to create the
encrypted message.

Encryption
cont… Key
Terms
• Cipher: When used as a verb, the transformation of the
individual components (characters, bytes, or bits) of an
unencrypted message into encrypted components or vice
versa;
• Cipher: When used as a noun, the process of encryption
or the algorithm used in encryption, and a term
synonymous with cryptosystem.

Encryption
cont… Key
Terms
• Encryption(Encipher):The process of
converting
an
origin
al
message (plaintext) into a form that cannot be used by
unauthorized
individuals (ciphertext). Also referred to as enciphering.
• Encryption renders the data contents to unreadable and
inaccessible form, unless one have the decryption key.

Encryption
cont… Key
Terms
• Decryption (Decipher): The process of converting an
encoded or enciphered message (ciphertext) back to its
original readable form (plaintext). Also referred to as
deciphering.
• Decryption requires two elements: the correct
password and the
corresponding decryption algorithm.

Encryption
cont… Key
Terms
• Plaintext or cleartext: is an
unencrypted, readable, plain message
that anyone can read.
• Ciphertext: is the result of the encryption process.
• The encrypted plaintext appears as
apparently random strings of characters.

Encryption
cont… Key
Terms
• Algorithm: The mathematical formula or method used to
convert an
unencrypted message into an encrypted message.
• This sometimes refers to the programs that enable the
cryptographic processes.
• Code: The process of converting components (words/
phrases) of an
unencrypted message into encrypted components.

Encryption
cont… Key
Terms
• Bit stream cipher: An encryption method that involves
converting plaintext to ciphertext one bit at a time.
• Block cipher: An encryption method that involves
dividing the plaintext into blocks or sets of bits and then
converting the plaintext to ciphertext one block at a time.

Encryption
cont… Key
Terms
• Key or cryptovariable: The information used in conjunction
with the algorithm to create the ciphertext from the
plaintext; it can be a series of bits used in a
mathematical algorithm or the knowledge of how to
manipulate the plaintext.
• Key tells the algorithm how to transform the plaintext into
ciphertext.

Encryption
cont… Key
Terms
• Kerckhoffs's principle states that “only
secrecy of the key provides security”.
• Another law states that: “encrypted data is only as
secure as its decryption key”.
• These statements influence the role of encryption, and keys.

Encryption
cont… Key
Terms
• Keeping the details of an entire
encryption
algorithm secret
is
extremely difficult; keeping a much smaller key secret is
easier.
• The key locks and unlocks the algorithm, allowing the
encryption or decryption process to function.
• Keyspace: The entire range of values that can be used to
construct an individual key.

Encryption
cont… Key
Terms
• Link encryption: A series of encryptions and decryptions
between a number of systems, wherein each system in
a network decrypts the message sent to it and then
reencrypts the message using different keys and sends it
to the next neighbor.
• This process continues until the message reaches the
final destination.

Encryption
cont… Key
Terms
• Steganography: The process of hiding messages; for
example, hiding a message within the digital encoding
of a picture or graphic so that it is almost impossible to
detect that the hidden message even exists.
• Work factor: The amount of effort (usually expressed in units
of time)
required to perform cryptanalysis on an encoded message.

Encryption
cont… Key
Terms
• Hash: When a website encrypts your password, it uses an
encryption algorithm to convert your plaintext password to a
hash.
• A hash is different from encryption in that once the data is
hashed, it cannot be unhashed. Or rather, it is extremely
difficult.
• Hashing is really useful when you need to verify

Encryption
cont… Key
Terms
• Symmetric and Asymmetric Algorithms:
two primary encryption
algorithm types: symmetric and asymmetric.
• They both encrypt data, but function in a slightly different
manner.

Encryption
cont… Key
Terms
• Symmetric algorithm: Also known as
secret-key encryption, private
Key encryption or shared-key encryption.
• Uses the same key for both encryption and decryption.
• Both parties must agreeon the algorithm key before
commencing communication.

Encryption
cont… Key
Terms
• Symmetric Encryption Algorithms types: 8. RC6
1. Advanced Encryption Standard (AES) 9. Serpent
2. Data Encryption Standard (DES) 10. Camellia
3. Triple Data Encryption Standard (3DES) 11. CAST-
128
4. Blowfish 12. CAST-
256
5. Twofish 13. IDEA
6. RC4 14. SEED
7. RC5 15. Skipjack

Encryption
cont… Key
Terms
• Advanced Encryption
Standard (AES): A widely
use
d
symmetri
c
encryption algorithm known for its security and
efficiency.
• It supports key sizes of 128, 192, or 256 bits.

Encryption
cont… Key
Terms
• Data Encryption Standard (DES): An
older symmetric encryption
algorithm that uses a 56-bit key.
• While DES is considered less secure by today's standards, it
still finds some limited use.

Encryption
cont… Key
Terms
• Triple Data Encryption Standard (3DES): It applies the DES
algorithm
three times to each data block, providinga higher level of
security than DES.
• 3DES supports key sizes of 112 or 168 bits.

Encryption
cont… Key
Terms
Average Time Required for Exhaustive Key Search

Encryption
cont… Key
Terms
• Asymmetric algorithm: Also known as public-key
encryption.
• Uses two different keys: a public key and a private
key.
• This enables secure encryptionwhile
communicating previously establishing a mutual
algorithm.
without
• This is also known as public key
cryptology.

Encryption
cont… Key
Terms
• Asymmetric Encryption Algorithms:
1. Rivest-Shamir-Adleman (RSA)
2. Elliptic Curve Cryptography
(ECC)
3. Diffie-Hellman (DH)
4. Digital Signature Algorithm
(DSA)
5. ElGamal
6. Paillier
7. McEliece
8. NTRU
9. Lattice-based encryption
algorithms
a. Learning With Errors (LWE)
b. Ring Learning With Errors (RLWE)
c. NTRU Prime
a.
b.
a.
b.
c.
d.
e.
f.
10. Merkle-Damgård-based Signature
Scheme
(MSS)
11. RSA-KEM
12. Identity-Based Encryption (IBE)
13. Attribute-Based Encryption (ABE)
14. Homomorphic Encryption
Partially Homomorphic
Encryption Fully Homomorphic
Encryption
15. Post-Quantum Cryptography (PQC)
algorithms (designed to resist attacks by
quantum computers)
Code-based
Cryptography Lattice-
based Cryptography
Multivariate
Cryptography
Supersingular Isogeny Diffie-Hellman
(SIDH) Hash-based Cryptography

Encryption
cont… Key
Terms
• Rivest-Shamir-Adleman (RSA):
One of the
asymmetric encryption algorithms.
mos
t
widel
y
use
d
• It usesthe conceptof public and private key pairs,with
encryption
performed using the public key and decryption using the
corresponding private key.

Encryption
cont… Key
Terms
• Elliptic Curve Cryptography (ECC): An
asymmetric
encryptio
n
algorithm that is gainingpopularity due to its strong security with
shorter key lengths compared to RSA.
• ECC uses the mathematical properties of elliptic curves for
encryption and decryption.

Encryption
cont… Key
Terms
• Diffie-Hellman (DH): Although notstrictly an
encryption algorithm,
Diffie-Hellman is a key exchangeprotocol used in
asymmetric encryption systems.
• It allows two parties to securely establish a shared secret key
over an insecure channel.

Encryption
cont… Key
Terms
• Public and Private Keys: Now we understand more about the
function of
keys in the encryption process, we can look at public and private
keys.
• An asymmetric algorithm uses two keys: a public key and a private
key.
• The public key can be sent to other people, while the private
key is only known by the owner. What's the purpose of this?

Encryption
cont… Key
Terms
• Well, anyone with the intended recipient's public key can
encrypt a
private message for them, while the recipient can only
read the contents of that message provided they have
access to the paired private key.

Encryption
cont… Key
Terms
• Public and private keys also play an
essential
role in
digital
signatures, whereby a sender can sign their message
with their
private encryption key.
• Those with the public key can then verify the message,
safe in the knowledge that the original message came
from the sender's private key.

Encryption
cont… Key
Terms
• Public and private keys also play an essential role in digital signatures,
whereby a
sender can sign their message with their private encryption key.
• Those with the public key can then verify the message, safe in the
knowledge that the original message came from the sender's private
key.
• A key pair is the mathematically linked public and private key generated
by an encryption algorithm.

Encryption
cont… Key
Terms
• HTTPS: Hyper Text Transfer Protocol Secure (HTTPS) is a
now widely
implemented security upgrade for the HTTP application protocol
that is a foundation of the internet as we know it.
• When using a HTTPS connection, your data
is encrypted using
Transport Layer Security (TLS), protecting your data while in
transit.

Encryption
cont… Key
Terms
• HTTPS generates long-term private and public keys that in
turn
are
used to create a short-term session key.
• The session key is a single-use symmetric key that the
connection destroys once you leave the HTTPS site
(closing the connection and ending its encryption).

Encryption
cont… Key
Terms
• However,when you revisitthe site,you will receiveanother single-
use
session key to secure your communication.
• A site must completely follow to HTTPS to offer users complete
security.
• Since 2018 the majority of sites online began offering HTTPS
connections over standard HTTP.

Encryption
cont… Key
Terms
• End-to-End Encryption: One of
the biggestencryption buzzwordsis
that of end-to-end encryption.
• Social messaging platform service WhatsApp began offering its
users end-to-end encryption (E2EE) in 2016, making sure
their messages are private at all times.

Encryption
cont… Key
Terms
• In the context of a messaging service, EE2E means that once
you hit
the send button, the encryption remains in place until the
recipient receives the messages.
• Well, this means that the private key used for encoding and
decoding your messages never leaves your device, in
turn ensuring that no one but you can send messages using

Information Security 05- Encryption.pdfn

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