The document defines different types of attacks on cryptography systems including passive and active attacks. Passive attacks attempt to learn information without affecting system resources, while active attacks try to alter system operations. The document also discusses cryptography, defining it as the practice of hiding information and converting plain text into unintelligible cipher text. Symmetric key cryptography uses a shared key for encryption and decryption, while asymmetric key cryptography uses public and private key pairs.

1. Cryptography and Attacks
Prof. Neeraj Bhargava
Astha Parihar
Department Of Computer Science
School and Engineering and System
Science
MDS University, Ajmer

2. Basic Definition of Attacks
An attack is an information security
threat that involves an attempt to obtain,
alter, destroy, remove, implant or reveal
information without authorized access or
permission.

4. Passive Attack
 A Passive attack attempts to learn
or make use of information from the
system but does not affect system
resources.
Example: Eavesdropping or
Monitoring.

5. Active Attack
An Active attack attempts to alter
system resources or effect their
operations. Active attack involve some
modification of the data stream or
creation of false statement.

6. Cryptography
Cryptography derived its name from a
Greek word called “krypto’s” which
means “Hidden Secrets”
Cryptography is the practice and
study of hiding information. It is the
Art or Science of converting a plain
intelligible data into an unintelligible
data and again retransforming that
message into its original form.

8. Vocabulary
Plain Text: The original message that the sender
sends to the receiver.
Example: You are very beautiful.
Encryption: Encryption is a process that encodes
a message or file so that it can be only be read by
certain people. Encryption uses an algorithm to
scramble, or encrypt, data and then uses a key for
the receiving party to unscramble, or decrypt, the
information.

9. Cipher Text: Cipher text is encrypted text
transformed from plaintext using an
encryption algorithm.
Decryption: The process of reverting
cipher text to its original plaintext is called
decryption.
Cryptanalysis: The art of breaking
ciphers, i.e. retrieving the plain text without
knowing the key.

11. Symmetric Key Cryptography
The encryption process where same keys
are used for encrypting and decrypting the
information is known as Symmetric Key
Encryption.
Both sender and receiver uses a common
key to encrypt and decrypt the message.

13. Asymmetric Key Cryptography
Public key cryptography is an asymmetric
scheme that uses a Pair of keys for
encryption: a Public key, which encrypts
data, and a corresponding Private key
(secret key) for decryption.
Sender and receiver use different keys to
encrypt and decrypt the message.

15. References
 https://www.tutorialspoint.com/cryptography/attacks_on_crypt
osystems.htm
 https://www.geeksforgeeks.org/active-and-passive-attacks-in-
information-security/
 https://www.acquireforensics.com/blog/attacks-in-
cryptography-network-security-types.html
 http://www.ncsa.illinois.edu/People/ncsairst/pgp/IntroToCrypt
o.pdf
 https://www.thecrazyprogrammer.com/2019/07/types-of-
cryptography.html