Cryptography and Network B.Tech
Security
UNIT- I:
Basic Principles
Security Goals, Cryptographic Attacks, Services and Mechanisms, Mathematics of Cryptography
WHAT IS NETWORK SECURITY ?
Network Security consists of the provisions and policies adapted by network Administrator to prevent and
monitor unauthorized access, misuse, modification, or denial of a computer network and network-accessible
resources.
WHAT IS CRYPTOGRAPHY?
Cryptography is the study of secure communications techniques that allow only the sender and intended
recipient of a message to view its contents.
The term is derived from the Greek word kryptos, which means hidden.
MODEL FOR NETWORK SECURITY - TERMINOLOGY
Plaintext - the original message
Cipher text - the coded message
Cipher - algorithm for transforming plaintext to cipher text
Key - info used in cipher known only to sender/receiver
Encipher (Encrypt) - converting plaintext to cipher text
Decipher (Decrypt) - recovering cipher text from plaintext
Cryptography - study of encryption principles/methods
Cryptanalysis (code breaking) - the study of principles/ methods of deciphering cipher text
without knowing key
Cryptology - the field of both cryptography and cryptanalysis
, Cryptography and Network B.Tech
Security
SECURITY GOALS
Cryptographic Attacks
Accessing of data by unauthorized entity is called as attack
Passive Attacks
Active Attacks
Passive Attacks:
In a passive attack, the attacker’s goal is just to obtain information. This means that the attack does not
modify data or harm the
system.Active Attacks:
An active attack may change the data or harm the system. Attacks that threaten the integrity and
availabilityare active attacks.
Passive Attacks
(a) Release of message content –
Capture and read the content transmissions.
(b) Traffic Analysis–
can’t read the information, but observe the pattern
determine the location and identity of communicating parties
observe frequency and length of communication
, Cryptography and Network B.Tech
Security
Active Attacks
(a) Masquerading: Masquerading or snooping happens when the attacker impersonates somebody else.
(b) Replay–
The attacker obtains a copy of a message sent by a user and later tries to replay it.
Security
UNIT- I:
Basic Principles
Security Goals, Cryptographic Attacks, Services and Mechanisms, Mathematics of Cryptography
WHAT IS NETWORK SECURITY ?
Network Security consists of the provisions and policies adapted by network Administrator to prevent and
monitor unauthorized access, misuse, modification, or denial of a computer network and network-accessible
resources.
WHAT IS CRYPTOGRAPHY?
Cryptography is the study of secure communications techniques that allow only the sender and intended
recipient of a message to view its contents.
The term is derived from the Greek word kryptos, which means hidden.
MODEL FOR NETWORK SECURITY - TERMINOLOGY
Plaintext - the original message
Cipher text - the coded message
Cipher - algorithm for transforming plaintext to cipher text
Key - info used in cipher known only to sender/receiver
Encipher (Encrypt) - converting plaintext to cipher text
Decipher (Decrypt) - recovering cipher text from plaintext
Cryptography - study of encryption principles/methods
Cryptanalysis (code breaking) - the study of principles/ methods of deciphering cipher text
without knowing key
Cryptology - the field of both cryptography and cryptanalysis
, Cryptography and Network B.Tech
Security
SECURITY GOALS
Cryptographic Attacks
Accessing of data by unauthorized entity is called as attack
Passive Attacks
Active Attacks
Passive Attacks:
In a passive attack, the attacker’s goal is just to obtain information. This means that the attack does not
modify data or harm the
system.Active Attacks:
An active attack may change the data or harm the system. Attacks that threaten the integrity and
availabilityare active attacks.
Passive Attacks
(a) Release of message content –
Capture and read the content transmissions.
(b) Traffic Analysis–
can’t read the information, but observe the pattern
determine the location and identity of communicating parties
observe frequency and length of communication
, Cryptography and Network B.Tech
Security
Active Attacks
(a) Masquerading: Masquerading or snooping happens when the attacker impersonates somebody else.
(b) Replay–
The attacker obtains a copy of a message sent by a user and later tries to replay it.
