Cryptography
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Transcript of Cryptography
‘’ The Science of Encryption ’’
• What is cryptography ?
• Why cryptography is important ?
Contents• The purpose of cryptography• History of cryptography and cryptanalysis• Modern cryptography(Types of Algorithms)
- Secret Key Cryptography- Hash Functions- Public Key Cryptography- Why Three Encryption Techniques?- The Significance of Passwords & Password Security
• Conclusion
Science of writing in secret code
THE PURPOSE OF CRYPTOGRAPHY Computer communications Data transfer and telecommunicationSpecific security requirements for communication:
Authentication:
Privacy/confidentiality:
Integrity:
Non-repudiation:
The history of cryptography can be divided into two parts:
(1) From ancient civilizations to the 19th century and the first part of the 20th century,
(2) Use of encrypting electro-mechanical machines, around the period of the WW II.
HISTORY OF CRYPTOGRAPHY
Cryptography:
Greek κρυπτός, kryptos,
"hidden, secret"
HISTORY OF CRYPTOGRAPHY
Cryptography was used in three kinds of contexts in ancient times :
Private communications
Art and religion
Military and diplomatic use
Here we have three types of algorithms that we can talk about:
MODERN CRYPTOGHRAPHY
Secret Key Cryptography
Hash Functions
Public Key Cryptography
MODERN CRYPTOGHRAPHY
Secret key
Secret Key(Symmetric) Cryptography uses a single key for both encryption and decryption.
SECRET KEY CRYPTOGHRAPHY
A single key is used
SECRET KEY CRYPTOGHRAPHY
Sender uses the key to encrypt
Receiver uses the same key to decrypt
Key must be known to both the sender and the receiver
The difficulty is the distribution of the key
Secret key cryptography algorithms that are in use today :
SECRET KEY CRYPTOGHRAPHY
Data Encryption Standard (DES):
Advanced Encryption Standard (AES):
International Data Encryption Algorithm (IDEA):
SECRET KEY SUMMARY
Hash functions(One-way cryptography) have no key since plaintext cannot be recovered from the ciphertext.
HASH FUNCTIONS
Called message compiler and one-way encryption
HASH FUNCTIONS
No key is used
Digital fingerprint
Provide the integrity
Hash algorithms that are in common use today:
HASH FUNCTIONS
Message Digest (MD) algorithms:
HAVAL (Hash of Variable Length):
Tiger:
PUBLIC KEY CRYPTOGHRAPHY
Public Key(Asymmetric) Cryptography. Two keys are used. One for encryption, one for decryption.
PUBLIC KEY CRYPTOGHRAPHY
Developed in the last 300-400 years.
Martin Hellman and graduate student Whitfield Diffie
A two-key crypto system
Mathematical functions
PUBLIC KEY CRYPTOGHRAPHY
Mathematical Functions :
Multiplication vs. factorization:
Exponentiation vs. logarithms:
PUBLIC KEY CRYPTOGHRAPHY
PUBLIC KEY SUMMARY
Why Three Encryption Techniques?
Why are there so many different types of cryptographic schemes?
Why can't we do everything we need with just one ?
Every password can be decyrpted.
THE SIGNIFICANCE OF PASSWORDS
In cryptography, size does matter.
How to create & use strong Passwords
Use lengthy passwords.
Combine letters, numbers, and symbols.
How to create & use strong Passwords
Use words and phrases.
THANK YOU FOR LISTENING TO US (: