Cryptography and Digital Signatures

Deciphering the concept behind Cryptology and its applications

Presented By:[ Catalyst ]

Cryptology

•Cryptography.•Cryptanalysis.

Confidentiality.Data integrity.Authentication.Non-repudiation

Why do we need such operations on the Data ???

Cryptography

•Plain Text Unencrypted Data•Cipher Text Encrypted Data•Keys Decrypt Data

Plain Text Key

Cipher Text

+Security ??Algorithm Strength.Key Secrecy.

Cryptography•Encryption.•Decryption.

Cipher Text

Plain Text Input

KEYS

Types of Cryptography

Symmetric

Cryptography

Asymmetric Cryptography

KEYS ?Very Large NumbersLength is measeared

in Bits

Symmetric Cryptography• Use of same Key.• Requires only one key • Also called Secret key Cryptography. Ex: DES, IDEA , Blowfish.• Very Fast

CATALYST{Plaintext}

ROT13{Key}

ROT13{Key}

PNGNYLFG{Encrypted Message }

+Encryption

+

Decryption

Decryption

Asymmetric Cryptography

•Public-key Cryptography.•Uses pair of cryptographic Keys !

• These keys have mathematical relation.• To encrypt Plaintext & verify Signature Public key is used.• Decrypt cipher text & create Digital Signature Private key is

Used.• Functions are inverse of each other.• It is not possible to Determine a private key from a public key.• Ex : RSA , ElGamal , DSS

Public Key Private Key

############HASH#############• It is an Algorithm.• One way Encryption. • Maps Data .• Generate fixed length Output Data• The output is called Hash Value/Hashes.• Easy to compute the hash value for any given message• It is infeasible to generate a message that has a given hash.• It is infeasible to modify a message without changing the hash.• It is infeasible to find two different messages with the same

hash.• Used to verify Integrity of file or messages.• Password Verification.• Ex : MD5, SHA1, SHA2, PANAMA , Gost

DIGITAL SIGNATURES

Digital Signatures