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PRESENTED BY ARVIND SINGH Guided By
BRANCH : I.T Dr. Gaurav JainCOLLEGE : R.C.E.R.T
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Introductiony Definitions
yWhy cryptography is important?
y Encryption & Decryption
yAvailable technologies
y Benefits & problems
y Future of cryptography
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Essential Termsy Cryptography
y EncryptionPlain text Cipher text
y DecryptionCipher text Plain text
y Cryptanalysis : is the study ofmethods for obtaining the
meaning of encrypted informationy Cryptology : The practice of
analysing encoded messages, inorder to decode them.
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Encryption & Decryptiony Encryption :Encryption is
the conversion of data intoa form, called a ciphertext, that cannot be easily
understood byunauthorized people.
y Decryption : Decryptionis the process ofconverting encrypted databack into its original form,so it can be understood.
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Information Se
curity use
d fory Defending against external/internal hacker
y Securing E-commerce
y
Securing bank accounts/electronic transfersy Securing data transfer
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Thre
ats
to Information Se
curity
y Online storage of sensitiveinformation
y
Insecure technologies (e.g.wireless)
y Trend towards paperlesssociety
y Weak legal protection of email
privacy
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Types of Secret Writing
Secret writing
Steganography Cryptography
Substitution Transposition
Code
Cipher
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Steganography
y Steganography covered writing
is an art of hidinginformation
y Popularcontemporary
steganographictechnologies hideinformation inimages
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Hiding information in pictures
Image in which to hide
another image
Image to hide within the
other image
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Retrieving information from pictures
Image with other
hidden withinRecreated image
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Public Key Cryptographyy Public-key cryptography: refers to a cryptographic
system requiring two separate keys.
yOne to lock or encrypt the plain text.
y One to unlock or decrypt the cipher text.
y Neither key will do both functions.
y One of these keys is public and the other is kept
private.
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Public Key Cryptographyy Private (symmetric) key the same key
used for encryption/decryption.
y Problem of key distribution arises.
y Public (asymmetric) key cryptography apublic key used for encryption and privatekey for decryption.
y Key distribution problem solved.
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Currently Available Crypto Algorithms(private key)
DES (Data Encryption Standard) andderivatives: double DES and triple DES
IDEA (International Data Encryption Standard)
Blowfish
RC5 (Rivest Cipher #5)
AES (Advance Encryption Standard)
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Currently Available Crypto Algorithms(public key)
RSA (Rivest, Shamir, Adleman)
DH (Diffie-Hellman Key AgreementAlgorithm)
ECDH (Elliptic Curve Diffie-Hellman KeyAgreement Algorithm)
RPK (Raike Public Key)
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Currently Available Technologies
PGP (Pretty Good Privacy) a hybrid
encryption technologyy Message is encrypted using a private key
algorithm (IDEA)
y Key is then encrypted using a public keyalgorithm (RSA)
y For file encryption, only IDEA algorithm is usedy PGP is free for home use
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Authe
ntication and DigitalSignatures
Preventing impostor attacks
Preventing content tampering
Preventing timing modification
Preventing repudiation
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Digital Signatures
y It is made by encrypting a message with
the senders private keyy Receiver decrypts with the senders public
key (roles of private and public keys areflipped)
y
Digital signature does not confirm identity
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J
AVA and XML Cryptography
y java.security package includes classes used
for authentication and digital signaturey javax.crypto package contains JavaCryptography Extension classes
yXMLmakes it possible to encrypt or
digitally sign parts of a message, differentencryption for different recipients, etc.
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Benefits of Cryptographic Technologies
y Data secrecy
y Data integrity
yAuthentication ofmessage originator
y Electronic certificationand digital signature
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Problems with Cryptographic Technologies?
y False sense of security ifbadly implemented
y Government regulation ofcryptographic technologiesrestrictions
y Encryption prohibited in
some countries
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H
ow Se
cure
are
Todays
Te
chnologies?
y Encryption does not guarantee security!
y Many ways to beat a crypto system NOTdependent on cryptanalysis, such as:y Viruses, worms, hackers, etc.
y TEMPEST attacks,
y Unauthorized physical access to secret keys
y
Cryptography is only one element ofcomprehensive computer security
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The Future of Secret Writing
Quantum cryptanalysisy A quantum computer can
perform practically unlimited
number of simultaneouscomputations
y Factoring large integers is anatural application for aquantum computer
y Quantum cryptanalysis wouldrender ALLmoderncryptosystems instantly obsolete
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The Future of Secret Writing (continued)
Quantum encryptiony
No need for a quantum computery A key cannot be intercepted without
altering its content
y It is theoretically unbreakable
y Central problem is transmitting a
quantum message over a significantdistance
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Summaryy Cryptography referred almost exclusively
to encryption, which is the process of
converting plaintext into cipher text.y Decryption is the reverse, in other words,
moving from the cipher text back to plain text.
Acipheris a pair of algorithms that create the
encryption and the reversing decryption. The detailedoperation of a cipher is controlled both by thealgorithm and in each instance by a key.
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