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Crypt Final Ppt

Apr 06, 2018

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    UDITA SHAH

    ECE-B

    8TH SEMESTER

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    WHAT IS CRYPTOGRAPHY?y Cryptography is the practice and study of hiding information.

    Modern cryptography intersects the disciplines of mathematics,

    computer science and electrical engineering.

    y Cryptanalysis -term used for the study of methods for obtaining

    the meaning of encrypted information without access to the key

    normally required to do so; i.e., it is the study of how to crack

    encryption algorithms or their implementations.

    y A basic task in cryptography is to enable users to communicate

    securely over an insecure channel in a way that guarantees their

    transmissions' privacy and authenticity.

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    TYPES OF CRYPTOGRAPHY

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    SECRET KEY CRYPTOGRAPHY

    y Also known as symmetric key cryptography.

    y Single key used to encrypt and decrypt.

    y Key must be known to both the parties.

    y Method works well only for limited number of people.

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    Plaintext encryption Cipher text decryption plaintext

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    PUBLIC KEY CRYPTOGRAPHY

    y Also calledasymmetric encryption.

    y Uses a pair of keys for encryption anddecryption.

    y Has 2 keys-

    1. private key (a secret)

    2. public key (well known)

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    plaintext encryption Cipher text decryption Plaintext

    Public key Private key

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    DIGITAL SIGNAL ALGORITHM Public key cryptography is also used to provide digitalPublic key cryptography is also used to provide digital

    signatures.signatures.

    signingsigningPlaintextPlaintext------------------------------ signed messagesigned message

    private keyprivate key

    verificationverificationsigned messagesigned message -------------------------------------- plaintextplaintext

    public keypublic key

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    TYPES OF ATTACK

    y Passive Attack:

    Carried out by a PassiveAttacker who can only

    readthe secret information being exchanged.

    yActive Attack:

    Carried

    out

    by anA

    ctiv

    eIn

    tru

    der who can r

    ea

    dand modifythe secret information.

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    Passive Attacks

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    Active Attacks

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    WHY DO WE NEED CRYPTOGRAPHY?

    Computers are used by millions of people for manypurposes-

    BankingShopping

    Tax return

    Military

    Student records

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    y Privacy is very important in all these applications. Itis a service usedto keep the content of informationfrom all butthose authorizedto posses it.

    y Data integrity is a service which addresses the

    unauthorized alteration ofdata.yAuthentication is a service relatedto identification.

    Two parties entering into a communication shouldidentifyeach other.

    y Non- repudiation is a service which prevents anentity from denying previous commitments or actions.

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    ADVANTAGES AND DISADVANTAGES

    ADVANTAGES:

    y The biggest advantage of public key cryptographyis the secure nature ofthe private key. In fact, itnever needs to betransmitted or revealedtoanyone.

    y Itenables the use ofdigital signatures, which is avery securetechnique of signature authorization.

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    DISADVANTAGES:

    y Transmission time for documents encrypted usingpublic key cryptography are significantly slowerthen symmetric cryptography.

    y Public key cryptography is susceptibletoimpersonation attacks.

    y public-key cryptography is usually not necessary ina single-user environment. For example, if youwantto keep your personal files encrypted, youcan do so with any secret- keyencryptionalgorithm using, say, your personal password asthe secret key.

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    HOW CRYPTO SYSTEM

    FAIL??y Crypto system fails by falling into either ofthetwo

    categories, in the cipher itself or in the operatingenvironment.

    The cipher is the mechanism by which wetransferplain textto cipher text.

    The operating environment in which code is usedincludes the rules of handling plaintext,distribution

    of keys, roles of people involve and physical protectiongiven to various elements.

    Cracking a code involves either an attack on code itselfor on way it is used.

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    CONCLUSION

    Cryptography has undergonetremendous development

    sincethedays it had comeinto existence some 4000years ago.Developments arealso taking place in the areaofdigital Steganography,

    quantum cryptography,etc.

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    THANKYOU !