pgp

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SIMULATION OF PGP

• -Sk.Shapeer Hussain,
• Final year (B.Tech),
• V.R.S.E.C.

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INTRODUCTION

• 5 Basic functions
• Authentication
• Hashing MD5, SHA
• Encryption RSA
• Confidentiality
• CAST-128, IDEA
• Compression
• ZIP
• E-mail Compatibility
• Radix-64 conversion
• Segmentation and reassembly

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OVERVIEW OF PGP
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Working of PGP
Concatenation of P and signed hash of P
Alices private key

• RSA

P1.z
P
MD5
RSA
ZIP
IDEA
BASE64
P1
Plain text
P1 compressed
ASCII text To network
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Authentication of PGP

• At the Sender-
• Prompt the message
• Prompt the key
• Generate hash code
• Encrypt hash code
• Transmit encrypted code message

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Authentication(2)

• At the Receiver-
• - Decrypt the hash code
• - Generate the hash code for the message
• - Compare the hash codes
• - If same message is authenticated else
• reject it.

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Functional Requirements

• Hash Function
• MD5 (Message Digest 5)
• Encryption Algorithm
• RSA ( Rivest-Shamir-Adleman)

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Hash Function

• h H( M )
• M Message
• H Hash Function
• h Hash Code
• Block of any size
• Fixed length output

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Encryption Algorithm

• Key Generation private and public key pairs
• Public key encryption
• D( E( P )) P
• P Plain text
• E Encryption
• D - Decryption

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MODULES

• 2 Modules
• MD5
• RSA

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Module 1

• Append padding bits
• Append length
• Initialize MD (Message Digest Buffer)
• Process message in 512 blocks
• 4 rounds

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Module 2

• Key generation
• Choose 2 prime numbers p, q
• Compute np q and z(p-1) (q-1)
• Choose a number d relatively prime to z
• Find e such that ed 1 mod z
• Encryption Decryption
• C P e (mod) n
• P C d (mod n)

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Security of RSA

• Brute Force all possible keys
• Mathematical attacks factoring the product into
  prime numbers
• Timing attacks Running time of decryption
  algorithm

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Advantages of PGP

• Best available cryptographic algorithms
• Run on a variety of platforms
• Integration of these algorithms into a
  general-purpose application that is independent
  of operating system and processor

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QUERIES
QUERIES
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THANQ