Network security CS6

Network Security
CS-6(CH11-12)
By: Prof. Ganesh Ingle

Session 2 objective
CS-5 Revision Previous Session revision
CS -6 Modes of Operation and its applications
CS – 6 Hash Functions and Properties, Secure Hash Algorithms
(SHA),Message Authentication Codes (MAC)
CS -6 SHA-1 and SHA-3
CS-6 HMAC and CBC-MAC and its Security
SUMMARY

CS -6 Modes of Operation & its applications

CS -6 Message authentication & types

Message Encryption

Message Encryption:

Message Authentication code:

Basic Hash Function:

Hash Function: Types of Hash Functions

CS -6 SHA 1
 SHA-1 (160 bit message)
 Step 1: Append Padding Bits….
Message is “padded” with a 1 and as many 0’s
as necessary to bring the message length to
64 bits fewer than an even multiple of 512.
 Step 2: Append Length....
64 bits are appended to the end of the padded
message. These bits hold the binary format of 64
bits indicating the length of the original message.

CS -6 SHA 1
 Step 3: Prepare Processing Functions….
SHA1 requires 80 processing functions defined as:
f(t;B,C,D) = (B AND C) OR ((NOT B) AND D) ( 0 <= t <= 19)
f(t;B,C,D) = B XOR C XOR D (20 <= t <= 39)
f(t;B,C,D) = (B AND C) OR (B AND D) OR (C AND D) (40 <= t
<=59)
f(t;B,C,D) = B XOR C XOR D (60 <= t <= 79)
 Step 4: Prepare Processing Constants....
SHA1 requires 80 processing constant words defined
as:
K(t) = 0x5A827999 ( 0 <= t <= 19)
K(t) = 0x6ED9EBA1 (20 <= t <= 39)
K(t) = 0x8F1BBCDC (40 <= t <= 59)
K(t) = 0xCA62C1D6 (60 <= t <= 79)

CS -6 SHA 1
 Step 5: Initialize Buffers….
SHA1 requires 160 bits or 5 buffers of words (32 bits):
H0 = 0x67452301
H1 = 0xEFCDAB89
H2 = 0x98BADCFE
H3 = 0x10325476
H4 = 0xC3D2E1F0
 Step 6: Processing Message in 512-bit blocks (L blocks in
total message)….
This is the main task of SHA1 algorithm which loops through the padded
and appended message in 512-bit blocks.
Input and predefined functions:
M[1, 2, ..., L]: Blocks of the padded and appended message f(0;B,C,D),
f(1,B,C,D), ..., f(79,B,C,D): 80 Processing Functions K(0), K(1), ..., K(79):
80 Processing Constant Words
H0, H1, H2, H3, H4, H5: 5 Word buffers with initial values

Thank you
Image Source
searchenterpriseai.techtarget.com
wikipedia

Network security CS6

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Network security CS6