The very first step in the SHA1 algorithm is to pad the message so that it is a multiple of 512 bits. This padding occurs as follows (from NIST FPS 180-2): Suppose the length of the message M is L bits. Append bit 1 to the end of the message, followed by K zero bits where K is the smallest non-negative solution to L+1+K 448 (mod 512). Next append a 64-bit block that is a binary representation of the length integer L. For example, Message = “abc” length L = 24 bits 001100001 01100010 01100011 1 00……000 00…011000 a b c <---423---> <---64----> <-------------------512------------------------------>. Why do we include the length of the message in the calculation of the hash code?
The very first step in the SHA1 algorithm is to pad the message so that it is a multiple of 512 bits. This padding occurs as follows (from NIST FPS 180-2): Suppose the length of the message M is L bits. Append bit 1 to the end of the message, followed by K zero bits where K is the smallest non-negative solution to L+1+K 448 (mod 512). Next append a 64-bit block that is a binary representation of the length integer L. For example, Message = “abc” length L = 24 bits 001100001 01100010 01100011 1 00……000 00…011000 a b c <---423---> <---64----> <-------------------512------------------------------>. Why do we include the length of the message in the calculation of the hash code?
Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
Problem 1PE
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The very first step in the SHA1 algorithm is to pad the message so that it is a multiple of 512 bits. This padding occurs as follows (from NIST FPS 180-2): Suppose the length of the message M is L bits. Append bit 1 to the end of the message, followed by K zero bits where K is the smallest non-negative solution to L+1+K 448 (mod 512). Next append a 64-bit block that is a binary representation of the length integer L. For example, Message = “abc” length L = 24 bits 001100001 01100010 01100011 1 00……000 00…011000 a b c <---423---> <---64----> <-------------------512------------------------------>. Why do we include the length of the message in the calculation of the hash code?
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