IS.HASH.SHA1: Generating SHA1 values with Generic MultiValue BASIC

Master Class Message Authentication Code Hashed Files

In cryptography, SHA-1 (Secure Hash Algorithm 1) is a cryptographic hash function designed by the United States National Security Agency and is a U.S. Federal Information Processing Standard published by the United States NIST. SHA1 is used in many places to generate a unique Hash value representing a string or file. It is widely used in place of MD4 and MD5 ash a more secure hash value. While not as secure as SHA256, it is still used in many places for data integrity, version control, and other features that need an unique one-way signatures.

SHA1 function

SHA-1 produces a 160-bit (20-byte) hash value known as a message digest. A SHA-1 hash value is typically rendered as a hexadecimal number, 40 digits long.

SHA1("The quick brown fox jumps over the lazy dog")

gives hexadecimal: 2fd4e1c67a2d28fced849ee1bb76e7391b93eb12

SHA1 will detect even small changes in the string and cause the returned hash value to change. You can always read more about SHA1 at:

https://en.wikipedia.org/wiki/SHA-1

MultiValue BASIC Hashing

Most versions MultiValue BASIC do not include built-in hashing functions. This requires developers to create their own.

This can be done in Pure/Generic MultiValue BASIC, but you may see a performance hit depending on how bit math is handled. For hash values like SHA1, the performance issues of generic bit math does not seem to be a problem.

Dave Meagher has done all the work to provide hash functions like SHA1 and MD5 in his FOSS4MV/mvCrypt code on BitBucket:

https://bitbucket.org/foss4mv/mvcrypt

The IS.HASH.SHA1 program attached to this article used Dave's mvCrypt SHA1 code, but formats it so that it is interchangeable with other versions of the IS.HASH.SHA1 code on the International Spectrum Website.

Example 

SHA1.MESSAGE = "The quick brown fox jumps over the lazy dog"
CALL IS.HASH.SHA1(SHA1.MESSAGE,HASH.VALUE)
*
TEST.VALUE = "2fd4e1c67a2d28fced849ee1bb76e7391b93eb12"
CRT HASH.VALUE : " =" : TEST.VALUE :" - "
IF (HASH.VALUE EQ TEST.VALUE) THEN
CRT "Ok"
END ELSE
CRT "Failed"
END

Output 

2fd4e1c67a2d28fced849ee1bb76e7391b93eb12 = 2fd4e1c67a2d28fced849ee1bb76e7391b93eb12 - Ok

Downloads:

NATHAN RECTOR

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