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Definition: SHA-1 is one of several cryptographic hash functions, most often used to verify that a file has been unaltered. SHA is short for Secure Hash Algorithm.

File verification using SHA-1 is accomplished by comparing the checksums created after running the algorithm on the two files you want to compare.

SHA-1 is the second iteration of this cryptographic hash function, replacing the previous SHA-0. An SHA-2 cryptographic hash function is also available and SHA-3 is being developed.

All Secure Hash Algorithms were developed by the US National Security Agency.

MD5 is another commonly used cryptographic hash function.

"I was looking for a secure cryptographic hash function so I could provide a checksum value to people who wanted to download my new software. SHA-1 seemed to fit the bill."

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