OS X
Verifying a file’s SHA1 hash on OS X
Mar 11, 2011 12:10 PM Filed in: Mac OS X | Programming
I frequently have to verify a file’s SHA1 hash, to ensure that the file downloaded correctly and has not been tampered with. While you can visually inspect the hash result to compare it to a known value, I find it very handy to have a script that does this for me, given a filename and a known valid hash.
#!/bin/bash
#
# Script to validate a SHA1 hash on a file
# Copyright (c)2011, Akamai Haole, LLC
#
# Usage: verifySHA1
#
# Executable paths
AWK=/usr/bin/awk
OPENSSL=/opt/local/bin/openssl
# Parameter sanity check
if [ "${1}x" == "x" -o "${2}x" == "x" ]; then
echo ""
echo "Usage: ${0} "
echo ""
exit
fi
# File existence sanity check
if [ ! -f "${2}" ]; then
echo ""
echo "ERROR: File (${2}) does not exist!"
echo ""
exit
fi
# Calculate SHA1 hash value and trim it
SHA1_HASH_VALUE=`${OPENSSL} sha1 ${2} | ${AWK} 'BEGIN {FS="="}; {gsub(/ /,"",$2); print $2}'`
# File information
echo ""
echo "File path: ${2}"
echo "Calculated SHA1 hash: ${SHA1_HASH_VALUE}"
echo ""
# Test with the SHA1 hash that was passed in
if [ "${SHA1_HASH_VALUE}x" != "${1}x" ]; then
echo "Hash comparison fails!"
else
echo "Hash comparison matches."
fi
echo ""
# End of script