check out:
/usr/bin/crc32 your_file_here
/sbin/md5 your_file_here
gnupg: gpg --print-md '*' your_file_here
you can use /usr/sbin/asr to scan a disk image such that when you use asr to restore the disk image to a blank drive, it will checksum the drive for you. You can also use /usr/bin/hdiutil to verify the checksums on diskimages. You can use /Applications/Utilities/Disk Utility.app for all of these as well.