rehash scans directories and calculates a hash value of each ".pem", ".crt", ".cer", or ".crl" file in the specified directory list and creates symbolic links for each file, where the name of the link is the hash value. (If the platform does not support symbolic links, a copy is made.) This utility is useful as many programs that use OpenSSL require directories to be set up like this in order to find certificates.
If any directories are named on the command line, then those are processed in turn. If not, then the SSL_CERT_DIR environment variable is consulted; this should be a colon-separated list of directories, like the Unix PATH variable. If that is not set then the default directory (installation-specific but often /usr/local/ssl/certs) is processed.
In order for a directory to be processed, the user must have write permissions on that directory, otherwise an error will be generated.
The links created are of the form "HHHHHHHH.D", where each H is a hexadecimal character and D is a single decimal digit. When processing a directory, rehash will first remove all links that have a name in that syntax, even if they are being used for some other purpose. To skip the removal step, use the -n flag. Hashes for CRL's look similar except the letter r appears after the period, like this: "HHHHHHHH.rD".
Multiple objects may have the same hash; they will be indicated by incrementing the D value. Duplicates are found by comparing the full SHA-1 fingerprint. A warning will be displayed if a duplicate is found.
A warning will also be displayed if there are files that cannot be parsed as either a certificate or a CRL or if more than one such object appears in the file.
$OPENSSL x509 -hash -fingerprint -noout -in FILENAME $OPENSSL crl -hash -fingerprint -noout -in FILENAME
where FILENAME is the filename. It must output the hash of the file on the first line, and the fingerprint on the second, optionally prefixed with some text and an equals sign.
Licensed under the OpenSSL license (the ``License''). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.