4 Original text by James Westby, contributed under the OpenSSL license.
8 c_rehash, rehash - Create symbolic links to files named by the hash values
25 On some platforms, the OpenSSL B<rehash> command is available as
26 an external script called B<c_rehash>. They are functionally equivalent,
27 except for minor differences noted below.
29 B<rehash> scans directories and calculates a hash value of each
30 C<.pem>, C<.crt>, C<.cer>, or C<.crl>
31 file in the specified directory list and creates symbolic links
32 for each file, where the name of the link is the hash value.
33 (If the platform does not support symbolic links, a copy is made.)
34 This utility is useful as many programs that use OpenSSL require
35 directories to be set up like this in order to find certificates.
37 If any directories are named on the command line, then those are
38 processed in turn. If not, then the B<SSL_CERT_DIR> environment variable
39 is consulted; this should be a colon-separated list of directories,
40 like the Unix B<PATH> variable.
41 If that is not set then the default directory (installation-specific
42 but often B</usr/local/ssl/certs>) is processed.
44 In order for a directory to be processed, the user must have write
45 permissions on that directory, otherwise an error will be generated.
47 The links created are of the form C<HHHHHHHH.D>, where each B<H>
48 is a hexadecimal character and B<D> is a single decimal digit.
49 When processing a directory, B<rehash> will first remove all links
50 that have a name in that syntax, even if they are being used for some
52 To skip the removal step, use the B<-n> flag.
53 Hashes for CRL's look similar except the letter B<r> appears after
54 the period, like this: C<HHHHHHHH.rD>.
56 Multiple objects may have the same hash; they will be indicated by
57 incrementing the B<D> value. Duplicates are found by comparing the
58 full SHA-1 fingerprint. A warning will be displayed if a duplicate
61 A warning will also be displayed if there are files that
62 cannot be parsed as either a certificate or a CRL or if
63 more than one such object appears in the file.
65 =head2 Script Configuration
67 The B<c_rehash> script
68 uses the B<openssl> program to compute the hashes and
69 fingerprints. If not found in the user's B<PATH>, then set the
70 B<OPENSSL> environment variable to the full pathname.
71 Any program can be used, it will be invoked as follows for either
74 $OPENSSL x509 -hash -fingerprint -noout -in FILENAME
75 $OPENSSL crl -hash -fingerprint -noout -in FILENAME
77 where B<FILENAME> is the filename. It must output the hash of the
78 file on the first line, and the fingerprint on the second,
79 optionally prefixed with some text and an equals sign.
87 Use old-style hashing (MD5, as opposed to SHA-1) for generating
88 links to be used for releases before 1.0.0.
89 Note that current versions will not use the old style.
93 Display a brief usage message.
97 Do not remove existing links.
98 This is needed when keeping new and old-style links in the same directory.
102 Print messages about old links removed and new links created.
103 By default, B<rehash> only lists each directory as it is processed.
113 The path to an executable to use to generate hashes and
114 fingerprints (see above).
116 =item B<SSL_CERT_DIR>
118 Colon separated list of directories to operate on.
119 Ignored if directories are listed on the command line.