Provided by: varnish-vmod-digest_6.4+20220108-1_amd64 
NAME
vmod_digest - Varnish Digest Module
SYNOPSIS
import digest;
digest.hmac_md5(<key>,<message>);
digest.hmac_sha1(<key>, <message>);
digest.hmac_sha256(<key>, <message));
digest.base64(<string>);
digest.base64url(<string>);
digest.base64url_nopad(<string>);
digest.base64_hex(<string>);
digest.base64url_hex(<string>);
digest.base64url_nopad_hex(<string>);
digest.base64_decode(<string>);
digest.base64url_decode(<string>);
digest.base64url_nopad_decode(<string>);
digest.version()
digest.hash_sha1(<string>);
digest.hash_sha224(<string>);
digest.hash_sha256(<string>);
digest.hash_sha384(<string>);
digest.hash_sha512(<string>);
digest.hash_gost(<string>);
digest.hash_md2(<string>);
digest.hash_md4(<string>);
digest.hash_md5(<string>);
digest.hash_crc32(<string>);
digest.hash_crc32b(<string>);
digest.hash_adler32(<string>);
digest.hash_haval128(<string>);
digest.hash_haval160(<string>);
digest.hash_haval192(<string>);
digest.hash_haval224(<string>);
digest.hash_haval256(<string>);
digest.hash_ripemd128(<string>);
digest.hash_ripemd160(<string>);
digest.hash_ripemd256(<string>);
digest.hash_ripemd320(<string>);
digest.hash_tiger(<string>);
digest.hash_tiger128(<string>);
digest.hash_tiger160(<string>);
digest.hash_snefru128(<string>);
digest.hash_snefru256(<string>);
DESCRIPTION
Varnish Module (vmod) for computing HMAC, message digests and working with base64.
All HMAC- and hash-functionality is provided by libmhash, while base64 is implemented
locally.
FUNCTIONS
Example VCL:
backend foo { ... };
import digest;
sub vcl_recv {
if (digest.hmac_sha256("key",req.http.x-data) != req.http.x-data-sig)
{
return (synth(401, "Naughty user!"));
}
}
hmac_(hash)
Prototype
digest.hmac_md5(<key>,<message>);
digest.hmac_sha1(<key>, <message>);
digest.hmac_sha256(<key>, <message));
Returns
String. Hex-encoded prepended with 0x.
Description
All the various hmac-functions work the same, but use a different hash mechanism.
Example
set resp.http.x-data-sig =
digest.hmac_sha256("secretkey",resp.http.x-data);
base64, base64url, base64url_nopad
Prototype
digest.base64(<string>);
digest.base64url(<string>);
digest.base64url_nopad(<string>);
Returns
String
Description
Returns the base64-encoded version of the input-string. The base64url-variant uses
base64 url-encoding (+/ replaced by -_) and the base64url_nopad does the same, but
avoids adding padding. The latter is more commonly used, though an (allowed)
exception to the RFC4648.
Example
set resp.http.x-data-sig =
digest.base64({"content with
newline in it"});
base64_hex, base64url_hex, base64url_nopad_hex
Prototype
digest.base64_hex(<string>);
digest.base64url_hex(<string>);
digest.base64url_nopad_hex(<string>);
Returns
String
Description
Returns the base64-encoded version of the hex encoded input-string. The
input-string can start with an optional 0x. Input is hex-decoded into binary and
the encoding is identical to base64, base64url, and base64url_nopad.
Example
set resp.http.x-data-sig =
digest.base64_hex("0xdd26bfddf122c1055d4c");
hash_(algorithm)
Prototype
digest.hash_sha1(<string>);
digest.hash_sha224(<string>);
digest.hash_sha256(<string>);
digest.hash_sha384(<string>);
digest.hash_sha512(<string>);
digest.hash_gost(<string>);
digest.hash_md2(<string>);
digest.hash_md4(<string>);
digest.hash_md5(<string>);
digest.hash_crc32(<string>);
digest.hash_crc32b(<string>);
digest.hash_adler32(<string>);
digest.hash_haval128(<string>);
digest.hash_haval160(<string>);
digest.hash_haval192(<string>);
digest.hash_haval224(<string>);
digest.hash_haval256(<string>);
digest.hash_ripemd128(<string>);
digest.hash_ripemd160(<string>);
digest.hash_ripemd256(<string>);
digest.hash_ripemd320(<string>);
digest.hash_tiger(<string>);
digest.hash_tiger128(<string>);
digest.hash_tiger160(<string>);
digest.hash_snefru128(<string>);
digest.hash_snefru256(<string>);
Returns
String
Description
Computes the digest/hash of the supplied, using the specified hash algorithm. If in
doubt as to which to pick, use SHA256. For detailed discussions, see The Internet.
Example
set resp.http.x-data-md5 =
digest.hash_md5(resp.http.x-data);
base64_decode, base64url_decode, base64url_nopad_decode
Prototype
digest.base64_decode(<string>);
digest.base64url_decode(<string>);
digest.base64url_nopad_decode(<string>);
Returns
String
Description
Decodes the bas64 and base64url-encoded strings. All functions treat padding the
same, meaning base64url_decode and base64url_nopad_decode are identical, but
available for consistency and practicality.
Example
:: synthetic(digest.base64_decode(req.http.x-parrot));
version
Prototype
digest.version()
Returns
string
Description
Returns the string constant version-number of the digest vmod.
Example
set resp.http.X-digest-version = digest.version();
INSTALLATION
The source tree is based on autotools to configure the building, and does also have the
necessary bits in place to do functional unit tests using the varnishtest tool.
Building requires the Varnish header files and uses pkg-config to find the necessary
paths.
Usage:
./autogen.sh
./configure
If you have installed Varnish to a non-standard directory, call autogen.sh and configure
with PKG_CONFIG_PATH pointing to the appropriate path. For example, when varnishd
configure was called with --prefix=$PREFIX, use
PKG_CONFIG_PATH=${PREFIX}/lib/pkgconfig export PKG_CONFIG_PATH
Make targets:
• make - builds the vmod.
• make install - installs your vmod.
• make check - runs the unit tests in src/tests/*.vtc
• make distcheck - run check and prepare a tarball of the vmod.
AUTHOR
Original author: Kristian Lyngstøl <kristian@varnish-software.com>.
This Vmod was written for Media Norge, Schibsted and others.
The bulk of the functionality is acquired through libmhash.
BUGS
No bugs at all!
If the key is NULL for hmac-functions, the function will fail and return NULL itself, and
do no hmac-computation at all. This should be used as an indication of some greater flaw
in your software/VCL. (I.e.: Your key should be under your control, not user-supplied
without verification).
The base64url_nopad_decode() and base64url_decode() functions do not differ much. The
exception is that nopad_decode() does not know about padding at all, and might get
confused if the input actually is padded.
SEE ALSO
• libmhash
• varnishd(1)
• vcl(7)
• https://github.com/varnish/libvmod-digest
AUTHOR
Kristian Lyngstøl