vmod_digest(3)

Usage

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>);

Overview

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.

Releases

2 releases since Debian 12 (Bookworm); the text changed 1 time.

12
13