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The digest vmod allows for computing HMAC, message digests and working with
base64.
All HMAC- and hash-functionality is provided by libmhash, while base64 is implemented locally.
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.
All the various hmac-functions work the same, but use a different hash mechanism. Hex-encoded prepended with 0x.
For example
set resp.http.x-data-sig = digest.hmac_sha256("secretkey",resp.http.x-data);
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.
For example
set resp.http.x-data-sig =
digest.base64({"content with
newline in it"});
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.
For example
set resp.http.x-data-sig =
digest.base64_hex("0xdd26bfddf122c1055d4c");
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.
For example
set resp.http.x-data-md5 = digest.hash_md5(resp.http.x-data);
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.
For example
synthetic(digest.base64_decode(req.http.x-parrot));
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!"));
}
}
STRING hmac_sha256(STRING, STRING)
Arguments: None
Type: Function
Returns: String
STRING hmac_sha1(STRING, STRING)
Arguments: None
Type: Function
Returns: String
STRING hmac_md5(STRING, STRING)
Arguments: None
Type: Function
Returns: String
STRING base64(STRING)
Arguments: None
Type: Function
Returns: String
STRING base64_hex(STRING)
Arguments: None
Type: Function
Returns: String
STRING base64_decode(STRING)
Arguments: None
Type: Function
Returns: String
STRING base64url(STRING)
Arguments: None
Type: Function
Returns: String
STRING base64url_hex(STRING)
Arguments: None
Type: Function
Returns: String
STRING base64url_decode(STRING)
Arguments: None
Type: Function
Returns: String
STRING base64url_nopad(STRING)
Arguments: None
Type: Function
Returns: String
STRING base64url_nopad_hex(STRING)
Arguments: None
Type: Function
Returns: String
STRING base64url_nopad_decode(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_sha1(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_sha224(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_sha256(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_sha384(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_sha512(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_gost(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_md2(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_md4(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_md5(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_crc32(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_crc32b(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_adler32(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_haval128(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_haval160(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_haval192(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_haval224(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_haval256(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_ripemd128(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_ripemd160(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_ripemd256(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_ripemd320(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_tiger(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_tiger128(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_tiger160(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_snefru128(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_snefru256(STRING)
Arguments: None
Type: Function
Returns: String
STRING hash_whirlpool(STRING)
Arguments: None
Type: Function
Returns: String
The digest VMOD is available in Varnish Enterprise version 6.0.0r0 and later.