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3 .\" Copyright (c) 2019 Martijn van Duren <martijn@openbsd.org>
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17 .Dd $Mdocdate$
18 .Dt FILTER-DKIM 8
19 .Os
20 .Sh NAME
21 .Nm filter-dkim
22 .Nd add dkim signature to messages
23 .Sh SYNOPSIS
24 .Nm
25 .Op Fl a Ar algorithm
26 .Op Fl c Ar canonicalization
27 .Op Fl h Ar headers
28 .Op Fl t
29 .Op Fl x Ar seconds
30 .Op Fl z
31 .Op Fl Z
32 .Fl d Ar domain
33 .Fl k Ar file
34 .Fl s Ar selector
35 .Sh DESCRIPTION
36 .Nm
37 adds a dkim signature to the message.
38 The following flags are supported:
39 .Bl -tag -width Ds
40 .It Fl a
41 The algorithm to use.
42 This implementation only supports rsa cryptography.
43 Only sha256 should be used for hashing, since other algorithms are most likely
44 not supported by verifiers.
45 Defaults to
46 .Ar rsa-sha256 .
47 .It Fl c
48 The canonicalization algorithm used to sign the messge.
49 Defaults to
50 .Ar simple/simple .
51 .It Fl d
52 The domain where the public key can be found.
53 .It Fl h
54 The email headers which are included in the mail signature.
55 Per RFC this option requires at least the from header to be included.
56 The headers are specified by separating them with a colon.
57 The default is
58 from:reply-to:subject:date:to:cc:resent-date:resent-from:resent-to:resent-cc:in-reply-to:references:list-id:list-help:list-unsubscribe:list-subscribe:list-post:list-owner:list-archive .
59 .It Fl k
60 .Ar file
61 should point to a file containing the RSA private key to sign the messages.
62 .It Fl s
63 The selector within the _domainkey subdomain of
64 .Ar domain
65 where the public key can be found.
66 .It Fl t
67 Add the time of signing to the dkim header.
68 .It Fl x
69 Add the amount of
70 .Ar seconds
71 the signature is valid to the dkim header.
72 .It Fl z
73 Add the mail headers used in the dkim signature to the dkim header.
74 Useful for debugging purposes.
75 .It Fl Z
76 Add all the mail headers to the dkim header.
77 Useful for debugging purposes.
78 .El
79 .Sh SEE ALSO
80 .Xr smtpd 8