DKIM: document generation of RSA keys

[exim.git] / doc / doc-docbook / spec.xfpt

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index f950a4dac31e9d6754c6e89b99c3f3f1bafcaa2b..7d5b3b3cf159ff90aa797e4dd9f38b528cb4f99c 100644 (file)
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -52,7 +52,7 @@
 .set I   "    "
 
 .macro copyyear
 .set I   "    "
 
 .macro copyyear

-2017
+2018

 .endmacro
 
 . /////////////////////////////////////////////////////////////////////////////
 .endmacro
 
 . /////////////////////////////////////////////////////////////////////////////


@@ -7839,6 +7839,19 @@ ${lookup redis{set keyname ${quote_redis:objvalue plus}}}
 ${lookup redis{get keyname}}
 .endd
 
 ${lookup redis{get keyname}}
 .endd
 

+.new
+As of release 4.91, "lightweight" support for Redis Cluster is available.
+Requires &%redis_servers%& list to contain all the servers in the cluster, all
+of which must be reachable from the running exim instance. If the cluster has
+master/slave replication, the list must contain all the master and slave
+servers.
+
+When the Redis Cluster returns a "MOVED" response to a query, exim does not
+immediately follow the redirection but treats the response as a DEFER, moving on
+to the next server in the &%redis_servers%& list until the correct server is
+reached.
+.wen
+

 .ecindex IIDfidalo1
 .ecindex IIDfidalo2
 
 .ecindex IIDfidalo1
 .ecindex IIDfidalo2
 


@@ -9141,6 +9154,7 @@ If the ACL returns defer the result is a forced-fail.  Otherwise the expansion f
 .vitem "&*${authresults{*&<&'authserv-id'&>&*}}*&"
 .cindex authentication "results header"
 .cindex headers "authentication-results:"
 .vitem "&*${authresults{*&<&'authserv-id'&>&*}}*&"
 .cindex authentication "results header"
 .cindex headers "authentication-results:"

+.cindex authentication "expansion item"

 This item returns a string suitable for insertion as an
 &'Authentication-Results"'&
 header line.
 This item returns a string suitable for insertion as an
 &'Authentication-Results"'&
 header line.


@@ -9159,6 +9173,7 @@ Example use (as an ACL modifier):
 .code
       add_header = :at_start:${authresults {$primary_hostname}}
 .endd
 .code
       add_header = :at_start:${authresults {$primary_hostname}}
 .endd

+This is safe even if no authentication reselts are available.

 .wen
 
 
 .wen
 
 


@@ -11923,6 +11938,13 @@ lookup succeeds, but there is a lookup problem such as a timeout when checking
 the result, the name is not accepted, and &$host_lookup_deferred$& is set to
 &"1"&. See also &$sender_host_name$&.
 
 the result, the name is not accepted, and &$host_lookup_deferred$& is set to
 &"1"&. See also &$sender_host_name$&.
 

+.new
+.cindex authentication "expansion item"
+Performing these checks sets up information used by the
+&$authresults$& expansion item.
+.wen
+
+

 .vitem &$host_lookup_failed$&
 .vindex "&$host_lookup_failed$&"
 See &$host_lookup_deferred$&.
 .vitem &$host_lookup_failed$&
 .vindex "&$host_lookup_failed$&"
 See &$host_lookup_deferred$&.


@@ -12878,6 +12900,7 @@ is compiled with the content-scanning extension. For details, see section
 .vitem &$spf_header_comment$& &&&
        &$spf_received$& &&&
        &$spf_result$& &&&
 .vitem &$spf_header_comment$& &&&
        &$spf_received$& &&&
        &$spf_result$& &&&

+       &$spf_result_guessed$& &&&

        &$spf_smtp_comment$&
 These variables are only available if Exim is built with SPF support.
 For details see section &<<SECSPF>>&.
        &$spf_smtp_comment$&
 These variables are only available if Exim is built with SPF support.
 For details see section &<<SECSPF>>&.


@@ -26091,6 +26114,12 @@ public name) of the authenticator driver that successfully authenticated the
 client from which the message was received. This variable is empty if there was
 no successful authentication.
 
 client from which the message was received. This variable is empty if there was
 no successful authentication.
 

+.new
+.cindex authentication "expansion item"
+Successful authentication sets up information used by the
+&$authresults$& expansion item.
+.wen
+

 
 
 
 
 
 


@@ -31806,9 +31835,9 @@ though individual ones can be included or not at build time:
 .vitem &%avast%&
 .cindex "virus scanners" "avast"
 This is the scanner daemon of Avast. It has been tested with Avast Core
 .vitem &%avast%&
 .cindex "virus scanners" "avast"
 This is the scanner daemon of Avast. It has been tested with Avast Core

-Security (currently at version 1.1.7).
-You can get a trial version at &url(http://www.avast.com) or for Linux
-at &url(http://www.avast.com/linux-server-antivirus).
+Security (currently at version 2.2.0).
+You can get a trial version at &url(https://www.avast.com) or for Linux
+at &url(https://www.avast.com/linux-server-antivirus).

 This scanner type takes one option,
 which can be either a full path to a UNIX socket,
 or host and port specifiers separated by white space.
 This scanner type takes one option,
 which can be either a full path to a UNIX socket,
 or host and port specifiers separated by white space.


@@ -31835,6 +31864,8 @@ $ socat UNIX:/var/run/avast/scan.sock STDIO:
     PACK
 .endd
 
     PACK
 .endd
 

+Only the first virus detected will be reported.
+

 
 .vitem &%aveserver%&
 .cindex "virus scanners" "Kaspersky"
 
 .vitem &%aveserver%&
 .cindex "virus scanners" "Kaspersky"


@@ -38888,7 +38919,8 @@ The result can either
 be a valid RSA private key in ASCII armor (.pem file), including line breaks
 .new
 .next
 be a valid RSA private key in ASCII armor (.pem file), including line breaks
 .new
 .next

-with GnuTLS 3.6.0 or later, be a valid Ed25519 private key (same format as above)
+with GnuTLS 3.6.0 or OpenSSL 1.1.1 or later,
+be a valid Ed25519 private key (same format as above)

 .wen
 .next
 start with a slash, in which case it is treated as a file that contains
 .wen
 .next
 start with a slash, in which case it is treated as a file that contains


@@ -38900,6 +38932,20 @@ is set.
 .endlist
 
 .new
 .endlist
 
 .new

+To generate keys under OpenSSL:
+.code
+openssl genrsa -out dkim_rsa.private 2048
+openssl rsa -in dkim_rsa.private -out /dev/stdout -pubout -outform PEM
+.endd
+Take the base-64 lines from the output of the second command, concatenated,
+for the DNS TXT record.
+
+Under GnuTLS:
+.code
+certtool --generate-privkey --rsa --bits=2048 --password='' -8 --outfile=dkim_rsa.private
+certtool --load-privkey=dkim_rsa.private --pubkey-info
+.endd
+

 Note that RFC 8301 says:
 .code
 Signers MUST use RSA keys of at least 1024 bits for all keys.
 Note that RFC 8301 says:
 .code
 Signers MUST use RSA keys of at least 1024 bits for all keys.


@@ -38914,6 +38960,21 @@ As they are a recent development, users should consider dual-signing
 for some transition period.
 The "_CRYPTO_SIGN_ED25519" macro will be defined if support is present
 for EC keys.
 for some transition period.
 The "_CRYPTO_SIGN_ED25519" macro will be defined if support is present
 for EC keys.

+
+As of writing, producing EC key materials is not well supported
+by the major libraries.  OpenSSL 1.1.1 and GnuTLS 3.6.0 can create private keys:
+.code
+openssl genpkey -algorithm ed25519 -out dkim_ed25519.private
+certtool --generate-privkey --key-type=ed25519 --outfile=dkim_ed25519.private
+.endd
+
+To help in producing the required public key value for a DNS record
+the release package &_util/_& directory contains source for a utility
+buildable with GnuTLS 3.6.0;
+use it like this:
+.code
+ed25519_privkey_pem_to_pubkey_raw_b64 dkim_ed25519.private
+.endd

 .wen
 
 .option dkim_hash smtp string&!! sha256
 .wen
 
 .option dkim_hash smtp string&!! sha256


@@ -38984,6 +39045,12 @@ To evaluate the signature in the ACL a large number of expansion variables
 containing the signature status and its details are set up during the
 runtime of the ACL.
 
 containing the signature status and its details are set up during the
 runtime of the ACL.
 

+.new
+.cindex authentication "expansion item"
+Performing verification sets up information used by the
+&$authresults$& expansion item.
+.wen
+

 Calling the ACL only for existing signatures is not sufficient to build
 more advanced policies. For that reason, the global option
 &%dkim_verify_signers%&, and a global expansion variable
 Calling the ACL only for existing signatures is not sufficient to build
 more advanced policies. For that reason, the global option
 &%dkim_verify_signers%&, and a global expansion variable


@@ -39099,7 +39166,8 @@ The key record selector string.
 .vitem &%$dkim_algo%&
 The algorithm used. One of 'rsa-sha1' or 'rsa-sha256'.
 .new
 .vitem &%$dkim_algo%&
 The algorithm used. One of 'rsa-sha1' or 'rsa-sha256'.
 .new

-If running under GnuTLS 3.6.0 or later, may also be 'ed25519-sha256'.
+If running under GnuTLS 3.6.0 or OpenSSL 1.1.1 or later,
+may also be 'ed25519-sha256'.

 The "_CRYPTO_SIGN_ED25519" macro will be defined if support is present
 for EC keys.
 .wen
 The "_CRYPTO_SIGN_ED25519" macro will be defined if support is present
 for EC keys.
 .wen


@@ -39243,6 +39311,12 @@ There is no Exim involvement on the trasmission of messages; publishing certain
 DNS records is all that is required.
 
 For verification, an ACL condition and an expansion lookup are provided.
 DNS records is all that is required.
 
 For verification, an ACL condition and an expansion lookup are provided.

+.new
+.cindex authentication "expansion item"
+Performing verification sets up information used by the
+&$authresults$& expansion item.
+.wen
+

 
 .cindex SPF "ACL condition"
 .cindex ACL "spf condition"
 
 .cindex SPF "ACL condition"
 .cindex ACL "spf condition"


@@ -39331,6 +39405,11 @@ variables:
   one of pass, fail, softfail, none, neutral, permerror or
   temperror.
 
   one of pass, fail, softfail, none, neutral, permerror or
   temperror.
 

+.vitem &$spf_result_guessed$&
+.vindex &$spf_result_guessed$&
+  This boolean is true only if a best-guess operation was used
+  and required in order to obtain a result.
+

 .vitem &$spf_smtp_comment$&
 .vindex &$spf_smtp_comment$&
   This contains a string that can be used in a SMTP response
 .vitem &$spf_smtp_comment$&
 .vindex &$spf_smtp_comment$&
   This contains a string that can be used in a SMTP response