DKIM: document Ed25519 private key generation under OpenSSL (1.1.1+)

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

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index aea31dd66e2000026b7b3f33435b0f1a3617947a..978d51fd7e59f78bcbd51d7652be086e27a74363 100644 (file)
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -9154,6 +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.


@@ -9172,6 +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
 
 


@@ -11936,6 +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 &$host_lookup_deferred$&.


@@ -12891,6 +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>>&.


@@ -26104,6 +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
+

 
 
 
 
 
 


@@ -38903,7 +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


@@ -38929,6 +38946,21 @@ 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


@@ -38999,6 +39031,12 @@ 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


@@ -39114,7 +39152,8 @@ 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


@@ -39258,6 +39297,12 @@ 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"


@@ -39346,6 +39391,11 @@ 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