X509: size of collumn in attachment changes and causes body alteration

[pr2007 at ibs.fr]

Hi,

As you know, when signing a message with X509 certificate, a checksum of 
the body is made.
When the recipient opens the signed message, the body should not have 
changed.

We have a *problem with attached files*. As Mailscanner *modified the 
body,* the *numeric signature is broken.*

*_Here is a example:_*

* Before mailscanner, this base64 attachment contained 73 columns.*

--------------ms050704040207000105000505
Content-Type: application/x-pkcs7-signature; name="test.pdf"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="smime.p7s"
Content-Description: S/MIME Cryptographic Signature
MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIHnTCC
A20wggJVoAMCAQICAQIwDQYJKoZIhvcNAQEEBQAwKzELMAkGA1UEBhMCRlIxDTALBgNVBAoT
...
AKNb/vSOP5gprnSi0cbMds8btE8HttC5xc46qETIu24iciSmwjkbgwrT6kIREFRKm2m/fJaQ
u/qieuH5tCOsQt8k4exj2A4xsZrQnGFsYfOHutdMSs1WAAAAAAAA
--------------ms050704040207000105000505--

* After mailscanner, the base64 attachment contains 61 columns only.*

--------------ms050704040207000105000505
Content-Type: application/x-pkcs7-signature; name="test.pdf"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="smime.p7s"
Content-Description: S/MIME Cryptographic Signature
MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEH
AQAAoIIHnTCCA20wggJVoAMCAQICAQIwDQYJKoZIhvcNAQEEBQAwKzELMAkG
...
tE8HttC5xc46qETIu24iciSmwjkbgwrT6kIREFRKm2m/fJaQu/qieuH5tCOs
Qt8k4exj2A4xsZrQnGFsYfOHutdMSs1WAAAAAAAA
--------------ms050704040207000105000505--

_* Context:*_
- Debian Testing
- Postfix
- Clamav with Perl Module
- SpamAssassin version 3.1.7
- Perl version 5.8.8 (updated with CPAN)
- MailScanner installed from debian package (v4.51.5)

*Is the problem known and is there a workaround ?*
Thanks in advance !

-- 
Pierre Rolland - Phone: +33(0)4 38 78 96 34
Institut de Biologie Structurale-CNRS (UMR 5075)/CEA/UJF - IBS
41 Av. Jules Horowitz - 38027 Grenoble Cedex 1 - France
Trust in CNRS's certificates: http://igc.services.cnrs.fr/Doc/General/trust.html 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.mailscanner.info/pipermail/mailscanner/attachments/20070221/d2659a78/attachment.html