What Cert is used (domain vs. user)?

Marc_Patermann · October 18, 2018, 10:12am

Hi,

is there a setting to see information about the cert that is actually
used to encrypt to a message?

Background:

Domain example.com uses user specific certs. If a user sends a signed
mail, ciphermail stores the cert as expected.

Sending S/MIME encrypted mails to a user at example.com depends if there
is a the stored cert.

Now we like to set up domain-domain-encryption.
example.com send a cert for the domain.
I created a domain in ciphermail and enabled the domain cert they send.
Now mails to every user at example.com can be send encrypted - with the
domain cert.

Users at example.com complain that they cannot decrypt the mail.

Is there any precedence of user cert to domain cert in ciphermail?

Information what cert ciphermail actually used to encrypt the message is
needed.

Regards,

Marc

martijn · October 18, 2018, 10:42am

Outgoing email will be S/MIME encrypted with all valid certificates for
the user. If a domain certificate has been setup for the recipient and
the certificate is valid, the email will be encrypted with the domain
certificate. If the user also has a personal certificate (i.e., issued
for his/her email address), then the email will *also* be encrypted with
the user certificate (i.e., the email will be encrypted with the domain
certificate *and* the personal certificate).

The gateway dynamically finds the certificates for a recipient (i.e., it
will check the domain and check if there is a personal certificate). If
you want to see which certificates are available for a recipient, you
need to add this recipient first. The click on the details for the
recipient (click on the email address). On the "Edit user: .." page,
click S/MIME and then from the pull down menu, select "encryption
certificates". You should now get an overview of all the S/MIME
certificates for the recipient.

Certificates are colored depending on whether the certificate is valid,
auto selected, inherited etc.

Green means the certificate is valid and auto selected (only if the
email address matches). Yellow means it's inherited (from the domain).

See the following page for more information

https://www.ciphermail.com/documents/html/administration-guide/#pf3b

What is important to know is that a certificate will only be used if the
certificate is trusted.

Kind regards,

Martijn Brinkers

···

On 18-10-18 12:12, Marc Patermann via Users wrote:

Hi,

is there a setting to see information about the cert that is actually
used to encrypt to a message?

Background:

Domain example.com uses user specific certs. If a user sends a signed
mail, ciphermail stores the cert as expected.

Sending S/MIME encrypted mails to a user at example.com depends if there
is a the stored cert.

Now we like to set up domain-domain-encryption.
example.com send a cert for the domain.
I created a domain in ciphermail and enabled the domain cert they send.
Now mails to every user at example.com can be send encrypted - with the
domain cert.

Users at example.com complain that they cannot decrypt the mail.

Is there any precedence of user cert to domain cert in ciphermail?

Information what cert ciphermail actually used to encrypt the message is
needed.

--
CipherMail email encryption

Email encryption with support for S/MIME, OpenPGP, PDF encryption and
secure webmail pull.

Twitter: http://twitter.com/CipherMail

Marc_Patermann · October 18, 2018, 3:37pm

Martijn,

thanks for your answer.

Outgoing email will be S/MIME encrypted with all valid certificates for
the user. If a domain certificate has been setup for the recipient and
the certificate is valid, the email will be encrypted with the domain
certificate. If the user also has a personal certificate (i.e., issued
for his/her email address), then the email will *also* be encrypted with
the user certificate (i.e., the email will be encrypted with the domain
certificate *and* the personal certificate).

The gateway dynamically finds the certificates for a recipient (i.e., it
will check the domain and check if there is a personal certificate). If
you want to see which certificates are available for a recipient, you
need to add this recipient first. The click on the details for the
recipient (click on the email address). On the "Edit user: .." page,
click S/MIME and then from the pull down menu, select "encryption
certificates". You should now get an overview of all the S/MIME
certificates for the recipient.

Certificates are colored depending on whether the certificate is valid,
auto selected, inherited etc.

Green means the certificate is valid and auto selected (only if the
email address matches). Yellow means it's inherited (from the domain).

This all looks pretty right in the admin GUI.

See the following page for more information

https://www.ciphermail.com/documents/html/administration-guide/#pf3b

What is important to know is that a certificate will only be used if the
certificate is trusted.

We checked this before. We made all the example.com certs "valid".

Is there any debug log to the see that this actually happenend?

Everything in the admin GUI looks OK. The certificat for
john(a)example.com is the yellow "inherited" one from the domain setting.

The admin at example.com says, the cannot decrypt the message.

The admin as a cert himself. He can read all my encrypted mails.

Marc

···

Am 18.10.2018 um 12:42 Uhr schrieb Martijn Brinkers via Users:

martijn · October 19, 2018, 6:12am

See comments inline

Outgoing email will be S/MIME encrypted with all valid certificates for
the user. If a domain certificate has been setup for the recipient and
the certificate is valid, the email will be encrypted with the domain
certificate. If the user also has a personal certificate (i.e., issued
for his/her email address), then the email will *also* be encrypted with
the user certificate (i.e., the email will be encrypted with the domain
certificate *and* the personal certificate).

The gateway dynamically finds the certificates for a recipient (i.e., it
will check the domain and check if there is a personal certificate). If
you want to see which certificates are available for a recipient, you
need to add this recipient first. The click on the details for the
recipient (click on the email address). On the "Edit user: .." page,
click S/MIME and then from the pull down menu, select "encryption
certificates". You should now get an overview of all the S/MIME
certificates for the recipient.

Certificates are colored depending on whether the certificate is valid,
auto selected, inherited etc.

Green means the certificate is valid and auto selected (only if the
email address matches). Yellow means it's inherited (from the domain).

This all looks pretty right in the admin GUI.

See the following page for more information

https://www.ciphermail.com/documents/html/administration-guide/#pf3b

What is important to know is that a certificate will only be used if the
certificate is trusted.

We checked this before. We made all the example.com certs "valid".

Is there any debug log to the see that this actually happenend?

Everything in the admin GUI looks OK. The certificat for
john(a)example.com is the yellow "inherited" one from the domain setting.

The admin at example.com says, the cannot decrypt the message.

What application do they use to decrypt the email?

The admin as a cert himself. He can read all my encrypted mails.

The best would be to analyze the encrypted email to check with which
certificates the email was encrypted with. An S/MIME encrypted email
contains a list of identifiers which identify which certificate the
message was encrypted with.

You should get a copy of the encrypted email. This can be the full email
(MIME) or only the smime.p7m attachment (either in binary form or base64).

CipherMail contains a tool which you can use to analyze S/MIME email.
This should be run from the command line (login to the shell)

cd /usr/share/djigzo

To show help:

java -cp /usr/share/djigzo/djigzo.jar mitm.common.tools.SMIME

To open a full MIME message:

java -cp djigzo.jar mitm.common.tools.SMIME --read -in <FILE>

The output will show which certificates (Recipient's) the message was
encrypted with:

*** Recipient 0

EMAILADDRESS=ca(a)example.com, CN=Test CA, L=Amsterdam, ST=NH,
C=NL/115FCD741088707366E9727452C9770//1.2.840.113549.1.1.1

The recipient is identified by:

Issuer/Serial number pairs. So in the above example the message was
encrypted with a certificate issues by "EMAILADDRESS=ca(a)example.com,
CN=Test CA, L=Amsterdam, ST=NH, C=NL" with serial number
"115FCD741088707366E9727452C9770"

There can be multiple Recipient lines depending on the number of
certificates the message was encrypted with.

If you do not have the full MIME message, only the smime.p7m blob in
base64 encoded form you can use:

java -cp djigzo.jar mitm.common.tools.SMIME --read -in <FILE> --p7m

And if the smime.p7m blob is in binary form (i.e., not base64 encoded),
add the --binary parameter.

java -cp djigzo.jar mitm.common.tools.SMIME --read -in <FILE>--p7m --binary

Note: to analyze which certificates the message was encrypted with, you
do not need the private key because you do not need to decrypt the email.