CIPHERMAIL EMAIL ENCRYPTION
Ciphermail S/MIME Setup Guide
April 4, 2016, Rev: 6882
Copyright © 2008-2016, ciphermail.com.
CONTENTS CONTENTS
Contents
1 Introduction 3
2 S/MIME 3
2.1 PKI................................... 3
2.2 X.509certicate ........................... 4
2.3 Revocation checking . . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Gateway S/MIME quick setup 6
3.1 Certificate Authority (CA) . . . . . . . . . . . . . . . . . . . . . . 6
3.2 Certificates for internal users . . . . . . . . . . . . . . . . . . . . 7
3.3 Certificates for external users . . . . . . . . . . . . . . . . . . . . 9
4 Email clients setup 11
4.1 Outlook ................................ 11
4.1.1 Importing the pfx attachment . . . . . . . . . . . . . . . . 11
4.1.2 Receiving and sending S/MIME . . . . . . . . . . . . . . . 14
4.1.3 Sending signed and encrypted email . . . . . . . . . . . . 16
4.2 OutlookExpress ........................... 16
4.2.1 Importing the pfx attachment . . . . . . . . . . . . . . . . 17
4.2.2 Receiving and sending S/MIME . . . . . . . . . . . . . . . 18
4.2.3 Sending signed and encrypted email . . . . . . . . . . . . 18
4.3 Thunderbird.............................. 20
4.3.1 Importing the pfx attachment . . . . . . . . . . . . . . . . 21
4.3.2 Receiving signed and encrypted email . . . . . . . . . . . 25
4.3.3 Sending signed and encrypted email . . . . . . . . . . . . 26
4.4 AppleMail............................... 27
4.4.1 Importing the pfx attachment . . . . . . . . . . . . . . . . 27
4.4.2 Receiving signed and encrypted email . . . . . . . . . . . 28
4.4.3 Sending signed and encrypted email . . . . . . . . . . . . 28
4.5 Gmail ................................. 28
4.5.1 Installing the Firefox add-in . . . . . . . . . . . . . . . . . 29
4.5.2 Importing the pfx attachment . . . . . . . . . . . . . . . . 29
4.5.3 Sending signed and encrypted email . . . . . . . . . . . . 33
4.5.4 Sending signed and encrypted email . . . . . . . . . . . . 33
4.5.5 Notes ............................. 35
4.6 LotusNotes.............................. 36
4.6.1 Importing the pfx attachment . . . . . . . . . . . . . . . . 36
4.6.2 Receiving signed and encrypted email . . . . . . . . . . . 37
4.6.3 Sending signed and encrypted email . . . . . . . . . . . . 40
A Ciphermail S/MIME headers 41
B Links 42
2
2 S/MIME
1 Introduction
The first part of this guide will give a short introduction on S/MIME. The second
part of this guide will briefly explain how to setup a Ciphermail gateway for
S/MIME (for a more detailed guide on managing a Ciphermail gateway see the
Ciphermail Administration Guide). The third part of this guide will explain how
to setup S/MIME for some of the most popular email clients (like Outlook, Lotus
Notes etc.).
2 S/MIME
S/MIME is a widely supported email encryption standard. S/MIME is natively
supported by most common email clients like Outlook, Outlook express, Windows
Mail, Lotus Notes, Thunderbird, Evolution, Apple Mail, BlackBerry etc. This
section will give a brief introduction to S/MIME. S/MIME is based on Public Key
Infrastructure (PKI) and uses X.509 certificates.
Note: this section is a direct copy of the S/MIME section of the Ciphermail
Administration Guide and can be skipped if the section has already been read.
2.1 PKI
Public Key Infrastructure is a technology which can be used to securely ex-
change information over insecure networks using public key cryptography. PKI
uses X.509 certificates to bind a public key to an identity. The main advantage
of PKI is that there is no need to directly trust everyone involved because trust
can be inferred. Roughly speaking there are two trust models in use today:
hierarchical (via trusted CAs) or “Web Of Trust”.
With the hierarchical trust model, trust is inferred bottom-up. The root (the
bottom) is blindly trusted (that makes it by definition a root) and all leaf nodes
and branches (the end-user and intermediate certificates) are trusted because
they are child’s of the trusted root (to be precise the intermediate certificates
are issued by the root certificate). S/MIME uses a hierarchical trust model.
In a “Web of Trust” model, trust is inferred from trusted neighbors in a mesh
like structure (a web). For example: Alice trusts Bob and Ted trusts Alice and
therefore Ted now also trusts Bob (through Allice). The hierarchical model can
be viewed as a “Web of Trust” model with additional constraints.
Because trust is inferred from other entities, it is possible to securely check
whether one entity trusts another entity and that it is not possible to “spoof” any
trust. Trust checking is done using Public Key Cryptography. An intermediate
certificate is digitally signed by the issuer of the certificate using the issuers
private key. With the public key of the issuer, it can be checked whether the
certificate was really issued by the issuer. The public key together with some
extra information forms an X.509 certificate.
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2.2 X.509 certificate 2 S/MIME
2.2 X.509 certificate
A typical X.509 certificate contains the following elements (this is a non-exhaustive
list):
Public Key
• Subject
Email address
• Issuer
Serial Number
Not Before
Not After
Key Usage
Extended Key Usage
An X.509 certificate is digitally signed by the issuer of the certificate. By digitally
signing the certificate, any changes done after signing will break the signature.
Any changes to the certificate will therefore be noticed. A brief introduction of
some of the main elements of an X.509 now follows.
Public Key The public key, like the name already implies, is the key that
everyone is allowed to know. If a message must be encrypted, the public key
of the recipient is used for encryption. The public key is used to verify a digital
signature (the digital signature is created with the associated private key).
Subject The subject of a certificate contains the name of the “owner” and
optionally an email address (or sometimes multiple email addresses).
Email address A certificate can contain multiple email addresses. X.509
certificates for S/MIME should normally contain the email address for which
the certificate was issued.
Issuer The issuer contains the name of the issuer of this certificate (i.e., the
issuer element should be equal to the subject of the issuer). If the subject of
a certificate is equal to the issuer of a certificate the certificate is most likely a
self-signed certificate. Root certificates are almost always self-signed.
Serial Number Every certificate should have a serial number. The serial
number should be unique for the issuer (i.e., an issuer should use the serial
number only once).
Not Before This is the date at which the certificate becomes valid. If the
current date is before the Not Before date, the certificate is not yet valid.
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2.2 X.509 certificate 2 S/MIME
Not After This is the date at which the certificate is no longer valid. If the
current date is after the Not After date, the certificate is no longer valid.
Key Usage The public key of the certificate can be used for multiple pur-
poses. Sometimes however the issuer of the certificate wants to restrict the
key usage to only certain types. The following key usage types can be identi-
fied:
• digitalSignature
• nonRepudiation
• keyEncipherment
• dataEncipherment
• keyAgreement
• keyCertSign
• CRLSign
• encipherOnly
• decipherOnly
If the key usage is not specified it implies that the key may be used for all
purposes. For S/MIME encryption, if a key usage is specified it should at least
contain keyEncipherment. For S/MIME signing, if a key usage is specified it
should at least contain digitalSignature or nonRepudiation.
Extended Key Usage The extended key usage, if specified, further specifies
for what purposes the certificate has been issued. The following extended key
usages can be identified:
• anyKeyUsage
• serverAuth
• clientAuth
• codeSigning
• emailProtection
• timeStamping
• OCSPSigning
• IPSecEndSystem
• IPSecUser
• IPSecTunnel
• smartcardLogin
If the extended key usage is not specified it implies that the key may be used
for all purposes. For S/MIME, if an extended key usage is specified, it should
at least contain anyKeyUsage or emailProtection.
5
2.3 Revocation checking 3 GATEWAY S/MIME QUICK SETUP
Thumbprint The thumbprint is strictly speaking not part of an X.509 certifi-
cate. The thumbprint is the cryptographic hash1calculated over the bytes of
the encoded certificate. The thumbprint uniquely identifies a certificate. The
default algorithm used by Ciphermail for calculating the thumbprint is SHA-512.
2.3 Revocation checking
Sometimes it can happen that a certificate should no longer be used. For
example because the private key has been compromised or an employee has
left the company. Certificates can be revoked by putting the certificates on a
“Certificate Revocation List” (CRL). A CRL is issued by a certificate authority
(CA) and is periodically updated. A revoked certificate should no longer be
used. When a CRL is not available or when the administrator would like to
“black list” a specific certificate, the certificate can be added to the Certificate
Trust List (CTL). For more info on CTL see the Certificate Trust List section in
the Ciphermail Administration Guide.
3 Gateway S/MIME quick setup
Ciphermail supports S/MIME encryption and digital signatures. Both the sender
and receiver require a certificate and private key. Ciphermail therefore has a
built-in CA server that can be used to issue certificates and keys to internal and
external users for free.
External users, without a Ciphermail gateway, can use any S/MIME capable
email client to start sending en receiving encrypted email once the certificate
has been installed. External and internal users however are not required to
use the built-in CA. If an external recipient already possesses an S/MIME cer-
tificate, the certificate can be used instead.
What now follows is a quick-start-guide on setting up a Ciphermail gateway
for S/MIME. It is assumed that the Ciphermail gateway is already setup and is
capable of sending email.
3.1 Certificate Authority (CA)
The Ciphermail gateway contains a built-in CA server which can be used to cre-
ate end-user certificates for internal and external users. This helps to quickly
setup an S/MIME infrastructure without having to resort to external CAs for cer-
tificates and keys. Certificates and private keys can be securely transported to
external recipients using a password encrypted certificate store (.pfx). The ex-
ternal recipients can use the certificate with any S/MIME capable email client
like Outlook,Outlook express,Lotus Notes and start receiving and sending
S/MIME encrypted email without having to install additional software.
A brief explanation of the CA functionality will now follow. This section can
be skipped if a CA is already setup.
1See http://en.wikipedia.org/wiki/Cryptographic_hash_function for more info on
cryptographic hash functions.
6
3.2 Certificates for internal users 3 GATEWAY S/MIME QUICK SETUP
Note: the built-in CA has limited functionality. If support for multiple CA pro-
files, OCSP, CRLs for intermediate and root certificates is required a dedicated
external CA should be used instead (for example EJBCA).
Creating new CA
A new CA can be created by clicking Create new CA on the CA page (CACreate
new CA). The Create new CA page will be opened (see figure 1).
With the following steps, a new CA can be created:
1. Set validity to 1825 days (5 years) and key length to 20482.
2. Leave the email field empty.
3. Set a common name that uniquely identifies your CA. The common name
of the root must be different from the common name of the intermediate.
4. Select make default CA.
5. Set signature algorithm to SHA1 With RSA3.
6. Click Create to create the new root and intermediate certificate.
3.2 Certificates for internal users
For every internal user an S/MIME certificate should be created. The domains
for which email is received should be internal domains and should be set to
allow encrypted S/MIME messages to be sent.
For every domain for which you receive email do the following:
1. Add the domain.
2. Set Encrypt mode to Allow4.
3. Set the Locality property to Internal.
4. Set the S/MIME Allow property.
For every internal user (i.e., a user from an internal domain) do the following:
1. Create a new end-user certificate by clicking CA (this opens the Create
end-user certificate page, see figure 2)
2. Set validity to 1825 days (5 years) and key length to 20485.
22048 is the best compromise between security and key length.
3Windows versions prior to XP-sp3 do not support SHA256 With RSA or better. If older Win-
dows versions should be supported, you are advised to use SHA1 With RSA. If support for older
Windows versions is not required, you are advised to select SHA256 With RSA.
4Alternatively No Encryption can be used in combination with a Subject trigger.
52048 is the best compromise between security and key length.
7
3.2 Certificates for internal users 3 GATEWAY S/MIME QUICK SETUP
Figure 1: Create new CA
8
3.3 Certificates for external users 3 GATEWAY S/MIME QUICK SETUP
3. Set signature algorithm to SHA1 With RSA6.
4. Set email to the email address of the internal user.
5. Set a common name to identify the user (for example use the first and
last name of the user).
6. Click Create to create the certificate and private key for the user.
Note: For advanced settings like CRL distribution point see the Ciphermail
Administration Guide for more information.
3.3 Certificates for external users
In order to send and receive S/MIME encrypted and digitally signed email,
every external recipient should possess a certificate and private key. An exter-
nal recipient can request a certificate from an external CA (for example from
Verisign). However, getting a certificate from Ciphermail’s built-in CA is much
simpler than requesting a certificate from an external CA. With Ciphermail’s
built-in CA, the external user only need to install a password protected pfx file.
Note: the email address of the CA should be specified before the password
protected pfx file can be sent. For more information, see CA email setting in
section CA settings of the Ciphermail Administration Guide.
For each external recipient requiring an S/MIME certificate do the following:
1. Create a new user.
2. Set the S/MIME Allow property.
3. Create a new end-user certificate by clicking CA (this opens the Create
end-user certificate page, see figure 2)
4. Set validity to 1825 days (5 years) and key length to 20487.
5. Set signature algorithm to SHA1 With RSA8.
6. Set email to the email address of the external user.
7. Set a common name to identify the user (for example use the first and
last name of the user).
8. If the certificate and private key should be sent by email to the external
recipient in a password encrypted pfx file, select Send by email and select
a secure password 9.
6Windows versions prior to XP-sp3 do not support SHA256 With RSA or better. If older Win-
dows versions should be supported, you are advised to use SHA1 With RSA. If support for older
Windows versions is not required, you are advised to select SHA256 With RSA.
72048 is the best compromise between security and key length.
8Windows versions prior to XP-sp3 do not support SHA256 With RSA or better. If older Win-
dows versions should be supported, you are advised to use SHA1 With RSA. If support for older
Windows versions is not required, you are advised to select SHA256 With RSA.
9the ’gear’ icon generates a secure random password
9
3.3 Certificates for external users 3 GATEWAY S/MIME QUICK SETUP
Figure 2: Create end-user certificate
10
4 EMAIL CLIENTS SETUP
9. If the recipient should receive the pfx password via an SMS Text mes-
sage, select SMS password. The recipients telephone number should be
set for the external user.
10. Click Create to create the certificate and private key for the user.
After the certificate has been created, the certificates will be added to the cer-
tificate store. If Send by email was selected, the certificate and private key
will be stored inside a password encrypted pfx file and a message with the pfx
file will be sent to the recipient. If the SMS password was selected, the pass-
word for the pfx file will be sent to the recipient via an SMS Text message. If
the password was not sent via an SMS Text message, an alternative channel
should be used to let the recipient know what the password is.
The pfx file with the certificate and private key should be installed on the re-
cipients email client. The next sections will briefly explain the pfx file installation
procedures for some of the most used email clients.
4 Email clients setup
The next sections will explain the pfx file installation procedures for some of the
most used email clients.
4.1 Outlook
4.1.1 Importing the pfx attachment
An Outlook recipient receives a message with the password encrypted pfx file
as an attachment (see figure 3).
Figure 3: Outlook pfx attachment
The pfx file can be imported with the following procedure:
11
4.1 Outlook 4 EMAIL CLIENTS SETUP
1. Start the “certificate import wizard”.
2. Go to password page.
3. Enter the private key password.
4. Go to finish page.
5. Accept the trusted root certificate.
These steps will now be explained in more detail.
1. Start the “certificate import wizard” Double click the attached pfx file
(alternatively save the pfx file and open it with the file Explorer). A warning will
be shown asking whether the pfx file should be opened (see figure 4). Click on
the Open button. The certificate import wizard will now be started.
Figure 4: Outlook open pfx file
2. Go to password page Click Next button until the password page (see
figure 5).
3. Enter the private key password Enter the pfx file password (see figure 6).
The following two options can optionally be enabled: Enable strong private key
protection and Mark this key as exportable
Enable strong private key protection If this option is selected Windows will
always ask for permission when a program tries to access the private key.
Mark this key as exportable If this option is selected, the private key can be
exported to create a backup of the private key.
4. Go to finish page Click next until the finish page (see figure 7).
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4.1 Outlook 4 EMAIL CLIENTS SETUP
Figure 5: Certificate import wizard
Figure 6: Enter pfx password
5. Accept the trusted root certificate On the final page, click Finish to start
the certificate and private key import procedure. The pfx file not only con-
tains an end-user certificate and private key, but also the root and intermediate
certificates. The import wizard will try to import the root and intermediate cer-
tificates. When importing a root certificate a warning dialog is shown asking for
permission to import the root certificate (see figure 8). Click Yes to accept the
root certificate.
13
4.1 Outlook 4 EMAIL CLIENTS SETUP
Figure 7: Certificate wizard finish
Warning: Only accept the root certificate if it comes from a trusted entity.
Figure 8: Certificate wizard root import warning
4.1.2 Receiving and sending S/MIME
Now a certificate and private key have been installed, S/MIME encrypted and
digitally signed email can be sent and received. An example of a signed an
encrypted email in Outlook is shown in figure 9.
The “padlock” indicates that the message was encrypted and the “ribbon”
indicates that the message was signed (see figure 10) The signed and en-
crypted message contains the public certificate of the sender. To make it pos-
14
4.1 Outlook 4 EMAIL CLIENTS SETUP
Figure 9: Outlook signed and encrypted
sible to reply to the message, the public certificate should be associated with
the sender. This can be done by clicking the senders email address then right-
click and select Add to Outlook Contacts (see figure 11).
Figure 10: Outlook sign and encrypt icons
Figure 11: Outlook add to contacts
Now save the newly added Outlook contact. If the contact is already part of
your contacts you will receive a “Duplicate Contact Detected” (see figure 12).
15
4.2 Outlook Express 4 EMAIL CLIENTS SETUP
Click Update to add the certificate to the contact.
Figure 12: Outlook duplicate contact
Note: You only need to associate the certificate with the sender contact the
first time you receive a signed and encrypted email.
4.1.3 Sending signed and encrypted email
Sending a signed and encrypted email with Outlook is similar to sending a
normal non-encrypted email. Sign and encrypt is triggered by selecting the
sign and encrypt options. Outlook 2007 adds these icons to the toolbar (see
figure 13). With older versions of Outlook the sign and encrypt icons can be
manually added to the toolbar or the sign and encrypt option can be selected
by opening the message options and selecting the Security Settings. . . (see
figure 14).
In order to encrypt an email for a recipient, the certificate of the recipient
must be available. If Outlook cannot find a certificate for one of the recipients
a warning will be shown (see figure 15).
A message cannot be encrypted when the recipient does not have a cer-
tificate associated with the contact. A copy of the recipients certificate can be
directly imported into the associated contact. To do this, open the contact and
select the Certificates for the contact10 (see figure 16) and import the certificate
file (.cer or .p7b).
4.2 Outlook Express
An Outlook Express recipient receives a message with the password encrypted
pfx file as an attachment (see figure 17).
10In Outlook 2003 you should open the Certificates tab.
16
4.2 Outlook Express 4 EMAIL CLIENTS SETUP
Figure 13: Outlook sign and encrypt options
Figure 14: Outlook security properties
4.2.1 Importing the pfx attachment
Importing the pfx from Outlook Express is similar to importing from Outlook.
See section 4.1.1 for a detailed explanation on how to import the pfx attach-
ment.
17
4.2 Outlook Express 4 EMAIL CLIENTS SETUP
Figure 15: Outlook encryption problems
Figure 16: Outlook contact certificates
4.2.2 Receiving and sending S/MIME
Now a certificate and private key have been installed, S/MIME encrypted and
digitally signed email can be sent and received. An example of a signed an
encrypted email in Outlook Express is shown in figure 18.
The “padlock” indicates that the message was encrypted and the “ribbon”
indicates that the message was signed (see figure 19) Outlook Express auto-
matically associates the certificate of the sender with the senders contact.
4.2.3 Sending signed and encrypted email
Sending a signed and encrypted email with Outlook is similar to sending a
normal non-encrypted email. Sign and encrypt is triggered by selecting the
sign and encrypt options (see figure 20)
18
4.2 Outlook Express 4 EMAIL CLIENTS SETUP
Figure 17: Outlook Express pfx attachment
Figure 18: Outlook Express signed and encrypted
Figure 19: Outlook Express sign and encrypt icons
19
4.3 Thunderbird 4 EMAIL CLIENTS SETUP
Figure 20: Outlook Express sign and encryption options
4.3 Thunderbird
A Thunderbird recipient receives a message with the password encrypted pfx
file as an attachment (see figure 21).
Figure 21: Thunderbird pfx attachment
20
4.3 Thunderbird 4 EMAIL CLIENTS SETUP
4.3.1 Importing the pfx attachment
The pfx file can be imported with the following procedure:
1. Save the pfx file to the desktop.
2. Open the certificate manager.
3. Import the pfx.
4. Set the master password.
5. Enter the pfx password.
6. Lookup the name of the imported root.
7. Enable the imported root for S/MIME.
8. Select a signing and encryption certificate.
These steps will now be explained in more detail.
1. Save the pfx file to the desktop The pfx attached to the messages should
be saved before the pfx can be imported. The the key.pfx attachment should be
saved to the desktop (or to any other location normally used for attachments).
2. Open the certificate manager Open the Thunderbird options dialog
(ToolsOptions11). Select the Advanced settings and select the Certificates
tab (see figure 22). Now click View Certificates. The Certificate Manager will
now be opened (see figure 23).
Figure 22: Thunderbird certificates options
3. Import the pfx On the Certificate Manager select the Your Certificates
tab, click the Import button and select the pfx file which was previously saved
in step 1.
11On some Thunderbird versions the options dialog should be opened with EditPreferences
21
4.3 Thunderbird 4 EMAIL CLIENTS SETUP
Figure 23: Thunderbird certificate manager
4. Set the master password The first time a certificate is added to Thunder-
bird, the Master Password for the key store should be set (see figure 24). The
master password is used to protect the private keys which are stored in Thun-
derbird. The private keys are encrypted with the Master Password to ensure
that only the owner can access the private keys.
Note: this is NOT the password of the pfx file from step 1! A secure master
password should be selected by the computer owner or administrator. If the
master password was already set, the master password should be entered
before a new certificate can be imported.
Figure 24: Thunderbird master password
5. Enter the pfx password The password for the pfx file should now be
entered (see figure 25). This is the password that was provided via an SMS
Text message or provided by other means. Clicking OK will start the import
process.
22
4.3 Thunderbird 4 EMAIL CLIENTS SETUP
Figure 25: Thunderbird password entry dialog
6. Lookup the name of the imported root The imported root certificate
is not yet enabled for S/MIME. Before the root certificate can be enabled for
S/MIME the name of the root certificate should be looked up first. Open the
Certificate Manager, select the Your Certificates tab and select the certificate
that was just imported (see figure 26).
Double click the certificate to open the certificate details page (see fig-
ure 27). The first entry in the Certificate Hierarchy is the root certificate. The
name of the root certificate is needed in the following steps.
Figure 26: Thunderbird manager your certificates
7. Enable the imported root for S/MIME Open the Certificate Manager and
select the Authorities tab (see figure 28). Select the root certificate from step 6
and click the Edit button to open the Edit CA certificate trust settings page.
On the Edit CA certificate trust settings page, select “This certificate can iden-
tify mail users” to enable the root certificate for S/MIME (see figure 29). Click
OK and close all dialogs.
8. Select a signing and encryption certificate Now that a certificate and
private key have been imported, the encryption and signing certificate should
23
4.3 Thunderbird 4 EMAIL CLIENTS SETUP
Figure 27: Thunderbird certificate details
Figure 28: Thunderbird authorities
Figure 29: Thunderbird CA certificate trust settings
24
4.3 Thunderbird 4 EMAIL CLIENTS SETUP
be selected. Open the Account Settings page (ToolsAccount Settings...12).
Now select the security options of the email account for which the signing and
encryption certificate should be set (see figure 30).
To select a signing and encryption certificate, click the Select... button for Dig-
ital Signing and Encryption and select the newly added certificate. Leave all
other settings to their default values and close the account settings dialog.
Thunderbird is now ready for sending and receiving signed and encrypted
email.
Figure 30: Thunderbird Account Settings
4.3.2 Receiving signed and encrypted email
An example of a signed an encrypted email in Thunderbird is shown in fig-
ure 32. The “padlock” indicates that the message was encrypted and the “rib-
bon” indicates that the message was signed (see figure 31)
Figure 31: Thunderbird sign and encrypt icons
12On some Thunderbird versions the Account Settings should be opened with EditAccount
Settings...
25
4.3 Thunderbird 4 EMAIL CLIENTS SETUP
Figure 32: Thunderbird signed and encrypted
4.3.3 Sending signed and encrypted email
A message in Thunderbird can be signed and encrypted by selecting Encrypt
This Message and Digitally Sign This Message from the Security pull-down
menu (see figure 33).
Figure 33: Thunderbird sign and encrypt
26
4.4 Apple Mail 4 EMAIL CLIENTS SETUP
4.4 Apple Mail
4.4.1 Importing the pfx attachment
The pfx file can be imported with the following procedure:
1. Start the Keychain Access application.
2. Enter the pfx password.
3. Accept the root certificate.
4. Restart Mail.
These steps will now be explained in more detail.
1. Start the Keychain Access application By double-clicking the pfx file, the
Keychain Access application will be started. The Keychain Access application
will automatically start the certificate and private key import process. If the
Keychain Access application is not automatically opened, drag the pfx file onto
the Keychain Access application icon13.
2. Enter the pfx password The password for the pfx file should now be
entered. This is the password that was provided via an SMS Text message or
provided by other means.
3. Accept the root certificate The pfx file not only contains the end-user
certificate and private key but also the root and intermediate certificate. When
import a root certificate, the Keychain Access application asks whether the root
certificate should be trusted14 (see figure 34). Select Always trust.
Figure 34: Apple Mail trust root certificate
13/Applications/Utilities
14This example is in Dutch. Dialogs for other languages should look similar.
27
4.5 Gmail 4 EMAIL CLIENTS SETUP
4. Restart Apple Mail After installing the private key, Apple Mail should be
restarted. Apple Mail is now setup for sending and receiving signed and en-
crypted email.
4.4.2 Receiving signed and encrypted email
An example of a signed an encrypted email in Apple Mail is shown in figure 35.
Figure 35: Apple Mail signed and encrypted
4.4.3 Sending signed and encrypted email
A message can be signed and encrypted by selecting the sign and encrypt
options in the compose window (see figure 36).
Figure 36: Apple Mail sign and encrypt buttons
4.5 Gmail
If Gmail is accessed via the Gmail web interface, a dedicated browser add-
in is required for reading and sending S/MIME messages since Gmail does
not natively support S/MIME. A cross-platform add-in is available for Firefox
with which S/MIME encrypted email can be sent and received directly from the
Gmail web interface.
Note: If Gmail is accessed with POP3 or IMAP using an email client, like for
instance Outlook, see the guide for the specific email client. This section only
explains how to use S/MIME with the Gmail web interface.
28
4.5 Gmail 4 EMAIL CLIENTS SETUP
4.5.1 Installing the Firefox add-in
The Gmail add-in can be downloaded from https://addons.mozilla.org/
en-US/firefox/addon/592. The add-in can be installed by clicking Add to
Firefox.
4.5.2 Importing the pfx attachment
A Gmail recipient receives a message with the password encrypted pfx file as
an attachment (see figure 37).
Figure 37: Gmail pfx attachment
The pfx file can be imported with the following procedure:
1. Save the pfx file to the desktop.
2. Open the certificate manager.
3. Import the pfx.
4. Set the master password.
5. Enter the pfx password.
6. Lookup the name of the imported root.
7. Enable the imported root for S/MIME.
These steps will now be explained in more detail.
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4.5 Gmail 4 EMAIL CLIENTS SETUP
1. Save the pfx file to the desktop Because the Gmail add-in works with
Firefox, the pfx file must be saved to the desktop (or to any other location)
before it can be imported into Firefox.
2. Open the certificate manager Open the Firefox options dialog from the
Firefox menu (ToolsOptions15). Select the Advanced settings and select
the Certificates tab (see figure 38). Now click View Certificates. The Certificate
Manager will now be opened (see figure 39).
Figure 38: Firefox certificates options
Figure 39: Firefox certificate manager
3. Import the pfx On the Certificate Manager select the Your Certificates
tab, click the Import button and select the pfx file which was previously saved
in step 1.
15On some Firefox versions the options dialog should be opened with EditPreferences
30
4.5 Gmail 4 EMAIL CLIENTS SETUP
4. Set the master password The first time a certificate is added to Firefox the
Master Password for the key store should be set (see figure 40). The master
password is used to protect the private keys which are stored in Firefox. The
private keys are encrypted with the Master Password to ensure that only the
owner can access the private keys.
Note: this is NOT the password of the pfx file from step 1! A secure master
password should be selected by the computer owner or administrator. If the
master password was already set, the master password should be entered
before a new certificate can be imported.
Figure 40: Firefox master password
5. Enter the pfx password The password for the pfx file should now be
entered (see figure 41. This is the password that was provided via an SMS
Text message or provided by other means. Clicking OK will start the import
process.
Figure 41: Firefox password entry dialog
6. Lookup the name of the imported root The imported root certificate
is not yet enabled for S/MIME. Before the root certificate can be enabled for
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4.5 Gmail 4 EMAIL CLIENTS SETUP
S/MIME the name of the root certificate should be looked up first. Open the
Certificate Manager, select the Your Certificates tab and select the certificate
that was just imported (see figure 42).
Double click the certificate to open the certificate details page (see fig-
ure 43). The first entry in the Certificate Hierarchy is the root certificate. The
name of the root certificate is needed in the following steps.
Figure 42: Firefox manager your certificates
Figure 43: Firefox certificate details
7. Enable the imported root for S/MIME Open the Certificate Manager and
select the Authorities tab (see figure 44). Select the root certificate from step 6
and click the Edit button to open the Edit CA certificate trust settings page.
On the Edit CA certificate trust settings page, select “This certificate can iden-
tify mail users” to enable the root certificate for S/MIME (see figure 45). Click
32
4.5 Gmail 4 EMAIL CLIENTS SETUP
OK and close all dialogs.
Gmail is now ready for sending and receiving signed and encrypted email.
Figure 44: Firefox authorities
Figure 45: Firefox CA certificate trust settings
4.5.3 Sending signed and encrypted email
An example of a signed an encrypted email in Gmail is shown in figure 46.
Note: The Gmail S/MIME add-in currently does not verify digital signatures.
4.5.4 Sending signed and encrypted email
A message can be signed and encrypted by selecting the sign and encrypt op-
tion (see figure 47).
Click Send to sign, encrypt and send the message. When a message is signed
33
4.5 Gmail 4 EMAIL CLIENTS SETUP
Figure 46: Gmail signed and encrypted
Figure 47: Gmail sign and encrypt options
a confirmation dialog will pop-up asking to confirm the signing of the message
(see figure 48).
To confirm the signing the master password from step 4 must be entered.
After clicking OK a pop-up dialog will be shown on which the Gmail password
34
4.5 Gmail 4 EMAIL CLIENTS SETUP
Figure 48: Gmail sign confirmation
should be entered (see figure 49). The Gmail add-in sends the signed and en-
crypted message via the Gmail SMTP servers. The Gmail password is required
for sending the message via the Gmail SMTP servers.
Figure 49: Gmail SMTP password
4.5.5 Notes
The Gmail S/MIME add-in has some shortcomings compared to S/MIME sup-
port in other mail clients.
Signatures are not verified.
35
4.6 Lotus Notes 4 EMAIL CLIENTS SETUP
Drafts are not stored securely.
For more information see http://richard.jones.name/google-hacks/gmail-smime/
gmail-smime.html.
4.6 Lotus Notes
A Lotus Notes recipient receives a message with the password encrypted pfx
file as an attachment (see figure 50).
Figure 50: Lotus Notes pfx attachment
4.6.1 Importing the pfx attachment
The pfx file can be imported with the following procedure:
1. Save the pfx file to the desktop.
2. Open the User Security settings.
3. Import Internet Certificates.
4. Enter the pfx password.
5. Accept all certificates.
These steps will now be explained in more detail.
1. Save the pfx file to the desktop The pfx attached to the messages should
be saved before the pfx can be imported. The the key.pfx attachment should be
saved to the desktop (or to any other location normally used for attachments).
36
4.6 Lotus Notes 4 EMAIL CLIENTS SETUP
2. Open the User Security settings Open the User Security settings page
from main menu FileSecurityUser Security... (see figure 51).
Figure 51: Lotus Notes Your Certificates
3. Import Internet Certificates On the User Security page, select Your
IdentityYour Certificates and click Get Certificates and select Import In-
ternet Certificates from the pull-down menu (see figure 52). Select the pfx file
which was saved in step 1. A pop-up dialog opens in which the file format of
the file to import should be selected (see figure 53). Select PKCS 12 encoded
and click Continue.
4. Enter the pfx password The password for the pfx file should now be
entered (see figure 54. This is the password that was provided via an SMS
Text message or provided by other means. Clicking OK will start the import
process.
5. Accept all certificates The import wizard will now be opened listing all
certificates which will be imported (see figure 55). Click Accept All to start
importing all the certificates.
4.6.2 Receiving signed and encrypted email
The first time a signed and encrypted message is received by Lotus Notes, the
signer certificates should be Cross certified. Click Cross certify to approve the
37
4.6 Lotus Notes 4 EMAIL CLIENTS SETUP
Figure 52: Lotus Notes Import Internet Certificates
Figure 53: Lotus Notes Import File Format
Figure 54: Lotus Notes PFX password
certificate (see figure 56).
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4.6 Lotus Notes 4 EMAIL CLIENTS SETUP
Figure 55: Lotus Notes confirm import
Note: A certificate only need to be cross certified once.
Figure 56: Lotus Notes Cross Certify
A signed and encrypted email can be recognized by clicking the Security icon
(see figure 57). This opens a pop-up page showing the security details of the
39
4.6 Lotus Notes 4 EMAIL CLIENTS SETUP
message.
Figure 57: Lotus Notes signed and encrypted
4.6.3 Sending signed and encrypted email
A message can be signed and encrypted by selecting the Sign and Encrypt
options on the Delivery Options page (see figure 58). The message will be
signed and encrypted when the message will be sent.
Figure 58: Lotus Notes delivery options
40
A CIPHERMAIL S/MIME HEADERS
A Ciphermail S/MIME headers
When an incoming email is handled by Ciphermail, special headers about the
security properties of the email are automatically added to the email. For ex-
ample, if an encrypted message sent to an internal users is decrypted by Ci-
phermail relevant information about the encryption algorithm and recipients is
added to the header. Because the message is decrypted by Ciphermail the
message is no longer encrypted. The internal recipient can therefore not see
that the message was encrypted. Ciphermail therefore adds some security re-
lated headers that can be used to check if the message was encrypted and or
signed.
The following headers will be added:
X-Djigzo-Info-Signer-ID -*
X-Djigzo-Info-Signer-Verified-*
X-Djigzo-Info-Signer-Trusted -*
X-Djigzo-Info-Signer-Trusted-Info-*
X-Djigzo-Info-Encryption-Algorithm -*
X-Djigzo-Info-Encryption-Recipient -*
Note: The * is replaced with an index and level as explained below.
[INDEX-]LEVEL
where INDEX and LEVEL are integer numbers starting at 0. INDEX is not used
for all headers (optional).
Example:
X-Djigzo-Info-Signer-ID-0-0
LEVEL denotes the S/MIME level the values applies to. An S/MIME message
supports multiple nested levels of protection (CMS layers). For example, a
message can first be signed and then encrypted. LEVEL 0 is the first level
found by the S/MIME handler. Multiple items can exist within one level. For
example, a message can be encrypted for multiple recipients. INDEX is the
index of an item within a level.
Example Headers:
X-Djigzo-Info-Encryption-Algorithm-0: AES128, Key size: 128
X-Djigzo-Info-Encryption-Recipient-0-0:
CN=Thawte Personal Freemail Issuing CA, O=Thawte Consulting (Pty) Ltd.,
C=ZA/6B55D312FF5F9D5DAD9866FF827FFEB5//1.2.840.113549.1.1.1
X-Djigzo-Info-Encryption-Recipient-1-0:
EMAILADDRESS=support@cacert.org, CN=CA Cert Signing Authority,
OU=http://www.cacert.org, O=Root CA/6683C//1.2.840.113549.1.1.1
41
B LINKS
X-Djigzo-Info-Signer-ID-0-1: CN=UTN-USERFirst-Client Authentication and Email,
OU=http://www.usertrust.com, O=The USERTRUST Network, L=Salt Lake City,
ST=UT, C=US/88F9874A02A53042E0228D78CBD55795/
X-Djigzo-Info-Signer-Verified-0-1: True
X-Djigzo-Info-Signer-Trusted-0-1: True
The example headers shows that the message was first signed and then en-
crypted. The encryption algorithm was AES128. The message was encrypted
with two certificates:
X-Djigzo-Info-Encryption-Recipient-0-0
X-Djigzo-Info-Encryption-Recipient-1-0
One certificate was issued by Thawte and the other was issued by CACert.
The message was signed by one signer with a certificate issued by Usertrust.
X-Djigzo-Info-Signer-Verified This headers shows whether the message con-
tent was signed and whether the message has not been changed after signing
(tampered).
X-Djigzo-Info-Signer-Trusted This headers shows whether the signing cer-
tificate was trusted (signed by root etc.) by the gateway. If the signing certifi-
cate was not trusted, the reason for not trusting the certificate is given in the
X-Djigzo-Info-Signer-Trusted header.
Note: When email is received by Ciphermail and delivered to an internal user,
it will remove all X-Djigzo-* headers to make sure that an external sender can-
not fake any Ciphermail specific headers.
B Links
Outlook
Using S/MIME in Microsoft Outlook http://searchexchange.techtarget.
com/generic/0,,sid43_gci1252311,00.html
Installing and using your certificate in Microsoft Outlook 2003 http://
www.globalsign.com/support/personal-certificate/per_outlook03.html
Overview of certificates and cryptographic e-mail messaging in Outlook
http://office.microsoft.com/en-us/outlook/HP012305341033.aspx?pid=
CH100622191033
42
B LINKS
Configuring S/MIME Security with Outlook Web Access 2003 http://
www.msexchange.org/tutorials/Configuring-SMIME-Security-Outlook-Web-Access-2003.
html
Implementing Outlook Web Access with the S/MIME Control http://
technet.microsoft.com/en-us/library/aa998939(EXCHG.65).aspx
Apple
How to Use a Secure Email Signing Certificate (Digital ID) http://support.
apple.com/kb/TA22353?viewlocale=en_US
S/MIME for Apple Mail http://joar.com/certificates/
Webmail
Gmail http://richard.jones.name/google-hacks/gmail-smime/gmail-smime.
html
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