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Office 2008 Planning
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Digital certificate requirements for sending and receiving messages
The Entourage cryptography model uses public key encryption to send and receive digitally signed
and encrypted e-mail messages. Encryption makes a message unreadable to anyone other than
the intended recipient. To send an encrypted message, the sender must have a copy of the
recipient’s digital certificate. The message is encrypted specifically for each recipient by using the
recipient’s public key; it can be decrypted only by using the associated private key, which is stored
on the recipient's computer. Entourage uses the sender’s keys to read and write encrypted
messages in the Drafts or Sent Items folders, which allows users to review encrypted messages that
they have created. If the sender has no digital certificate, this review is not possible.
A digital signature helps the recipient verify the sender’s identity and the message integrity.
Digitally signing a message helps the recipient verify that you are the authentic sender and that
the contents of the message were not altered in transit.
Tip We recommend that digital certificates have a key size of 1,024 bits or more. Using a digital
certificate of this size makes it extremely difficult to decode an encrypted message or forge a
digital signature. For more information about the digital certificate key size, see Entourage
Help.
To The digital certificate requirement is
Send an encrypted
message
The sender must have a copy of each recipient’s digital certificate. The
sender does not need to have a digital certificate of his or her own. However,
if the sender does not have a digital certificate, he or she will not be able to
read the saved message in the Draft or Sent Items folder, and will not be
able to receive an encrypted response from a recipient.
Receive an
encrypted
message
The recipient must have a digital certificate of his or her own. The sender
must have a copy of the recipient's digital certificate in order to encrypt the
message.
Entourage 2008 can encrypt messages with any of the following encryption
algorithms: AES-256, AES-192, AES-128, and 3DES. Of these four algorithms,
3DES is the most compatible with other S/MIME applications and AES-256 is
the most secure.
Entourage 2008 supports the following signing algorithms for digital
signatures, which are listed from strongest to weakest: SHA-512, SHA-384,
SHA-256, and SHA-1. Of these four algorithms, SHA-1 is the most
compatible with other S/MIME application, and SHA-512 is the most secure.