LESSON 9 E-MAIL SECURITY part VI

9.3 Safe E-mail Usage Part 2: Sending
Sending mail is a little more care free. There are some things you can do to make sure your
conversation is secure though. The first is to ensure your connection is secure (see section 9.4
Connection Security for more information). There are also methods to allow you to digitally
sign your messages, which guarantees that the message is from you and has not been
tampered with en route. And for maximum security, you can encrypt your messages to make
sure no one reads them.
Digital signatures prove who e-mail comes from, and that it has not been altered in transit. If
you establish the habit of using digital signatures for important e-mail, you will have a lot of
credibility if you ever need to disown forged mail that appears to be from you. They also allow
you to encrypt e-mail so that no one can read it except the recipient. PGP in particular offers
high levels of encryption which to break would require extreme computing power.

 

9.3.1 Digital Certificates
A digital certificate is unique to an individual, kind of like a drivers license or passport, and is
composed of 2 parts. These parts are a public and private key. The certificate is unique to
one person, and typically certificates are issued by a trusted Certificate Authority, or CA. The
list of Certificate Authorities you trust is distributed automatically (if you are a Microsoft
Windows User) by Windows Update and the list is accessible in your browser under
tools>internet options>content>certificates. You can go here to view certificates installed on
your machine (yours and others), and other certificate authorities you trust.

 

9.3 安全邮件使用 第二部分：发送邮件

发送邮件需要注意的事情不是很多。当然，你也可以采取一些措施来确定通信安全。第一件事是保证联机安全（参考9.4部分）。也可以通过一些方法来对邮件进行数字签名，用来保证邮件在发送途中没有被篡改过。也可以通过对邮件进行加密保证没有人能读懂，这种方法的安全度最高。

数字签名验证了发送方的身份，并且保证在传输途中没有被篡改。如果你养成了对重要邮件进行数字签名的习惯，你的信誉就会很好。你也可以对邮件加密，使除了接收方外的任何人都不能读懂。特别是PGP套件保证了很高的加密性能，没有很强大的计算能力不能破解密码。

 

9.3.1 数字证书

每个人的数字证书都是不同的，数字证书有点像驾照和护照，由两部分组成。证书由一个可信度高的证书权威认证机构颁发，你信任的认证机构名单通过窗口操作系统更新自动更新。在网页浏览器选择 工具->Internet选项->内容->证书。你可以通过这种方式查看安装在你电脑上的证书以及你信任的证书颁发机构。

 

You can disable the automatic update of CAs, and choose to remove all CAs from the list,
although this is not recommended. Instructions on how to do this are on Microsoft’s web site.

 

你可以取消认证机构的自动更新，选择删除名单上所有的认证机构。在Microsoft的网页上有关于该操作的详细讲解。