Lesson: Exchanging Files课程：交换文件

If you want to electronically send an important document, (like a Contract) to someone else, it is a good idea to digitally "sign" the document, so your recipient can check that the document indeed came from you and was not altered in transit.如果你想以电子方式将重要文件（如合同）发送给其他人，最好对文件进行数字“签名”，这样你的收件人就可以检查文件是否确实来自你，并且在传输过程中没有被更改。

This lesson shows you how to use Security tools for the exchange of an important document, in this case a contract.本课将向您展示如何使用安全工具交换重要文档，在本例中为合同。

You first pretend that you are the contract sender, Stan Smith. This lesson shows the steps Stan would use to put the contract in a JAR file, sign it, and export the public key certificate for the public key corresponding to the private key used to sign the JAR file.你先假装你是合同发送者斯坦·史密斯。本课将展示Stan将使用的步骤，将合同放入JAR文件中，对其进行签名，并导出与用于签名JAR文件的私钥对应的公钥的公钥证书。

Then you pretend that you are Ruth, who has received the signed JAR file and the certificate. You'll use keytool to import the certificate into Ruth's keystore in an entry aliased by stan, and use the jarsigner tool to verify the signature.然后，您假装自己是Ruth，她已经收到了签名的JAR文件和证书。您将使用keytool将证书导入到Ruth的密钥库中，并使用jarsigner工具验证签名。

For further information about digital signatures, certificates, keystores, and the tools, see the API and Tools Use for Secure Code and File Exchanges lesson.有关数字签名、证书、密钥库和工具的更多信息，请参阅API和用于安全代码和文件交换的工具课程。

Here are the steps:以下是步骤：

• Steps for the Contract Sender合同发送方的步骤
• Steps for the Contract Receiver合同接收方的步骤