The recipient of the payload can validate the digital signature using the public key of the sender.

有效载荷的接收者可以使用发送者的公开密钥验证数字签名。

youdao

The sender USES the recipient's public key (available via published digital certificates) to encrypt the message. The recipient then USES his private key to decrypt the message.

发送方使用接收方的公开密钥(可以通过公开的数字证书得到)加密消息，然后接收方使用私钥解密消息。

youdao

The sender of the message USES the public key of the receiver to encrypt the message to be sent.

消息的发送方使用接受方的公钥加密消息并发送。

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Messages that appear in the priority box will initially be determined by an algorithm based on such as factors as the identity of the sender, key phrases in the message and whether the mail was sent to an individual or a large group.

CNN: Gmail looks to clear clutter with Priority Inbox

You have to modify the sender's public-key certificate, make sure the sender would have a copy of that and modify the recipient's key as well, Jones says.

CNN: Technology - Security flaw discovered in Network Associates PGP software

But after the time limit specified by the sender, the decryption key is erased from Disappearing's key server, making the message unreadable and effectively destroying it, even if the recipient stored it.

CNN: Make your e-mail disappear