邮箱如何秘密发送多个人邮件

Cryptography is the science of using codes and ciphers to protect messages, at its most basic level. Encryption is encoding messages with the intent of only allowing the intended recipient to understand the meaning of the message. It is a two way function (you need to be able to undo whatever scrambling you’ve done to the message). This is designed to protect data in transit.

密码术是在最基本的级别上使用代码和密码保护消息的科学。 加密是在对消息进行编码时，仅允许目标收件人理解消息的含义。 这是一种双向功能(您需要能够撤消对消息所做的任何加扰操作)。 旨在保护传输中的数据。

One of the earliest ciphers involved a simple shift. For example, if you just shift all the letters in the alphabet by a few, the alphabet might look like the following:

最早的密码之一就是简单的转换。 例如，如果仅将字母表中的所有字母移位几个，则该字母表可能如下所示：

ABCDEFGHIJKLMNOPQRSTUVWXYZ

ABCDEFGHIJKLMNOPQRSTUVWXYZ

NOPQRSTUVWXYZABCDEFGHIJKLM

NOPQRSTUVWXYZABCDEFGHIJKLM

Then, each letter of the alphabet corresponds to a different letter, but it is difficult to figure out which one, if you don’t already know. Using this cipher, the message, ‘Hello’ translates to ‘Uryyb’.

然后，字母表中的每个字母对应一个不同的字母，但是如果您不知道哪个字母，则很难弄清楚哪个字母。 使用此密码，消息“ Hello”将转换为“ Uryyb”。

Unfortunately, advances in analysis, particularly pattern analysis driven by very powerful computers, made these types of cyphers very easy to break.

不幸的是，分析的进步，特别是由功能强大的计算机驱动的模式分析，使得这些类型的密码非常容易破解。

In response to that, we’ve developed very strong, complex algorithms. These can be broken down into two basic types of encryptions — symmetric algorithms and asymmetric algorithms.

为此，我们开发了非常强大的复杂算法。 它们可以分为两种基本类型的加密-对称算法和非对称算法。

Symmetric algorithms are also known as ‘secret key’ algorithms, and asymmetric algorithms are known as ‘public key’ algorithms. The key difference between the two is that symmetric algorithms use the same key to encode and decode (see the first figure below), while asymmetric algorithms use different keys for encryption and decryption (see the second figure below).

对称算法也称为“秘密密钥”算法，非对称算法也称为“公共密钥”算法。 两者之间的关键区别在于对称算法使用相同的密钥进行编码和解码(请参见下面的第一张图)，而非对称算法使用不同的密钥进行加密和解密(请参见下面的第二张图)。

As you can see in the above figure, with symmetric encryption, if Bob and Midge want to communicate, Bob first encrypts his message with the secret key (the encrypted message is called ciphertext). Then he sends it to Midge. Midge then decrypts the message with the same secret key and is able to read the message. To send a message back, the process is reversed.

如上图所示，使用对称加密，如果Bob和Midge想要进行通信，Bob首先使用秘密密钥对他的消息进行加密(加密的消息称为密文)。 然后，他将其发送给Midge。 然后，Midge使用相同的密钥解密该消息，并能够读取该消息。 要发回消息，该过程被逆转。

This process is fast, scalable, and very secure. The problem with it is that it requires both parties to already have the same secret key. If they don’t, they need to pass it along insecure channels, which essentially removes the security of the encryption.

此过程快速，可扩展且非常安全。 它的问题在于，它要求双方已经拥有相同的密钥。 如果不这样做，则需要将其沿着不安全的通道传递，这实际上消除了加密的安全性。

With Asymmetric encryption, as in the above figure, if Bob and Midge want to communicate, Bob encrypts his message with Midge’s public key and sends it to her. She then decrypts the message with her private key to read it. To send a message back, the process is reversed.

如上图所示，使用非对称加密，如果Bob和Midge想要通信，Bob将使用Midge的公钥加密其消息并将其发送给她。 然后，她用她的私钥解密该消息以读取它。 要发回消息，该过程可以逆转。

In this way, anyone can send Midge a message, as she can make her public key available to anyone, but only she can decrypt a message (as she keeps her private key secret). It also solves the need to pass a secret key along insecure channels, because there is no need to pass a secret at all. The disadvantage is that it requires everyone who wants to communicate to have two different keys (not scalable), and it is relatively slow.

这样，任何人都可以向Midge发送消息，因为她可以将其公共密钥提供给任何人，但是只有她可以解密消息(因为她将私有密钥保密)。 这也解决了沿着不安全的通道传递秘密密钥的需要，因为根本不需要传递秘密。 缺点是它要求每个要通信的人都具有两个不同的密钥(不可伸缩)，并且速度较慢。

In general, when talking about encryption, the most important considerations are:

通常，在谈论加密时，最重要的注意事项是：

• Authentication/Nonrepudiation — Whether or not you can prove where messages originated (Am I sure who sent this message?).身份验证/不可否认性-您是否可以证明消息的来源(我确定谁发送了此消息吗？)。
• Reuse — Can I continue to use this key or will it need to be regenerated for each new communication?重用-我可以继续使用此密钥，还是需要为每个新通信重新生成它？
• Effectiveness — How fast can I transfer large amounts of data?有效性-我可以多快地传输大量数据？
• Scalability — Is this feasible for large groups?可伸缩性—这对于大型团体是否可行？
• Distribution — how do you distribute keys to the people who you’re communicating with, without divulging the secret to anyone else?分发-您如何将密钥分发给与您交流的人，而又不将秘密泄露给其他任何人？

That’s where significant differences start to come up between symmetric and asymmetric encryption, summarized below:

这就是对称和非对称加密之间开始出现显着差异的地方，总结如下：

In order to use the best of both worlds, many modern encryption protocols will use asymmetric encryption to establish a connection and create a shared secret. Then, they will switch to symmetric encryption to benefit from the speed difference.

为了使用两全其美，许多现代加密协议将使用非对称加密来建立连接并创建共享机密。 然后，他们将切换到对称加密以从速度差异中受益。

翻译自: https://www.freecodecamp.org/news/how-to-send-secret-messages/

邮箱如何秘密发送多个人邮件