Graphic explanation: What is a digital signature

graphic Explanation: What is a digital signatureA brief introduction to digital signatures by David Youd
Preface

Recently in the Internet Browsing SSL protocol encryption related articles, the more sense of "digital signature" produced a little confusion. Search directly for "What is digital signature" and discover this early article:

Http://www.youdzone.com/signature.html, very early. But still intriguing. On the net paste also found the relevant translation: Http://www.ruanyifeng.com/blog/2011/08/what_is_a_digital_signature.html.

Read it down and think that it is actually just a translation. Even the "storyline" has changed a lot. So he began to move his hands, so there is this article.

translationBob has two keys, one called the public key. That is, the public key, and one is called the private key.

Bob's public key is available to anyone who needs it, but his private key is reserved for himself. A key (public and private) is used to encrypt information.

The process of encrypting information means "confusion", so that only people with the right key are able to become readable again.

Bob's two keys, no matter what one is used to encrypt data, one can decrypt the data.

Susan (for example, shown below) encrypts a message with Bob's public key and sends it to Bob,bob to decrypt the information with the private key for reading. Any colleague of Bob may be able to get the information that Susan has encrypted. But without Bob's private key, this data is useless.

Take advantage of his private key and the appropriate software. Bob places a digital signature in the document and some data. This digital signature, which Bob puts in the data, is the only "logo" for Bob, which is hard to fabricate. Furthermore, this signature ensures that the data will be discovered whenever any changes occur.
When the document is signed. Bob's software will crush the data into just a few lines. This process is called "hash check". The resulting lines are called summaries of the information. (It is not possible to restore the information digest directly to the original data information)

Bob's software then uses his private key to encrypt the digest of the information. The result is a digital signature.

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Finally, Bob's software puts this digital signature in a piece with the information document. All the data has been identified.

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Now Bob passes the document to Pat.

Plot tangled ing. (Tragedy, no story ...) ）

It happens to be. Suan works at the company's CA Center (certificate authentication). Susan was able to sign Bob's public key and some of his information, simply to make a digital certificate for Bob.

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Now Bob's colleagues can make sure that the public key they have is bob by checking Bob's trusted credentials. In fact, no one in Bob's company would accept the signature without Susan generating the certificate. This gives Susan the right to revoke the digital certificate that the private key was compromised. And that's almost impossible.

Susan's CA certificate validation is widely accepted.
We went on to say that Bob sent the signed document to Pat.

In order to verify the digital signature on the document. Pat first uses the software to test the certificate on Bob's document with the public key of Susan (the CA). Assuming that the certificate is successfully untied, it proves that Susan generated it.

After the certificate is untied. Pat can be contacted by contacting CA Center. Compare the information on the Bob certificate to check if the document has been altered.
And then. Pat gets Bob's public key from the certificate. Use it to check Bob's signature.

Assuming Bob's public key is able to unlock the signature, Pat will determine that the signature was generated using Bob's private key. At the same time, the public key of the certificate that Susan issued was also matched. And. Assuming the signature is a comparison, it also shows that Doug could not change the contents of the document.
Although these steps look daunting, they are hand-in-hand with Pat's user-friendly software scene.

To verify the signature information, Pat just needs to click:

(Figure to verify the identity of the digital certificate)

for Downloads

Link: http://pan.baidu.com/s/1qWNrSZy password:vsi1

Graphic explanation: What is a digital signature