Introduction to digital signature technology

• digital signature （ Also known as public key digital signature ） Only the sender of information can produce a digital string that others can't forge , This digital string is also an effective proof of the authenticity of the information sent by the sender . Digital signature is the application of asymmetric key encryption technology and digital digest technology
• Digital signature mechanism is one of the means to ensure the security of network information , Sure Solve forgery 、 Deny 、 Impersonation and tampering problems . One of the purposes of digital signature is to replace the traditional manual signature and seal in the network environment , It plays an important role
• Digital signature in modern times web It is of great significance in business . Most countries have regarded digital signature as an authorization mechanism with the same legal effect as manual signature .

Introduction to the principle of digital signature

• The sender A Use the private key to encrypt the information ( Also called signature ), Get the ciphertext ( It's also called digital signature ).
• The receiving party B After receiving the ciphertext , Use public key to decrypt ( Also called signature verification ), Get the original .
• We know , In theory, anyone can get the public key . If C Get A The public key , that C Intercepted ciphertext information , Is it possible to decrypt information directly . Here we will talk about the role of digital signature , Digital signatures are not intended to encrypt data , But to make sure that the information is indeed A Emitted , And the information has not been tampered . hypothesis C I forged a set of data , however C No, A The private key , Therefore, you cannot encrypt your forged data , perhaps C Encrypt data with your private key , Send to B,B It can't be decrypted . therefore B I know the news is not A Emitted . hypothesis C Intercepted A Ciphertext sent , Tampered with the ciphertext ,B Also cannot decrypt . therefore , as long as B The message is received and can be decrypted successfully , that B You can be sure , The message is indeed A Sent and the message has not been tampered .

The practical application

• The application of digital signature technology in practice is introduced below .

1 Summary of calculation

Introduction to Algorithm

• The sender A Use a digest algorithm for messages M Make a summary calculation , Get a summary of the news (MD1)
  

2 Signature

• The sender A Encrypt the message digest with the private key , Get a digital signature (DS)
  

3 Send a message

• The sender A The message is M And digital signatures (DS) Send it to the receiver together B
  

4 The receiver calculates the message digest

• B Received a message M And digital signatures (DS) after , First, use the same message summarization algorithm to summarize messages M Make a summary , Get a summary of the news (MD2).

5 The receiver's signature

• The receiving party B Decrypt the digital signature with the sender's public key ( Also called signature verification ). obtain MD1.
  

6 Compare and verify

• B Compare the message summary obtained from the signature verification MD1 And the message summary calculated by summarizing the original message MD2 Are they the same? . If the same , The information is really A Sent without tampering .