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Today, I will talk to you about the difference and usage of the signature algorithm HS256 and RS256 in C#, which may not be well understood by many people. in order to make you understand better, the editor has summarized the following content for you. I hope you can get something according to this article.

I. the difference between RS256 and HS256

HS256 uses keys to generate fixed signatures, and RS256 uses asymmetric signatures.

In a nutshell, HS256 must share secrets with any client or API that wants to authenticate JWT.

RS256 generates an asymmetric signature, which means that the private key must be used to sign the JWT, and the corresponding public key must be used to verify the signature. Unlike symmetric algorithms, the use of RS256 ensures that the server is the signer of the JWT, because the server is the only party with the private key. This eliminates the need to share private keys among many applications.

2. Two signature algorithms commonly used in JWT

Generally, there are two choices in JWT signature algorithm, one is to use HS256, the other is to use RS256.

A signature is actually an encryption process that generates an identity (which is also part of the JWT) as a basis for the receiver to verify that the information has been tampered with.

RS256 (RSA signature with SHA-256) is an asymmetric algorithm that uses a public / private key pair: the identity provider uses the private key to generate the signature, and the user of JWT obtains the public key to verify the signature. Because the public key (compared to the private key) does not require protection, most identity providers make it easy for users to obtain and use (usually through a metadata URL).

On the other hand, HS256 (HMAC with SHA-256) is a symmetric algorithm in which only one key is shared between the two parties. Because you use the same key to generate and verify signatures, care must be taken to ensure that the key is not compromised.

Enabling JWT when developing applications, using RS256 is more secure, and you can control who can use what types of keys. In addition, if you can not control the client, can not achieve the complete confidentiality of the key, RS256 will be a better choice, JWT users only need to know the public key.

Because the public key is usually available from the metadata URL node, the client can be programmed to retrieve the public key automatically. If you use this way, download the public key information directly from the server, you can effectively reduce the configuration information.

III. Introduction to JWT

JWT stands for JSON Web Token, which is an token format for authentication headers. This token enables you to communicate information between two systems in a secure way. For teaching purposes, we temporarily regard JWT as a "bearer token". An anonymous token consists of three parts: header,payload,signature.

Header is part of token and is used to store the type and encoding of token, usually using base-64 encoding.

Payload contains information. You can store any kind of information, such as user information, product information, etc. They are all stored using base-64 coding.

Signature includes a mixture of header,payload and key. The key must be securely stored on the server.

You can see below that JWT is about to work with an instance token:

IV. Practical exercise of HS256 and RS256

1. HS256 uses:

Generate Token based on specified user

Verify that the Token of the specified user is valid

2. HS256 uses:

Generate an rsa asymmetric key pair.

Private key encryption, public key verification.

After reading the above, do you have any further understanding of the difference and usage of the signature algorithm HS256 and RS256 in C #? If you want to know more knowledge or related content, please follow the industry information channel, thank you for your support.

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