Public key

As explained in ASP.NET Core in Action, 3e

A public key is a cryptographic key intended for distribution that can be used with its corresponding private key for encryption or verification.

A public key is the shareable half of a cryptographic key pair. In HTTPS, a server sends its public key so a browser can encrypt data that only the server’s private key can decrypt. section 28.2

Keep these roles distinct:

• Public key: distributed openly and used by the browser for encryption. section 28.2
• Private key: retained by the server and used to decrypt data encrypted with the public key. section 28.2
• Certificate trust: depends on a trusted certificate authority and root certificate, not merely on possessing a public key. section 28.2

HTTPS development certificate

When an ASP.NET Core application uses a development certificate, the server presents its public key to the browser. An untrusted certificate can trigger a browser warning even though the public/private key relationship still supports HTTPS encryption. section 28.2

Figure 28.4 The developer certificate is not trusted by default, so apps serving HTTPS traffic using it will be marked as insecure by browsers. Although you can bypass the warnings if necessary, you should instead update the certificate to be trusted.

Use the figure to recognize how an untrusted development certificate appears in a browser. section 28.2

How ASP.NET Core in Action, 3e covers it

How deep it goes

Defines the public/private relationship and certificate trust chain, but stops short of cryptographic algorithms or implementation internals.

Examples

Uses browser-to-server encryption and an ASP.NET Core development certificate that produces an untrusted-certificate warning.

What you can do after

Evaluate HTTPS certificate warnings by separating encryption provided by the key pair from trust provided by certificate authorities.

How it connects

Connects public-key cryptography with private keys, HTTPS, TLS certificates, certificate authorities, and root certificates.

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Also explained in

• 

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  Software Security for DevelopersA public key is the openly distributable member of a cryptographic key pair used for operations such as encryption or signature verification.
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  Real-World CryptographyA value in a public-key cryptosystem that may be distributed openly for verification or encryption operations.
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  liveBookmanning.com
  Hacking CryptographyThe public key is the openly distributable member of an asymmetric key pair used for operations such as encryption or signature verification.
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  liveBookmanning.com
  Secure APIsA public key is the openly distributable half of an asymmetric cryptographic key pair used to verify signatures or perform public-key operations.
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  liveBookmanning.com
  Elliptic Curve Cryptography for DevelopersA public key is a cryptographic value distributed openly and paired with a private key for encryption, signature verification, or related public-key operations.
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  liveBookmanning.com
  API Design PatternsA public key is the openly distributable component of an asymmetric cryptographic key pair used to verify signatures or perform other public-key operations.
• 

  liveBookmanning.com
  Road to KubernetesA public SSH key is the shareable half of an SSH key pair used by a remote system to authenticate the corresponding private key.

Compare how 8 books explain public key →

Related concepts

• certificatepart of · A digital certificate is a digitally signed credential that binds an identity to a public key and supports authentication or secure communication.
• public-private key pairpart of · A public-private key pair is a mathematically related public key and private key used together for asymmetric cryptographic operations.
• digital signatureused by · A digital signature is cryptographic data generated with a private key and verified with corresponding public information to authenticate data or its signer and detect alteration.
• signature verificationused by · Signature verification is the cryptographic process of checking a digital signature against data and a corresponding public key to determine whether it is valid.
• DKIMused by · DKIM is an email-authentication standard that uses domain-associated digital signatures to verify message integrity and claimed origin.

This explainer was generated by Manning's knowledge graph from the text of ASP.NET Core in Action, 3e. The section links point to the parts of the book it draws on.