Basic asymmetric crypto question + can you do this with crypto?

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In summary, the individual is asking if there is a way to use public key cryptography to encrypt a message for a recipient and also have the ability to decrypt it using a "master" key. They also inquire if a hierarchy of keys can be created so that any private key can generate multiple public/private key pairs that can be decrypted by both the recipient and the "master" keys. They mention the concept of key escrow and thank the previous commenter for clarifying the process.
  • #1
cool_arrow
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Hi. Crypto noob here learning a little about the subject lately and I have some questions:

1) If I am using public key cryptography (like openpgp) and I encrypt a message for a recipient using their public key, can I decrypt that message using my private key in the future?

2) Does a method of asymmetric cryptography exist that allows one to generate public and private key pairs based on a "master" key such that the "master" can always decrypt anything encrypted with the keys generated/computed from it?

The reason I ask these questions is that I am wondering if there exists a cryptographic method whererby a hierarchy of keys can be created such that any private key can be used to generate any number of public/private key pairs and any message encrypted using these keys derived from the "master" can not only be decrypted by the recipient (of course), but also by the "master" keys from which it was derived.

Does something like this currently exist? Any info is appreciated.
 
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  • #2
cool_arrow said:
1) If I am using public key cryptography (like openpgp) and I encrypt a message for a recipient using their public key, can I decrypt that message using my private key in the future?
No. Why would you ever have to do that, considering you would have the plaintext to begin with?

2) Does a method of asymmetric cryptography exist that allows one to generate public and private key pairs based on a "master" key such that the "master" can always decrypt anything encrypted with the keys generated/computed from it?
This does not make sense. The public/private keys are a pair- if something is encrypted with your public key, you can decrypt it with your private key and VV. There is no need for a "master" key.


The reason I ask these questions is that I am wondering if there exists a cryptographic method whererby a hierarchy of keys can be created such that any private key can be used to generate any number of public/private key pairs and any message encrypted using these keys derived from the "master" can not only be decrypted by the recipient (of course), but also by the "master" keys from which it was derived.

Does something like this currently exist? Any info is appreciated.

Sounds like key escrow to me. In that case you'd just give the private key to the trusted escrow authority...like the US Government! Oh, wait...
 
  • #3
thanks fss. I think I'm clear on how it works now.
 

Related to Basic asymmetric crypto question + can you do this with crypto?

Question 1: What is asymmetric cryptography?

Asymmetric cryptography, also known as public-key cryptography, is a type of encryption where two different keys are used for encryption and decryption. One key, known as the public key, is used to encrypt the data, while the other key, known as the private key, is used to decrypt the data. This allows for secure communication between two parties without the need for a shared secret key.

Question 2: How does asymmetric cryptography differ from symmetric cryptography?

Asymmetric cryptography differs from symmetric cryptography in that it uses two different keys for encryption and decryption, while symmetric cryptography uses a single shared key. Asymmetric cryptography also provides additional security by allowing the public key to be freely distributed, while the private key remains secret.

Question 3: Can asymmetric cryptography be used for digital signatures?

Yes, asymmetric cryptography can be used for digital signatures. A digital signature is created by using the private key to encrypt a message, and then the recipient can use the corresponding public key to verify the signature and ensure that the message has not been altered.

Question 4: Is it possible to use asymmetric cryptography for secure online transactions?

Yes, asymmetric cryptography can be used for secure online transactions. Many websites use asymmetric cryptography, such as SSL certificates, to encrypt sensitive information like credit card numbers and passwords, making it difficult for hackers to intercept and steal this information.

Question 5: How can I generate my own public and private keys for asymmetric cryptography?

You can generate your own public and private keys using a key generation algorithm, such as RSA or Elliptic Curve. These algorithms use mathematical functions to generate a pair of keys that are mathematically related, but it is computationally infeasible to determine one key from the other. There are also many tools and software programs available that can generate keys for you.

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