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i was studying asymmetric encryption and i have a question about this encryption , i know that i can use public key to drcrypt message encrypted using private key and i can use private key to drcrypt message encrypted using private key.

but i was wondering if there is an ability to be using private key to decrypt message is encrypted using itself (private key)?

because i read that the private key is the complete key and you can extract the public key from it , but i searched about this thing but i have not found any decisive answer until now.

Pythoner-sh
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  • Sometimes the public key is stored together with the private key ... – Ebbe M. Pedersen Apr 02 '23 at 17:15
  • Does this answer your question? [Given a private key, is it possible to derive its public key?](https://stackoverflow.com/questions/696472/given-a-private-key-is-it-possible-to-derive-its-public-key) – not2savvy Apr 02 '23 at 19:51
  • There are multiple different asymmetric crypto systems. Is your question targeting a specific one like RSA or elleptic curves? Because I don't think the properties of all asymmetric crypto systems are the same. – Robert Apr 02 '23 at 20:43

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This is not possible in the wildest dream.

  1. Encrypt with public and decrypt with private -- possible
  2. Encrypt with private and decrypt with the public -- possible

This is possible due to the fact that both the private and public keys are related in a Mathematical way. But there is no way that a public key can be retrieved from the private key.

If this would have been possible then there would be no meaning of security as a terminology.

Hope this helps. Thanks.

Suchandra T
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    _„If this would have been possible then there would be no meaning of security as a terminology.“_ Why do you think so? (See the answers to [this question](https://stackoverflow.com/questions/696472/given-a-private-key-is-it-possible-to-derive-its-public-key).) – not2savvy Apr 02 '23 at 19:50