Why do we use asymmetric key cryptography to then just generate a symmetric key to use?

stacksonstacksonstackoverflow

5/22/23, 6:52 PM

I'm learning about public key cryptography (asymmetric key cryptography), but from what I've gathered, we basically use public key crypto to just move directly onto private key cryptography (symmetric key cryptography).

Why not just always use asymmetric? (Note: I'm a software developer but not a cryptography expert. I'm just learning and find it fascinating. Thank you)

0 + 0

encryption

public-key

kelalaka

5/22/23, 7:09 PM

Does this answer your question? [Why is asymmetric cryptography bad for huge data?](https://crypto.stackexchange.com/questions/5782/why-is-asymmetric-cryptography-bad-for-huge-data) also [Why is hybrid encryption more effective than other encryption scheme?](https://crypto.stackexchange.com/q/31234/18298)

Evan Su

5/22/23, 7:13 PM

Asymmetric encryption is slow, so it's common to use asymmetric encryption to pass a symmetric encryption key to the other party and use something fast like AES to transfer data securely.

Georgy Firsov

5/22/23, 7:15 PM

Asymmetric algorithms require longer keys (but this problem is partially eliminated by ECC), they operate slower than symmetric ones, they potentially produce bigger ciphertexts (if we talk about ciphers)

Maarten Bodewes

5/22/23, 7:54 PM

I don't like the term "private key cryptography" myself. If you'd use symmetric cryptography and you have more then one party, then the key cannot be kept private (to one party), but it does need to remain secret. So "secret key cryptography" seems more appropriate.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Why do we use asymmetric key cryptography to then just generate a symmetric key to use?

TH: เหตุใดเราจึงใช้การเข้ารหัสคีย์อสมมาตรเพื่อสร้างคีย์สมมาตรเพื่อใช้

RO: De ce folosim criptografia cu cheie asimetrică pentru a genera apoi doar o cheie simetrică de utilizat?

RU: Почему мы используем криптографию с асимметричным ключом, а затем просто генерируем симметричный ключ для использования?

VI: Tại sao chúng ta sử dụng mật mã khóa bất đối xứng để sau đó chỉ cần tạo khóa đối xứng để sử dụng?

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