Is there a cryptography primitive for public/private keys such that only keys from a predefined set will be valid

user491880

7/20/23, 5:59 PM

I am trying to accomplish the following:

$Alice$ is an authority that can provide a secret $x$ to $Bob$, $x$ will enable $Bob$ to generate a public/private key pair $(p,q)$ which he can then use to sign messages. $Alice$ will not be able to sign messages as $Bob$.
Anyone can trivially verify that the public key $Bob$ used was authorized by $Alice$.

My initial thought is that one could implement a rough version of this by requiring $Bob$ to submit his public key to $Alice$ then collect a digital signature on the public key which is then included as an addendum to his public key. The only problem is that now $Alice$ knows $Bob$'s public key.

0 + 0

signature

Daniel S

7/20/23, 6:29 PM

You've just described how certifying authorities work in such protocols as TLS. Why is it a problem if Alice knows Bob's public key? This still does not allow Alice to sign messages as Bob (which would require Bob's private key).

poncho

7/20/23, 6:33 PM

If it's an issue that Alice knows Bob's public key, well, Alice to do a blind signature of Bob's public key...

Elon Musk

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

EN: Is there a cryptography primitive for public/private keys such that only keys from a predefined set will be valid

TH: มีการเข้ารหัสดั้งเดิมสำหรับคีย์สาธารณะ/ส่วนตัวหรือไม่ เช่น คีย์จากชุดที่กำหนดไว้ล่วงหน้าเท่านั้นจึงจะใช้ได้

RO: Există o primitivă de criptare pentru cheile publice/private, astfel încât numai cheile dintr-un set predefinit să fie valide

RU: Существует ли криптографический примитив для открытых/закрытых ключей, чтобы действительными были только ключи из предопределенного набора?

VI: Có một mã hóa nguyên thủy cho các khóa công khai/riêng tư sao cho chỉ các khóa từ một tập hợp được xác định trước mới hợp lệ

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