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Crypto

Is there a cryptography algorithm for signing values with two keys and requiring both to verify it?

eja

8/25/23, 7:35 AM

Is there an algorithm that lets me sign a value with two keys at the same time, and in turn requires both keys to verify the signature?

For instance, a scheme could work like this:

Sign X with Key1 and Key2 at the same time
Verify X is signed by these two keys

This would be like a joint bank account: to do anything on this account, the bank will require signatures from the two persons that initially created the account together.

I wouldn't bring the value into question, but the goal would be the ability to verify X was signed by two specific parties.

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signature

hash-signature

Ruben De Smet

8/25/23, 7:45 AM

Is there a reason that signing the value X separate with both keys does not work out? I think you can sign X with k1, then with k2, and for verification, require both signatures to be present.

eja

8/25/23, 8:14 AM

It can be done, but I'd have to enforce the verification ie. require both keys -- but if anyone else would check the signed value against k1 only, verification would be ok, while it was intended to require the k2 as well, right? I was thinking there might be an algorithm that does this out of the box

fgrieu

8/25/23, 8:25 AM

Is it really wanted that both (public) keys are required for verification? Isn't what wanted a single common public verification key proving that both private keys have been involved in signing?

eja

8/25/23, 9:07 AM

you mind explaining more how this would work? also, to understand this idea better - this approach would mean that we generate an additional key each time whenever we sign a document with k1 and k2? and then this new key can verify the signature?

poncho

8/25/23, 12:00 PM

"It can be done, but I'd have to enforce the verification ie. require both keys"; actually, you can't force the verifier to do anything; he could accept any signature as valid, or perhaps any signature with exactly 42 '1' bits.

Maeher

8/25/23, 3:16 PM

It's called a multi-signature.

eja

8/25/23, 4:07 PM

@Maeher thanks a lot

eja

8/25/23, 4:07 PM

@poncho "it can be done" only if it's you who will be verifying it and nobody else

Elon Musk

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

EN: Is there a cryptography algorithm for signing values with two keys and requiring both to verify it?

TH: มีอัลกอริทึมการเข้ารหัสสำหรับการลงนามค่าด้วยสองคีย์และกำหนดให้ทั้งคู่ตรวจสอบหรือไม่

RO: Există un algoritm de criptare pentru semnarea valorilor cu două chei și care solicită ambelor să-l verifice?

RU: Существует ли криптографический алгоритм для подписи значений двумя ключами и требования обоих для его проверки?

VI: Có thuật toán mật mã nào để ký các giá trị bằng hai khóa và yêu cầu cả hai khóa xác minh không?

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