different signatures for the same pk and message

[talip_ozturk]

Hi,

With the privateKey: 619c335025c7f4012e556c2a58b2506e30b8511b53ade95ea316fd8c3286feb9
which gives me the publicKey: 025476c2e83188368da1ff3e292e7acafcdb3566bb0ad253f62fc70f07aeee6357
I am signing the following message:
c37af31116d1b27caf68aae9e3ac82f1477929014d5b917657d0eb49478cb670

The signature I create is always (repeatable):
304502203609e17b84f6a7d30c80bfa610b5b4542f32a8a0d5447a12fb1366d7f01cc44a022100a 8c56ab3bae7ccea9ebf906fcff170cb61b9c3bddb0c7f1133238e5ee9b75553

which is different from the one at https://github.com/bitcoin/bips/blob/master/bip-0143.mediawiki#Native_P2WPKH:
304402203609e17b84f6a7d30c80bfa610b5b4542f32a8a0d5447a12fb1366d7f01cc44a0220573 a954c4518331561406f90300e8f3358f51928d43c212a8caed02de67eebee

I can verify that the message is valid with both signatures (mine and the one on the website).

Is it normal that two (or more) different signatures can be created from the same privateKey & message? If so why? If it is because of the randomness feature of the ECDSA then why do I create the exact same signature -everytime- I ran the signing code with the same private key & message above?

[1715096310]

1715096310

[1715096310]

1715096310

[1715096310]

1715096310

[achow101]

Is it normal that two (or more) different signatures can be created from the same privateKey & message? If so why?

Yes. This is because of random numbers which are used during the signing process.

If it is because of the randomness feature of the ECDSA then why do I create the exact same signature -everytime- I ran the signing code with the same private key & message above?

Probably because the signing software is caching signatures.

[pepethefrog]

Probably because the signing software is caching signatures.

Don't think it is caching signatures, but rather reusing parameters of the RNG.

[amaclin]

Is it normal that two (or more) different signatures can be created from the same privateKey & message?

yes

If so why?

because there is random parameter while creating signature

If it is because of the randomness feature of the ECDSA then why do I create the exact same
signature -everytime- I ran the signing code with the same private key & message above?

google for "deterministic ecdsa"
your software uses it