Segfault using secp256k1 | Bitcointalksearch.org

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legendary

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Reverse engineer from time to time

Quote from: Sophokles on July 30, 2014, 05:06:52 PM

Code:

 /** * In: compressed: whether the computed public key should be compressed

* seckey: pointer to a 32-byte private key.

* Out: pubkey: pointer to a 33-byte (if compressed) or 65-byte (if uncompressed)

* area to store the public key.

* pubkeylen: pointer to int that will be updated to contains the pubkey's

* length.

* Returns: 1: secret was valid, public key stores

* 0: secret was invalid, try again.

*/

int secp256k1_ecdsa_pubkey_create(unsigned char *pubkey, int *pubkeylen, const unsigned char *seckey, int compressed);

The function returns an int. Have the return value assigned to a variable.

Just wanted to let you know, that in C or C++ and in many languages in fact, you are not forced to store the return value of a function. It means that, that wasn't what was causing the issue Wink

Sophokles

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Cool. Will fiddle with this library a little later as well. Looks really interesting. Just today completely wrapped my mind around ECDSA signatures, fascinating stuff.

joschua011

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Activity: 86

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I forgot to call secp256k1_start();

works now, anyway thanks for your help!

joschua011

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Activity: 86

Merit: 10

Quote from: Sophokles on July 30, 2014, 05:06:52 PM

The function returns an int. Have the return value assigned to a variable.

I tried:

Code:

    int result;
    result = secp256k1_ecdsa_pubkey_create(pubkeyptr, l, privkeyptr, compressed);

But still segfault :/

Sophokles

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Code:

 /** * In: compressed: whether the computed public key should be compressed

* seckey: pointer to a 32-byte private key.

* Out: pubkey: pointer to a 33-byte (if compressed) or 65-byte (if uncompressed)

* area to store the public key.

* pubkeylen: pointer to int that will be updated to contains the pubkey's

* length.

* Returns: 1: secret was valid, public key stores

* 0: secret was invalid, try again.

*/

int secp256k1_ecdsa_pubkey_create(unsigned char *pubkey, int *pubkeylen, const unsigned char *seckey, int compressed);

The function returns an int. Have the return value assigned to a variable.

joschua011

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Quote from: Sophokles on July 30, 2014, 04:23:54 PM

Did you just change the code? I was going to look it up, could swear it looked different a few minutes ago. Anyway, the definition of the pointers is screwed up.

Actually i did, added pubkeyptr and privkeyptr, but its still not working...

Sophokles

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Quote from: joschua011 on July 30, 2014, 03:17:30 PM

Not sure if this is the right place to ask this but i guess quite some people here are familliar with sipa's version of secp256k1
https://github.com/bitcoin/secp256k1

when i try to run this code:

Quote

unsigned char privateKeyBytes[33];
// some code to fill privateKeyBytes[]
unsigned char publicKeyBytes[33];

int length;
int* l;
l = &length;

unsigned char* pubkeyptr;
unsigned char* privkeyptr;
pubkeyptr = &publicKeyBytes[0];
privkeyptr = &privateKeyBytes[0];

secp256k1_ecdsa_pubkey_create(pubkeyptr, l, privkeyptr, 1);

I get Segmentation fault (core dumped) Huh

stuck at this for some time now....any ideas?

Did you just change the code? I was going to look it up, could swear it looked different a few minutes ago. Anyway, the definition of the pointers is screwed up.

joschua011

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Activity: 86

Merit: 10

Not sure if this is the right place to ask this but i guess quite some people here are familliar with sipa's version of secp256k1
https://github.com/bitcoin/secp256k1

when i try to run this code:

Quote

unsigned char privateKeyBytes[33];
// some code to fill privateKeyBytes[]
unsigned char publicKeyBytes[33];

int length;
int* l;
l = &length;

unsigned char* pubkeyptr;
unsigned char* privkeyptr;
pubkeyptr = &publicKeyBytes[0];
privkeyptr = &privateKeyBytes[0];

secp256k1_ecdsa_pubkey_create(pubkeyptr, l, privkeyptr, 1);

I get Segmentation fault (core dumped) Huh

stuck at this for some time now....any ideas?

Topic: Segfault using secp256k1 (Read 988 times)