Segfault using secp256k1

[joschua011]

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:

    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)  

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

[Sophokles]

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:

    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)  

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]

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]

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]

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 :/

[joschua011]

I forgot to call secp256k1_start();

works now, anyway thanks for your help!

[Sophokles]

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.

[Remember remember the 5th of November]

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