simple ASN1 sequence - not quite understanding what goes wrong

[Dirk-Willem van Gulik <dirkx@xxxxxxxxxxxxxx>]

I've got a very simple sequence of to integers that I am trying to convert to DER.

Bt I am getting an error or segfault in the final i2d step (lengt -1 for i2d_X9_62).

Any advice on what is going wrong here ?

With kind regards,

Dw.


#include <openssl/bn.h>
#include <openssl/ec.h>

#include <openssl/asn1.h>
#include <openssl/asn1t.h>

#include <err.h>
#include <assert.h>
#include <stdio.h>

typedef struct X9_62_st {
	ASN1_INTEGER *p;
	ASN1_INTEGER *q;
} X9_62;

ASN1_SEQUENCE(X_9_62) =
{
	ASN1_SIMPLE(X9_62, p, ASN1_INTEGER),
	ASN1_SIMPLE(X9_62, q, ASN1_INTEGER)
};
const ASN1_ITEM	X9_62_it;

DECLARE_ASN1_ALLOC_FUNCTIONS(X9_62)
DECLARE_ASN1_FUNCTIONS(X9_62)
IMPLEMENT_ASN1_FUNCTIONS(X9_62)

int	main(int argc, char **argv)
{

	const unsigned char pbin[] = {1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 
		8, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8};
	const unsigned char qbin[] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7,
		8, 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8};

	assert(sizeof(pbin) == 32);
	assert(sizeof(qbin) == 32);

	X9_62          *x962 = X9_62_new();

	BIGNUM * p = BN_bin2bn(pbin, sizeof(pbin), NULL);
	assert(p);
	fprintf(stderr,"P: %s\n",BN_bn2hex(p));

	BIGNUM * q = BN_bin2bn(qbin, sizeof(qbin), NULL);
	assert(q);
	fprintf(stderr,"Q: %s\n",BN_bn2hex(q));

	x962->p = BN_to_ASN1_INTEGER(p, NULL);
	assert(x962->p);

	x962->q = BN_to_ASN1_INTEGER(q, NULL);
	assert(x962->q);

	unsigned char		buff [32 * 1024];
	unsigned char           *outp = buff;

	int len = i2d_X9_62(x962, NULL);
	assert(len >=0 && len < sizeof(buff);

	len = i2d_X9_62(x962, outp);

	for (size_t i = 0; i < len; i++)
		putchar(buff[i]);

	X9_62_free(x962);

	return (0);
};