Mailing List Archive

Greetings all!

We are trying to develop a sample program in ANSI C running on Linux to understand how we can use libgcrypt functions to encrypt data via a web interface for secure storage. I have spent days searching through the libgcrypt documentation and the web, trying to find a reason/solution for this 'out of core' problem, but came up empty.

I was having the same problems as Spencer Ogden
(http://lists.gnupg.org/pipermail/gcrypt-devel/2003-May/000276.html)
with the sexp_sscan delivering an error 201. To get around it, I've emulated the testsexp.c example and used the gcry_sexp_build function to generate an rsa key pair, encapsulate a short string into an sexp, and encrypt the sexp. So far all is good.

The problem is when I try to decrypt the encrypted sexp, I get an 'out of core in secure memory' fatal error. This occurs whether running as root or not. Everyone in our shop is quite novice at using encryption software (why the senior engineers gave me the project, I suppose) but it doesn't make sense to me why the gcry_pki_decrypt function should fail if I give it a freshly created sKey, an encrypted sexp and a valid sexp* -- I'm stumped.

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We're running on:
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Red Hat Linux 7.2
Kernel 2.4.9-13smp on an i686
(Not sure if you need any other info)




*****************************
Source code follows...
*****************************


/* Sample libgcryp Program - v0.1 */
/* 08 MAY 03 */

#include <stdio.h>
#include "/usr/local/include/gcrypt.h"


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

GcrySexp data2;
char encryptMe[] = "";
const char *decrypted;
char name[20];
char fkey[3000];
FILE *fp;
char pubkey[]="public-key";
char secKey[]="private-key";
GcrySexp PARMS, result, data;
GCRY_MPI mData;
GcrySexp pKey, sKey, Key;
size_t n;
int i, rcode, nbits = 1024;

memset( &data2, 0, sizeof( data2 ) );
memset( &data, 0, sizeof( data ) );
memset( &PARMS, 0, sizeof( PARMS ) );
memset( &result, 0, sizeof( result ) );

printf( "Enter data to encode:" );
scanf( "%s", encryptMe );
printf( "data entered: %s", encryptMe);
n=strlen(encryptMe);

gcry_mpi_scan( &mData, GCRYMPI_FMT_HEX, encryptMe, NULL);
printf( "\n\n" );

gcry_control( GCRYCTL_INIT_SECMEM, 32768, 0 );

rcode = gcry_sexp_build (&data, NULL, "(data(flags raw)(value %d))", mData);
printf("\nreturn value for data sexp generation is [%d]", rcode);
printf( "\n" );


rcode = gcry_sexp_build (&PARMS, NULL, "(genkey(rsa(nbits %d)))", nbits);
printf("return code for sexp_new(PARMS) is [%d]", rcode);
printf("\n\n");

rcode = gcry_pk_genkey (&Key, PARMS);
printf("return code for genkey is [%d]", rcode);


printf("\n");
if (!rcode)
{gcry_sexp_release( PARMS );}

pKey = gcry_sexp_find_token(Key, pubkey, strlen(pubkey));
sKey = gcry_sexp_find_token(Key, secKey, strlen(secKey));
printf( "\n\n" );
if (sKey&&pKey)
{gcry_sexp_release( Key );}
printf( "\n\n" );

printf( "\n\n" );
rcode = gcry_pk_testkey (sKey);
printf("return code for testkey is [%d]", rcode);

rcode = gcry_pk_encrypt (&result, data, pKey);
printf("Return value for encryption with pKey is [%d]", rcode);
printf( "\n\n" );

rcode = gcry_pk_decrypt (&data2, result, sKey); <-----Fatal error occurs here
printf("Return value for decryption: [%d]", rcode); out of core in secure memory
if (!rcode)
{gcry_sexp_dump (data2);}
printf( "\n\n" );

decrypted = gcry_sexp_nth_data(data, 2, &n);
printf( "\n\nDecrypted data: %s", decrypted );
printf( "\n\n" );
gcry_sexp_dump (data);

printf( "\n\n" );

/*************************************************
// Cleaning House - memory-wise...
*/
if (Key) { gcry_sexp_release( Key ); }
if (result) { gcry_sexp_release( result ); }
if (data2) { gcry_sexp_release( data2 ); }
if (sKey) { gcry_sexp_release( sKey ); }
if (pKey) { gcry_sexp_release( pKey ); }
if (data) { gcry_sexp_release( data ); }

} // end main


********************
Results:
********************

Enter data to encode:12345678909876543210
data entered: 12345678909876543210


return value for data sexp generation is [0]
return code for sexp_new(PARMS) is [0]

return code for genkey is [0]

return code for testkey is [0]

Return value for encryption with pKey is [0]


Fatal error: out of core in secure memory
Aborted (core dumped)

********************
/Results
********************


Thanks for any assistance or information you can direct this way.


--
Tony Warren
Prairie Systems, Inc.
Omaha, NE USA

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