wolfcryp RSA Parse Key Segmentation Failed - c

Question

Am trying to verify a message using RSA public key with help of WolfCrypt library. The message signing and verification is done using Openssl is successful with below commands.
openssl dgst -sha256 -sign private.pem -out Message.sign.rsa1024-sha-256 Message.txt
openssl dgst -sha256 -verify public.der -signture Message.sign.rsa1024-sha-256 Message.txt
Now, while trying to write a program using WolfCrypt library to verify the message(the program is not complete, Am stuck at parse public key part), the program is raising segmentation fault while parsing the public key itself. However, while trying to debug the program using GDB, the parse key section of code executes does not raise any segmentation fault and going to next step and exiting normally.
To avoid segfault, I tried malloc instead, still getting alloc(): memory corruption error.
It looks like the problem lies in wc_RsaPublicKeyDecode parameters. on GDB, while step-in to this function, the parameters looks empty. Any suggestion is welcome.
#include <stdio.h>
#include <stdlib.h>
/* Import APIs for Signing and Verification */
#include "wolfssl/wolfcrypt/rsa.h"
#include "wolfssl/wolfcrypt/hash.h"
#include "wolfssl/wolfcrypt/signature.h"
/* Import WolfSSL Types */
#include "wolfssl/wolfcrypt/types.h"
typedef struct wrap_Key
{
word32 _KeyIndex;
RsaKey _RsaKey;
}Key_t;
typedef struct wrap_Signature
{
/* Signature Algorithms */
enum wc_SignatureType _TYPE;
enum wc_HashType _DIGEST;
/* Message & Signature */
byte *_Message;
word32 _MessageLength;
byte *_Signature;
word32 _SignatureLength;
byte *_KeyBuffer;
word32 _KeyBufferLength;
/* RSA Key Structure */
Key_t _PKCS;
}Signature_t;
static int wrap_ReadFileToBuffer( byte **BufferData, word32* BufferLength, byte* URI )
{
int ret = EXIT_SUCCESS;
FILE *file = NULL;
file = fopen(URI, "r");
if( NULL == file )
{
printf( "Error! Unable to stat file.\r\n" );
return EXIT_FAILURE;
}
/* Get content length & Reset Cursor */
fseek( file, 0, SEEK_END );
*BufferLength = (word32) ftell(file);
fseek( file, 0, SEEK_SET );
/* Allocate Enough Buffer */
*BufferData = (byte*)(malloc( *BufferLength ));
if( NULL == *BufferData )
{
fclose(file);
printf("Error! Memory Allocation Failed.\r\n");
return EXIT_FAILURE;
}
/* Read File Content */
if( ( ret = fread( *BufferData, 1, *BufferLength, file ) )
!= *BufferLength )
{
fclose(file);
printf("Error! Unable to read file.\r\n");
return EXIT_FAILURE;
}
fclose(file);
return ret;
}
Signature_t *RSA1;
int main()
{
int ret = EXIT_SUCCESS;
RSA1 = malloc(sizeof(Signature_t));
/* Define Signagure & Type */
RSA1->_TYPE = WC_SIGNATURE_TYPE_RSA;
RSA1->_DIGEST = WC_HASH_TYPE_SHA256;
/* Initialize Message & Signature */
RSA1->_Message = NULL;
RSA1->_Signature = NULL;
/* Verify does the Hash given above is supproted? */
if( wc_HashGetDigestSize( RSA1->_DIGEST ) <= 0 )
{
printf("Hash type %d not supported!\n", RSA1->_DIGEST);
return EXIT_FAILURE;
}
if( wrap_ReadFileToBuffer( &(RSA1->_Message),
&(RSA1->_MessageLength), "Message.txt" ) <= 0 )
{
printf("Error! Reading Message Failed.\r\n");
return EXIT_FAILURE;
}
if( wrap_ReadFileToBuffer( &(RSA1->_Signature),
&(RSA1->_SignatureLength),
"Message.sign.rsa1024-sha-256" ) <= 0 )
{
printf("Error! Reading Signature Failed.\r\n");
return EXIT_FAILURE;
}
if( wrap_ReadFileToBuffer( &(RSA1->_KeyBuffer), &(RSA1->_KeyBufferLength),
"public.der" ) <= 0 )
{
printf("Error! Reading Key Failed.\r\n");
return EXIT_FAILURE;
}
if( ( ret = wc_InitRsaKey( &(RSA1->_PKCS._RsaKey), NULL ) ) )
{
printf("Error! Initialize Key Failed: -%d.\r\n", -ret);
return EXIT_FAILURE;
}
RSA1->_PKCS._KeyIndex = 0;
if( ( ret = wc_RsaPublicKeyDecode( RSA1->_KeyBuffer,
&RSA1->_PKCS._KeyIndex,
&RSA1->_PKCS._RsaKey,
RSA1->_KeyBufferLength ) ) )
{
printf("Error! Reading Key Failed: -%d.\r\n", -ret);
return EXIT_FAILURE;
}
free(RSA1);
printf("WolfCrypt - Sample program!\r\n");
return ret;
}
While trying to debug using GDB, found that after wc_InitRsaKey function, the entire structure *RSA1 is getting char array(byte here) is missing it's data.
(gdb) p *RSA1
$43 = {_TYPE = WC_SIGNATURE_TYPE_RSA, _DIGEST = WC_HASH_TYPE_SHA256,
_Message = 0x5555557585d0 "This is sample message to be signed!\n", _MessageLength = 37,
_Signature = 0x555555758600 "$\372\324#\340M\353\"\216\226\302V\372\265\210\242\377\362\343ɮ\032\021\206K\016/\f2\002\020!\274\234\024\212,\034\276\276,31\217\277\274sP\341c\024=u\236\233l\207\330\320>Ė\300K\211]\325\322x\307_9\251\017#\021&apos;\225Oƞ\276\311\a\177\063`\016\271G8\r;\201\036,7x\246\251Wd\246j\273\272\220\304\354\244\305\370\027\321\312\017\250n\336&apos;\375v{\251\267\270\237M", _SignatureLength = 128,
_KeyBuffer = 0x555555758690 "0\201\237\060\r\006\t*\206H\206\367\r\001\001\001\005",
_KeyBufferLength = 162, _PKCS = {_KeyIndex = 0, _RsaKey = {n = {used = 0, alloc = 0,
sign = 0, dp = 0x0}, e = {used = 0, alloc = 0, sign = 0, dp = 0x0}, d = {used = 0,
alloc = 0, sign = 0, dp = 0x0}, p = {used = 0, alloc = 0, sign = 0, dp = 0x0}, q = {
used = 0, alloc = 0, sign = 0, dp = 0x0}, dP = {used = 0, alloc = 0, sign = 0,
dp = 0x0}, dQ = {used = 0, alloc = 0, sign = 0, dp = 0x0}, u = {used = 0, alloc = 0,
sign = 0, dp = 0x0}, heap = 0x0, data = 0x0, type = 0, state = 0, dataLen = 0,
dataIsAlloc = 0 &apos;\000&apos;}}}
(gdb) n
133 RSA1->_PKCS._KeyIndex = 0;
(gdb) p *RSA1
$44 = {_TYPE = WC_SIGNATURE_TYPE_RSA, _DIGEST = WC_HASH_TYPE_SHA256,
_Message = 0x5555557585d0 "", _MessageLength = 37, _Signature = 0x555555758600 "",
_SignatureLength = 128, _KeyBuffer = 0x555555758690 "", _KeyBufferLength = 162, _PKCS = {
_KeyIndex = 0, _RsaKey = {n = {used = 0, alloc = 0, sign = 0, dp = 0x0}, e = {used = 0,
alloc = 0, sign = 0, dp = 0x0}, d = {used = 0, alloc = 0, sign = 0, dp = 0x0}, p = {
used = 0, alloc = 0, sign = 0, dp = 0x0}, q = {used = 0, alloc = 0, sign = 0,
dp = 0x0}, dP = {used = 0, alloc = 0, sign = 0, dp = 0x0}, dQ = {used = 0, alloc = 0,
sign = 0, dp = 0x0}, u = {used = 0, alloc = 0, sign = 0, dp = 0x0}, heap = 0x0,
data = 0x0, type = 0, state = 0, dataLen = 0, dataIsAlloc = 0 &apos;\000&apos;}}}

Answer 1

#Gopi,
The most common cause of such a segmentation fault is a misconfiguration of application and library. The first thing to check is the headers included.
/* Import APIs for Signing and Verification */
#include "wolfssl/wolfcrypt/rsa.h"
#include "wolfssl/wolfcrypt/hash.h"
#include "wolfssl/wolfcrypt/signature.h"
/* Import WolfSSL Types */
#include "wolfssl/wolfcrypt/types.h"
Notice that neither "wolfssl/options.h" or "wolfssl/wolfcrypt/settings.h" was included. If you built the wolfSSL library with ./configure && make please include "wolfssl/options.h" before all other wolfSSL headers. If you are only using "wolfssl/wolfcrypt/settings.h" to control the build and options.h is not found then at least include "wolfssl/wolfcrypt/settings.h" before all other wolfSSL headers:
/* Import APIs for Signing and Verification */
#include <wolfssl/options.h> // If not found or not available then include <wolfssl/wolfcrypt/settings.h>
#include "wolfssl/wolfcrypt/rsa.h"
#include "wolfssl/wolfcrypt/hash.h"
#include "wolfssl/wolfcrypt/signature.h"
/* Import WolfSSL Types */
#include "wolfssl/wolfcrypt/types.h"
Cheers,
K