Thanks Stephen and Dave....Thank you very much for your inputs..
X509 *x509;
int main()
{
x509 = NULL;
fp=fopen("RSAKey.cer","rb");
if(fp == NULL)
{
printf("Could not open the file \n");
return 0;
}
else
{
printf("Certificate file opened successfully \n");
}
x509 = PEM_read_X509(fp,NULL,NULL,NULL);
if(x509 == NULL)
{
printf("error reading \n");
}
else
{
printf("reading success\n");
ExtractSerialNumber();
ExtractPubKey();
}
fclose(fp);
X509_free(x509);
}
int ExtractSerialNumber()
{
ASN1_INTEGER *ptr;
int iIndex = 0;
printf("Entered func - ExtractSerialNumber\n");
ptr = X509_get_serialNumber(x509);
printf("\nThe length of the serial number is %d \n",ptr->length);
while(iIndex < (int)ptr->length )
{
sprintf(gszSerialNumber+iIndex*2, "%0.2X",ptr->data[iIndex++]);
}
printf("Serial Number is = %s\n", gszSerialNumber);
return 1;
}
int ExtractPubKey()
{
FILE *fp;
EVP_PKEY *PubKey;
int iRetVal = 0;
printf("Entered func - ExtractPubKey\n");
fp = fopen("RSAPubKey.Dat", "w+");
if(fp == NULL)
{
printf("Some problem with the file opening/creation \n");
return 0;
}
else
{
printf("File is opened \n");
}
PubKey = X509_get_pubkey(x509);
iRetVal = PEM_write_PUBKEY(fp, PubKey);
printf("The return value of PEM_write_PUBKEY is %d \n", iRetVal);
free(fp);
return iRetVal;
}
Thank you very much....
Dr. Stephen Henson wrote:
>
> On Mon, Feb 20, 2012, Dave Thompson wrote:
>
>> > From: owner-openssl-us...@openssl.org On Behalf Of praveenpvs
>> > Sent: Sunday, 19 February, 2012 23:15
>>
>> > I am new to OPENSSL. I have a certificate, i need to extract
>> > public key and
>> > serial number from it. I know the command to do that, but i
>> > wanted to use
>> > api in my application.
>> <snip>
>> > Could you please help me with the corresponding apis for
>> > these two commands?
>> >
>> OpenSSL's X509_* module is mostly older code and does not
>> have a full opaque API as some more recent modules do.
>>
>> You first get the cert into a variable of type X509
>> which is actually struct x509_st declared in x509.h.
>> Actually your code uses a pointer to such a struct
>> which is allocated and deallocated by OpenSSL calls.
>> For a cert in a PEM-format file, which is what your
>> commandlines used, PEM_read_X509 declared in pem.h
>> reads it in and creates the X509. For other input
>> formats there are other options.
>>
>> Then just use fields from the struct as needed.
>> myx509->cert_info->serialNumber is the serial and
>> myx509->cert_info->key is the subjectPublicKeyInfo.
>> Note these are in internal formats: serialNumber
>> is an ASN1_INTEGER which can be converted with ASN1_*
>> routines to (or from) other numeric or text forms;
>> key is another struct containing an AlgorithmIdentifier
>> (containing an OID and possibly but rarely parameters)
>> and a BIT STRING which in turn contains the encoding of
>> the actual key in a format dependent on the type of key.
>> What you do with these depends on what you want to do.
>>
>> When you're done, x509_free() the pointer.
>>
>
> Although some modules don't have an opaque API direct structure access is
> inadvisable if functions exist which can be used instead.
>
> In ths OPs case they do and the functions X509_get_serialNumber and
> X509_get_pubkey should be used.
>
> Steve.
> --
> Dr Stephen N. Henson. OpenSSL project core developer.
> Commercial tech support now available see: http://www.openssl.org
> ______________________________________________________________________
> OpenSSL Project http://www.openssl.org
> User Support Mailing List openssl-users@openssl.org
> Automated List Manager majord...@openssl.org
>
>
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