Hi Trung,
One thing I will conform you is " we can not get public key from a private
key ". I do not remember where i studied , but it is true.
So do not try to get a public key from private key.
And I have mistakenly typed as BEGIN RSA CERTIFICATE , as you told it is
BEGIN RSA PUBLIC KEY only.
So PEM_read_RSAPublicKey() or PEM_read_RSA_PUBKEY() can be used to load
public key from a private key
The main concept (and also the general concept )in my program ( or any other
programs )is we have to load public key from the certificate only .
In the certificte if the public key does not have header like BEGIN RSA
PUBLIC KEY , then these functions wont work . so I have used other procedure
to get the RSA public key ..
if you still have doubts , mail me ...
--- Shankar
On 4/13/08, Thà nh Trung Nguyễn <[EMAIL PROTECTED]> wrote:
>
> Thank you for fast response !
>
> But it's ok if I use PEM_read_RSAPublicKey() to load public key from file
> save by using PEM_write_RSAPublicKey().
> And even publickey extract by openssl command doesn't have any line as
> "BEGIN RSA CERTIFICATE". It just has line as "BEGIN RSA PUBLIC KEY".
>
> I've tried your code, but it can't read public key save by openssl.
>
> So can PEM_read_RSAPublicKey() or PEM_read_RSA_PUBKEY() can load public
> key from a private key ? In my program, I use PEM_write_RSAPublicKey() to
> store public key and use PEM_read_RSAPublicKey() to load it. I just want to
> know if user can use my program to read public key from a private key.
>
> p/s :
> I used openssl to extract publickey like this ( I don't know if there
> is another way) :
> openssl rsa -in privatekey.pem -out publickey.pem -pubout
>
>
> *shankar ks <[EMAIL PROTECTED]>* wrote:
>
> Hi Trung,
> The error which u got was you can not read the public key as in the
> certificate it is not finding the lines as "BEGIN RSA CERTIFICATE"
> so here i am giving you the code , use it directly , it will work fine as
> i refined it many times ... and one more thing is error string funtion will
> give you the reason also , so it is human readible message only...
>
>
> pubk = RSA_new();
> if(pubk == NULL)
> printf("error to create new RSA structure \n");
> fp = fopen (recevercert, "r");
> if (fp == NULL){
> pri ntf("err ");
> exit (1);
> }
> x509 = PEM_read_X509(fp, NULL, NULL, NULL);
> fclose (fp);
>
> if (x509 == NULL) {
> printf("error reading the certificate \n");
> ERR_print_errors_fp (stderr);
> exit (1);
> }
> pub=X509_get_pubkey(x509);
> if (pub == NULL) {
> printf("error reading the public key \n");
> ERR_print_errors_fp (stderr);
> exit (1);
> }
> pubk = EVP_PKEY_get1_RSA(pub);
>
>
>
>
> On 4/13/08, Th�nh Trung Nguyễn <[EMAIL PROTECTED]> wrote:
> >
> > Hi !
> >
> > I used PEM_write_RSAPrivateKey() to write private key to a pem file.
> > Then I used PEM_read_RSAPublicKey() to read public key from that file,
> > but it returned an error.
> > The ERR_error_string() only return message like :
> > error:0906D06C:lib(9):func(109):reason(108)
> > So can any one tell me can i use PEM_read_RSAPublicKey() to load public
> > key from a private key ?
> > And are the any way to get human understandable error message ?
> >
> > Thanks !
> >
> >
> > trungnt __________________________________________________
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>
>
>
> --
> --Best Regards
> Shankar
>
>
>
>
> trungnt
>
> __________________________________________________
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>
--
--Best Regards
Shankar
