Hi shankar,
Thanks you for your answer !
You said " we can not get public key from a private key ".
Then you said "So PEM_read_RSAPublicKey() or PEM_read_RSA_PUBKEY() can be used
to load public key from a private key"
I'm being confused. Did you mean we those 2 functions can not be use to load
public key from a private key ?
In fact, i don't try to get public key from private key, but may be the users
will. So I want to have a right answer for that. I'm still new with
cryptography and this library so I don't know if I'm right or wrong.
shankar ks <[EMAIL PROTECTED]> wrote: 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, Thành 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
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Shankar
trungnt
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