Question

I could use some help, I need to display a public key the same way Windows does when double clicking on a certificate (see image). Thanks.

I can get the public key with either:

RSA *pubKey = X509_get_pubkey( csc->current_cert )->pkey.rsa;

or

EVP_PKEY *pubKey = X509_get_pubkey(csc->current_cert);

If found this snippet somewhere but the values I get are different from what Windows displays:

unsigned char enc_bin[1024] = {0};
int enc_len = 0;
unsigned char dec_bin[1024] = {0};
int dec_len = 0;

enc_len = RSA_size( pubKey );
memset( enc_bin, 1, enc_len );

if( 0 < ( dec_len = RSA_public_decrypt( enc_len, enc_bin, dec_bin, pubKey, RSA_NO_PADDING) ) )
{
    for (int i = 0; i < dec_len; i++)
    {
        CString str;
        if( 0 == i )
            str.Format( L"%02X", dec_bin[i] );
        else
            str.Format( L" %02X", dec_bin[i] );

        PubKey += str;
    }
}

Answer 1

I found the answer, thanks for the reply.

ASN1_BIT_STRING *pubKey = X509_get0_pubkey_bitstr(csc->current_cert); // csc->current_cert is an X509 struct

for (int i = 0; i < pubKey->length; i++)
{
    CString str;
    if( 0 == i )
        str.Format( L"%02X", pubKey->data[i] );
    else
        str.Format( L" %02X", pubKey->data[i] );

    PubKey += str;
}