C++ OpenSSL Verify X509 Certificate

g++ main.cpp -o main -lcrypto

#include <openssl/pem.h>
#include <openssl/x509.h>
#include <openssl/x509v3.h>
 
int sig_verify(const char* cert_pem, const char* intermediate_pem)
{
    BIO *b = BIO_new(BIO_s_mem());
    BIO_puts(b, intermediate_pem);
    X509 * issuer = PEM_read_bio_X509(b, NULL, NULL, NULL);
    EVP_PKEY *signing_key=X509_get_pubkey(issuer);
 
    BIO *c = BIO_new(BIO_s_mem());
    BIO_puts(c, cert_pem);
    X509 * x509 = PEM_read_bio_X509(c, NULL, NULL, NULL);
 
    int result = X509_verify(x509, signing_key);
 
    EVP_PKEY_free(signing_key);
    BIO_free(b);
    BIO_free(c);
    X509_free(x509);
    X509_free(issuer);
 
    return result;
}
 
void cert_info(const char* cert_pem)
{
    BIO *b = BIO_new(BIO_s_mem());
    BIO_puts(b, cert_pem);
    X509 * x509 = PEM_read_bio_X509(b, NULL, NULL, NULL);
 
    BIO *bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);
 
    //Subject
    BIO_printf(bio_out,"Subject: ");
    X509_NAME_print(bio_out,X509_get_subject_name(x509),0);
    BIO_printf(bio_out,"\n");
 
    //Issuer
    BIO_printf(bio_out,"Issuer: ");
    X509_NAME_print(bio_out,X509_get_issuer_name(x509),0);
    BIO_printf(bio_out,"\n");
 
    //Public Key
    EVP_PKEY *pkey=X509_get_pubkey(x509);
    EVP_PKEY_print_public(bio_out, pkey, 0, NULL);
    EVP_PKEY_free(pkey);
 
    //Signature
    X509_signature_print(bio_out, x509->sig_alg, x509->signature);
    BIO_printf(bio_out,"\n");
 
    BIO_free(bio_out);
    BIO_free(b);
    X509_free(x509);
}
 
//----------------------------------------------------------------------
 
int main(int argc, char **argv)
{
    OpenSSL_add_all_algorithms();
    OpenSSL_add_all_ciphers();
    OpenSSL_add_all_digests(); 
    const char cert[] = "-----BEGIN CERTIFICATE-----" "\n"
"MIIFGzCCBKGgAwIBAgIQA8TAm6Yf9god6g9PkdJfazAKBggqhkjOPQQDAzBMMQsw" "\n"
"CQYDVQQGEwJVUzEVMBMGA1UEChMMRGlnaUNlcnQgSW5jMSYwJAYDVQQDEx1EaWdp" "\n"
"Q2VydCBFQ0MgU2VjdXJlIFNlcnZlciBDQTAeFw0xMzA5MzAwMDAwMDBaFw0xNjEw" "\n"
"MDQxMjAwMDBaMGAxCzAJBgNVBAYTAlVTMQ0wCwYDVQQIEwRVdGFoMQ0wCwYDVQQH" "\n"
"EwRMZWhpMRcwFQYDVQQKEw5EaWdpQ2VydCwgSW5jLjEaMBgGA1UEAxMRYmxvZy5k" "\n"
"aWdpY2VydC5jb20wWTATBgcqhkjOPQIBBggqhkjOPQMBBwNCAATmpgkfE9I8G/Eo" "\n"
"IYPyu+X5Er6nll65D8gZ2OfTLCzebHwdybes1TDSde3E1V1tccz5aWqzJNgJrkPD" "\n"
"+uzLc5r/o4IDTzCCA0swHwYDVR0jBBgwFoAUo53mH/naOU/AbuiRy5Wl2jHiCp8w" "\n"
"HQYDVR0OBBYEFAjOkz5ghkAzC1h+65zS3yI6Y5ewMBwGA1UdEQQVMBOCEWJsb2cu" "\n"
"ZGlnaWNlcnQuY29tMA4GA1UdDwEB/wQEAwIFoDAdBgNVHSUEFjAUBggrBgEFBQcD" "\n"
"AQYIKwYBBQUHAwIwaQYDVR0fBGIwYDAuoCygKoYoaHR0cDovL2NybDMuZGlnaWNl" "\n"
"cnQuY29tL3NzY2EtZWNjLWcxLmNybDAuoCygKoYoaHR0cDovL2NybDQuZGlnaWNl" "\n"
"cnQuY29tL3NzY2EtZWNjLWcxLmNybDCCAcQGA1UdIASCAbswggG3MIIBswYJYIZI" "\n"
"AYb9bAEBMIIBpDA6BggrBgEFBQcCARYuaHR0cDovL3d3dy5kaWdpY2VydC5jb20v" "\n"
"c3NsLWNwcy1yZXBvc2l0b3J5Lmh0bTCCAWQGCCsGAQUFBwICMIIBVh6CAVIAQQBu" "\n"
"AHkAIAB1AHMAZQAgAG8AZgAgAHQAaABpAHMAIABDAGUAcgB0AGkAZgBpAGMAYQB0" "\n"
"AGUAIABjAG8AbgBzAHQAaQB0AHUAdABlAHMAIABhAGMAYwBlAHAAdABhAG4AYwBl" "\n"
"ACAAbwBmACAAdABoAGUAIABEAGkAZwBpAEMAZQByAHQAIABDAFAALwBDAFAAUwAg" "\n"
"AGEAbgBkACAAdABoAGUAIABSAGUAbAB5AGkAbgBnACAAUABhAHIAdAB5ACAAQQBn" "\n"
"AHIAZQBlAG0AZQBuAHQAIAB3AGgAaQBjAGgAIABsAGkAbQBpAHQAIABsAGkAYQBi" "\n"
"AGkAbABpAHQAeQAgAGEAbgBkACAAYQByAGUAIABpAG4AYwBvAHIAcABvAHIAYQB0" "\n"
"AGUAZAAgAGgAZQByAGUAaQBuACAAYgB5ACAAcgBlAGYAZQByAGUAbgBjAGUALjB7" "\n"
"BggrBgEFBQcBAQRvMG0wJAYIKwYBBQUHMAGGGGh0dHA6Ly9vY3NwLmRpZ2ljZXJ0" "\n"
"LmNvbTBFBggrBgEFBQcwAoY5aHR0cDovL2NhY2VydHMuZGlnaWNlcnQuY29tL0Rp" "\n"
"Z2lDZXJ0RUNDU2VjdXJlU2VydmVyQ0EuY3J0MAwGA1UdEwEB/wQCMAAwCgYIKoZI" "\n"
"zj0EAwMDaAAwZQIxAMNQ2j9Ua2jMEfRvhkhwRxF6NWVVFwxiV/D071rYkh1fNRFY" "\n"
"1HRwzkxwfNR1och05gIweNMRY3kbaVp4Nv3LwiT2v/n9hm8IoOG8G4lXTWrwQHWA" "\n"
"Rps5Urye1f8nmWtvxWeY" "\n"
"-----END CERTIFICATE-----";
    const char intermediate[] = "-----BEGIN CERTIFICATE-----" "\n"
"MIIDrDCCApSgAwIBAgIQCssoukZe5TkIdnRw883GEjANBgkqhkiG9w0BAQwFADBh" "\n"
"MQswCQYDVQQGEwJVUzEVMBMGA1UEChMMRGlnaUNlcnQgSW5jMRkwFwYDVQQLExB3" "\n"
"d3cuZGlnaWNlcnQuY29tMSAwHgYDVQQDExdEaWdpQ2VydCBHbG9iYWwgUm9vdCBD" "\n"
"QTAeFw0xMzAzMDgxMjAwMDBaFw0yMzAzMDgxMjAwMDBaMEwxCzAJBgNVBAYTAlVT" "\n"
"MRUwEwYDVQQKEwxEaWdpQ2VydCBJbmMxJjAkBgNVBAMTHURpZ2lDZXJ0IEVDQyBT" "\n"
"ZWN1cmUgU2VydmVyIENBMHYwEAYHKoZIzj0CAQYFK4EEACIDYgAE4ghC6nfYJN6g" "\n"
"LGSkE85AnCNyqQIKDjc/ITa4jVMU9tWRlUvzlgKNcR7E2Munn17voOZ/WpIRllNv" "\n"
"68DLP679Wz9HJOeaBy6Wvqgvu1cYr3GkvXg6HuhbPGtkESvMNCuMo4IBITCCAR0w" "\n"
"EgYDVR0TAQH/BAgwBgEB/wIBADAOBgNVHQ8BAf8EBAMCAYYwNAYIKwYBBQUHAQEE" "\n"
"KDAmMCQGCCsGAQUFBzABhhhodHRwOi8vb2NzcC5kaWdpY2VydC5jb20wQgYDVR0f" "\n"
"BDswOTA3oDWgM4YxaHR0cDovL2NybDMuZGlnaWNlcnQuY29tL0RpZ2lDZXJ0R2xv" "\n"
"YmFsUm9vdENBLmNybDA9BgNVHSAENjA0MDIGBFUdIAAwKjAoBggrBgEFBQcCARYc" "\n"
"aHR0cHM6Ly93d3cuZGlnaWNlcnQuY29tL0NQUzAdBgNVHQ4EFgQUo53mH/naOU/A" "\n"
"buiRy5Wl2jHiCp8wHwYDVR0jBBgwFoAUA95QNVbRTLtm8KPiGxvDl7I90VUwDQYJ" "\n"
"KoZIhvcNAQEMBQADggEBAMeKoENL7HTJxavVHzA1Nm6YVntIrAVjrnuaVyRXzG/6" "\n"
"3qttnMe2uuzO58pzZNvfBDcKAEmzP58mrZGMIOgfiA4q+2Y3yDDo0sIkp0VILeoB" "\n"
"UEoxlBPfjV/aKrtJPGHzecicZpIalir0ezZYoyxBEHQa0+1IttK7igZFcTMQMHp6" "\n"
"mCHdJLnsnLWSB62DxsRq+HfmNb4TDydkskO/g+l3VtsIh5RHFPVfKK+jaEyDj2D3" "\n"
"loB5hWp2Jp2VDCADjT7ueihlZGak2YPqmXTNbk19HOuNssWvFhtOyPNV6og4ETQd" "\n"
"Ea8/B6hPatJ0ES8q/HO3X8IVQwVs1n3aAr0im0/T+Xc=" "\n"
"-----END CERTIFICATE-----";
    cert_info(cert);
    cert_info(intermediate);
    sig_verify(cert,intermediate);
}