Adding Server-Side TLS 1.0 Support - Implementing SSL/TLS Using Cryptography and PKI - page 404

md5_hash( passphrase_hash_in,
sizeof( int ) * MD5_RESULT_SIZE,
( unsigned int * ) passphrase_hash_out );
}
decrypted_key = ( unsigned char * ) malloc( encrypted_key->length );
des_decrypt( encrypted_key->data, encrypted_key->length, decrypted_key,
( unsigned char * ) passphrase_hash_out + DES_KEY_SIZE,
( unsigned char * ) passphrase_hash_out );
// sanity check
if ( decrypted_key[ encrypted_key->length - 1 ] > 8 )
{
fprintf( stderr, “Decryption error, bad padding\n”);
asn1free( &pkcs8_key );
free( decrypted_key );
return 1;
}
asn1parse( decrypted_key,
encrypted_key->length - decrypted_key[ encrypted_key->length - 1 ],
&private_key );
free( decrypted_key );
key_type_oid = private_key.children->next->children;
if ( memcmp( OID_RSAPrivateKey, key_type_oid->data, key_type_oid->length ) )
{
fprintf( stderr, “Unsupported private key type” );
asn1free( &pkcs8_key );
asn1free( &private_key );
}
priv_key_data = private_key.children->next->next;
parse_private_key( privkey, priv_key_data->data, priv_key_data->length );
asn1free( &pkcs8_key );
asn1free( &private_key );
return 0;
}
The fi rst part is pretty straightforward; at this point, you're dealing with an
ASN.1 DER-encoded structure just like the ones you examined in Chapter 5.
Parse it with asn1parse and extract the information, after making sure that the
encryption algorithm is actually the one supported by this routine.
asn1parse( buffer, buffer_length, &pkcs8_key );
encryptionId = pkcs8_key.children->children;
if ( memcmp( OID_pbeWithMD5andDES_CBC, encryptionId->data,
encryptionId->length ) )
{