invalid conversion

[itroublee]

I am using Arduino with ATMEGA 328 and the IDE is version 16.7 installed on Windows 10.
tried to run the example in the documentation. Just to create a HMAC256. I tried to verify the code in the IDE, I get this error which I do not know how to fix. Can you help.

invalid conversion from 'const char_' to 'const uint8_t_ {aka const unsigned char*}' [-fpermissive]

The Code is:

include "sha256.h"

void setup() {
// put your setup code here, to run once:
uint8_t *hash;
//static const char hash[450]={};
//const char *hash; hash={};
Sha256.initHmac("hash key",8); // key, and length of key in bytes
Sha256.print("This is a message to hash");
hash = Sha256.resultHmac();
//Serial.print(hash,HEX);
}

void loop() {
// put your main code here, to run repeatedly:

}

[samyxdev]

Maybe late but here is the list of changes to avoid the "invalid conversion" error (you can modify the sha256 files if you just use this sha type):
0ee3a5b