In file included from ShowerWithFriends.ino:1:
/Users/george/Documents/Arduino/libraries/Sha/sha1.h:26: error: conflicting return type specified for 'virtual void Sha1Class::write(uint8_t)'
/Applications/Arduino.app/Contents/Resources/Java/hardware/arduino/cores/arduino/Print.h:48: error: overriding 'virtual size_t Print::write(uint8_t)'

A similar error happens for sha256.h

The compiling error message is shown below:

Arduino: 1.7.4 (Mac OS X), Board: "Arduino Uno"

In file included from /Users/../Documents/Arduino/libraries/Sha/sha256.cpp:3:0:
/Users/../Documents/Arduino/libraries/Sha/sha256.cpp:6:20: error: variable 'sha256K' must be const in order to be put into read-only section by means of 'attribute((progmem))'
uint32_t sha256K[] PROGMEM = {
^
/Users/../Documents/Arduino/libraries/Sha/sha256.cpp:19:27: error: variable 'sha256InitState' must be const in order to be put into read-only section by means of 'attribute((progmem))'
uint8_t sha256InitState[] PROGMEM = {
^

Error compiling.

Read-only variables must be const as above suggestion.
Thanks!

Thank you for this code! It is much appreciated!
I'd like to know under which license it may be used.
A commented out header describing the license would be ideal.

Best Regards

I've followed the instructions on how to add this library to the Arduino IDE; and have selected a Sketch from the examples providers, however all examples result in the following :--

In file included from sha256test.pde:1:0:
C:\Users...\Documents\Arduino\libraries\Sha/sha256.h:26:18: error: conflicting return type specified for 'virtual void Sha256Class::write(uint8_t)'
virtual void write(uint8_t);
^
In file included from C:\Users...\Documents\Arduino\libraries\Sha/sha256.h:5:0,
from sha256test.pde:1:
C:\Users...\AppData\Roaming\Arduino15\packages\esp8266\hardware\esp8266\1.6.5-1160-gef26c5f\cores\esp8266/Print.h:55:24: error: overriding 'virtual size_t Print::write(uint8_t)'
virtual size_t write(uint8_t) = 0;
^
Error compiling.

Last commit was a long time ago...
Thanks

I propose the following changes:
sha1.cpp should be changed:
void Sha1Class::write(uint8_t data) {
to:
size_t Sha1Class::write(uint8_t data) {

uint8_t sha1InitState[] PROGMEM = {
to:
const uint8_t sha1InitState[] PROGMEM = {

sha256.cpp should be changed:
uint32_t sha256K[] PROGMEM = {
to:
const uint32_t sha256K[] PROGMEM = {

uint8_t sha256InitState[] PROGMEM = {
to:
const uint8_t sha256InitState[] PROGMEM = {

Both sha1.h and sha256.h should be changed from:
virtual void write(uint8_t);
to:
virtual size_t write(uint8_t);

I suggest a rewrite of this project under the terms of the GNU LGPLv3 (or a similar license) within a project with multiple maintainers.

This would fit the needs of the community (in my opinion) and would make an active development possible.

If I would get some support (about two or three other developers) I would start a rewrite in three or four weeks.

Feel free to join the Telegram group about this topic.

please consider support for ESP8266 and/or NodeMCU

I'm new to SH256 and HMAC.

In my loop, I have
`
void loop(void) {

uint8_t sk[32] = {0x91,0x2F,0xC9,0xA2,0x46,0x16,0xB7,0x60,0x40,0xCA,0x7A,0x81,0x44,0x22,0xFB,0xB9,0x60,0x6A,0x70,0x20,0x56,0x69,0xF7,0x12,0x19,0x5B,0xA4,0x62,0xC5,0x64,0x52,0x67};

Sha256.initHmac(sk, 32);
Sha256.print("68C63AA0F4AE");
printHash(Sha256.resultHmac());
delay(1000);

}
`
The key and message is the same, but the result is different everytime I reboot the ESP.

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:

}