The & # 39; @ & # 39; character can not be included in hmac encryption data

The character & # 39; @ & # 39; or a local character such as Japanese can not be included in the hmac encryption data

$ data = & # 39; version=1&cmd=create_transaction&key=xxxxxxxx&format=json&email=my.email@gmail.com&#39 ;;

$ hmac = hash_hmac (& # 39; SHA512 & # 39 ;, $ data, key);

Are there any solutions to solve this?