Also, do you primarily use the word Bitcoin, or do you use some translated form of that word.
we only use the word "bitcoin", i don't know any german translation
the exact translation of "authentic" is "authentisch", in my eary it sounds a little old fashioned
the translation of original is also "original". if you say "original bitcoins", it also can mean that your and only your product is the original and was the first of its kind.
as you see, it is quite hard for me to find a translation that fits your needs, but maybe others have better ideas
I think he is right! "Original" is probably the closest translation. If you want to use it for a word in singular (like 1 Bitcoin) it would be "Original Bitoin" - plural (some Bitcoins): "Originale Bitcoins".
"echt"(sl) or "echte"(pl) could suit too. It means 'not fake' like if you would say 'a thing's made of real gold'.
Btw bitcoin in german is always written with a capital B.
Could you give us the exact term you want to use or do you just want to print the single word?