Did some checking on seed generation by dice on Coldcard vs. Ian Colemans Mnemonic Code Converter and have some questions. Coldcard might reduce your security by missleading guidance!

So Coinkite guidance displayed on the display is: "... each roll adds only 2.585 of entropy. For 128-bit security, which is considered the minimum, you need 50 rolls, and for 256-bits of security, 99 rolls."

They let you press the buttons 1-6 (and only those) for each roll. So you can only use a D6. If you did it 50 times, you think you did the minimum to have 128-Bit security.

Here are my questions:

• The 2.585 entropy per roll are based on entropy values 0-9 (base 10), right?
• If I limit the entropy values to 1-6 (D6 dice) I introduce a massive bias, right?
• Is it fair to assume that the resulting entropy is just 1.67 per roll?
• Is my ColdCard dice genrated seed realy secured by the minimum 128 bit, or more like with just 84 bits?

Look, I'm no expert, indeed hope I'm wrong.

UPDATE: I was wrong - see below.