It probably means 80 decimal digits. But even then it's a bit off. As a 256 bits number would require at most 78 decimal digits.

yeani

bitcoin

deleted by author

A bitcoin private key is 256 bits long, that's 32 bytes, which when represented in hexadecimal would yield 64 characters.

However I'm puzzled by the extra 2 or even the other question marks. Are they spread all over the sequence of characters? or are they kept at one side?

Oh and both Armory and Multibit were started in 2011, so this is almost certainly from bitcoin core.