please explain the exact making of the digest

[aaannndddyyy]

Reading through the code comments I'm having a hard time understanding exactly which random bytes you use in the message digest and what else, if anything, you do with them. Could you please make the comment more clear?

[kfogel]

Thank you. Yes, I will improve the explanatory comments about this.

[aaannndddyyy]

After reading the code, I had a go at it in my branch. But you may well dislike my wording.