> I think that the doc numbers confuse me 3,4,5,6,7 are just the 'index' of the bit ?
absolutely correct.
> Just to be sure when you MESSAGEPRAIR is x0, by x you mean any digits right ? or is it a HEX convention ?
This is an xdigit hex 0x00 to 0xff (the entire hash line consists of xdigits)
not binary 00000000 to 11111111
not decimal 0 to 255
The information about the type of the MESSAGEPAIR (CHALLENGE, AUTHORIZATION) is part of the last xdigit.
Only the last three bits (0 to 2) are in use while bit 3 is reserved.
*x2 = the explanation does not take care about bit 4 to 7) so it is masked by x
A bitmask can contain a lot of information, so what not take advantage of this.
Unfortunately binary values are long and they are a way too long to use them inside a hash line.
HEX values are much better to handle.
absolutely correct.
> Just to be sure when you MESSAGEPRAIR is x0, by x you mean any digits right ? or is it a HEX convention ?
This is an xdigit hex 0x00 to 0xff (the entire hash line consists of xdigits)
not binary 00000000 to 11111111
not decimal 0 to 255
The information about the type of the MESSAGEPAIR (CHALLENGE, AUTHORIZATION) is part of the last xdigit.
Only the last three bits (0 to 2) are in use while bit 3 is reserved.
*x2 = the explanation does not take care about bit 4 to 7) so it is masked by x
A bitmask can contain a lot of information, so what not take advantage of this.
Unfortunately binary values are long and they are a way too long to use them inside a hash line.
HEX values are much better to handle.