Octet String

[Jenski]

Does anybody know what an "Octet String" is and how to convert them?

 

I have this value

"255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255"

 

and want to convert it to a sensible format...

 

(its the logonHours attribute from LDAP)

 

[Daniel0]

An octet means a group of 8 (from Greek okta-). An eight-digit unsigned binary number has the range [0,11111111₂]=[0,255₁₀], so assuming that each 255 in your string is in base 2 and then converted to base 10, each group is one octet, i.e. one byte.

 

I'm not sure what a "sensible format" would constitute. Your string is just a space delimited numbers.

[Jenski]

"Sensible format" = base10 value...

 

255 octal = 10101101 binary

10101101 = 173 decimal

 

"255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255"

"173 173 173 173 173 173 173 173 173 173 173 173 173 173 173 173 173 173 173 173 173"

 

if the spaces are delimiters what do I do with the numbers? any ideas?

[Jenski]

There are 21 "173"s.

21 * 173 = 3633

 

Does that sound feasable?

[Daniel0]

"Sensible format" = base10 value...

 

How do you know they aren't already base 10? It wouldn't make sense calling it an "octet string" for other bases than 10. The words "octet" and "octal" aren't the same. "Octet" means a group of 8, while octet is the just the positional number system with the base 8.

 

It makes sense that your 255's is in decimal. If you assume that it's the highest value then if you convert it to hex you'll have FF₁₆, but that's only two digits. If you convert it to octal then you'll get 377₈, but that's only three digits. However, if you convert it to binary then you'll get 11111111₂, that's eight digits, i.e. an octet of digits.

 

if the spaces are delimiters what do I do with the numbers? any ideas?

 

You'll probably have to lookup what that string means in the docs from where it came from.