How to denote 160 bits SHA-1 string as 20 characte

问题:

For an input "hello", SHA-1 returns "aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d", which are 40 hex outputs. I know 1 byte can denote as 1 character, so the 160 bits output should be able to converted to 20 characters. But when I look up "aa" in an ASCII table, there are no such hex value, and I'm confused about that. How to map 160 bits SHA-1 string as 20 characters in ANSI?

回答1:

ASCII only has 128 characters (7 bits), while ANSI has 256 (8 bits). As to the ANSI value of hex value AA (decimal 170), the corresponding ANSI character would be ª (see for example here).

Now, you have to keep in mind that a number of both ASCII and ANSI characters (0-31) are non-printable control characters (system bell, null character, etc.), so turning your hash into a readable 20 character string will be not possible in most cases. For instance, your example contains the hex value 0F, which would translate to a shift-in character.