Rosetta Code task: Password generator

[David Drake]

I created the code below for the Rosetta Code task "Password generator" (found at rosettacode.org/wiki/Password_generator).  The task has a surprisingly long list of requirements: 

Create a password generation program which will generate passwords containing random ASCII characters from the following groups:
lower-case letters: a ──► z
upper-case letters: A ──► Z
digits: 0 ──► 9

other printable characters: !"#$%&'()*+,-./:;<=>?@[]^_{|}~
(the above character list excludes white-space, backslash and grave)

The generated password(s) must include at least one (of each of the four groups):
lower-case letter,
upper-case letter,
digit (numeral), and
one "other" character.

The user must be able to specify the password length and the number of passwords to generate.

The passwords should be displayed or written to a file, one per line.

The randomness should be from a system source or library.

The program should implement a help option or button which should describe the program and options when invoked.

You may also allow the user to specify a seed value, and give the option of excluding visually similar characters.

For example: Il1 O0 5S 2Z where the characters are:
capital eye, lowercase ell, the digit one
capital oh, the digit zero
the digit five, capital ess
the digit two, capital zee

My code does everything except allow the user to specify a seed value.

I'm sure the character checking algorithm could be better.  I look forward to seeing your comments and suggestions.



[variables]
   dim w$(92),pw$(10)
   for a = 33 to 126 'load available characters into array
       if a<>92 and a<>96 then
           ct=ct+1
           w$(ct)=chr$(a)
       end if
   next a

[start]
   input "Number of passwords to generate (enter 0 for help): ";n
   if n=0 then 'show help
       print "======================================================"
       print "This program generates passwords of random characters."
       print "When prompted, enter the number of passwords you would"
       print "like to create, press enter, then enter the number of"
       print "characters you would like in the generated passwords."
       print "======================================================"
       print ""
       goto [start]
   end if

   input "Length of password (n>4):";p
   if p<4 then p=4
   print
   print "Creating ";n;" passwords of length ";p
   print
   print "  Generated passwords"
   print "======================="

   for a = 1 to n
       [tryagain]
       pw$=""
       for b = 1 to p 'create string of random characters from loaded array
           pw$=pw$+w$(int(rnd(1)*92)+1)
       next b
       'test for 1 uppercase, 1 lowercase, 1 digit, 1 other
       'test for other characters
       if fail(33,47,pw$)=1 and fail(58,64,pw$)=1 and fail(91,96,pw$) and fail(123,126,pw$) then [tryagain]
       'test for digits
       if fail(48,57,pw$)=1 then [tryagain]
       'test for lower case
       if fail(97,122,pw$)=1 then [tryagain]
       'test for upper case
       if fail(65,90,pw$)=1 then [tryagain]

       'check for visually similar characters
       if sim(pw$,"I","1")=1 then [tryagain]
       if sim(pw$,"I","l")=1 then [tryagain]
       if sim(pw$,"1","l")=1 then [tryagain]
       if sim(pw$,"O","0")=1 then [tryagain]
       if sim(pw$,"5","S")=1 then [tryagain]
       if sim(pw$,"2","Z")=1 then [tryagain]
       print pw$
   next a

   print "======================="
   print
   input "Create more passwords (Y/N)?";yn$
   if left$(lower$(yn$),1)="y" then goto [start]
   print
   print "Goodbye"
end

function fail(min,max,p$)'check for existance of a character
   for c = min to max
       if instr(p$,chr$(c))<>0 then
           fail=0
           exit for
       else
           fail=1
       end if
    next c
end function

function sim(pw$,a$,b$)'check for visually similar characters
    if instr(pw$,a$)<>0 and instr(pw$,b$)<>0 then sim=1
end function


[tsh73]

Hello David
I pretty sure

excluding visually similar characters

actually mean "do not allow such characters, at all".
So not "do not use 2 and Z in same password"
but "do not use Z or 2 at all"

---

Also
this is obviously magic
if fail(65,90,pw$)=1 then [tryagain]
while this
if inRange("A","Z",pw$)=1 then [tryagain]
much less so.

(could be done like this for example
function inRange(min$,max$,p$)'check for existance of a character
   inRange=1
   for c = asc(min$) to asc(max$)
       if p$=chr$(c) then exit function
    next c
   inRange=0
end function

)

As to "other characters" I think enumerating them is less of an evil.

otherChars$="!#$%&'()*+,-./:;<=>?@[]^_{|}~"+chr$(34) 'last one is "
if instr(otherChars$,pw$)<>0 then [tryagain]

[David Drake]

Feb 27, 2020 7:23:02 GMT -5 tsh73 said:

Hello David
I pretty sure

excluding visually similar characters

actually mean "do not allow such characters, at all".
So not "do not use 2 and Z in same password"
but "do not use Z or 2 at all"

---

Also
this is obviously magic
if fail(65,90,pw$)=1 then [tryagain]
while this
if inRange("A","Z",pw$)=1 then [tryagain]
much less so.

(could be done like this for example
function inRange(min$,max$,p$)'check for existance of a character
   inRange=1
   for c = asc(min$) to asc(max$)
       if p$=chr$(c) then exit function
    next c
   inRange=0
end function

)

As to "other characters" I think enumerating them is less of an evil.

otherChars$="!#$%&'()*+,-./:;<=>?@[]^_{|}~"+chr$(34) 'last one is "
if instr(otherChars$,pw$)<>0 then [tryagain]

Good points, all. 
- I still think my interpretation of "excluding visually similar characters" is more interesting to implement, so I'd prefer to leave it.
- Your take on the inRange function is clearer.  I will attempt to make that work.
- I agree 100% on the "otherChar$" approach.  I thought about doing that for all the character sets but didn't.  Will it actually work the way you have it written?  Guess I'll find out.

[David Drake]

How about this?
- Gave the user the option to not include any visually similar characters.
- Incorporated the inRange function as suggested.
- For clarity, changed the way the passwords characters are randomly selected (from one string instead of an array)
- For clarity, changed the way the program checks for "other" characters.
- Generally cleaned things up.
[variables]
   global other$
   other$="~!@#$%^&*()_-+=/*-+[{]}\|;:',<.>/?"+chr$(34) 'permitted characters that are not numbers or letters

[start]
   input "> Number of passwords to generate (enter 0 for help): ";n
   if n=0 then
       print "======================================================"
       print "This program generates passwords of random characters."
       print "When prompted, enter the number of passwords you would"
       print "like to create, press enter, then enter the number of"
       print "characters you would like in the generated passwords."
       print "======================================================"
       print ""
       goto [start]
   end if

   input "> Length of password (n>4):";p
   if p<4 then p=4
   input "> Exclude the following character sets that appear similar (l1I O0 5S 2Z) (y/n)?";ans$
   if lower$(ans$)="y" then
       characters$="#$%&'()*+,-./346789:;<=>?@ABCDEFGHJKLMNPQRTUVWXY[]^_abcdefghijkmnopqrstuvwxyz{|}~"+chr$(34)
       else
       characters$="#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[]^_abcdefghijklmnopqrstuvwxyz{|}~"+chr$(34)
   end if

   print
   print "Creating ";n;" passwords of length ";p
   print
   print "Generated passwords"
   print "======================="

   for a = 1 to n 'build n passwords length p
       [tryagain]
       pw$=""
       for b = 1 to p
           pw$=pw$+mid$(characters$,int(rnd(1)*92)+1,1)
       next b
       'test for 1 uppercase, 1 lowercase, 1 digit, 1 other
       if testOther(pw$) then [tryagain]'test for other characters
       if inRange("0","9",pw$) then [tryagain]'test for digits
       if inRange("a","z",pw$) then [tryagain]'test for lower case
       if inRange("A","Z",pw$) then [tryagain]'test for upper case
       print pw$
   next a

   print "======================="
   input "> Create more passwords (Y/N)?";yn$
   if left$(lower$(yn$),1)="y" then goto [start]
   print "> Goodbye"
end

function testOther(p$)
   testOther=1
   for c = 1 to len(other$)
       if instr(p$,mid$(other$,c,1))<>0 then testOther=0:exit function
   next c
end function

function inRange(min$,max$,p$)
   inRange=1
   for c = asc(min$) to asc(max$)
       if instr(p$,chr$(c))<>0 then inRange=0:exit function
    next c
end function


[sarossell]

David, you're a coding machine! Lovin' all the Rosetta activity. And nice touch with the ">" text prompt style. I had to flashback to my old CP/M days.

:@)

[David Drake]

Unless there are more comments or suggestions, I plan to post this to Rosetta Code later today.

[BeeTrap]

I like to watch this code run, I have added many "print" statements, it helps me to keep up with what the heck is going on. The only problem I found is that sometimes the generated password is shorter than expected. I got LEN() of 9 sometimes when 12 was requested. I added
if Len(pw$)<p then [tryagain] after the 3 "if inRange" lines. I appreciate all of your code!!!