validating password in R with regex and POSIX character classes

I'm trying to validate a password in R using regex and POSIX character classes. I know a fair amount of regex but not the POSIX pieces. I've looked up the SO resources when asking a regex question, plus half a dozen SO questions and answers, such as this and that. The rules for the password are:

one uppercase letter
one lowercase letter
one or more special characters (ASCII punctuation)
between 8 and 32 characters
ASCII visible and space characters only

I've tried a number of code variations, as seen by the code that is commented out. I started building the regex at a lower level then worked my way up to the regex that should include all requirements.

    ValidatePassword <- function(stringChar) {
    #  validPW <- "([[:lower:]]+[[:upper:]]+){8,32}"
    #  validPW <- "[[:lower:]]+[[:upper:]]+"
    #  validPW <- "^(?=.*[[:lower:]])(?=.*[[:upper:]])(?=.*[[:punct:]])[[:print:]]{8,32}$"
    #  validPW <- "^(?:[[:lower:]])(?:[[:upper:]])(?:[[:punct:]])[[:print:]]{8,32}$"
    #  validPW <- "^(?:.*[[:lower:]])(?:.*[[:upper:]])(?:.*[[:punct:]])[[:print:]]{8,32}$"
    #  validPW <- "^([[:lower:]]+|[[:upper:]]+|[[:punct:]]+)[[:print:]]{8,32}$"
    #  validPW <- "^(?=.*[a-z])(?=.*[A-Z])(?=.*[[:punct:]])[[:print:]]{8,32}$"
    #  validPW <- "^([[:lower:][:upper:][:punct:]])[[:print:]]{8,32}"
      validPW <- "^([[:lower:]]+|[[:upper:]]+|[[:punct:]]+)[[:print:]]{8,32}$"
      return(length(grep(validPW, stringChar, value = TRUE)))
    }
    ifelse(ValidatePassword("#Password"), "valid", "not valid") # valid
    ifelse(ValidatePassword("_PASSWORD"), "valid", "not valid") # not valid
    ifelse(ValidatePassword("Password"), "valid", "not valid") # not valid
    ifelse(ValidatePassword("password"), "valid", "not valid") # not valid
    ifelse(ValidatePassword("passwor"), "valid", "not valid") # not valid
    ifelse(ValidatePassword("pAsswords"), "valid", "not valid") # not valid
    ifelse(ValidatePassword("Pa&sword"), "valid", "not valid") # valid
    ifelse(ValidatePassword("Pa&s word"), "valid", "not valid") # valid

I realize that the code is not working properly even when the result says "valid". Can someone offer assistance? ty

Solution

You could use the following regular expression to validate:

is.validpw <- function(x) {
  grepl('(?x)                 # free-spacing mode
          ^                   # assert position = beginning of string
           (?=.*[[:upper:]])  # match one uppercase letter
           (?=.*[[:lower:]])  # match one lowercase letter
           (?=.*[[:punct:]])  # match one special character
           [ -~]{8,32}        # match printable ascii characters
          $                   # assert position = end of string', x, perl = TRUE)
}

is.validpw(c('#Password', '_PASSWORD', 'Password', 'password', 
             'passwor', 'pAsswords', 'Pa&sword', 'Pa&s word'))

## [1]  TRUE FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE