aboutsummaryrefslogtreecommitdiffstats
path: root/makepass.zsh
blob: c3379399b5b296386b713238a1c22ab0e503595a (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
#!/usr/bin/env zsh
emulate zsh
# Filename:      ~/bin/makepass.zsh
# Purpose:       Creating random passwords.
# Authors:       Dennis Eriksen <d@ennis.no>
# Bug-Reports:   Email <git@dnns.no>
# License:       This file is licensed under the BSD 3-Clause license.
################################################################################
# This file takes randomness from /dev/urandom and turns it into random
# passwords.
################################################################################
# Copyright (c) 2018-2023 Dennis Eriksen • d@ennis.no


# Help-function
function _makepass_help() {
  local string='NAME
    makepass - create several random passwords

SYNOPSIS
    makepass [OPTIONS] [NUM]

    If a NUM is provided, passwords will be NUM characters long.

    By default `makepass` will output passwords from the three following classes:

    - Normal passwords - 10 random strings with letters (both lower and upper
      case), numbers, and dashes and underscores.

    - Passwords with special characters - six random strings generated from
      lower and upper case letters, numbers, and the following characters:
      !#$%&/()=?+-_,.;:<>[]{}|\@*

    - Passphrases - if we find a dictionary, five series of eight random words
      from the dictionary, separated by dashes. The number of words can not be
      changed, but you do not have to use all of them. Use as mane as you want.

DESCRIPTION
    makepass has the following options:

    -h
        output this help-text
    -l
        length of passwords. See MAKEPASS_LENGTH below
    -n
        number of passwords. See MAKEPASS_NUMBER below

ENVIRONMENT
    makepass examines the following environmental variables.

    MAKEPASS_LENGTH
        Specifies the length of passwords. Valid values are 0-255. If 0, a
        random value between 8 and 42 will be used for each password. -l
        overrides this environmental variable, and NUM overrides that again. So
        `MAKEPASS_LENGTH=10 makepass -l 12 14` will give passwords that are 14
        characters long.

    MAKEPASS_NUMBER
        The default number of passwords from each group to output. By default
        10 normal passwords, six special passwords, and six passphrases, are
        printed. Valid values are 1-255.

    MAKEPASS_NORMAL
        String of characters from which to generate "normal" passwords.
        Defaults to:
        abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_

    MAKEPASS_SPECIAL
        String of characters from which to generate passwords with special
        characters. Defaults to the same characters as in MAKEPASS_NORMAL, plus
        these:
        !#$%&/()=?+-_,.;:<>[]{}|\@*

    MAKEPASS_WORDLIST
        Specifies the dictionary we find words for passphrases in. If this is
        unset or empty, we try "/usr/share/dict/words". If that file does not
        exist, no passphrases will be provided.

NOTES
    This scripts makes use of $RANDOM - a builtin in zsh which produces a
    pseudo-random integer between 0 and 32767, newly generated each time the
    parameter is referenced. We initially seed the random number generator with
    a random 32bit integer generated from /dev/urandom. This should provide
    enough randomnes to generate sufficiently secure passwords.

AUTHOR
    Dennis Eriksen <https://dnns.no>'

  print -- $string
  return 0
}



# Create random passphrase
function randphrase() {
  setopt localoptions rematch_pcre
  local -i len=${1:-8}
  local prestring string

  # Put together $len random words, separated by '-'
  repeat $len prestring+=$words[$((RANDOM % $#words + 1))]'-'
  prestring=$prestring[1,-2]  # remove trailing dash

  # This while-loop removes any characters NOT in '[^0-9a-zA-Z_-]'
  while [[ -n $prestring ]]; do
    if [[ $prestring =~ '[^0-9a-zA-Z_-]' ]]; then
      string+=${prestring[1,MBEGIN-1]}
      prestring=${prestring[MEND+1,-1]}
    else
      break
    fi
  done
  string+=$prestring # append the rest of $prestring

  printf '%s\n' $string; return
}

# Function to create random strings
function randstring() {
  # Default is a number between 8 and 44
  local -i len=$(( $1 ? $1 : RANDOM % (44 - 8 + 1) + 8 ))
  local chars=${2:-$alnum}
  local flc=${3:-} # first-last-character
  local string
  repeat $len string+=$chars[$((RANDOM % $#chars + 1))]

  # If a third value is provided, it is used as the first and last character in
  # the string
  # TODO: Maybe this needs to be redone? Do it like in the perl-version?
  if [[ -n $flc ]]; then
    string=$flc[$((RANDOM % $#flc + 1))]$string[2,-2]
    (( len >= 2 )) && string+=$flc[$((RANDOM % $#flc + 1))]
  fi

  printf '%s\n' "$string"; return
}

# Function to die
function die() {
  print -u2 -- "$@"
  print -u2 -- "Maybe try running \`$ZSH_SCRIPT -h\` for help"
  exit 1
}

# makepass-function. This is where the magic happens
function makepass() {
  setopt localoptions
  local lower='abcdefghijklmnopqrstuvwxyz'
  local upper='ABCDEFGHIJKLMNOPQRSTUVWXYZ'
  local digit='0123456789'
  local other='!#$%&/()=?+-_,.;:<>[]{}|\@*'
  local alpha=${lower}${upper}
  local alnum=${alpha}${digit}
  local every=${alnum}${other}

  local -i length=${MAKEPASS_LENGTH:-0}
  local normal=${MAKEPASS_NORMAL:-$alnum'-_'}
  local special=${MAKEPASS_SPECIAL:-$every}
  local wordlist=${MAKEPASS_WORDLIST:-/usr/share/dict/words}

  # Seed $RANDOM with a random 32bit integer from /dev/urandom
  local r4 # will be filled with 4 random bytes from /dev/urandom
  IFS= read -rk4 -u0 r4 < /dev/urandom || return
  local b1=$r4[1] b2=$r4[2] b3=$r4[3] b4=$r4[4]
  RANDOM=$(( #b1 << 24 | #b2 << 16 | #b3 << 8 | #b4 ))

  # Getopts
  while getopts 'hl:n:' opt; do
    case $opt in
      h)
        _makepass_help && return 0;;
      l)
        [[ ! $OPTARG = <0-255> ]] && die "-l takes a number between 0 and 255"
        length=$OPTARG;;
      n)
        [[ ! $OPTARG = <1-255> ]] && die "-n takes a number between 1 and 255"
        number=$OPTARG;;
      *)
        die "Unknown argument";;
    esac
  done

  shift $((OPTIND - 1))

  # Some error-checking
  # We only take one argument in addition to the optargs
  (( ARGC > 1 )) && die "only one argument"

  [[ -n $1 ]] && length=$1
  [[ $length = <0-255> ]] || die "length must be a number between 0 and 255"
  #
  # Print!
  #
  # Normal passwords
  print "Normal passwords:"
  print -c -- $(repeat 10 { randstring $length $normal; : $RANDOM })
  : $RANDOM
  print

  # Passowrds with special characters
  print "Passwords with special characters:"
  print -c -- $(repeat 6 { randstring $length $special $alpha; : $RANDOM })
  : $RANDOM

  # Passphrases - but only if a wordlist is available
  if [[ -r $wordlist ]]; then
    print
    print "Passphrases:"
    local -a words=(${(f)"$(<"$wordlist")"})
    repeat 6 randphrase
  fi
}

makepass "${@:-}"

# Last time I redid this script I benchmarked some ways to generate random
# strings. Here's the results:

# subshell with tr | fold | head
# % time (repeat 10000 { string=''; string=$(tr -cd '[:alpha:]' </dev/urandom | fold -w 20 | head -n1 ) } )
# 45.32s user 22.38s system 201% cpu 33.598 total
#
# subshell with head | tr | tail
# % time (repeat 10000 { string=''; string=$(head -n100 /dev/urandom | tr -cd '[:alpha:]' | tail -c20 ) } )
# 40.88s user 17.87s system 187% cpu 31.249 total
#
# subshell sysread | tr in brace-expansion instead of head/tail
# % time (repeat 10000 { string=''; string=${${:-"$(sysread -i 1 </dev/urandom | tr -cd '[:alpha:]')"}[1,20]} } )
# 24.13s user 11.38s system 120% cpu 29.442 total
#
# string-addition with randint32()-function to get random 32bit integer from /dev/urandom
# % time (repeat 10000 { string='';repeat 20 string+=$alpha[$((randint32() % $#alpha + 1))] })
# 8.17s user 3.28s system 99% cpu 11.475 total
#
# string-addition and $RANDOM
# % time (repeat 10000 { string='';repeat 20 string+=$alpha[$((RANDOM % $#alpha + 1))] } )
# 0.74s user 0.00s system 99% cpu 0.741 total


## END OF FILE #################################################################