Generate Unique Random String With Letters And Numbers In Lower Case

Question

How can I fix this code so it generates unique random letters and numbers in lower case?

api_string = (0...32).map{65.+(rand(25)).chr}.join

At the moment, it generates only letters.

The range for numbers is 48 to 57. These must be included in your range. — soandos, May 11 '11 at 15:41
Thanks for the answer. Can you give an example so I can mark it as correct? — donald, May 11 '11 at 15:43
possible duplicate of [How best to generate a random string in Ruby](http://stackoverflow.com/questions/88311/how-best-to-generate-a-random-string-in-ruby) — user, Mar 25 '15 at 08:20

score 84 · Accepted Answer · answered May 11 '11 at 15:52

84

If you are using ruby 1.9.2 you can use SecureRandom:

irb(main):001:0> require 'securerandom'
=> true
irb(main):002:0> SecureRandom.hex(13)
=> "5bbf194bcf8740ae8c9ce49e97"
irb(main):003:0> SecureRandom.hex(15)
=> "d2413503a9618bacfdb1745eafdb0f"
irb(main):004:0> SecureRandom.hex(32)
=> "432e0a359bbf3669e6da610d57ea5d0cd9e2fceb93e7f7989305d89e31073690"

answered May 11 '11 at 15:52

Vasiliy Ermolovich

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2

This is handy for simple needs but the alpha range is only a-f, so the security/complexity of the generated string isn't as high as it could be. – John Bachir Feb 06 '13 at 10:20
5

Better to use base64, which is also built in: SecureRandom.base64(16).gsub(/=+$/,'') – Michael Chaney May 24 '13 at 04:34
4

Not an issue for an API key, but there's also the handy urlsafe_base64 method: SecureRandom.urlsafe_base64(16) => "XpMnLfc3FySd-C4V2Ipxag" – upasaka Aug 25 '13 at 13:03
Why is it better to use base64 – ckarbass Mar 13 '14 at 05:26
8

Even better `SecureRandom.urlsafe_base64(length)` – Dennis May 16 '14 at 14:03
@ckarbass Hex only allows 0-9 and a-f. Base64 uses a wider character set. – sscirrus Feb 17 '17 at 23:27
Mentioned below but newer versions of ruby support `SecureRandom.base58(n)` which is pretty ideal for this use case. – Meekohi Oct 16 '19 at 22:43

score 28 · Answer 2 · answered May 11 '11 at 15:57

28

All letters and digits, that's how numbers are represented in base 36.

api_string = Array.new(32){rand(36).to_s(36)}.join

answered May 11 '11 at 15:57

steenslag

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score 15 · Answer 3 · answered May 07 '15 at 11:28

15

8.times.map { [*'0'..'9', *'a'..'z'].sample }.join

answered May 07 '15 at 11:28

Anuja Joshi

678
6
13

`'0'..'9'` generates an array from 0 to 9, and `'a'..'z'` generates an array from a to z, but what exactly does the * before each of them does? – Vipin Verma May 30 '16 at 12:21
1

`'0'..'9'` is range and `*` is splat operator. It splits the elements of the range into single items which are returned as a group, so basically `*` is helping you to separate out elements so that they can be sampled out using `sample` method – Anuja Joshi Jun 01 '16 at 06:34

score 3 · Answer 4 · answered Dec 26 '18 at 20:09

3

Newer versions of Ruby support SecureRandom.base58, which will get you much denser tokens than hex, without any special characters.

> SecureRandom.base58(24)
> "Zp9N4aYvQfz3E6CmEzkadoa2"

answered Dec 26 '18 at 20:09

Meekohi

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This answer it's much way better than the accepted one. – fsinisi90 Oct 16 '19 at 18:08

Kokizzu · Answer 5 · 2014-06-12T06:14:14.080

2

i forgot from where, but i've read this somehow this morning

l,m = 24,36
rand(m**l).to_s(m).rjust(l,'0')

it create random number from 0 to power(36,24), then convert it to base-36 string (that is 0-9 and a-z)

edited Jun 12 '14 at 06:14

answered Aug 22 '13 at 15:23

Kokizzu

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This is faster than steenslag's https://gist.github.com/cameron-martin/a7a91f0bc952e8a5c795 – Cameron Martin Jun 12 '14 at 02:41
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Except it's not always true that `rand(36**len).to_s(36).length == len`, so you will have to do `rand(36**len).to_s(36).rjust(len, '0')` – Cameron Martin Jun 12 '14 at 02:54

score 2 · Answer 6 · answered May 11 '11 at 15:51

2

Here's one way to do it:

POSSIBLE = (('A'..'Z').to_a + (0..9).to_a)
api_string = (0...32).map { |n| POSSIBLE.sample }.join

If you have Active Support available you can also do this to make an API-key-like string:

ActiveSupport::SecureRandom.hex(32)

answered May 11 '11 at 15:51

Jimmy

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AGS · Answer 7 · 2013-09-29T12:19:13.833

1

((('a'..'z').to_a + (0..9).to_a)*3).shuffle[0,(rand(100).to_i)].join

Replace rand(100) with rand(n) where n is the maximum length of your desired string.

edited Sep 29 '13 at 12:19

answered Sep 29 '13 at 01:09

AGS

14,118
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score 1 · Answer 8 · answered Dec 06 '18 at 14:54

1

This will generate a lower random string from 32 to 50 characters including numbers and letters, both:

require 'string_pattern'

puts "32-50:/xN/".gen

answered Dec 06 '18 at 14:54

Mario Ruiz

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score 1 · Answer 9 · answered May 11 '11 at 15:49

1

CHARS = (?0..?9).to_a + (?a..?z).to_a
api_string = 32.times.inject("") {|s, i| s << CHARS[rand(CHARS.size)]}

answered May 11 '11 at 15:49

Guilherme Bernal

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score 0 · Answer 10 · edited Jan 22 '15 at 13:33

0

using SecureRandom of ruby language.

require 'securerandom' randomstring = SecureRandom.hex(5)

It will generate the n*2 random string contains “0-9″ and “a-f”

edited Jan 22 '15 at 13:33

Bill the Lizard

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answered Jan 16 '15 at 11:31

veeresh yh

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John Doe · Answer 11 · 2016-08-31T01:13:13.350

-1

Process.clock_gettime(Process::CLOCK_REALTIME, :nanosecond).to_s(36)

edited Aug 31 '16 at 01:13

answered Jul 14 '16 at 03:08

John Doe

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Generate Unique Random String With Letters And Numbers In Lower Case

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