Looking for Base64url encoder

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#1

I’m looking for a Base64url encoder for lua, and thought I’d ask here to see if anyone knew of one or was working on one so that I don’t have to make it my self.

Thanks.

#2
#3

I’ll expose my self and say that I’m not sure of the exact differences between Base64 encoders and Base64url encoders, but they are different: regular Base64 encoders do not work well with URLs.

This is exactly my problem, as I need it to work with URLs. I’ve read over the post you linked already but it is not a Base64url encoder.

#4

Do your research first.

The way base64url encoding works is exactly the same as base64 encoding other than two exceptions: the character - is used in base64url encoding instead of the character + in base64 encoding, and the character _ is used in base64url encoding instead of the character / in base64 encoding.Dec 17, 2019

Answer 1 by TheCrimulo
answered Feb 9, 2016 at 22:19
Code goes as followed:

local b='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/' -- You will need this for encoding/decoding
-- encoding
function enc(data)
    return ((data:gsub('.', function(x) 
        local r,b='',x:byte()
        for i=8,1,-1 do r=r..(b%2^i-b%2^(i-1)>0 and '1' or '0') end
        return r;
    end)..'0000'):gsub('%d%d%d?%d?%d?%d?', function(x)
        if (#x < 6) then return '' end
        local c=0
        for i=1,6 do c=c+(x:sub(i,i)=='1' and 2^(6-i) or 0) end
        return b:sub(c+1,c+1)
    end)..({ '', '==', '=' })[#data%3+1])
end

-- decoding
function dec(data)
    data = string.gsub(data, '[^'..b..'=]', '')
    return (data:gsub('.', function(x)
        if (x == '=') then return '' end
        local r,f='',(b:find(x)-1)
        for i=6,1,-1 do r=r..(f%2^i-f%2^(i-1)>0 and '1' or '0') end
        return r;
    end):gsub('%d%d%d?%d?%d?%d?%d?%d?', function(x)
        if (#x ~= 8) then return '' end
        local c=0
        for i=1,8 do c=c+(x:sub(i,i)=='1' and 2^(8-i) or 0) end
            return string.char(c)
    end))
end

Before you make a post and waste everyone’s time, Do your research.

#5

It’s as simple as replacing the - with a + and a _ instead of a /

#6

Incase you need help with that, I’ve done it for you in about 3 seconds here by replacing 2 characters. It’s simple as that.

local b='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_' -- You will need this for encoding/decoding
-- encoding
function enc(data)
    return ((data:gsub('.', function(x) 
        local r,b='',x:byte()
        for i=8,1,-1 do r=r..(b%2^i-b%2^(i-1)>0 and '1' or '0') end
        return r;
    end)..'0000'):gsub('%d%d%d?%d?%d?%d?', function(x)
        if (#x < 6) then return '' end
        local c=0
        for i=1,6 do c=c+(x:sub(i,i)=='1' and 2^(6-i) or 0) end
        return b:sub(c+1,c+1)
    end)..({ '', '==', '=' })[#data%3+1])
end

-- decoding
function dec(data)
    data = string.gsub(data, '[^'..b..'=]', '')
    return (data:gsub('.', function(x)
        if (x == '=') then return '' end
        local r,f='',(b:find(x)-1)
        for i=6,1,-1 do r=r..(f%2^i-f%2^(i-1)>0 and '1' or '0') end
        return r;
    end):gsub('%d%d%d?%d?%d?%d?%d?%d?', function(x)
        if (#x ~= 8) then return '' end
        local c=0
        for i=1,8 do c=c+(x:sub(i,i)=='1' and 2^(8-i) or 0) end
            return string.char(c)
    end))
end
#7

Thanks, but there is no need to be condescending about it. I did do research prior to asking and couldn’t find what I needed, which is why I asked here. I continued searching after yoshi’s reply and found and solved this my self.

2 Likes
#8

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