Hex to String & String to Hex conversion in nodejs

Question

I need to convert data into String to Hex and then again from Hex to String using nodejs 8

I have issue while decoding from Hex to String

Code to convert string into hex

function stringToHex(str)
{
    const buf = Buffer.from(str, 'utf8');
    return buf.toString('hex');
}

Code to convert hex into string

function hexToString(str)
{
    const buf = new Buffer(str, 'hex');
    return buf.toString('utf8');
}

I have string dailyfile.host

output of encoding: 3162316637526b62784a5a37697a45796c656d465643747a4a505a6f59774641534c75714733544b4446553d

output of decoding: 1b1f7RkbxJZ7izEylemFVCtzJPZoYwFASLuqG3TKDFU=

Required output of decoding: dailyfile.host

Solution

You need to use Buffer.from() for decoding as well. Consider writing a higher-order function to reduce the amount of repeated code:

const convert = (from, to) => str => Buffer.from(str, from).toString(to)
const utf8ToHex = convert('utf8', 'hex')
const hexToUtf8 = convert('hex', 'utf8')

hexToUtf8(utf8ToHex('dailyfile.host')) === 'dailyfile.host'

Comments

[Hassaan]

This still does not work for me, I am using nodejs v8.11.

[Patrick Roberts]

@Hassaan "This does not work" is not a problem statement. Be more specific about the issue you're having.

[Hassaan]

Issue is still the same while decoding. Encoded string 4d6a772b646e316c4e314867684c435431724a53674e5934303063336752‌​74474753506742672f62‌​2b4f6b3d but decoded string is Mjw+dn1lN1HghLCT1rJSgNY400c3gRtGGSPgBg/b+Ok=

[Patrick Roberts]

That's because your hexadecimal string is the hex encoding of that output string. What's the output of utf8ToHex('dailyfile.host')? It should be 6461696c7966696c652e686f7374.

[Hassaan]

I see, how to resolve it? Can you please update answer for this?

[Patrick Roberts]

Where is that "encoded string" coming from? Can you update your question to clarify?

[Hassaan]

I am giving string to as parameter of GET request to URL. I am updating my question

[Hassaan]

I have tested your provided answer as sandbox. Its working fine but there was issue with my code as you mentioned in above comment. I was using @skavinvarnan/cryptlib module for encryption and while while decoding I was not using that module. Thanks man for pointing me in right way :)

[krupesh Anadkat]

Just check that hex string doesnot start with '0x', and above code should work while converting from hex to utf8