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@thomasdarimont
Last active May 20, 2024 22:58
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Example for decoding a JWT Payload with your Shell (bash, zsh...)

Setup

Add this to your .profile, .bashrc, .zshrc...

decode_base64_url() {
  local len=$((${#1} % 4))
  local result="$1"
  if [ $len -eq 2 ]; then result="$1"'=='
  elif [ $len -eq 3 ]; then result="$1"'=' 
  fi
  echo "$result" | tr '_-' '/+' | openssl enc -d -base64
}

decode_jwt(){
   decode_base64_url $(echo -n $2 | cut -d "." -f $1) | jq .
}

# Decode JWT header
alias jwth="decode_jwt 1"

# Decode JWT Payload
alias jwtp="decode_jwt 2"

Usage

jwtp eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiYWRtaW4iOnRydWV9.TJVA95OrM7E2cBab30RMHrHDcEfxjoYZgeFONFh7HgQ

Output

{
  "sub": "1234567890",
  "name": "John Doe",
  "admin": true
}
@vithalreddy
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Using Jq

function jwt_decode(){
    jq -R 'split(".") | .[1] | @base64d | fromjson' <<< "$1"
}

Usage:

╰─ jwt_decode eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c
{
  "sub": "1234567890",
  "name": "John Doe",
  "iat": 1516239022
}

@frittenlab
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@vithalreddy Perfect cheers :)

@christopheblin
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@vithalreddy beautiful, thanks !

@sumitjainn
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Solution from @vithalreddy works perfectly across platforms, thanks!

@tanduong
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Perfect. Thanks @vithalreddy.

@jrichardsz
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Awesome when people share their knowledge for free. Thanks men!

I will add your script to my jarvis assistant

https://github.com/jrichardsz/linux-commandline-assistant/tree/master/commands

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