TOTP VALIDATION (WITHOUT CREATING CREDENTIAL)

{
  "name": "TOTP VALIDATION (WITHOUT CREATING CREDENTIAL)",
  "nodes": [
    {
      "id": "56f102c4-5b84-4e30-955c-0ea1221c328f",
      "name": "When clicking ‘Test workflow’",
      "type": "n8n-nodes-base.manualTrigger",
      "position": [
        480,
        680
      ],
      "parameters": {},
      "typeVersion": 1
    },
    {
      "id": "4f562819-ee42-42ad-b821-aff2cbebbc0f",
      "name": "TOTP VALIDATION",
      "type": "n8n-nodes-base.code",
      "position": [
        920,
        680
      ],
      "parameters": {
        "language": "python",
        "pythonCode": "import hmac
import hashlib
import time
import base64

def base32_decode(key):
    \"\"\"Decodes a base32 key into bytes\"\"\"
    key += '=' * (-len(key) % 8)  # Add necessary '=' for valid length
    return base64.b32decode(key.upper(), casefold=True)

def generate_totp(secret, interval=30, digits=6):
    \"\"\"Generates a TOTP code based on a secret key\"\"\"
    interval_count = int(time.time() // interval)
    interval_bytes = interval_count.to_bytes(8, byteorder='big')

    hmac_hash = hmac.new(secret, interval_bytes, hashlib.sha1).digest()
    
    offset = hmac_hash[-1] & 0x0F
    binary_code = ((hmac_hash[offset] & 0x7F) << 24 |
                   (hmac_hash[offset + 1] & 0xFF) << 16 |
                   (hmac_hash[offset + 2] & 0xFF) << 8 |
                   (hmac_hash[offset + 3] & 0xFF))
    
    otp_code = binary_code % (10 ** digits)
    
    # Format with leading zeros if necessary
    otp_code_str = str(otp_code).zfill(digits)
    
    return otp_code_str

def verify_totp(secret, code, interval=30, digits=6):
    \"\"\"Checks whether the TOTP code is valid\"\"\"
    secret_bytes = base32_decode(secret)
    generated_code = generate_totp(secret_bytes, interval, digits)
    
    return generated_code == code

# Example of use
secret = _input.item.json.totp_secret_example  # Secret key base32 (example)
code =  _input.item.json.code_to_verify_example # Code to check (example)

# Return 1 if code is valid. Return 0 if invalid
if verify_totp(secret, code):
    return [{\"status\": 1}]
else:
    return [{\"status\": 0}]"
      },
      "typeVersion": 2
    },
    {
      "id": "9760b31c-5ba8-4001-9cbe-2be2ae58d58e",
      "name": "IF CODE IS VALID",
      "type": "n8n-nodes-base.if",
      "position": [
        1140,
        680
      ],
      "parameters": {
        "options": {},
        "conditions": {
          "options": {
            "leftValue": "",
            "caseSensitive": true,
            "typeValidation": "strict"
          },
          "combinator": "and",
          "conditions": [
            {
              "id": "470cf368-daee-4136-b907-a3539765871d",
              "operator": {
                "type": "number",
                "operation": "equals"
              },
              "leftValue": "={{ $json.status }}",
              "rightValue": 1
            }
          ]
        }
      },
      "typeVersion": 2.1
    },
    {
      "id": "3a029863-8fd0-42ef-b8ff-9f7cdf6e8d94",
      "name": "Sticky Note",
      "type": "n8n-nodes-base.stickyNote",
      "position": [
        440,
        180
      ],
      "parameters": {
        "width": 883,
        "height": 430,
        "content": "## TOTP Validation with Function Node

This template allows you to verify if a 6-digit TOTP code is valid using the corresponding TOTP secret. It can be used in an authentication system.
### Example usage:
- You retrieve the user's TOTP secret from a database, then you want to verify if the 2FA code provided by the user is valid.

## Setup Guidelines

You only need the \"TOTP VALIDATION\" node.
You will need to modify lines 39 and 40 of the \"TOTP VALIDATION\" node with the correct values for your specific context.

## Testing the Template
You can define a sample secret and code in the \"EXAMPLE FIELDS\" node below, then click \"Test Workflow\".
If the code is valid for the provided secret, the flow will proceed to the \"true\" branch of the \"IF CODE IS VALID\" node. Otherwise, it will go to the \"false\" branch."
      },
      "typeVersion": 1
    },
    {
      "id": "f660a50f-2c33-49bb-b975-8d51e9bf24ed",
      "name": "EXAMPLE FIELDS",
      "type": "n8n-nodes-base.set",
      "position": [
        700,
        680
      ],
      "parameters": {
        "options": {},
        "assignments": {
          "assignments": [
            {
              "id": "03a66bf9-1bf4-44c0-92e0-edd45929e467",
              "name": "code_to_verify_example",
              "type": "string",
              "value": "516620"
            },
            {
              "id": "7bb18b0a-1851-4f27-a91f-5f93b663cfd0",
              "name": "totp_secret_example",
              "type": "string",
              "value": "CNSUKUMZLQJEZJ3"
            }
          ]
        }
      },
      "typeVersion": 3.4
    }
  ],
  "active": false,
  "pinData": {},
  "settings": {
    "executionOrder": "v1"
  },
  "connections": {
    "EXAMPLE FIELDS": {
      "main": [
        [
          {
            "node": "TOTP VALIDATION",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "TOTP VALIDATION": {
      "main": [
        [
          {
            "node": "IF CODE IS VALID",
            "type": "main",
            "index": 0
          }
        ]
      ]
    },
    "When clicking ‘Test workflow’": {
      "main": [
        [
          {
            "node": "EXAMPLE FIELDS",
            "type": "main",
            "index": 0
          }
        ]
      ]
    }
  }
}