Why we use <crypt_key> from magento 1 local.xml while migration from magento 1 to magento 2?

Question

Because if I use that crypt_key from magento 1 and try to migrate another database, data-migration-tool runs and start to migrate that db.

Why is this happening?

What are the reasons to use that crypt_key?

Answer 1

crypt_key is used for encryption of sensitive information of site. eg. customer password When you migrate data from magento 1 to magento 2, you must need to define <crypt_key> field in config.xml file.

crypt_key convert encoded value of Magento 1 to value compatible with Magento2.

when you run migrate command, magento 2 data migration tool check data validation from Encrypt.php file, You can check file,

vendor/magento/data-migration-tool/src/Migration/Handler/Settings/Encrypt.php

Inside Handle() function you can check $this->validate($recordToHandle); function for validate of old data for crypt_key.

public function validate(Record $record)
    {
        if (empty($this->cryptKey)) {
            throw new Exception("\"crypt_key\" option is not defined the configuration.");
        }

        parent::validate($record);
    }

if you haven't defined crypt_key in config.xml file, data validatin throws error from above file.

So using crypt_key, Magento system use crypt key with encoding mechanism to encode sensitive information of users to store in db.