The blog post discusses the design decisions and migration strategies for implementing column encryption in a Rails application using ActiveRecord::Encryption. The focus is on migrating existing plaintext or previously encrypted columns to a new encryption standard and handling key rotation. The authors opted for a custom approach using a "previous encryptor" strategy to manage plaintext during migration and a feature flag mechanism to control the rollout of the new encryption system. The post also addresses challenges encountered, such as dealing with false alerts in audit logs due to the changed_in_place? method, and outlines how to use the MaintenanceTasks gem for backfilling records. By adding a new encryption key, the migration process ensures records are re-encrypted with the latest key, thereby maintaining data security. The guide aims to assist organizations in adopting ActiveRecord::Encryption for securing sensitive database information.