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Many software projects use secrets - usually, keys to external APIs or credentials to access an external resource such as a database. Your application needs these keys at runtime, so you need to be able to provide them when you deploy your application. Git-crypt aims to solve this problem by encrypting your secrets whenever you push them to your git repository, and decrypting them whenever you pull them. This happens transparently, from your point of view, so the secrets are in cleartext as far as you and your deployment code are concerned.