A system and method mediate transfer of encrypted data files between local applications and external computer systems. Application containers perform cryptographic operations using stored credentials to decrypt data coming from these external systems and configurably forward them to the local applications, and to encrypt data sent from the local applications to the external systems. Access to this encryption-as-a-service (EaaS) functionality is gated by a fingerprint service that classifies requests by security level, and detects anomalous requests. Security classification is performed by a supervised machine learning algorithm, while anomalous request detection is performed by unsupervised machine learning algorithm. Stored keys are monitored, and when they near expiration or are damaged, embodiments proactively undertake key renewal and key exchange with the external computer systems. Containerization enables key storage in multiple vaults, thereby making such storage vendor-agnostic.