Format-preserving encryption for PII in Polars: FF3-1 vs FF1 for RUT, CPF, and DNI

Short summary

MaskOps provides format-preserving encryption for PII masking, letting you encrypt identifiers like RUTs/CPF/DNI while preserving format and enabling reversal with the right key. FF3-1 is being phased out by NIST; FF1 is the recommended mode. FPE output is pseudonymized, not anonymous—requiring separate key storage for GDPR compliance.

• •FPE enables reversible, format-preserving masking of PII in datasets for secure third-party sharing
• •FF3-1 is deprecated by NIST in favor of FF1; both are safe for typical domain sizes but FF1 is the standard for new work
• •FPE output is pseudonymized under GDPR, not anonymous—key must be stored separately for compliance

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