Lasing　emissions　with　multiple　and　tunable　modes　are　promising　in　coding　field　as　a　novel　cryptographic　primitive.　With　the　advantages　of　simple　fabrication,　full-color　and　high-quality-factor　whispering　gallery　mode　lasing　inside　a　circular　cross-section,　polymer　microfibers　are　attractive　for　photonic　devices.　However,　polymer　lasing　microfibers　for　information　encryption　have　never　been　reported.　Herein,　we　propose　a　design　of　printable　lasing　microfiber　encryption　chip　by　in-situ　tuning　the　effective　refractive　index　of　the　microresonator　arrays　via　a　facile　approach.　Through　inkjet　printing　high-refractive-index　nanoparticles　on　the　designated　position　of　lasing　microfiber　arrays,　the　effective　refractive　index　of　the　microcavities　is　regulated,　and　the　ratio　of　wavenumber　spacing　between　transverse　electric　and　transverse　magnetic　mode　to　the　free　spectral　range　can　be　modulated,　particularly　with　neglectable　influence　by　the　size　factor.　Thus,　the　programmable　region　selective　encoding　process　can　be　conducted　simply　by　a　printing　program　within　several　minutes.　Besides,　the　encoded　microfiber　arrays　are　encapsulated　into　polydimethylsiloxane　to　reduce　the　scattering　loss　and　environmental　interference,　and　a　printable　encryption　chip　is　realized.　This　work　is　expected　to　provide　a　platform　for　the　printable　encrypted　devices.　[Figure　not　available:　see　fulltext.].　©　2023,　Tsinghua　University　Press.