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Symmetric encryption (AES-GCM). Free online tool, no login, no sign-up.

LocalPersonal data security

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Usage Guide & Tech FAQ

Usage Guide

  1. Confirm encrypt/decrypt direction and mode (CBC, GCM, CTR…); mode mismatch yields garbage or auth failures.
  2. Key sizes must match the cipher (AES-128/192/256); hex keys should have an even digit count.
  3. For modes needing IVs, randomize IVs and transmit/store them with ciphertext—don’t ship zero IVs to prod.
  4. For AEAD (e.g., GCM), align tag length and additional authenticated data (AAD) with the peer implementation.
  5. Ciphertext is often hex/base64—avoid stray spaces, newlines, or `0x` prefixes unless agreed.
  6. If decryption fails, re-check key, IV, mode, padding (PKCS#7), and ciphertext completeness.
  7. Interop across languages: verify text encoding, endianness, and ciphertext||tag concatenation order.
  8. For large files, if chunking is supported, confirm per-chunk IV rules and whether chaining state is required.
  9. Align with published test vectors before switching to real data.
  10. Clear keys and plaintext after use; never paste production secrets into tickets.
  11. Read the title and description first to confirm this utility matches your task (avoid using the wrong tool and misinterpreting output).
  12. Paste or type input in the editor; if a sample/template is provided, load it first to learn the expected output shape.

Related Tech Knowledge

  • AES is a symmetric block cipher; safety needs secret keys, correct modes, and random IVs/nonces.
  • ECB leaks repeated patterns and is rarely appropriate alone; prefer AEAD like GCM.
  • Padding-oracle class bugs historically leaked plaintext—protocols and implementations must prevent them.
  • WebCrypto exposes a browser-dependent subset; some modes/key lengths may be unavailable.
  • Derive keys from passwords with PBKDF2/Argon2 instead of trimming text to 16 bytes manually.
  • Reusing IV/key pairs breaks confidentiality; protocols need counters or random nonces per message.
  • Hybrid schemes often RSA-wrap a random AES key—this tool may only cover the AES half.
  • Browser crypto suits dev/test; high-assurance workloads belong in HSMs or hardened servers.
  • Timing side channels are hard to eliminate in pure JS—don’t rely on front-end crypto alone for high threat models.
  • When outputs differ, compare raw bytes (hex) rather than interpreted text.
  • Core parsing and computation run in your browser; by default your raw business payload is not persisted to this site’s servers (see on-page privacy notes).
  • The pipeline is typically: read input → parse (lexical/syntactic/structured) → transform → render; failures aim to be diagnosable.