Online AES encrypt & decrypt

AES-GCM/CBC with passphrase or hex key—processed locally, not uploaded.

About this online tool

hidevtool AES encrypts and decrypts UTF-8 text in your browser. Choose block mode (including GCM), padding, IV length, hex key or passphrase, and Base64 or hex output—nothing is uploaded.

Online AES encrypt & decrypt capabilities

What is AES?

AES (Advanced Encryption Standard) is a symmetric cipher: the same key encrypts and decrypts. It is widely used to protect data at rest and in transit. This tool supports CBC, CFB, CTR, OFB, ECB, and GCM (authenticated encryption).

Block modes

  1. CBC — needs a 16-byte IV; strong default for general text.
  2. GCM — AEAD: 12-byte IV (24 hex), built-in integrity tag; no padding.
  3. ECB — no IV; identical blocks leak patterns (avoid for structured data).
  4. CFB / OFB — stream-like; good for incremental or real-time data.
  5. CTR — parallel-friendly; needs a unique IV per message.

Padding

  • Pkcs7 — most common; good interoperability.
  • Iso97971 / AnsiX923 — ISO/ANSI variants for legacy systems.
  • ZeroPadding — zero fill; verify length on decrypt.
  • NoPadding — plaintext must already be a multiple of 16 bytes.
  • GCM — padding does not apply (AEAD).

Output encoding

  • Base64 — compact; easy in JSON, URLs, and email.
  • Hex — readable; handy for logs and byte-level debugging.

Security tips

  1. 1Generate keys and IVs with a cryptographically secure random source.
  2. 2Prefer GCM or CBC over ECB; never reuse an IV/nonce with the same key.
  3. 3Use AES-256 hex keys (64 hex chars) or strong passphrases in production.
  4. 4Rotate keys and IVs on a schedule; store secrets outside source code.
  5. 5Use this page for debugging and tests; production apps need proper key management and reviewed implementations.

Common use cases

Transport encryption

Protect sensitive fields before they cross the network; match mode, IV, and encoding with your backend.

File & config secrets

Encrypt local notes or config blobs; keep the packed token or raw parameters with your backup.

API debugging

Reproduce client-side AES steps against a gateway or mobile SDK without sending keys to a server.

Frequently asked questions

How do I encrypt with AES online?
Paste plaintext, pick mode and padding, set IV (32 hex for most modes, 24 hex for GCM), enter a hex key or passphrase, choose Base64 or hex output, then click Encrypt.
Hex key or passphrase?
Valid 32/48/64-character hex strings are treated as raw AES-128/192/256 keys. Anything else is derived as a passphrase and encrypted with your selected mode.
What IV length should I use?
Block modes (CBC, CFB, CTR, OFB) use 16 bytes (32 hex). GCM uses 12 bytes (24 hex). ECB ignores IV.
Is my key sent to hidevtool?
No. Encryption and decryption run entirely in your browser.