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IV Generator

Random Initialisation Vectors — computed locally in your browser.

Generate an initialisation vector

Value
Bit strength:
Byte length:
Match the cipher block size and send the IV with the ciphertext.

How to use the IV Generator

  1. Choose the initialisation vector length that your cipher expects.
  2. Pick hex, Base64 or Base64url as the output format.
  3. Copy the IV and store it with the ciphertext, never inside the key.

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Frequently Asked Questions

Common questions about the free online iv generator.

An IV is the random starting block that makes the first encrypted block different each time the same key is used.
It must match the block size of the cipher, so AES-CBC needs 16 bytes and AES-GCM normally uses 12 bytes.
No. Reusing an IV with the same key weakens or breaks the encryption, so every message needs a fresh random IV.
No. The IV can be sent or stored in the clear with the ciphertext, but it must be unpredictable for CBC mode.
Prefix it to the ciphertext, or store it in a separate field, so the decrypting side can read it before decryption.
The two terms overlap. An IV is the initial block of a cipher while a nonce is any value used once in a protocol.
No, and never derive the key from the IV. The IV adds randomness while the key must stay secret.
Tutorials sometimes use a fixed IV for clarity, but that is unsafe for real data because it removes the randomness.
Yes. Either side can generate it as long as it is random and unique per message and is transmitted with the ciphertext.

Last updated: October 10, 2026