AES Decryption

Use the steps below to recover text from a test ciphertext.

Recover text from a test ciphertext

1. Paste the full IV-prefixed value into Ciphertext. Use Input Encoding: Hex for hexadecimal input or Base64 for Base64 input; the UTF-8 default is also treated as Base64 here.
2. Keep Decryption Key & IV enabled. Enter the key in Decryption Key / Password and select its representation with Key Encoding (Search/Type):.
3. Keep Auto / Live on to update the result as you edit. To work manually, turn Auto / Live off and click Run.
4. Read Decrypted Plaintext. A decryption error can indicate the wrong key, encoding, IV prefix, or cipher settings.
5. Click Copy to copy the result. Use Clear where shown, or a field's clear control, to clear the text.

For example, select Base64 input and use ciphertext AAECAwQFBgcICQoLDA0OD/MLhMBQYo2mLm1PZkeSwm0= with UTF-8 key 12345678901234567890123456789012. The recovered plaintext is Hello. This fixed IV is only a test fixture.

Match the ciphertext envelope

Decode the transport representation into bytes, then interpret the first 16 bytes as the IV. Ciphertext from a different mode, a separate-IV format, or a password-derived envelope is not automatically compatible. There is no separate IV field despite the switch label.

Interpret recovered text cautiously

Keys are raw bytes padded or truncated to 32 bytes; no password KDF is applied. Recovered bytes are displayed as UTF-8 text, so binary data or another text encoding may not display correctly. CBC decryption alone does not verify the message’s authenticity.