AES Decrypt
Decrypt AES-256-GCM ciphertext created with the AES Encrypt tool. Verifies integrity tag and decrypts message safely in your browser.
Step-by-Step Instructions
Paste Encrypted Ciphertext
Paste the Base64 or Hex encrypted string containing the ciphertext payload.
Enter Secret Passphrase / Key
Input the exact password or 256-bit key used during encryption.
Select Encryption Mode
Choose matching AES mode (AES-GCM or AES-CBC) with PBKDF2 key derivation.
Decrypt & View Plaintext
Click decrypt to verify authentication integrity and restore original plaintext message.
Key Features & Capabilities
- AES-GCM and AES-CBC decryption supporting 128, 192, and 256-bit keys
- Automated payload unpacking extracting Salt, IV (Nonce), Auth Tag, and Ciphertext from Base64 bundles
- Integrity verification alerting immediately if ciphertext has been corrupted or tampered with
- Client-side zero-knowledge decryption executed entirely within browser memory
Frequently Asked Questions
What causes an 'Authentication Tag Mismatch' or 'Decryption Failed' error?
In AES-GCM mode, decryption fails if: 1) The **password or key is incorrect**; 2) The **ciphertext was modified or corrupted** in transit; 3) The **wrong AES mode** (GCM vs CBC) or key derivation parameters were selected. AES-GCM will never output partial decrypted data if the authentication tag check fails.
How does the decryptor extract the Salt and IV from the encrypted string?
Standard encrypted Base64 payloads bundle the components: `[16-byte Salt] + [12-byte IV] + [Ciphertext] + [16-byte Auth Tag]`. The decryptor splits this binary buffer, uses the Salt to derive the AES key via PBKDF2, and initializes the cipher with the IV.
Can an encrypted message be decrypted if the password is lost?
No. Symmetric AES-256 encryption has no backdoors. If the encryption key or passphrase is lost, the data is mathematically unrecoverable.
Is decryption secure against browser extensions?
Decryption runs inside an isolated web worker using native browser Web Crypto primitives in ephemeral memory. For maximum security when handling high-value secrets, use an incognito browser window with extensions disabled.
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