About AES Decryption Tool
Advanced Encryption Standard (AES) is a U.S. Federal Information Processing Standard (FIPS). It was selected after a 5-year process where 15 competing designs were evaluated. Key: The following algorithms will be used based on the size of the key:16 bytes = AES-128 24 bytes = AES-192 32 bytes = AES-256 IV: The Initialization Vector should be 16 bytes long. If not entered, it will default to 16 null bytes. Padding: In CBC and ECB mode, PKCS#7 padding will be used as a default. GCM Tag: This field is ignored unless 'GCM' mode is used.
Input: text. Output: text.
Format reference: AES Decrypt background and specification
Example
Use “Try example” to load this public sample and its settings, then run it.
Settings used in this example
| Parameter | Example value | Input and choices |
|---|---|---|
| Key | {"option":"Hex","string":"00112233445566778899aabbccddeeff"} | Key/text encoding: Hex, UTF8, Latin1, Base64 |
| IV | {"option":"Hex","string":"00000000000000000000000000000000"} | Key/text encoding: Hex, UTF8, Latin1, Base64 |
| IV Length | 16 | Number |
| Mode | "CTR" | CBC, CFB, OFB, CTR, GCM, ECB, CBC/NoPadding, ECB/NoPadding |
| Input | Hex | Hex, Raw |
| Output | Raw | Raw, Hex |
| GCM Tag | {"option":"Hex","string":""} | Key/text encoding: Hex, UTF8, Latin1, Base64 |
| Additional Authenticated Data | {"option":"Hex","string":""} | Key/text encoding: Hex, UTF8, Latin1, Base64 |
| IV from input | "Off" | Off, From start, From end |
Sample keys and passwords are public. Never use them to protect real data.
Input
a98c9e8e3b7c894384d740e4f0f4ed0be2bbb1e0e13a255812c3c6b0a629e4ad759c075b2469c6f4fb2c0cf9
Result
The quick brown fox jumps over the lazy dog.
Why does decryption fail?
Check whether the ciphertext is hex, Base64 or raw bytes, then match key encoding, IV, mode and padding. A successful padding check alone is not proof of authenticity.
Parameters
| Parameter | Default value | Input and choices |
|---|---|---|
| Key | {"option":"Hex","string":""} | Key/text encoding: Hex, UTF8, Latin1, Base64 |
| IV | {"option":"Hex","string":""} | Key/text encoding: Hex, UTF8, Latin1, Base64 |
| IV Length | 16 | Number |
| Mode | "CBC" | CBC, CFB, OFB, CTR, GCM, ECB, CBC/NoPadding, ECB/NoPadding |
| Input | Hex | Hex, Raw |
| Output | Raw | Raw, Hex |
| GCM Tag | {"option":"Hex","string":""} | Key/text encoding: Hex, UTF8, Latin1, Base64 |
| Additional Authenticated Data | {"option":"Hex","string":""} | Key/text encoding: Hex, UTF8, Latin1, Base64 |
| IV from input | "Off" | Off, From start, From end |
Before interpreting the result
Use the exact key encoding, mode, padding and IV expected by the source system. Historical ciphers are useful for learning and analysis. Encoding alone provides no confidentiality.
How to use this page
- Paste your input or open a local file.
- Adjust tool options if needed, then choose Run tool.
- Copy the result or download the original output bytes.
Inputs and results are not added to the public catalogue or saved in the URL. Processing happens in your browser; HTTP Request and DNS over HTTPS send the requests you explicitly run. Files up to 128 MiB can be opened; decompression and image tools may have smaller processing limits. Large results have a shortened preview. Text and HTML downloads use UTF-8; binary downloads preserve output bytes. Pasted text follows browser newline handling; open a file when exact input bytes matter.