What key formats are supported?

Hex strings (e.g. a1b2c3...) and standard base64 strings (e.g. oRrT...). The tool auto-detects the format. Whitespace and hyphens are stripped automatically.

What is a good Shannon entropy score?

The theoretical maximum is 8.0 bits per byte. A cryptographically random key should score between 7.0 and 8.0. Keys below 6.0 are considered weak regardless of length.

Does key length affect AES security?

AES-128 (16 bytes) is considered secure against classical attacks. AES-256 (32 bytes) provides extra margin against future quantum attacks. AES-192 (24 bytes) is valid but rarely used. Any non-standard length is rejected by AES implementations.

Is my key sent to a server?

No. All analysis runs entirely in your browser using JavaScript. Nothing is transmitted or stored. You can disconnect from the internet and the tool still works.

Why is an all-zero key flagged as weak?

An all-zero key (000000...0) is a well-known degenerate value often used as a default or placeholder. It has essentially zero entropy and is among the first values an attacker tries.

What should I use to generate a strong AES key?

Use a cryptographically secure random number generator: openssl rand -hex 32 (Linux/Mac), window.crypto.getRandomValues() in browsers, or secrets.token_hex(32) in Python.

AES Key Strength Analyzer

Name: AES Key Strength Analyzer
Availability: InStock
Author: Nham Vu

Paste a hex or base64 AES key to instantly check its length, entropy, and common weaknesses.

AES Key Input

Key (hex or base64)

Auto-detect

Quick Examples

Paste an AES key and click Analyze

Supports hex and base64 — 128, 192, or 256-bit keys

Summary

Paste a hex or base64 AES key to instantly check its length, entropy, and common weaknesses.

How it works

Paste your AES key as a hex string (e.g. a1b2c3d4...) or base64 string into the input field.
The tool auto-detects the encoding format and decodes the raw bytes.
Key length is checked: valid AES sizes are 128-bit (16 bytes), 192-bit (24 bytes), or 256-bit (32 bytes).
Shannon entropy is calculated across the byte distribution; a perfect random key scores ~8.0 bits/byte.
Weakness patterns are tested: all-zero bytes, all-same-byte, sequential ramps, and low unique byte count.
A combined strength score and pass/fail report is displayed with actionable recommendations.

Use cases

Validate AES keys generated by your application before deploying to production.
Audit legacy configuration files for weak or placeholder encryption keys.
Verify that a key derivation function (KDF) is producing high-entropy output.
Check manually typed keys for accidental patterns or truncation errors.
Teach developers how key entropy and bit length affect AES security.
Quickly confirm a 256-bit key is exactly 32 bytes (64 hex characters).

Frequently Asked Questions

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Last updated: 2026-05-23 · Reviewed by Nham Vu