Encryption Key Generator

About Encryption key generator

Symmetric keys are just random bytes, and the only requirement is that the randomness be unpredictable. This generator draws bytes from the browser's cryptographically secure random source and formats them as hex, Base64 or Base64url, in AES sizes or any custom length up to 512 bytes, singly or in batches of up to 50.

How to use it

1. Choose a Key size: AES-128, AES-192, AES-256 or Custom, and for Custom set the Length in bytes.
2. Pick an Output format of Hex, Base64 or Base64url, and set How many keys you want.
3. Select Generate. One 256-bit key is already shown when the page loads.
4. Copy a single key, use Copy all for a batch, or Download a text file. Turn on Show every encoding to see all three formats at once.

Lengths of a 32-byte key in each format

AES-256 preset, 32 bytes

Hex is 64 characters, Base64 is 44 characters ending in =, and Base64url is 43 characters with no padding. A 16-byte key gives 32, 24 and 22 characters.

When to use it

• Creating the master key for an application that encrypts data at rest with AES-256.
• Generating a batch of independent API signing secrets for different environments.
• Making a 64-byte random secret to sign session cookies or tokens.
• Producing a Base64url key for a place where plus and slash characters cause trouble.

Questions about Encryption key generator

How do I know these keys are truly random?

They come from crypto.getRandomValues, the browser interface backed by the operating system's secure random generator. Math.random is never used, since its output can be predicted from earlier values.

Which key size should I choose?

AES-256 is the usual choice, and AES-128 is also considered secure today. Match the size to what your cipher requires: a 32-byte key for AES-256, or 32 or 64 bytes for common HMAC secrets.

What is the difference between Base64 and Base64url?

Base64url replaces plus and slash with hyphen and underscore and drops the equals padding, so the key can sit in a URL, file name or JWT without escaping. The bytes underneath are identical.

Where should I store the generated key?

In a secrets manager or your platform's encrypted configuration, never in source control. Keys are shown only in this page and nothing is saved, so copy or download what you need before leaving.

What are the limits on length and count?

Length runs from 1 to 512 bytes and the batch size from 1 to 50. Values outside those ranges are refused with a message rather than clamped.

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