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Araneus Alea I

True Random Number Generator

The Alea I is a compact true random number generator (TRNG), also known as a hardware random number generator (HWRNG), non-deterministic random bit generator (NRBG), or entropy source, with a USB interface.

The Alea I is a legacy product available in limited quantity while stocks last and not recommended for new designs. The Alea II is a fully software compatible replacement.

The Alea I is designed for demanding cryptographic applications such as key generation, DSA signature generation, cryptographic nonces, and one time pads. It can also be used in a number of other applications such as lotteries, games, Monte Carlo simulations, and random sampling for scientific studies.


The Alea I provides a stream of high quality random bits that passes a number of stringent statistical tests including the Diehard and NIST STS test suites. We also test the output of every Alea I for uniqueness using the Known Number Oracle.

You can download random data produced by an Alea I TRNG here, for example to run your own statistical tests.


The Alea I plugs directly into, and is powered by, the USB port — no cable or external power supply is needed.


The Alea I comes with driver support for Microsoft Windows XP, Windows Vista, Windows 7, Windows 8, and Windows 10, and an ActiveX control that enables access to the device through COM. It can also be used with any operating system that supports generic user-space USB access, for example through the libusb library. Example code is provided for libusb-based access on Linux and NetBSD, and the Alea I has also been successfully used with other systems such as FreeBSD and MacOS X. The USB protocol of the Alea I is fully open and documented, allowing users to write their own drivers if desired.

How it Works

The Alea I uses a reverse biased semiconductor junction to generate wide-band Gaussian white noise. This noise is amplified and digitized using an analog-to-digital converter. The raw output bits from the A/D converter are then further processed by an embedded microprocessor to combine the entropy from multiple samples into each final output bit, resulting in a random bit stream that is practically free from bias and correlation.

Technical specifications

Random data rate: 100 kilobits / second typ.
Interface: Full speed USB
Power consumption: less than 250 mW
Dimensions: 80 x 27 x 9 mm including the USB connector
Specifications are subject to change without notice.


The Alea I can be ordered online directly from us. For pricing and ordering information, please click here.