---
name: "rngtest"
section: "1"
platform: "linux"
package: "rng-tools"
version: "6.17-3"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/rngtest"
---

# rngtest(1)

Check the randomness of data using FIPS 140-2 tests

## NAME

rngtest - Check the randomness of data using FIPS 140-2 tests

## SYNOPSIS

**rngtest** \[**-c** *n* \| **--blockcount=***n*\] \[**-b** *n* \| **--blockstats=***n*\] \[**-t** *n* \| **--timedstats=***n*\] \[**-p** \| **--pipe**\] \[**-?**\] \[**--help**\] \[**-V**\] \[**--version**\]

## DESCRIPTION

*rngtest* works on blocks of 20000 bits at a time, using the FIPS 140-2 (errata of 2001-10-10) tests to verify the randomness of the block of data.

It takes input from *stdin*, and outputs statistics to *stderr*, optionally echoing blocks that passed the FIPS tests to *stdout* (when operating in *pipe mode*).  Errors are sent to *stderr*.

At startup, *rngtest* will trow away the first 32 bits of data when operating in *pipe mode*.  It will use the next 32 bits of data to bootstrap the FIPS tests (even when not operating in *pipe mode*). These bits are not tested for randomness.

Statistics are dumped to *stderr* when the program exits.

## OPTIONS

- **-p**, **--pipe**

  Enable *pipe mode*.  All data blocks that pass the FIPS tests are echoed to *stdout*, and *rngtest* operates in silent mode.

- **-c** *n*, **--blockcount=***n* (default: 0)

  Exit after processing n input blocks, if n is not zero.

- **-b** *n*, **--blockstats=***n* (default: 0)

  Dump statistics every n blocks, if n is not zero.

- **-t** *n*, **--timedstats=***n* (default: 0)

  Dump statistics every n seconds, if n is not zero.

- **-?**, **--help**

  Give a short summary of all program options.

- **-V**, **--version**

  Print program version

## STATISTICS

*rngtest* will dump statistics to *stderr* when it exits, and when told to by *blockstats* or *timedstats*.

**FIPS 140-2 successes** and **FIPS 140-2 failures** counts the number of 20000-bit blocks either accepted or rejected by the FIPS 140-2 tests.  The other statistics show a breakdown of the FIPS 140-2 failures by FIPS  140-2 test.  See the FIPS 140-2 document for more information (note that these tests are defined on FIPS 140-1 and FIPS 140-2 errata of 2001-10-10. They were removed in FIPS 140-2 errata of 2002-12-03).

The speed statistics are taken for every 20000-bit block transferred or processed.

## EXIT STATUS

- **0** if no errors happen, and no blocks fail the FIPS tests.

  - **1** if no errors happen, but at least one block fails the FIPS tests.

  - **10** if there are problems with the parameters.

  - **11** if an input/output error happens.

  - **12** if an operating system or resource starvation error happens.

  ## SEE ALSO

[random(4)](/random/4.md), [rngd(8)](/rngd/8.md)

- FIPS PUB 140-2 Security Requirements for Cryptographic Modules, NIST,

  http://csrc.nist.gov/groups/STM/cmvp/standards.html

## AUTHORS

Henrique de Moraes Holschuh \<hmh@debian.org\>