diff options
Diffstat (limited to 'raw-wiki-dump/GitRepositories%2Fcore%2Frng%2Ftrng')
| -rw-r--r-- | raw-wiki-dump/GitRepositories%2Fcore%2Frng%2Ftrng | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/raw-wiki-dump/GitRepositories%2Fcore%2Frng%2Ftrng b/raw-wiki-dump/GitRepositories%2Fcore%2Frng%2Ftrng new file mode 100644 index 0000000..cda0112 --- /dev/null +++ b/raw-wiki-dump/GitRepositories%2Fcore%2Frng%2Ftrng @@ -0,0 +1,192 @@ +{{{ +#!htmlcomment + +This page is maintained automatically by a script. Don't modify this page by hand, +your changes will just be overwritten the next time the script runs. Talk to your +Friendly Neighborhood Repository Maintainer if you need to change something here. + +}}} + +{{{ +#!html +<h1>trng</h1> + +<p>True Random Number Generator core implemented in Verilog.</p> + +<h2>Introduction</h2> + +<p>This repo contains the design of a True Random Number Generator (TRNG) +for the <a href="http://cryptech.is/">Cryptech OpenHSM</a> project.</p> + +<h2>Design inspiration, ideas and principles</h2> + +<p>The TRNG <strong>MUST</strong> be a really good one. Furthermore it must be trustable +by its users. That means it should not do wild and crazy stuff. And +users should be able to verify that the TRNG works as expected.</p> + +<ul> +<li>Follow best practice</li> +<li>Be conservative - No big untested ideas.</li> +<li>Support transparency - The parts should be testable.</li> +</ul> + +<p>Some of our inspiration comes from: +* The Fortuna RNG by Ferguson and Schneier as described in Cryptography +Engineering.</p> + +<ul> +<li>/dev/random in OpenBSD</li> +</ul> + +<h2>System description</h2> + +<p>The TRNG consists of a chain with three main subsystems</p> + +<ul> +<li>Entropy generation</li> +<li>Entropy mixing</li> +<li>Random generation</li> +</ul> + +<h3>Entropy generation</h3> + +<p>The entropy generation subsystems consists of at least two separate entropy +generators. Each generator collects entropy from an independent physical +process. The entropy sources MUST be of different types. For example +avalance noise from a reversed bias P/N junction as one source and RSSI +LSB from a receiver.</p> + +<p>The reason for having multiple entropy sources is both to provide +redundancy as well as making it harder for an attacker to affect the +entropy collection by forcing the attacker to try and affect different +physical processes simultaneously.</p> + +<p>A given entropy generator is responsible for collecting the entropy +(possibly including A/D conversion.). The entropy generator MUST +implement some on-line testing of the physical entropy source based on +the entropy collected. The tests shall be described in detail here but +will at least include tests for:</p> + +<ul> +<li>No long run lengths in generated values.</li> +<li>Variance that exceeds a given threshhold.</li> +<li>Mean value that don't deviate from expected mean.</li> +<li>Frequency for all possible values are within expected variance.</li> +</ul> + +<p>If the tests fails over a period of generated values the entropy source +MUST raise an error flag. And MAY also block access to the entropy it +otherwise provides.</p> + +<p>There shall also be possible to read out the raw entropy collected from +a given entropy generator. This MUST ONLY be possible in a specific +debug mode when no random generation is allowed. Also the entropy +provided in debug mode MUST NOT be used for later random number +generation. </p> + +<p>The entropy generator SHALL perform whitening on the collected entropy +before providing it as 32-bit values to the entropy accumulator.</p> + +<h3>Entropy mixing</h3> + +<p>The entropy mixer subsystems reads 32-bit words from the entropy +generators to build a block of bits to be mixed.</p> + +<p>When 1024 bits of mixed entropy has been collected the entropy is used +as a message block which is fed into a hash function.</p> + +<p>The hash function used is SHA-512 (NIST FIPS 180-4).</p> + +<p>The digest is then extracted and provided to the random generation as as +a seed.</p> + +<h3>Random generation</h3> + +<p>The random generation consists of a cryptographically secure pseudo random +number generator (CSPRNG). The CSPRNG used in the trng is the stream +cipher ChaCha.</p> + +<p>ChaCha is seeded with:</p> + +<ul> +<li>512 bits block</li> +<li>256 bits key</li> +<li>64 bits IV</li> +<li>64 bits counter</li> +</ul> + +<p>In total the seed used is: 896 bits. This requires getting two seed +blocks of 512 bits from the mixer.</p> + +<p>The number of rounds used in ChaCha is conservatively +selected. We propose that the number of rounds shall be at least 24 +rounds. Possibly 32 rounds. Given the performance in HW for ChaCha and +the size of the keystream block, the TRNG should be able to generate +plentiful of random values even with 32 rounds.</p> + +<p>The random generator shall support the ability to test its functionality +by seeding it with a user supplied value and then generate a number of +values in a specific debug mode. The normal access to generated random +values MUST NOT be allowed during the debug mode. The random generator +MUST also set an error flag during debug mode. Finally, when exiting the +debug mode, reseeding MUST be done.</p> + +<p>Finally the random generator provides random numbers as 32-bit +values. the 512 bit keystream blocks from ChaCha are divided into 16 +32-bit words and provided in sequence.</p> + +<h2>Implementation details</h2> + +<p>The core supports multpiple entropy sources as well as a CSPRNG. For +each entropy source there are some estimators that checks that the +sources are not broken.</p> + +<p>There are also an ability to extract raw entropy as well as inject test +data into the CSPRNG to verify the functionality.</p> + +<p>The core will include one FPGA based entropy source but expects the +other entropy source(s) to be connected on external ports. It is up to +the user/system implementer to provide physical entropy souces. We will +suggest and provide info on how to design at least one such source.</p> + +<p>For simulation there are simplistic fake entropy sources that can be +found in the tb/fake_modules directory. This modules SHOULD NOT be used +as real sources.</p> + +<p>For synthesis there are wrappers for the real entropy source cores to +adapt their interfaces to what we need in the trng. These wrappers +should not be included during simulation.</p> + +<h2>API</h2> + +<p>Normal operation: +* Extract 32-bit random words.</p> + +<p>Config parameters:</p> + +<ul> +<li>Number of blocks in warm-up.</li> +<li>Number of keystream blocks before reseeding.</li> +</ul> + +<p>Debug access</p> + +<ul> +<li>Enable/disable entropy generator X</li> +<li>Check health of entropy generator X</li> +<li>Read raw entropy from entropy generator X as 32-bit word.</li> +<li>Write 256 bit seed value as 8 32-bit words</li> +<li>Read out one or more 512 bit keystream blocks as 32-bit words.</li> +</ul> + +<h2>Status</h2> + +<p><strong>* (2014-09-11) *</strong></p> + +<p>The first version of the CSPRNG is debugged and completed. This version +supports automatic reseeding and an output fifo.</p> +}}} + +[[RepositoryIndex(format=table,glob=core/rng/trng)]] + +|| Clone `https://git.cryptech.is/core/rng/trng.git` || |