No sooner had posted on doing file and string hashes in PowerShell, when I (again) got asked by Jim - "What about SHA3?  Shouldn't we be using Quantum Safe algorithms if we have them?"

Looking around, support for SHA3 is pretty sparse no matter what the OS.  For Windows there's a decent solution in bouncycastle (https://www.bouncycastle.org/), but the install is likely more than folks want to tackle, especially if it gets rolled into PowerShell at some future date.  Similarly, the SCCM ConfigurationManager module does implement them in some fashion, but that's kind of a dead-end for most of us too.

In a pinch, hashify.net has a public API that supports just about any hashing algorithm you'd care to mention:

curl --location --request GET "api.hashify.net/hash/sha3-512/hex?value=CQCQCQ"
{"Digest":"bcc7a070db5dd926bfbef21c6c5e8081402a79e45f96c4cd7fedc405e1a7fcb6b047cff266235f19f0d1219d2f0fd9299b93cd28d69517d7aefec8cf0c9ffdcc","DigestEnc":"hex","Type":"SHA3-512","Key":""}

The problem with that is - if the information you are hashing (presumably to verify against either now or later) is important or sensitive enough to warrant using one of the fancy SHA3 algorithms, it's likely not data that you want sent to a public website in the clear.

I eventually decided to use the functionality in OpenSSL, with the rationale that anyone who needs this function will likely have OpenSSL already installed locally, at most we'd be asking them to upgrade - you'll need OpenSSL 1.1.1 or better for SHA3-xxx hash support.  The syntax is:

echo "some string" | openssl dgst -hashalgorithm

or

type "somefilespec" | openssl dgst -hashalgorithm

where "hashalgorithm" is any of:

blake2b512                blake2s256                md4
md5                       md5-sha1                  mdc2
ripemd                    ripemd160                 rmd160
sha1                      sha224                    sha256
sha3-224                  sha3-256                  sha3-384
sha3-512                  sha384                    sha512
sha512-224                sha512-256                shake128
shake256                  sm3                       ssl3-md5
ssl3-sha1                 whirlpool

So for implementing this in PowerShell, it's as easy as creating the command in a string, then calling it with "Invoke-Expression" (shortened to "iex" in the examples below).

So for now, until Microsoft rolls better support for SHA3 family of hashing algorithms, my quick-and-dirty implementation for the newer, shinier hash algorithms is below.  Note that if OpenSSL isn't in the path, I've got a variable pointed to the path to the binary (update this variable to match your install).  In any "real" code you would put this in a config file of course (because we all need more config files in our life right?)

If you've worked out a way to get these algorithms into PowerShell without IEX or any 3rd party installs, please share using our comment form. 

(And yes, I did riff on the title of Mark Baggett's presentation next week - Tech Tuesday Workshop - O Hacker, Where Art Thou?: A Hands-On Python Workshop for Geolocating Attackers  https://www.sans.org/webcasts/hacker-art-thou-hands-on-python-workshop-geolocating-attackers-115340 )

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Rob VandenBrink
www.coherentsecurity.com