To simulate failures opening a cache file, fixtures are written without the read permission bits.
Since Unix permission bits have no meaning on Windows, a slightly more complicated solution is required to achieve the same permissions.
Thankfully, there's a library to abstract that already.
Tests cover most of the cache and download related code paths and specify the expected result of various starting states and external failure modes.
Where the current code's behaviour doesn't match a test's expectations, the test is disabled and annotated with a TODO until it can be fixed.
Added dependency on `github.com/powerman/check` and ran `go mod vendor`.
```console
$ go mod tidy -v
(snip)
unused github.com/agl/ed25519
```
Also add base .gitattributes file to normalize line endings in the repository across differing developer environments.
This works over DNSCrypt and DoH, but requires a specifically configured
server.
Instead of sending the actual DNS queries, the SH-T system works as follows:
Step 1: the client query is evaluated through Argon2id, a military-grade,
memory-hard, CPU-hard stretching function. This makes it very expensive
for an attacker to find the original query, even using GPUs and ASICs.
For post-quantum resistance, we use it to generate a 1024-bit key.
Step 2: in case the Argon2id algorithm has a vulnerability, or, since this
is a popular function used for hashing passwords and for cryptocurrencices,
and people may have built rainbow tables already, we use a hash function over
the result of the previous function. This immediately defeats rainbow tables.
Step 3: the output of the hash function is truncated to 64-bit.
Due to a property of this operation known as collision-misresistance, and even
if the previous steps fail due to a nation-state actor, it is impossible for a
server operator to prove what exact query was originally sent by a client.
This feature is experimental.
