Profiles discovered that lookups into the signature cache included an
expensive comparison to the stored `sigInfo` struct. This lookup had the
potential to be more expensive than directly verifying the signature
itself!
In addition, evictions were rather expensive because they involved
reading from /dev/urandom, or equivalent, for each eviction once the
signature cache was full as well as potentially iterating over every
item in the cache in the worst-case.
To remedy this poor performance several changes have been made:
* Change the lookup key to the fixed sized 32-byte signature hash
* Perform a full equality check only if there is a cache hit which
results in a significant speed up for both insertions and existence
checks
* Override entries in the case of a colliding hash on insert Add an
* .IsEqual() method to the Signature and PublicKey types in the
btcec package to facilitate easy equivalence testing
* Allocate the signature cache map with the max number of entries in
order to avoid unnecessary map re-sizes/allocations
* Optimize evictions from the signature cache Delete the first entry
* seen which is safe from manipulation due to
the pre image resistance of the hash function
* Double the default maximum number of entries within the signature
cache due to the reduction in the size of a cache entry
* With this eviction scheme, removals are effectively O(1)
Fixes#575.
First, it removes the documentation section from all the README.md files
and instead puts a web-based godoc badge and link at the top with the
other badges. This is being done since the local godoc tool no longer
ships with Go by default, so the instructions no longer work without
first installing godoc. Due to this, pretty much everyone uses the
web-based godoc these days anyways. Anyone who has manually installed
godoc won't need instructions.
Second, it makes sure the ISC license badge is at the top with the other
badges and removes the textual reference in the overview section.
Finally, it's modifies the Installation section to Installation and
Updating and adds a '-u' to the 'go get' command since it works for both
and thus is simpler.
This commit adds two new verification flags to txscript named
ScriptVerifyStrictEncoding and ScriptVerifyDerSignatures.
The ScriptVerifyStrictEncoding flag enforces signature scripts
and public keys to follow the strict encoding requirements.
The ScriptVerifyDerSignatures flag enforces signature scripts
to follow the strict encoding requirements.
These flags mimic Bitcoin Core's SCRIPT_VERIFY_STRICTENC and
SCRIPT_VERIFY_DERSIG flags and brings the Bitcoin Core test scripts up
to date.
This commit modifies the pre-computed table used to optimize the secp256k1
scalar multiplication to a string instead of a byte slice. This change
makes the compile more efficient since the Go compiler internally
represents bytes slices inefficiently.
This reduces the memory needed to compile btcec to 3MB versus the previous
40MB before this change.
In addition, it modifies the code which loads the pre-computed table to
deserialize directly into the table instead of into locals that are then
copied.
Fixes#297.
This commit contains various modifications for code and comment
consistency in the btcec package:
- Call out references at the top and reference them by their identifier in
the other comments
- Remove a TODO that no longer applies
- Add comments to the fields in the KoblitzCurve struct and reorder them
slightly
- Make comments wrap to 80
- Cleanup code that was far exceeding col 80 (only function declarations
typically do this)
- Extend block comments to use as much of the 80 cols as available
- Add a bit more explanation in a couple of places
- Update copyright year on secp256k1.go
- Fix a couple of typos in the comments
The benchmarks are still only compiled when running 'go test' so this has
no effect on regular usage. This is being done because benchmarks often
need access to internal state.
Normal tests are kept in a separate package since they also serve to
exercise the public API, and by intentionally making it more difficult to
reach into the internals, it helps ensure the public API is sanely usable.
Since the benchmarks can now access the internals directly, this commit
also removes the functions which exposed the internals to the test package
from internal_test.go which were only used by the benchmarks.
Also, it removes a duplicate benchmark.
This commit converts the initialization of the constants to use a function
which panics on error instead of just ignoring the error. This is
acceptable since they are hard-coded constants and should never fail.
This commit adds code which generates the linearly independent vectors
used by the secp256k1 endomorphism code. These value are hard-coded into
the curve already, but having the code used to generate them is handy
should any future curves be added which can also make use of the same
class of endomorphism.
