F compression function implementation for Blake2b #1
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F is a compression function for Blake2. It takes as an argument the state vector h, message block vector blocks, 2-bit offset counter t, final block indicator flag f, and the number of rounds to execute. The state vector is modified in-place by the function. Number of rounds can be anything from 0 to 12 (inclusive). The code has been borrowed from golang/crypto/blake2b and adjusted so that it can support any number of rounds between 0-12. Parameters have been also adjusted to match those in RFC 7693 https://tools.ietf.org/html/rfc7693 Test vectors were generated from those in golang/crypto/blake2b. The current test coverage is certainly not enough and we'll add some additional test vectors in the future.
pdyraga
commented
Jun 7, 2019
pdyraga
commented
Jun 7, 2019
pdyraga
commented
Jun 7, 2019
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The Zcash team has confirmed we're good on rounds and blocksize. I gave a shot at generating test vectors with |
Those test vectors were generated from golang.org/x/crypto/blake2b test hashes in the testHashashes function before and after each F execution.
Just like in the original RFC (https://tools.ietf.org/html/rfc7693#section-3.2), f parameter is now represented as boolean. If it is enabled, bits are inverted.
We use test vectors generated from test functions in golang.org/x/crypto/blake2b. Each unique call to hashBlocks has been transformed into a test vector. Here, we add test vectors from TestHashes2X test function. We also moved test vectors generated from TestHashes test function into a separate file so that test vectors generated from individual test functions are stored separately.
I mistakenly changed it in one of the previous commits - fixing it now.
Extracted common test code to a separate function.
Message block vector length has to match block size (128) so that we don't blow up when evaluating m vector later. In the original implementation, F was an internal function and other public functions calling it were making sure the correct vector is passed. Here, after making F public, we need to carve this requirement in the interface.
pdyraga
changed the title
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@mhluongo All comments addressed, I am happy with what's here. It's ready for your review 👀. |
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#3 will be covered in go-ethereum PR - each contract has benchmarks there. |
mhluongo
reviewed
Jun 18, 2019
| // Use of this source code is governed by a BSD-style | ||
| // license that can be found in the LICENSE file. | ||
| // | ||
| // Modified by KEEP SEZC to expose F compression function. |
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Going to touch this up after this PR
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Yeah, I had no idea what to put here. Worth double-checking if we do not have to alter LICENSE as well.
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🎉 |
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Closes: #1
Fis a compression function for Blake2. It takes as an argument thestate vector
h, message block vectormb, offset countert,final block indicator flag
f, and the number of roundsroundsto execute.The state vector is modified in-place by the function.
The code has been borrowed from
golang/crypto/blake2band adjusted sothat this function can be safely exposed as public. Parameters have
been also adjusted to match those in RFC 7693
Test vectors were generated from those in
golang/crypto/blake2b