e306be7429 Use 72 byte dummy signatures when watching only inputs may be used (Andrew Chow)
48b1473c89 Use 71 byte signature for DUMMY_SIGNATURE_CREATOR (Andrew Chow)
18dfea0dd0 Always create 70 byte signatures with low R values (Andrew Chow)
Pull request description:
When creating signatures for transactions, always make one which has a 32 byte or smaller R and 32 byte or smaller S value. This results in signatures that are always less than 71 bytes (32 byte R + 32 byte S + 6 bytes DER + 1 byte sighash) with low R values. In most cases, the signature will be 71 bytes.
Because R is not mutable in the same way that S is, a low R value can only be found by trying different nonces. RFC 6979 for deterministic nonce generation has the option to specify additional entropy, so we simply use that and add a uin32_t counter which we increment in order to try different nonces. Nonces are sill deterministically generated as the nonce used will the be the first one where the counter results in a nonce that results in a low R value. Because different nonces need to be tried, time to produce a signature does increase. On average, it takes twice as long to make a signature as two signatures need to be created, on average, to find one with a low R.
Having a fixed size signature makes size calculations easier and also saves half a byte of transaction size, on average.
DUMMY_SIGNATURE_CREATOR has been modified to produce 71 byte dummy signatures instead of 72 byte signatures.
Tree-SHA512: 3cd791505126ce92da7c631856a97ba0b59e87d9c132feff6e0eef1dc47768e81fbb38bfbe970371bedf9714b7f61a13a5fe9f30f962c81734092a4d19a4ef33
When extra entropy is not specified by the caller, CKey::Sign will
now always create a signature that has a low R value and is at most
70 bytes. The resulting signature on the stack will be 71 bytes when
the sighash byte is included.
Using low R signatures means that the resulting DER encoded signature
will never need to have additional padding to account for high R
values.
fac1223a56 Cache witness hash in CTransaction (MarcoFalke)
faab55fbb1 Make CMutableTransaction constructor explicit (MarcoFalke)
Pull request description:
This speeds up:
* compactblocks (v2)
* ATMP
* validation and miner (via `BlockWitnessMerkleRoot`)
* sigcache (see also unrelated #13204)
* rpc and rest (nice, but irrelevant)
This presumably slows down rescan, which uses a `CTransaction` and its `GetHash`, but never uses the `GetWitnessHash`. The slow down is proportional to the number of witness transactions in the rescan window. I.e. early in the chain there should be no measurable slow down. Later in the chain, there should be a slow down, but acceptable given the speedups in the modules mentioned above.
Tree-SHA512: 443e86acfcceb5af2163e68840c581d44159af3fd1fce266cab3504b29fcd74c50812b69a00d41582e7e1c5ea292f420ce5e892cdfab691da9c24ed1c44536c7
364bae5 qa: Pad scriptPubKeys to get minimum sized txs (MarcoFalke)
7485488 Policy to reject extremely small transactions (Johnson Lau)
0f8719b Add transaction tests for constant scriptCode (Johnson Lau)
9dabfe4 Add constant scriptCode policy in non-segwit scripts (Johnson Lau)
Pull request description:
This disables `OP_CODESEPARATOR` in non-segwit scripts (even in an unexecuted branch), and makes a positive `FindAndDelete` result invalid. This ensures that the `scriptCode` serialized in `SignatureHash` is always the same as the script passing to the `EvalScript`.
Tree-SHA512: a0552cb920294d130251c48053fa2ff1fbdd26332e62b52147d918837852750f0ce35ce2cd1cbdb86588943312f8154ccb4925e850dbb7c2254bc353070cd5f8
This disables OP_CODESEPARATOR in non-segwit scripts (even in an unexecuted branch), and makes a positive FindAndDelete result invalid. This ensures that the scriptCode serialized in SignatureHash() is always the same as the script passing to the EvalScript.
54a5a21 [MOVEONLY] Turn CScript::GetOp2 into a function and move to cpp (Pieter Wuille)
6a7456a [MOVEONLY] Move CSCript::FindAndDelete to interpreter (Pieter Wuille)
33a8ecf Delete unused non-const-iterator CSCript::GetOp overloads (Pieter Wuille)
2fb168b Make iterators in CScript::FindAndDelete const (Pieter Wuille)
Pull request description:
This PR moves `FindAndDelete` and `GetOp2` out of CScript (the first is only used inside the interpreter and moved there, the second does not actually depend on any script specifics and works on any vector). Furthermore, all non-const-iterator versions of GetOp are replaced by const ones, removing a number of methods in the process.
The longer term goal here is making the script interpreter independent from the CScript representation.
Note for reviewers: both `FindAndDelete` and `GetScriptOp` are consensus critical.
Tree-SHA512: c4ccf91c0b33c37cff0d474aa8dd2dab25b5b7655e2ed69a9b15e29daf0a67b21d51c23e1defb3a72ec762bd6138de96f69c6db1fb9c1fe1e976e421261aedb7
01013f5 Simplify tx validation tests (Pieter Wuille)
2dd6f80 Add a test that all flags are softforks (Pieter Wuille)
2851b77 Make all script verification flags softforks (Pieter Wuille)
Pull request description:
This change makes `SCRIPT_VERIFY_UPGRADABLE_NOPS` not apply to `OP_CHECKLOCKTIMEVERIFY` and `OP_CHECKSEQUENCEVERIFY`. This is a no-op as `UPGRADABLE_NOPS` is only set for mempool transactions, and those always have `SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY` and `SCRIPT_VERIFY_CHECKSEQUENCEVERIFY` set as well. The advantage is that setting more flags now always results in a reduction in acceptable scripts (=softfork).
This results in a nice and testable property for validation, for which a new test is added.
This also means that the introduction of a new definition for a NOP or witness version will likely need the following procedure (example OP_NOP8 here)
* Remove OP_NOP8 from being affected by `SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS`.
* Add a `SCRIPT_VERIFY_DISCOURAGE_NOP8`, which only applies to `OP_NOP8`.
* Add a `SCRIPT_VERIFY_NOP8` which implements the new consensus logic.
* Before activation, add `SCRIPT_VERIFY_DISCOURAGE_NOP8` to the mempool flags.
* After activation, add `SCRIPT_VERIFY_NOP8` to both the mempool and consensus flags.
Tree-SHA512: d3b4538986ecf646aac9dba13a8d89318baf9e308e258547ca3b99e7c0509747f323edac6b1fea4e87e7d3c01b71193794b41679ae4f86f6e11ed6be3fd62c72
6e8c48dc5 Add const to methods that do not modify the object for which it is called (practicalswift)
Pull request description:
Tree-SHA512: a6888111ba16fb796e320e60806e1a77d36f545989b5405dc7319992291800109eab0b8e8c286b784778f41f1ff5289e7cb6b4afd7aec77f385fbcafc02cffc1
5a9b508 [trivial] Add end of namespace comments (practicalswift)
Tree-SHA512: 92b0fcae4d1d3f4da9e97569ae84ef2d6e09625a5815cd0e5f0eb6dd2ecba9852fa85c184c5ae9de5117050330ce995e9867b451fa8cd5512169025990541a2b
d7f80b6 Rename first iterator to prevent shadowing. (Pavel Janík)
b42ff60 Fix shadowing of local variables. (Pavel Janík)
c4b60b3 Make some global variables less-global (static) (Pavel Janík)
bb2aaee Prevent -Wshadow warnings with gcc versions 4.8.5, 5.3.1 and 6.2.1. (Pavel Janík)
Tree-SHA512: 3aea4e28146c8f2a31351c6e2b0cce88b6f1e567a0ea0e6131624453e7193d0904e30d81b1439d8c69e281cf0e369b895851fb882ae48d5967b5c2e2c227404e
Makes it an error to use flags that have not been defined
on the libconsensus API.
There has been some confusion as to what pass to libconsensus, and
(combined with mention in the release notes) this should clear it up.
Using undocumented flags is a risk because their meaning,
and what combinations are allowed, changes from release to release.
E.g. it is no longer possible to pass (CLEANSTACK | P2SH) without
running into an assertion after the segwit changes.
