* make govet linter pass

Refs #3262

* close PipeReader and check for err

`secp256k1.S256().N` directly instead

* switch from fork (tendermint/btcd) to orig package (btcsuite/btcd); also

 - remove obsolete check in test `size != -1` is always true
 - WIP as the serialization still needs to be wrapped

* WIP: wrap signature & privkey, pubkey needs to be wrapped as well

* wrap pubkey too

* use "github.com/ethereum/go-ethereum/crypto/secp256k1" if cgo is
available, else use "github.com/btcsuite/btcd/btcec" and take care of
lower-S when verifying

Annoyingly, had to disable pruning when importing
github.com/ethereum/go-ethereum/ :-/

* update comment

* update comment

* emulate signature_nocgo.go for additional benchmarks:
592bf6a59c/crypto/signature_nocgo.go (L60-L76)

* use our format (r || s) in lower-s form when in the non-cgo case

* remove comment about using the C library directly

* vendor github.com/btcsuite/btcd too

* Add test for the !cgo case

* update changelog pending

Closes #3162 #3163
Refs #1958, #2091, tendermint/btcd#1

* Don't use pointer receivers for PubKeyMultisigThreshold

* test that showcases panic when PubKeyMultisigThreshold are used in sdk:

 - deserialization will fail in `readInfo` which tries to read a
 `crypto.PubKey` into a `localInfo` (called by
  cosmos-sdk/client/keys.GetKeyInfo)

* Update changelog

* Rename routeTable to nameTable, multisig key is no longer a pointer

* sed -i 's/PubKeyAminoRoute/PubKeyAminoName/g' `grep -lrw PubKeyAminoRoute .`

upon Jae's request

* AminoRoutes -> AminoNames

* sed -e 's/PrivKeyAminoRoute/PrivKeyAminoName/g'

* Update crypto/encoding/amino/amino.go

Co-Authored-By: alessio <quadrispro@ubuntu.com>

* crypto: revert to mainline Go crypto lib

We used to use a fork for a modified bcrypt so we could pass our own
randomness but this was largely unecessary, unused, and a burden.
So now we just use the mainline Go crypto lib.

* changelog

* fix tests

* version and changelog

* ed25519: use golang/x/crypto fork

* changelog

* gix GenerateFromPassword

* fixes from review

* crypto/secp256k1: Fix signature malleability, adopt more efficient encoding

This removes signature malleability per ADR 14, and makes secp match
the encoding in ADR 15.

* (squash this) add lock

* crypto: Remove unnecessary ed25519 and secp256k1 prefixes from amino routes.

* (squash this) add changelog

* (squash this) multisig amino fixes

* (squash this) fix build error

Signatures are now []byte, which saves on the number of bytes after
amino encoding

(squash this) address Ismail's comment

* crypto: Add benchmarking code for signature schemes

This does a slight refactor for the key generation code. It now calls a
seperate unexported method to allow generation from a reader. I think this
will actually reduce time in generation, due to no longer initializing an
extra slice. This was needed in order to enable benchmarking.

This uses an internal package for the benchmarking code, so that this can
be standardized without being exported in the public API. The benchmarking
code is derived from agl/ed25519's benchmarking code, and has copied the
license over.

Closes #1984

* crypto/secp256k1: Add godocs, remove indirection in privkeys

The following was previously done for creating secp256k1 private keys:

First obtain privkey bytes. Then create a private key in the
underlying library, with scalar exponent equal to privKeyBytes.
(The method called was secp256k1.PrivKeyFromBytes,
fb90c334df/btcec/privkey.go (L21))

Then the private key was serialized using the underlying library, which just
returns back the bytes that comprised the scalar exponent, but padded to be
exactly 32 bytes.
fb90c334df/btcec/privkey.go (L70)

Thus the entire indirection of calling the underlying library can be avoided
by just ensuring that we pass in a 32 byte value. A test case has even be written
to show this more clearly in review.

* crypto/secp256k1: Address PR comments

Squash this commit

* crypto: Remove note about re-registering amino paths when unnecessary.

This commit should be squashed.

Currently the top level directory contains basically all of the code
for the crypto package. This PR moves the crypto code into submodules
in a similar manner to what `golang/x/crypto` does. This improves code
organization.

Ref discussion: https://github.com/tendermint/tendermint/pull/1966

Closes #1956