lib/sha256: Remove it (#9643)

### Purpose

Remove the `lib/sha256` package, because it's no longer necessary. Go's
standard library now has the same performance and is on par with
`sha256-simd` since [Since Go
1.21](https://github.com/golang/go/commit/1a64574f42b95594cf9c8a12e9ca13d75585429c).
Therefore using `sha256-simd` has no benefits anymore.

ARM already has optimized sha256 assembly code since
https://github.com/golang/go/commit/7b8a7f8272fd1941a199af1adb334bd9996e8909,
`sha256-simd` published their results before that optimized assembly was
implemented,
https://github.com/minio/sha256-simd/commit/f941fedda826b68a196de2e0a9183e273ec0cb91.
The assembly looks very similar and the benchmarks in the Go commit
match that of `sha256-simd`.

This patch removes all of the related code of `lib/sha256` and makes
`crypto/sha256` the 'default'.

Benchmark of `sha256-simd` and `crypto/sha256`:
<details>

```
cpu: AMD Ryzen 5 3600X 6-Core Processor
                │  simd.txt   │               go.txt                │
                │   sec/op    │    sec/op     vs base               │
Hash/8Bytes-12    63.25n ± 1%    73.38n ± 1%  +16.02% (p=0.002 n=6)
Hash/64Bytes-12   98.73n ± 1%   105.30n ± 1%   +6.65% (p=0.002 n=6)
Hash/1K-12        567.2n ± 1%    572.8n ± 1%   +0.99% (p=0.002 n=6)
Hash/8K-12        4.062µ ± 1%    4.062µ ± 1%        ~ (p=0.396 n=6)
Hash/1M-12        512.1µ ± 0%    510.6µ ± 1%        ~ (p=0.485 n=6)
Hash/5M-12        2.556m ± 1%    2.564m ± 0%        ~ (p=0.093 n=6)
Hash/10M-12       5.112m ± 0%    5.127m ± 0%        ~ (p=0.093 n=6)
geomean           13.82µ         14.27µ        +3.28%

                │   simd.txt   │               go.txt                │
                │     B/s      │     B/s       vs base               │
Hash/8Bytes-12    120.6Mi ± 1%   104.0Mi ± 1%  -13.81% (p=0.002 n=6)
Hash/64Bytes-12   618.2Mi ± 1%   579.8Mi ± 1%   -6.22% (p=0.002 n=6)
Hash/1K-12        1.682Gi ± 1%   1.665Gi ± 1%   -0.98% (p=0.002 n=6)
Hash/8K-12        1.878Gi ± 1%   1.878Gi ± 1%        ~ (p=0.310 n=6)
Hash/1M-12        1.907Gi ± 0%   1.913Gi ± 1%        ~ (p=0.485 n=6)
Hash/5M-12        1.911Gi ± 1%   1.904Gi ± 0%        ~ (p=0.093 n=6)
Hash/10M-12       1.910Gi ± 0%   1.905Gi ± 0%        ~ (p=0.093 n=6)
geomean           1.066Gi        1.032Gi        -3.18%
```

</details>


### Testing

Compiled and tested on Linux.

### Documentation

https://github.com/syncthing/docs/pull/874

cmd/stcompdirs/main.go

@@ -7,6 +7,7 @@
 package main
 
 import (
+	"crypto/sha256"
 	"errors"
 	"flag"
 	"fmt"
@@ -16,7 +17,6 @@ import (
 	"path/filepath"
 
 	_ "github.com/syncthing/syncthing/lib/automaxprocs"
-	"github.com/syncthing/syncthing/lib/sha256"
 )
 
 func main() {

cmd/stcrashreceiver/main.go

@@ -14,6 +14,7 @@ package main
 
 import (
 	"context"
+	"crypto/sha256"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -29,7 +30,6 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	_ "github.com/syncthing/syncthing/lib/automaxprocs"
 	"github.com/syncthing/syncthing/lib/build"
-	"github.com/syncthing/syncthing/lib/sha256"
 	"github.com/syncthing/syncthing/lib/ur"
 )
 

cmd/stcrashreceiver/util.go

@@ -9,14 +9,13 @@ package main
 import (
 	"bytes"
 	"compress/gzip"
+	"crypto/sha256"
 	"fmt"
 	"net"
 	"net/http"
 	"os"
 	"path/filepath"
 	"time"
-
-	"github.com/syncthing/syncthing/lib/sha256"
 )
 
 // userIDFor returns a string we can use as the user ID for the purpose of

cmd/stwatchfile/main.go

@@ -7,6 +7,7 @@
 package main
 
 import (
+	"crypto/sha256"
 	"flag"
 	"fmt"
 	"io"
@@ -14,7 +15,6 @@ import (
 	"time"
 
 	_ "github.com/syncthing/syncthing/lib/automaxprocs"
-	"github.com/syncthing/syncthing/lib/sha256"
 )
 
 func main() {

cmd/syncthing/crash_reporting.go

@@ -9,6 +9,7 @@ package main
 import (
 	"bytes"
 	"context"
+	"crypto/sha256"
 	"fmt"
 	"net/http"
 	"os"
@@ -16,8 +17,6 @@ import (
 	"sort"
 	"strings"
 	"time"
-
-	"github.com/syncthing/syncthing/lib/sha256"
 )
 
 const (

cmd/syncthing/main.go

@@ -92,11 +92,6 @@ above.
  STLOCKTHRESHOLD   Used for debugging internal deadlocks; sets debug
                    sensitivity.  Use only under direction of a developer.
 
- STHASHING         Select the SHA256 hashing package to use. Possible values
-                   are "standard" for the Go standard library implementation,
-                   "minio" for the github.com/minio/sha256-simd implementation,
-                   and blank (the default) for auto detection.
-
  STVERSIONEXTRA    Add extra information to the version string in logs and the
                    version line in the GUI. Can be set to the name of a wrapper
                    or tool controlling syncthing to communicate this to the end

cmd/syncthing/monitor.go

@@ -241,22 +241,6 @@ func copyStderr(stderr io.Reader, dst io.Writer) {
 		if panicFd == nil {
 			dst.Write([]byte(line))
 
-			if strings.Contains(line, "SIGILL") {
-				l.Warnln(`
-*******************************************************************************
-* Crash due to illegal instruction detected. This is most likely due to a CPU *
-* incompatibility with the high performance hashing package. Switching to the *
-* standard hashing package instead. Please report this issue at:              *
-*                                                                             *
-*   https://github.com/syncthing/syncthing/issues                             *
-*                                                                             *
-* Include the details of your CPU.                                            *
-*******************************************************************************
-`)
-				os.Setenv("STHASHING", "standard")
-				return
-			}
-
 			if strings.HasPrefix(line, "panic:") || strings.HasPrefix(line, "fatal error:") {
 				panicFd, err = os.Create(locations.GetTimestamped(locations.PanicLog))
 				if err != nil {

go.mod

@@ -25,7 +25,6 @@ require (
 	github.com/maruel/panicparse/v2 v2.3.1
 	github.com/maxbrunsfeld/counterfeiter/v6 v6.8.1
 	github.com/maxmind/geoipupdate/v6 v6.1.0
-	github.com/minio/sha256-simd v1.0.1
 	github.com/miscreant/miscreant.go v0.0.0-20200214223636-26d376326b75
 	github.com/oschwald/geoip2-golang v1.11.0
 	github.com/pierrec/lz4/v4 v4.1.21
@@ -68,7 +67,6 @@ require (
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/hashicorp/errwrap v1.1.0 // indirect
 	github.com/hashicorp/go-multierror v1.1.1 // indirect
-	github.com/klauspost/cpuid/v2 v2.2.8 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/nxadm/tail v1.4.11 // indirect
 	github.com/onsi/ginkgo/v2 v2.20.0 // indirect

go.sum

@@ -130,8 +130,6 @@ github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51 h1:Z9n2FFNU
 github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51/go.mod h1:CzGEWj7cYgsdH8dAjBGEr58BoE7ScuLd+fwFZ44+/x8=
 github.com/kisielk/errcheck v1.5.0/go.mod h1:pFxgyoBC7bSaBwPgfKdkLd5X25qrDl4LWUI2bnpBCr8=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
-github.com/klauspost/cpuid/v2 v2.2.8 h1:+StwCXwm9PdpiEkPyzBXIy+M9KUb4ODm0Zarf1kS5BM=
-github.com/klauspost/cpuid/v2 v2.2.8/go.mod h1:Lcz8mBdAVJIBVzewtcLocK12l3Y+JytZYpaMropDUws=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
@@ -147,8 +145,6 @@ github.com/maxbrunsfeld/counterfeiter/v6 v6.8.1/go.mod h1:eyp4DdUJAKkr9tvxR3jWhw
 github.com/maxmind/geoipupdate/v6 v6.1.0 h1:sdtTHzzQNJlXF5+fd/EoPTucRHyMonYt/Cok8xzzfqA=
 github.com/maxmind/geoipupdate/v6 v6.1.0/go.mod h1:cZYCDzfMzTY4v6dKRdV7KTB6SStxtn3yFkiJ1btTGGc=
 github.com/mgutz/ansi v0.0.0-20200706080929-d51e80ef957d/go.mod h1:01TrycV0kFyexm33Z7vhZRXopbI8J3TDReVlkTgMUxE=
-github.com/minio/sha256-simd v1.0.1 h1:6kaan5IFmwTNynnKKpDHe6FWHohJOHhCPchzK49dzMM=
-github.com/minio/sha256-simd v1.0.1/go.mod h1:Pz6AKMiUdngCLpeTL/RJY1M9rUuPMYujV5xJjtbRSN8=
 github.com/miscreant/miscreant.go v0.0.0-20200214223636-26d376326b75 h1:cUVxyR+UfmdEAZGJ8IiKld1O0dbGotEnkMolG5hfMSY=
 github.com/miscreant/miscreant.go v0.0.0-20200214223636-26d376326b75/go.mod h1:pBbZyGwC5i16IBkjVKoy/sznA8jPD/K9iedwe1ESE6w=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=

gui/default/syncthing/core/aboutModalView.html

@@ -65,7 +65,6 @@ Jakob Borg, Audrius Butkevicius, Jesse Lucas, Simon Frei, Tomasz Wilczyński, Al
           <li><a href="https://github.com/lib/pq">lib/pq</a>, Copyright &copy; 2011-2013, 'pq' Contributors, portions Copyright &copy; 2011 Blake Mizerany.</li>
           <li><a href="https://github.com/mattn/go-isatty">mattn/go-isatty</a>, Copyright &copy; Yasuhiro MATSUMOTO.</li>
           <li><a href="https://github.com/matttproud/golang_protobuf_extensions">matttproud/golang_protobuf_extensions</a>, Copyright &copy; 2012 Matt T. Proud.</li>
-          <li><a href="https://github.com/minio/sha256-simd">minio/sha256-simd</a>, Copyright &copy; 2016-2017 Minio, Inc.</li>
           <li><a href="https://github.com/oschwald/geoip2-golang">oschwald/geoip2-golang</a>, Copyright &copy; 2015, Gregory J. Oschwald.</li>
           <li><a href="https://github.com/oschwald/maxminddb-golang">oschwald/maxminddb-golang</a>, Copyright &copy; 2015, Gregory J. Oschwald.</li>
           <li><a href="https://github.com/petermattis/goid">petermattis/goid</a>, Copyright &copy; 2015-2016 Peter Mattis.</li>

lib/build/build.go

@@ -40,7 +40,6 @@ var (
 
 	envTags = []string{
 		"STGUIASSETS",
-		"STHASHING",
 		"STNORESTART",
 		"STNOUPGRADE",
 	}

lib/db/lowlevel.go

@@ -9,6 +9,7 @@ package db
 import (
 	"bytes"
 	"context"
+	"crypto/sha256"
 	"encoding/binary"
 	"errors"
 	"fmt"
@@ -22,7 +23,6 @@ import (
 	"github.com/syncthing/syncthing/lib/events"
 	"github.com/syncthing/syncthing/lib/fs"
 	"github.com/syncthing/syncthing/lib/protocol"
-	"github.com/syncthing/syncthing/lib/sha256"
 	"github.com/syncthing/syncthing/lib/stringutil"
 	"github.com/syncthing/syncthing/lib/svcutil"
 	"github.com/syncthing/syncthing/lib/sync"

lib/fs/tempname.go

@@ -7,12 +7,12 @@
 package fs
 
 import (
+	"crypto/sha256"
 	"fmt"
 	"path/filepath"
 	"strings"
 
 	"github.com/syncthing/syncthing/lib/build"
-	"github.com/syncthing/syncthing/lib/sha256"
 )
 
 const (

lib/ignore/ignore.go

@@ -9,6 +9,7 @@ package ignore
 import (
 	"bufio"
 	"bytes"
+	"crypto/sha256"
 	"errors"
 	"fmt"
 	"io"
@@ -21,7 +22,6 @@ import (
 	"github.com/syncthing/syncthing/lib/fs"
 	"github.com/syncthing/syncthing/lib/ignore/ignoreresult"
 	"github.com/syncthing/syncthing/lib/osutil"
-	"github.com/syncthing/syncthing/lib/sha256"
 	"github.com/syncthing/syncthing/lib/sync"
 )
 

lib/model/folder_sendrecv.go

@@ -9,6 +9,7 @@ package model
 import (
 	"bytes"
 	"context"
+	"crypto/sha256"
 	"errors"
 	"fmt"
 	"io"
@@ -28,7 +29,6 @@ import (
 	"github.com/syncthing/syncthing/lib/protocol"
 	"github.com/syncthing/syncthing/lib/scanner"
 	"github.com/syncthing/syncthing/lib/semaphore"
-	"github.com/syncthing/syncthing/lib/sha256"
 	"github.com/syncthing/syncthing/lib/sync"
 	"github.com/syncthing/syncthing/lib/versioner"
 	"github.com/syncthing/syncthing/lib/weakhash"

lib/protocol/bep_extensions.go

@@ -4,6 +4,7 @@ package protocol
 
 import (
 	"bytes"
+	"crypto/sha256"
 	"encoding/binary"
 	"encoding/json"
 	"errors"
@@ -12,7 +13,6 @@ import (
 
 	"github.com/syncthing/syncthing/lib/build"
 	"github.com/syncthing/syncthing/lib/rand"
-	"github.com/syncthing/syncthing/lib/sha256"
 )
 
 const (

lib/protocol/deviceid.go

@@ -4,13 +4,12 @@ package protocol
 
 import (
 	"bytes"
+	"crypto/sha256"
 	"encoding/base32"
 	"encoding/binary"
 	"errors"
 	"fmt"
 	"strings"
-
-	"github.com/syncthing/syncthing/lib/sha256"
 )
 
 const (

lib/protocol/encryption.go

@@ -8,6 +8,7 @@ package protocol
 
 import (
 	"context"
+	"crypto/sha256"
 	"encoding/base32"
 	"encoding/binary"
 	"errors"
@@ -20,7 +21,6 @@ import (
 	lru "github.com/hashicorp/golang-lru/v2"
 	"github.com/miscreant/miscreant.go"
 	"github.com/syncthing/syncthing/lib/rand"
-	"github.com/syncthing/syncthing/lib/sha256"
 	"golang.org/x/crypto/chacha20poly1305"
 	"golang.org/x/crypto/hkdf"
 	"golang.org/x/crypto/scrypt"

lib/scanner/blocks.go

@@ -9,12 +9,12 @@ package scanner
 import (
 	"bytes"
 	"context"
+	"crypto/sha256"
 	"hash"
 	"hash/adler32"
 	"io"
 
 	"github.com/syncthing/syncthing/lib/protocol"
-	"github.com/syncthing/syncthing/lib/sha256"
 )
 
 var SHA256OfNothing = []uint8{0xe3, 0xb0, 0xc4, 0x42, 0x98, 0xfc, 0x1c, 0x14, 0x9a, 0xfb, 0xf4, 0xc8, 0x99, 0x6f, 0xb9, 0x24, 0x27, 0xae, 0x41, 0xe4, 0x64, 0x9b, 0x93, 0x4c, 0xa4, 0x95, 0x99, 0x1b, 0x78, 0x52, 0xb8, 0x55}

lib/scanner/blocks_test.go

@@ -10,6 +10,7 @@ import (
 	"bytes"
 	"context"
 	"crypto/rand"
+	"crypto/sha256"
 	"fmt"
 	origAdler32 "hash/adler32"
 	mrand "math/rand"
@@ -18,7 +19,6 @@ import (
 
 	rollingAdler32 "github.com/chmduquesne/rollinghash/adler32"
 	"github.com/syncthing/syncthing/lib/protocol"
-	"github.com/syncthing/syncthing/lib/sha256"
 )
 
 var blocksTestData = []struct {

lib/scanner/walk_test.go

@@ -9,6 +9,7 @@ package scanner
 import (
 	"bytes"
 	"context"
+	"crypto/sha256"
 	"errors"
 	"fmt"
 	"io"
@@ -26,7 +27,6 @@ import (
 	"github.com/syncthing/syncthing/lib/ignore"
 	"github.com/syncthing/syncthing/lib/protocol"
 	"github.com/syncthing/syncthing/lib/rand"
-	"github.com/syncthing/syncthing/lib/sha256"
 	"golang.org/x/text/unicode/norm"
 )
 

lib/sha256/sha256.go

@@ -1,157 +0,0 @@
-// Copyright (C) 2016 The Syncthing Authors.
-//
-// This Source Code Form is subject to the terms of the Mozilla Public
-// License, v. 2.0. If a copy of the MPL was not distributed with this file,
-// You can obtain one at https://mozilla.org/MPL/2.0/.
-
-package sha256
-
-import (
-	cryptoSha256 "crypto/sha256"
-	"encoding/hex"
-	"fmt"
-	"hash"
-	"math/rand"
-	"os"
-	"time"
-
-	minioSha256 "github.com/minio/sha256-simd"
-	"github.com/syncthing/syncthing/lib/logger"
-)
-
-var l = logger.DefaultLogger.NewFacility("sha256", "SHA256 hashing package")
-
-const (
-	benchmarkingIterations = 3
-	benchmarkingDuration   = 150 * time.Millisecond
-	defaultImpl            = "crypto/sha256"
-	minioImpl              = "minio/sha256-simd"
-	Size                   = cryptoSha256.Size
-)
-
-// May be switched out for another implementation
-var (
-	New    = cryptoSha256.New
-	Sum256 = cryptoSha256.Sum256
-)
-
-var (
-	selectedImpl = defaultImpl
-	cryptoPerf   float64
-	minioPerf    float64
-)
-
-func SelectAlgo() {
-	switch os.Getenv("STHASHING") {
-	case "":
-		// When unset, probe for the fastest implementation.
-		benchmark()
-		if minioPerf > cryptoPerf {
-			selectMinio()
-		}
-
-	case "minio":
-		// When set to "minio", use that.
-		selectMinio()
-
-	default:
-		// When set to anything else, such as "standard", use the default Go
-		// implementation. Make sure not to touch the minio
-		// implementation as it may be disabled for incompatibility reasons.
-	}
-
-	verifyCorrectness()
-}
-
-// Report prints a line with the measured hash performance rates for the
-// selected and alternate implementation.
-func Report() {
-	var otherImpl string
-	var selectedRate, otherRate float64
-
-	switch selectedImpl {
-	case defaultImpl:
-		selectedRate = cryptoPerf
-		otherRate = minioPerf
-		otherImpl = minioImpl
-
-	case minioImpl:
-		selectedRate = minioPerf
-		otherRate = cryptoPerf
-		otherImpl = defaultImpl
-	}
-
-	if selectedRate == 0 {
-		return
-	}
-
-	l.Infof("Single thread SHA256 performance is %s using %s (%s using %s).", formatRate(selectedRate), selectedImpl, formatRate(otherRate), otherImpl)
-}
-
-func selectMinio() {
-	New = minioSha256.New
-	Sum256 = minioSha256.Sum256
-	selectedImpl = minioImpl
-}
-
-func benchmark() {
-	// Interleave the tests to achieve some sort of fairness if the CPU is
-	// just in the process of spinning up to full speed.
-	for i := 0; i < benchmarkingIterations; i++ {
-		if perf := cpuBenchOnce(benchmarkingDuration, cryptoSha256.New); perf > cryptoPerf {
-			cryptoPerf = perf
-		}
-		if perf := cpuBenchOnce(benchmarkingDuration, minioSha256.New); perf > minioPerf {
-			minioPerf = perf
-		}
-	}
-}
-
-func cpuBenchOnce(duration time.Duration, newFn func() hash.Hash) float64 {
-	chunkSize := 100 * 1 << 10
-	h := newFn()
-	bs := make([]byte, chunkSize)
-	r := rand.New(rand.NewSource(time.Now().UnixNano()))
-	r.Read(bs)
-
-	t0 := time.Now()
-	b := 0
-	for time.Since(t0) < duration {
-		h.Write(bs)
-		b += chunkSize
-	}
-	h.Sum(nil)
-	d := time.Since(t0)
-	return float64(int(float64(b)/d.Seconds()/(1<<20)*100)) / 100
-}
-
-func formatRate(rate float64) string {
-	decimals := 0
-	if rate < 1 {
-		decimals = 2
-	} else if rate < 10 {
-		decimals = 1
-	}
-	return fmt.Sprintf("%.*f MB/s", decimals, rate)
-}
-
-func verifyCorrectness() {
-	// The currently selected algo should in fact perform a SHA256 calculation.
-
-	// $ echo "Syncthing Magic Testing Value" | openssl dgst -sha256 -hex
-	correct := "87f6cfd24131724c6ec43495594c5c22abc7d2b86bcc134bc6f10b7ec3dda4ee"
-	input := "Syncthing Magic Testing Value\n"
-
-	h := New()
-	h.Write([]byte(input))
-	sum := hex.EncodeToString(h.Sum(nil))
-	if sum != correct {
-		panic("sha256 is broken")
-	}
-
-	arr := Sum256([]byte(input))
-	sum = hex.EncodeToString(arr[:])
-	if sum != correct {
-		panic("sha256 is broken")
-	}
-}

lib/signature/signature.go

@@ -11,6 +11,7 @@ package signature
 import (
 	"crypto/ecdsa"
 	"crypto/elliptic"
+	"crypto/sha256"
 	"crypto/x509"
 	"encoding/asn1"
 	"encoding/pem"
@@ -20,7 +21,6 @@ import (
 	"math/big"
 
 	"github.com/syncthing/syncthing/lib/rand"
-	"github.com/syncthing/syncthing/lib/sha256"
 )
 
 // GenerateKeys returns a new key pair, with the private and public key

lib/syncthing/syncthing.go

@@ -37,7 +37,6 @@ import (
 	"github.com/syncthing/syncthing/lib/osutil"
 	"github.com/syncthing/syncthing/lib/protocol"
 	"github.com/syncthing/syncthing/lib/rand"
-	"github.com/syncthing/syncthing/lib/sha256"
 	"github.com/syncthing/syncthing/lib/svcutil"
 	"github.com/syncthing/syncthing/lib/tlsutil"
 	"github.com/syncthing/syncthing/lib/upgrade"
@@ -153,11 +152,6 @@ func (a *App) startup() error {
 	l.SetPrefix(fmt.Sprintf("[%s] ", a.myID.String()[:5]))
 	l.Infoln("My ID:", a.myID)
 
-	// Select SHA256 implementation and report. Affected by the
-	// STHASHING environment variable.
-	sha256.SelectAlgo()
-	sha256.Report()
-
 	// Emit the Starting event, now that we know who we are.
 
 	a.evLogger.Log(events.Starting, map[string]string{

man/syncthing.1

@@ -555,11 +555,6 @@ passing \fI\%\-\-gui\-apikey\fP\&.
 Directory to load GUI assets from. Overrides compiled in assets. Useful for
 developing webgui, commonly use \fBSTGUIASSETS=gui bin/syncthing\fP\&.
 .TP
-.B STHASHING
-Specify which hashing package to use. Defaults to automatic based on
-performance. Specify “minio” (compatibility) or “standard” for the default
-Go implementation.
-.TP
 .B STHEAPPROFILE
 Write heap profiles to \fBheap\-$pid\-$timestamp.pprof\fP each time heap usage
 increases.

test/util.go

@@ -11,6 +11,7 @@ package integration
 
 import (
 	cr "crypto/rand"
+	"crypto/sha256"
 	"errors"
 	"fmt"
 	"io"
@@ -27,7 +28,6 @@ import (
 
 	"github.com/syncthing/syncthing/lib/build"
 	"github.com/syncthing/syncthing/lib/rc"
-	"github.com/syncthing/syncthing/lib/sha256"
 )
 
 func init() {