Use Minio's optimized SHA-256

internal/repository benchmarks on an Intel i7-3770k:

name               old speed      new speed       delta
PackerManager-8     209MB/s ± 1%    291MB/s ± 1%  +38.94%  (p=0.008 n=5+5)
SaveAndEncrypt-8    112MB/s ± 1%    135MB/s ± 1%  +20.25%  (p=0.008 n=5+5)

cmd/restic/cmd_stats.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"context"
-	"crypto/sha256"
 	"encoding/json"
 	"fmt"
 	"os"
@@ -11,6 +10,8 @@ import (
 	"github.com/restic/restic/internal/errors"
 	"github.com/restic/restic/internal/restic"
 	"github.com/restic/restic/internal/walker"
+
+	"github.com/minio/sha256-simd"
 	"github.com/spf13/cobra"
 )
 

go.mod

@@ -21,6 +21,7 @@ require (
 	github.com/kurin/blazer v0.5.3
 	github.com/marstr/guid v1.1.0 // indirect
 	github.com/minio/minio-go/v6 v6.0.43
+	github.com/minio/sha256-simd v0.1.1
 	github.com/ncw/swift v1.0.47
 	github.com/pkg/errors v0.8.1
 	github.com/pkg/profile v1.3.0

internal/repository/packer_manager.go

@@ -2,7 +2,6 @@ package repository
 
 import (
 	"context"
-	"crypto/sha256"
 	"os"
 	"sync"
 
@@ -14,6 +13,8 @@ import (
 	"github.com/restic/restic/internal/debug"
 	"github.com/restic/restic/internal/fs"
 	"github.com/restic/restic/internal/pack"
+
+	"github.com/minio/sha256-simd"
 )
 
 // Saver implements saving data in a backend.

internal/repository/repository.go

@@ -3,7 +3,6 @@ package repository
 import (
 	"bytes"
 	"context"
-	"crypto/sha256"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -17,6 +16,8 @@ import (
 	"github.com/restic/restic/internal/hashing"
 	"github.com/restic/restic/internal/pack"
 	"github.com/restic/restic/internal/restic"
+
+	"github.com/minio/sha256-simd"
 	"golang.org/x/sync/errgroup"
 )
 

internal/restic/id.go

@@ -2,13 +2,14 @@ package restic
 
 import (
 	"crypto/rand"
-	"crypto/sha256"
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
 	"io"
 
 	"github.com/restic/restic/internal/errors"
+
+	"github.com/minio/sha256-simd"
 )
 
 // Hash returns the ID for data.