diff --git a/internal/checker/checker_test.go b/internal/checker/checker_test.go
index 58dc7c744..bdc2f9f77 100644
--- a/internal/checker/checker_test.go
+++ b/internal/checker/checker_test.go
@@ -72,6 +72,7 @@ func assertOnlyMixedPackHints(t *testing.T, hints []error) {
 }
 
 func TestCheckRepo(t *testing.T) {
+	repository.TestInjectKey(t, restic.TestParseID("7bb3065bfb17da7430dc4dde4741d6db3dd83fdb0829500cf105755e067f879a"), `{"mac":{"k":"W1Y8bmQNJg6TAmuDt7lbpQ==","r":"r43DBmAdmwtQneoBTGAABQ=="},"encrypt":"JuZGBs6joRiLzqkyMWhmbZMLHe8+5oH6MDE5I6M8R/I="}`)
 	repo, _ := repository.TestFromFixture(t, checkerTestData)
 
 	chkr := checker.New(repo, false)
@@ -89,6 +90,7 @@ func TestCheckRepo(t *testing.T) {
 }
 
 func TestMissingPack(t *testing.T) {
+	repository.TestInjectKey(t, restic.TestParseID("7bb3065bfb17da7430dc4dde4741d6db3dd83fdb0829500cf105755e067f879a"), `{"mac":{"k":"W1Y8bmQNJg6TAmuDt7lbpQ==","r":"r43DBmAdmwtQneoBTGAABQ=="},"encrypt":"JuZGBs6joRiLzqkyMWhmbZMLHe8+5oH6MDE5I6M8R/I="}`)
 	repo, be := repository.TestFromFixture(t, checkerTestData)
 
 	packID := restic.TestParseID("657f7fb64f6a854fff6fe9279998ee09034901eded4e6db9bcee0e59745bbce6")
@@ -114,6 +116,7 @@ func TestMissingPack(t *testing.T) {
 }
 
 func TestUnreferencedPack(t *testing.T) {
+	repository.TestInjectKey(t, restic.TestParseID("7bb3065bfb17da7430dc4dde4741d6db3dd83fdb0829500cf105755e067f879a"), `{"mac":{"k":"W1Y8bmQNJg6TAmuDt7lbpQ==","r":"r43DBmAdmwtQneoBTGAABQ=="},"encrypt":"JuZGBs6joRiLzqkyMWhmbZMLHe8+5oH6MDE5I6M8R/I="}`)
 	repo, be := repository.TestFromFixture(t, checkerTestData)
 
 	// index 3f1a only references pack 60e0
@@ -141,6 +144,7 @@ func TestUnreferencedPack(t *testing.T) {
 }
 
 func TestUnreferencedBlobs(t *testing.T) {
+	repository.TestInjectKey(t, restic.TestParseID("7bb3065bfb17da7430dc4dde4741d6db3dd83fdb0829500cf105755e067f879a"), `{"mac":{"k":"W1Y8bmQNJg6TAmuDt7lbpQ==","r":"r43DBmAdmwtQneoBTGAABQ=="},"encrypt":"JuZGBs6joRiLzqkyMWhmbZMLHe8+5oH6MDE5I6M8R/I="}`)
 	repo, be := repository.TestFromFixture(t, checkerTestData)
 
 	snapshotID := restic.TestParseID("51d249d28815200d59e4be7b3f21a157b864dc343353df9d8e498220c2499b02")
@@ -175,6 +179,7 @@ func TestUnreferencedBlobs(t *testing.T) {
 }
 
 func TestModifiedIndex(t *testing.T) {
+	repository.TestInjectKey(t, restic.TestParseID("7bb3065bfb17da7430dc4dde4741d6db3dd83fdb0829500cf105755e067f879a"), `{"mac":{"k":"W1Y8bmQNJg6TAmuDt7lbpQ==","r":"r43DBmAdmwtQneoBTGAABQ=="},"encrypt":"JuZGBs6joRiLzqkyMWhmbZMLHe8+5oH6MDE5I6M8R/I="}`)
 	repo, be := repository.TestFromFixture(t, checkerTestData)
 
 	done := make(chan struct{})
@@ -214,6 +219,7 @@ func TestModifiedIndex(t *testing.T) {
 var checkerDuplicateIndexTestData = filepath.Join("testdata", "duplicate-packs-in-index-test-repo.tar.gz")
 
 func TestDuplicatePacksInIndex(t *testing.T) {
+	repository.TestInjectKey(t, restic.TestParseID("b9883c60bed42db51be171ca52f055104b6ea7cfa2bc381c05b2b1f78231280c"), `{"mac":{"k":"maQ4ILA872XnDxHVEno94A==","r":"OptMBABwkgIsMQcHME8cBw=="},"encrypt":"janrR1efN7HyQ8kOZ9zhHixooZ/e+WelH0mT4v9WskQ="}`)
 	repo, _ := repository.TestFromFixture(t, checkerDuplicateIndexTestData)
 
 	chkr := checker.New(repo, false)
@@ -413,6 +419,7 @@ func (r *loadTreesOnceRepository) LoadBlob(ctx context.Context, bh restic.BlobHa
 }
 
 func TestCheckerNoDuplicateTreeDecodes(t *testing.T) {
+	repository.TestInjectKey(t, restic.TestParseID("7bb3065bfb17da7430dc4dde4741d6db3dd83fdb0829500cf105755e067f879a"), `{"mac":{"k":"W1Y8bmQNJg6TAmuDt7lbpQ==","r":"r43DBmAdmwtQneoBTGAABQ=="},"encrypt":"JuZGBs6joRiLzqkyMWhmbZMLHe8+5oH6MDE5I6M8R/I="}`)
 	repo, _ := repository.TestFromFixture(t, checkerTestData)
 	checkRepo := &loadTreesOnceRepository{
 		Repository:  repo,
@@ -562,6 +569,7 @@ func TestCheckerBlobTypeConfusion(t *testing.T) {
 }
 
 func loadBenchRepository(t *testing.B) (*checker.Checker, restic.Repository) {
+	repository.TestInjectKey(t, restic.TestParseID("7bb3065bfb17da7430dc4dde4741d6db3dd83fdb0829500cf105755e067f879a"), `{"mac":{"k":"W1Y8bmQNJg6TAmuDt7lbpQ==","r":"r43DBmAdmwtQneoBTGAABQ=="},"encrypt":"JuZGBs6joRiLzqkyMWhmbZMLHe8+5oH6MDE5I6M8R/I="}`)
 	repo, _ := repository.TestFromFixture(t, checkerTestData)
 
 	chkr := checker.New(repo, false)
diff --git a/internal/repository/checker_test.go b/internal/repository/checker_test.go
index 10fe94970..f344443ed 100644
--- a/internal/repository/checker_test.go
+++ b/internal/repository/checker_test.go
@@ -34,6 +34,7 @@ func testWrapCheckPack(ctx context.Context, t *testing.T, repo *Repository,
 
 // TestGapInBlobs creates a gap in the blob list by omitting the first entry before passing it to checkPack
 func TestGapInBlobs(t *testing.T) {
+	TestInjectKey(t, restic.TestParseID("7bb3065bfb17da7430dc4dde4741d6db3dd83fdb0829500cf105755e067f879a"), `{"mac":{"k":"W1Y8bmQNJg6TAmuDt7lbpQ==","r":"r43DBmAdmwtQneoBTGAABQ=="},"encrypt":"JuZGBs6joRiLzqkyMWhmbZMLHe8+5oH6MDE5I6M8R/I="}`)
 	repo, _ := TestFromFixture(t, checkerTestData)
 
 	err := repo.LoadIndex(context.TODO(), restic.NoopTerminalCounterFactory)
diff --git a/internal/repository/key.go b/internal/repository/key.go
index e5d1b0724..94a4184e6 100644
--- a/internal/repository/key.go
+++ b/internal/repository/key.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"os"
 	"os/user"
+	"sync"
 	"time"
 
 	"github.com/restic/restic/internal/errors"
@@ -47,6 +48,9 @@ type Key struct {
 // calibrated on the first run of AddKey().
 var params *crypto.Params
 
+// testKeyInjection is used to speed up tests by skipping the key decryption step.
+var testKeyInjection = sync.Map{}
+
 const (
 	// KDFTimeout specifies the maximum runtime for the KDF.
 	KDFTimeout = 500 * time.Millisecond
@@ -63,6 +67,14 @@ func createMasterKey(ctx context.Context, s *Repository, password string) (*Key,
 
 // openKey tries do decrypt the key specified by name with the given password.
 func openKey(ctx context.Context, s *Repository, id restic.ID, password string) (*Key, error) {
+	if key, ok := testKeyInjection.Load(id); ok {
+		return &Key{
+			master: key.(*crypto.Key),
+			user:   key.(*crypto.Key), // not correct but good enough for testing
+			id:     id,
+		}, nil
+	}
+
 	k, err := LoadKey(ctx, s, id)
 	if err != nil {
 		debug.Log("LoadKey(%v) returned error %v", id.String(), err)
diff --git a/internal/repository/repository_test.go b/internal/repository/repository_test.go
index b830458e7..331cea1c8 100644
--- a/internal/repository/repository_test.go
+++ b/internal/repository/repository_test.go
@@ -319,6 +319,7 @@ func benchmarkLoadUnpacked(b *testing.B, version uint) {
 var repoFixture = filepath.Join("testdata", "test-repo.tar.gz")
 
 func TestRepositoryLoadIndex(t *testing.T) {
+	repository.TestInjectKey(t, restic.TestParseID("7bb3065bfb17da7430dc4dde4741d6db3dd83fdb0829500cf105755e067f879a"), `{"mac":{"k":"W1Y8bmQNJg6TAmuDt7lbpQ==","r":"r43DBmAdmwtQneoBTGAABQ=="},"encrypt":"JuZGBs6joRiLzqkyMWhmbZMLHe8+5oH6MDE5I6M8R/I="}`)
 	repo, _ := repository.TestFromFixture(t, repoFixture)
 
 	rtest.OK(t, repo.LoadIndex(context.TODO(), restic.NoopTerminalCounterFactory))
@@ -372,6 +373,7 @@ func (be *damageOnceBackend) Load(ctx context.Context, h backend.Handle, length
 }
 
 func TestRepositoryLoadUnpackedRetryBroken(t *testing.T) {
+	repository.TestInjectKey(t, restic.TestParseID("7bb3065bfb17da7430dc4dde4741d6db3dd83fdb0829500cf105755e067f879a"), `{"mac":{"k":"W1Y8bmQNJg6TAmuDt7lbpQ==","r":"r43DBmAdmwtQneoBTGAABQ=="},"encrypt":"JuZGBs6joRiLzqkyMWhmbZMLHe8+5oH6MDE5I6M8R/I="}`)
 	repodir := rtest.Env(t, repoFixture)
 
 	be, err := local.Open(context.TODO(), local.Config{Path: repodir, Connections: 2}, t.Logf)
diff --git a/internal/repository/testing.go b/internal/repository/testing.go
index 27dd98f2f..976ae3b8a 100644
--- a/internal/repository/testing.go
+++ b/internal/repository/testing.go
@@ -2,6 +2,7 @@ package repository
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"os"
 	"sync"
@@ -193,3 +194,12 @@ func TestCheckRepo(t testing.TB, repo *Repository) {
 		t.Error(err)
 	}
 }
+
+func TestInjectKey(t testing.TB, keyID restic.ID, key string) {
+	var k crypto.Key
+	err := json.Unmarshal([]byte(key), &k)
+	if err != nil {
+		t.Fatal(err)
+	}
+	testKeyInjection.Store(keyID, &k)
+}