diff --git a/api/v1beta1/gitrepository_types.go b/api/v1beta1/gitrepository_types.go
index 8bc69ff24..3596e034a 100644
--- a/api/v1beta1/gitrepository_types.go
+++ b/api/v1beta1/gitrepository_types.go
@@ -80,6 +80,11 @@ type GitRepositorySpec struct {
 	// +kubebuilder:default:=go-git
 	// +optional
 	GitImplementation string `json:"gitImplementation,omitempty"`
+
+	// CertSecretRef
+	//
+	// +optional
+	CertSecretRef *meta.LocalObjectReference `json:"certSecretRef,omitempty"`
 }
 
 // GitRepositoryRef defines the Git ref used for pull and checkout operations.
diff --git a/api/v1beta1/zz_generated.deepcopy.go b/api/v1beta1/zz_generated.deepcopy.go
index 24e929f38..fd8c18acd 100644
--- a/api/v1beta1/zz_generated.deepcopy.go
+++ b/api/v1beta1/zz_generated.deepcopy.go
@@ -263,6 +263,11 @@ func (in *GitRepositorySpec) DeepCopyInto(out *GitRepositorySpec) {
 		*out = new(string)
 		**out = **in
 	}
+	if in.CertSecretRef != nil {
+		in, out := &in.CertSecretRef, &out.CertSecretRef
+		*out = new(meta.LocalObjectReference)
+		**out = **in
+	}
 }
 
 // DeepCopy is an autogenerated deepcopy function, copying the receiver, creating a new GitRepositorySpec.
diff --git a/config/crd/bases/source.toolkit.fluxcd.io_gitrepositories.yaml b/config/crd/bases/source.toolkit.fluxcd.io_gitrepositories.yaml
index 75e8f1614..a74cea203 100644
--- a/config/crd/bases/source.toolkit.fluxcd.io_gitrepositories.yaml
+++ b/config/crd/bases/source.toolkit.fluxcd.io_gitrepositories.yaml
@@ -49,6 +49,15 @@ spec:
           spec:
             description: GitRepositorySpec defines the desired state of a Git repository.
             properties:
+              certSecretRef:
+                description: CertSecretRef
+                properties:
+                  name:
+                    description: Name of the referent
+                    type: string
+                required:
+                - name
+                type: object
               gitImplementation:
                 default: go-git
                 description: Determines which git client library to use. Defaults
diff --git a/controllers/gitrepository_controller.go b/controllers/gitrepository_controller.go
index ccad45e90..4c55c51a8 100644
--- a/controllers/gitrepository_controller.go
+++ b/controllers/gitrepository_controller.go
@@ -179,25 +179,41 @@ func (r *GitRepositoryReconciler) reconcile(ctx context.Context, repository sour
 
 	// determine auth method
 	auth := &common.Auth{}
-	if repository.Spec.SecretRef != nil {
+	if repository.Spec.SecretRef != nil || repository.Spec.CertSecretRef != nil {
 		authStrategy, err := git.AuthSecretStrategyForURL(repository.Spec.URL, repository.Spec.GitImplementation)
 		if err != nil {
 			return sourcev1.GitRepositoryNotReady(repository, sourcev1.AuthenticationFailedReason, err.Error()), err
 		}
 
-		name := types.NamespacedName{
-			Namespace: repository.GetNamespace(),
-			Name:      repository.Spec.SecretRef.Name,
+		var secret *corev1.Secret
+		if repository.Spec.SecretRef != nil {
+			secret = &corev1.Secret{}
+			name := types.NamespacedName{
+				Namespace: repository.GetNamespace(),
+				Name:      repository.Spec.SecretRef.Name,
+			}
+
+			err = r.Client.Get(ctx, name, secret)
+			if err != nil {
+				err = fmt.Errorf("auth secret error: %w", err)
+				return sourcev1.GitRepositoryNotReady(repository, sourcev1.AuthenticationFailedReason, err.Error()), err
+			}
 		}
 
-		var secret corev1.Secret
-		err = r.Client.Get(ctx, name, &secret)
-		if err != nil {
-			err = fmt.Errorf("auth secret error: %w", err)
-			return sourcev1.GitRepositoryNotReady(repository, sourcev1.AuthenticationFailedReason, err.Error()), err
+		var certSecret *corev1.Secret
+		if repository.Spec.CertSecretRef != nil {
+			certSecret = &corev1.Secret{}
+			name := types.NamespacedName{
+				Namespace: repository.GetNamespace(),
+				Name:      repository.Spec.CertSecretRef.Name,
+			}
+			err = r.Client.Get(ctx, name, certSecret)
+			if err != nil {
+				return sourcev1.GitRepositoryNotReady(repository, sourcev1.AuthenticationFailedReason, err.Error()), err
+			}
 		}
 
-		auth, err = authStrategy.Method(secret)
+		auth, err = authStrategy.Method(secret, certSecret)
 		if err != nil {
 			err = fmt.Errorf("auth error: %w", err)
 			return sourcev1.GitRepositoryNotReady(repository, sourcev1.AuthenticationFailedReason, err.Error()), err
diff --git a/controllers/gitrepository_controller_test.go b/controllers/gitrepository_controller_test.go
index f5596ca94..5fce938f5 100644
--- a/controllers/gitrepository_controller_test.go
+++ b/controllers/gitrepository_controller_test.go
@@ -18,7 +18,9 @@ package controllers
 
 import (
 	"context"
+	"crypto/tls"
 	"fmt"
+	"net/http"
 	"net/url"
 	"os"
 	"path"
@@ -30,6 +32,8 @@ import (
 	"github.com/go-git/go-git/v5/config"
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/go-git/go-git/v5/plumbing/object"
+	"github.com/go-git/go-git/v5/plumbing/transport/client"
+	httptransport "github.com/go-git/go-git/v5/plumbing/transport/http"
 	"github.com/go-git/go-git/v5/storage/memory"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/ginkgo/extensions/table"
@@ -38,6 +42,7 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/types"
 
+	"github.com/fluxcd/pkg/apis/meta"
 	"github.com/fluxcd/pkg/gittestserver"
 
 	sourcev1 "github.com/fluxcd/source-controller/api/v1beta1"
@@ -65,6 +70,18 @@ var _ = Describe("GitRepositoryReconciler", func() {
 			err = k8sClient.Create(context.Background(), namespace)
 			Expect(err).NotTo(HaveOccurred(), "failed to create test namespace")
 
+			cert := corev1.Secret{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "cert",
+					Namespace: namespace.Name,
+				},
+				Data: map[string][]byte{
+					"caFile": exampleCA,
+				},
+			}
+			err = k8sClient.Create(context.Background(), &cert)
+			Expect(err).NotTo(HaveOccurred())
+
 			gitServer, err = gittestserver.NewTempGitServer()
 			Expect(err).NotTo(HaveOccurred())
 			gitServer.AutoCreate()
@@ -88,6 +105,7 @@ var _ = Describe("GitRepositoryReconciler", func() {
 			expectRevision string
 
 			gitImplementation string
+			certSecretRef     *meta.LocalObjectReference
 		}
 
 		DescribeTable("Git references tests", func(t refTestCase) {
@@ -274,6 +292,55 @@ var _ = Describe("GitRepositoryReconciler", func() {
 			Expect(err).NotTo(HaveOccurred())
 			u.Path = path.Join(u.Path, fmt.Sprintf("repository-%s.git", randStringRunes(5)))
 
+			var transport = httptransport.NewClient(&http.Client{
+				Transport: &http.Transport{
+					TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
+				},
+			})
+			client.InstallProtocol("https", transport)
+
+			fs := memfs.New()
+			gitrepo, err := git.Init(memory.NewStorage(), fs)
+			Expect(err).NotTo(HaveOccurred())
+
+			wt, err := gitrepo.Worktree()
+			Expect(err).NotTo(HaveOccurred())
+
+			ff, _ := fs.Create("fixture")
+			_ = ff.Close()
+			_, err = wt.Add(fs.Join("fixture"))
+			Expect(err).NotTo(HaveOccurred())
+
+			commit, err := wt.Commit("Sample", &git.CommitOptions{Author: &object.Signature{
+				Name:  "John Doe",
+				Email: "john@example.com",
+				When:  time.Now(),
+			}})
+			Expect(err).NotTo(HaveOccurred())
+
+			gitrepo.Worktree()
+
+			for _, ref := range t.createRefs {
+				hRef := plumbing.NewHashReference(plumbing.ReferenceName(ref), commit)
+				err = gitrepo.Storer.SetReference(hRef)
+				Expect(err).NotTo(HaveOccurred())
+			}
+
+			remote, err := gitrepo.CreateRemote(&config.RemoteConfig{
+				Name: "origin",
+				URLs: []string{u.String()},
+			})
+			Expect(err).NotTo(HaveOccurred())
+
+			err = remote.Push(&git.PushOptions{
+				RefSpecs: []config.RefSpec{"refs/heads/*:refs/heads/*", "refs/tags/*:refs/tags/*"},
+			})
+			Expect(err).NotTo(HaveOccurred())
+
+			t.reference.Commit = strings.Replace(t.reference.Commit, "<commit>", commit.String(), 1)
+
+			client.InstallProtocol("https", httptransport.DefaultClient)
+
 			key := types.NamespacedName{
 				Name:      fmt.Sprintf("git-ref-test-%s", randStringRunes(5)),
 				Namespace: namespace.Name,
@@ -288,6 +355,8 @@ var _ = Describe("GitRepositoryReconciler", func() {
 					Interval:          metav1.Duration{Duration: indexInterval},
 					Reference:         t.reference,
 					GitImplementation: t.gitImplementation,
+					SecretRef:         nil,
+					CertSecretRef:     t.certSecretRef,
 				},
 			}
 			Expect(k8sClient.Create(context.Background(), created)).Should(Succeed())
@@ -316,13 +385,22 @@ var _ = Describe("GitRepositoryReconciler", func() {
 				expectStatus:  metav1.ConditionFalse,
 				expectMessage: "x509: certificate signed by unknown authority",
 			}),
-			Entry("self signed v2", refTestCase{
+			Entry("self signed v2 without CA", refTestCase{
 				reference:         &sourcev1.GitRepositoryRef{Branch: "main"},
 				waitForReason:     sourcev1.GitOperationFailedReason,
 				expectStatus:      metav1.ConditionFalse,
 				expectMessage:     "error: user rejected certificate",
 				gitImplementation: sourcev1.LibGit2Implementation,
 			}),
+			Entry("self signed v2 with CA", refTestCase{
+				reference:         &sourcev1.GitRepositoryRef{Branch: "some-branch"},
+				createRefs:        []string{"refs/heads/some-branch"},
+				waitForReason:     sourcev1.GitOperationSucceedReason,
+				expectStatus:      metav1.ConditionTrue,
+				expectRevision:    "some-branch",
+				certSecretRef:     &meta.LocalObjectReference{Name: "cert"},
+				gitImplementation: sourcev1.LibGit2Implementation,
+			}),
 		)
 	})
 })
diff --git a/docs/api/source.md b/docs/api/source.md
index c0de25e90..e50eb728c 100644
--- a/docs/api/source.md
+++ b/docs/api/source.md
@@ -400,6 +400,20 @@ string
 Defaults to go-git, valid values are (&lsquo;go-git&rsquo;, &lsquo;libgit2&rsquo;).</p>
 </td>
 </tr>
+<tr>
+<td>
+<code>certSecretRef</code><br>
+<em>
+<a href="https://godoc.org/github.com/fluxcd/pkg/apis/meta#LocalObjectReference">
+github.com/fluxcd/pkg/apis/meta.LocalObjectReference
+</a>
+</em>
+</td>
+<td>
+<em>(Optional)</em>
+<p>CertSecretRef</p>
+</td>
+</tr>
 </table>
 </td>
 </tr>
@@ -1246,6 +1260,20 @@ string
 Defaults to go-git, valid values are (&lsquo;go-git&rsquo;, &lsquo;libgit2&rsquo;).</p>
 </td>
 </tr>
+<tr>
+<td>
+<code>certSecretRef</code><br>
+<em>
+<a href="https://godoc.org/github.com/fluxcd/pkg/apis/meta#LocalObjectReference">
+github.com/fluxcd/pkg/apis/meta.LocalObjectReference
+</a>
+</em>
+</td>
+<td>
+<em>(Optional)</em>
+<p>CertSecretRef</p>
+</td>
+</tr>
 </tbody>
 </table>
 </div>
diff --git a/go.mod b/go.mod
index c8dccd194..2f60fa109 100644
--- a/go.mod
+++ b/go.mod
@@ -20,12 +20,12 @@ require (
 	github.com/go-git/go-billy/v5 v5.0.0
 	github.com/go-git/go-git/v5 v5.2.0
 	github.com/go-logr/logr v0.3.0
-	github.com/libgit2/git2go/v31 v31.3.0
+	github.com/libgit2/git2go/v31 v31.4.7
 	github.com/minio/minio-go/v7 v7.0.5
 	github.com/onsi/ginkgo v1.14.1
 	github.com/onsi/gomega v1.10.2
 	github.com/spf13/pflag v1.0.5
-	golang.org/x/crypto v0.0.0-20201002170205-7f63de1d35b0
+	golang.org/x/crypto v0.0.0-20201203163018-be400aefbc4c
 	golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e
 	helm.sh/helm/v3 v3.5.0
 	k8s.io/api v0.20.2
diff --git a/go.sum b/go.sum
index 311fe6918..3bbc6502b 100644
--- a/go.sum
+++ b/go.sum
@@ -427,6 +427,8 @@ github.com/google/pprof v0.0.0-20191218002539-d4f498aebedc/go.mod h1:ZgVRPoUq/hf
 github.com/google/pprof v0.0.0-20200212024743-f11f1df84d12/go.mod h1:ZgVRPoUq/hfqzAqh7sHMqb3I9Rq5C59dIz2SbBwJ4eM=
 github.com/google/pprof v0.0.0-20200229191704-1ebb73c60ed3/go.mod h1:ZgVRPoUq/hfqzAqh7sHMqb3I9Rq5C59dIz2SbBwJ4eM=
 github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
+github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 h1:El6M4kTTCOh6aBiKaUGG7oYTSPP8MxqL4YI3kZKwcP4=
+github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510/go.mod h1:pupxD2MaaD3pAXIBCelhxNneeOaAeabZDe5s4K6zSpQ=
 github.com/google/uuid v1.0.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/google/uuid v1.1.1/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/google/uuid v1.1.2 h1:EVhdT+1Kseyi1/pUmXKaFxYsDNy9RQYkMWRH68J/W7Y=
@@ -553,8 +555,8 @@ github.com/lib/pq v1.2.0/go.mod h1:5WUZQaWbwv1U+lTReE5YruASi9Al49XbQIvNi/34Woo=
 github.com/lib/pq v1.8.0/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=
 github.com/lib/pq v1.9.0 h1:L8nSXQQzAYByakOFMTwpjRoHsMJklur4Gi59b6VivR8=
 github.com/lib/pq v1.9.0/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=
-github.com/libgit2/git2go/v31 v31.3.0 h1:d8ciyYVKir+gKwra3KuNxTyVvbgGKn4admdt1PNNAOg=
-github.com/libgit2/git2go/v31 v31.3.0/go.mod h1:mnc0hPGPs0nDi9INrurTpioeRzje9DvSXqON/+JEhwY=
+github.com/libgit2/git2go/v31 v31.4.7 h1:P85qB5at5un4qPqUcvOZbAom7P0G4KAG/OLVyD29kQ0=
+github.com/libgit2/git2go/v31 v31.4.7/go.mod h1:c/rkJcBcUFx6wHaT++UwNpKvIsmPNqCeQ/vzO4DrEec=
 github.com/liggitt/tabwriter v0.0.0-20181228230101-89fcab3d43de h1:9TO3cAIGXtEhnIaL+V+BEER86oLrvS+kWobKpbJuye0=
 github.com/liggitt/tabwriter v0.0.0-20181228230101-89fcab3d43de/go.mod h1:zAbeS9B/r2mtpb6U+EI2rYA5OAXxsYw6wTamcNW+zcE=
 github.com/lightstep/lightstep-tracer-common/golang/gogo v0.0.0-20190605223551-bc2310a04743/go.mod h1:qklhhLq1aX+mtWk9cPHPzaBjWImj5ULL6C7HFJtXQMM=
@@ -903,6 +905,8 @@ golang.org/x/crypto v0.0.0-20200709230013-948cd5f35899/go.mod h1:LzIPMQfyMNhhGPh
 golang.org/x/crypto v0.0.0-20200728195943-123391ffb6de/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20201002170205-7f63de1d35b0 h1:hb9wdF1z5waM+dSIICn1l0DkLVDT3hqhhQsDNUmHPRE=
 golang.org/x/crypto v0.0.0-20201002170205-7f63de1d35b0/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/crypto v0.0.0-20201203163018-be400aefbc4c h1:9HhBz5L/UjnK9XLtiZhYAdue5BVKep3PMmS2LuPDt8k=
+golang.org/x/crypto v0.0.0-20201203163018-be400aefbc4c/go.mod h1:jdWPYTVW3xRLrWPugEBEK3UY2ZEsg3UU495nc5E+M+I=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190306152737-a1d7652674e8/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190510132918-efd6b22b2522/go.mod h1:ZjyILWgesfNpC6sMxTJOJm9Kp84zZh5NQWvqDGG3Qr8=
@@ -1032,6 +1036,10 @@ golang.org/x/sys v0.0.0-20200625212154-ddb9806d33ae/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201112073958-5cba982894dd h1:5CtCZbICpIOFdgO940moixOPjc0178IU44m4EjOO5IY=
 golang.org/x/sys v0.0.0-20201112073958-5cba982894dd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20201204225414-ed752295db88 h1:KmZPnMocC93w341XZp26yTJg8Za7lhb2KhkYmixoeso=
+golang.org/x/sys v0.0.0-20201204225414-ed752295db88/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/term v0.0.0-20201117132131-f5c789dd3221 h1:/ZHdbVpdR/jk3g30/d4yUL0JU9kksj8+F/bnQUVLGDM=
+golang.org/x/term v0.0.0-20201117132131-f5c789dd3221/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.1-0.20180807135948-17ff2d5776d2/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
diff --git a/pkg/git/common/common.go b/pkg/git/common/common.go
index 3b949fbb3..9ec4d602a 100644
--- a/pkg/git/common/common.go
+++ b/pkg/git/common/common.go
@@ -46,5 +46,5 @@ type Auth struct {
 }
 
 type AuthSecretStrategy interface {
-	Method(secret corev1.Secret) (*Auth, error)
+	Method(secret *corev1.Secret, certSecret *corev1.Secret) (*Auth, error)
 }
diff --git a/pkg/git/v1/transport.go b/pkg/git/v1/transport.go
index f8f64f5ae..554f55a43 100644
--- a/pkg/git/v1/transport.go
+++ b/pkg/git/v1/transport.go
@@ -17,6 +17,7 @@ limitations under the License.
 package v1
 
 import (
+	"errors"
 	"fmt"
 	"net/url"
 
@@ -46,7 +47,11 @@ func AuthSecretStrategyForURL(URL string) (common.AuthSecretStrategy, error) {
 
 type BasicAuth struct{}
 
-func (s *BasicAuth) Method(secret corev1.Secret) (*common.Auth, error) {
+func (s *BasicAuth) Method(secret *corev1.Secret, certSecret *corev1.Secret) (*common.Auth, error) {
+	if certSecret != nil {
+		return nil, errors.New("git2go HTTP transport does not support custom certificates.")
+	}
+
 	auth := &http.BasicAuth{}
 	if username, ok := secret.Data["username"]; ok {
 		auth.Username = string(username)
@@ -64,7 +69,11 @@ type PublicKeyAuth struct {
 	user string
 }
 
-func (s *PublicKeyAuth) Method(secret corev1.Secret) (*common.Auth, error) {
+func (s *PublicKeyAuth) Method(secret *corev1.Secret, certSecret *corev1.Secret) (*common.Auth, error) {
+	if certSecret != nil {
+		return nil, errors.New("git2go SSH transport does not support custom certificates.")
+	}
+
 	identity := secret.Data["identity"]
 	knownHosts := secret.Data["known_hosts"]
 	if len(identity) == 0 || len(knownHosts) == 0 {
diff --git a/pkg/git/v1/transport_test.go b/pkg/git/v1/transport_test.go
index 8e27033e5..07f889739 100644
--- a/pkg/git/v1/transport_test.go
+++ b/pkg/git/v1/transport_test.go
@@ -112,7 +112,7 @@ func TestBasicAuthStrategy_Method(t *testing.T) {
 				tt.modify(secret)
 			}
 			s := &BasicAuth{}
-			got, err := s.Method(*secret)
+			got, err := s.Method(secret, nil)
 			if (err != nil) != tt.wantErr {
 				t.Errorf("Method() error = %v, wantErr %v", err, tt.wantErr)
 				return
@@ -145,7 +145,7 @@ func TestPublicKeyStrategy_Method(t *testing.T) {
 				tt.modify(secret)
 			}
 			s := &PublicKeyAuth{}
-			_, err := s.Method(*secret)
+			_, err := s.Method(secret, nil)
 			if (err != nil) != tt.wantErr {
 				t.Errorf("Method() error = %v, wantErr %v", err, tt.wantErr)
 				return
diff --git a/pkg/git/v2/transport.go b/pkg/git/v2/transport.go
index 992e4d94a..03362d6f0 100644
--- a/pkg/git/v2/transport.go
+++ b/pkg/git/v2/transport.go
@@ -20,16 +20,23 @@ import (
 	"bufio"
 	"bytes"
 	"crypto/sha1"
+	"crypto/x509"
+	"errors"
 	"fmt"
-	"golang.org/x/crypto/ssh"
 	"net/url"
 	"strings"
 
+	"golang.org/x/crypto/ssh"
+
 	"github.com/fluxcd/source-controller/pkg/git/common"
 	git2go "github.com/libgit2/git2go/v31"
 	corev1 "k8s.io/api/core/v1"
 )
 
+const (
+	CACert = "caFile"
+)
+
 func AuthSecretStrategyForURL(URL string) (common.AuthSecretStrategy, error) {
 	u, err := url.Parse(URL)
 	if err != nil {
@@ -48,35 +55,66 @@ func AuthSecretStrategyForURL(URL string) (common.AuthSecretStrategy, error) {
 
 type BasicAuth struct{}
 
-func (s *BasicAuth) Method(secret corev1.Secret) (*common.Auth, error) {
-	var username string
-	if d, ok := secret.Data["username"]; ok {
-		username = string(d)
-	}
-	var password string
-	if d, ok := secret.Data["password"]; ok {
-		password = string(d)
-	}
-	if username == "" || password == "" {
-		return nil, fmt.Errorf("invalid '%s' secret data: required fields 'username' and 'password'", secret.Name)
+func (s *BasicAuth) Method(secret *corev1.Secret, certSecret *corev1.Secret) (*common.Auth, error) {
+	var credCallback git2go.CredentialsCallback = nil
+	if secret != nil {
+		var username string
+		if d, ok := secret.Data["username"]; ok {
+			username = string(d)
+		}
+		var password string
+		if d, ok := secret.Data["password"]; ok {
+			password = string(d)
+		}
+		if username == "" || password == "" {
+			return nil, fmt.Errorf("invalid '%s' secret data: required fields 'username' and 'password'", secret.Name)
+		}
+		credCallback = func(url string, username_from_url string, allowed_types git2go.CredType) (*git2go.Cred, error) {
+			cred, err := git2go.NewCredUserpassPlaintext(username, password)
+			if err != nil {
+				return nil, err
+			}
+			return cred, nil
+		}
 	}
 
-	credCallback := func(url string, username_from_url string, allowed_types git2go.CredType) (*git2go.Cred, error) {
-		cred, err := git2go.NewCredUserpassPlaintext(username, password)
-		if err != nil {
-			return nil, err
+	var certCallback git2go.CertificateCheckCallback = nil
+	if certSecret != nil {
+		caCert, ok := certSecret.Data[CACert]
+		if !ok {
+			return nil, fmt.Errorf("invalid '%s' cert secret data: required field '%s'", secret.Name, CACert)
+		}
+
+		certCallback = func(cert *git2go.Certificate, valid bool, hostname string) git2go.ErrorCode {
+			roots := x509.NewCertPool()
+			ok := roots.AppendCertsFromPEM(caCert)
+			if !ok {
+				return git2go.ErrCertificate
+			}
+
+			opts := x509.VerifyOptions{
+				Roots: roots,
+			}
+			_, err := cert.X509.Verify(opts)
+			if err != nil {
+				return git2go.ErrCertificate
+			}
+			return git2go.ErrOk
 		}
-		return cred, nil
 	}
 
-	return &common.Auth{CredCallback: credCallback, CertCallback: nil}, nil
+	return &common.Auth{CredCallback: credCallback, CertCallback: certCallback}, nil
 }
 
 type PublicKeyAuth struct {
 	user string
 }
 
-func (s *PublicKeyAuth) Method(secret corev1.Secret) (*common.Auth, error) {
+func (s *PublicKeyAuth) Method(secret *corev1.Secret, cert *corev1.Secret) (*common.Auth, error) {
+	if cert != nil {
+		return nil, errors.New("libgit2 SSH transport does not support custom certificates.")
+	}
+
 	identity := secret.Data["identity"]
 	knownHosts := secret.Data["known_hosts"]
 	if len(identity) == 0 || len(knownHosts) == 0 {
diff --git a/pkg/git/v2/transport_test.go b/pkg/git/v2/transport_test.go
index 8428229ea..e9069fd6e 100644
--- a/pkg/git/v2/transport_test.go
+++ b/pkg/git/v2/transport_test.go
@@ -110,7 +110,7 @@ func TestBasicAuthStrategy_Method(t *testing.T) {
 				tt.modify(secret)
 			}
 			s := &BasicAuth{}
-			got, err := s.Method(*secret)
+			got, err := s.Method(secret, nil)
 			if (err != nil) != tt.wantErr {
 				t.Errorf("Method() error = %v, wantErr %v", err, tt.wantErr)
 				return
@@ -143,7 +143,7 @@ func TestPublicKeyStrategy_Method(t *testing.T) {
 				tt.modify(secret)
 			}
 			s := &PublicKeyAuth{}
-			_, err := s.Method(*secret)
+			_, err := s.Method(secret, nil)
 			if (err != nil) != tt.wantErr {
 				t.Errorf("Method() error = %v, wantErr %v", err, tt.wantErr)
 				return