fix(kas): Do not log index object (#2910)

### Proposed Changes

1.) Have `key_indexers` implement `slog.LogValuer` and `fmt.Stringer` so
that object internals are not accidentally logged


Example of log after change:
```json
time=2025-11-14T13:04:24.587-06:00 level=WARN msg="failure to decrypt dek" namespace=kas error="decrypt: unable to find key by ID 'r3' within index opentdf.io/in-process: not found" request-id=34d60cdd-879e-4840-b133-65c6f080c956 user-agent="connect-go/1.18.1 (go1.25.4)" request-ip=None actor-id=5bc210a6-f501-4e0a-9f0b-34a41673f1f3

```

### Checklist

- [ ] I have added or updated unit tests
- [ ] I have added or updated integration tests (if appropriate)
- [ ] I have added or updated documentation

### Testing Instructions

Author: c-r33d

service/internal/security/in_process_provider.go

@@ -134,6 +134,16 @@ func (a *InProcessProvider) WithLogger(logger *slog.Logger) *InProcessProvider {
 	return a
 }
 
+// Implement fmt.Stringer so Index's default to our String() method
+func (a *InProcessProvider) String() string {
+	return inProcessSystemName
+}
+
+// Implement slog.LogValuer for slog logging.
+func (a *InProcessProvider) LogValue() slog.Value {
+	return slog.StringValue(a.String())
+}
+
 // FindKeyByAlgorithm finds a key by algorithm using the underlying CryptoProvider.
 // This will only return default keys if legacy is false.
 // If legacy is true, it will return the first legacy key found that matches the algorithm.

service/kas/access/publicKey_test.go

@@ -9,6 +9,7 @@ import (
 	"crypto/x509"
 	"encoding/pem"
 	"errors"
+	"log/slog"
 	"math/big"
 	"os"
 	"testing"
@@ -98,6 +99,14 @@ func NewMockSecurityProvider() *MockSecurityProvider {
 	}
 }
 
+func (m *MockSecurityProvider) String() string {
+	return "MockSecurityProvider"
+}
+
+func (m *MockSecurityProvider) LogValue() slog.Value {
+	return slog.StringValue(m.String())
+}
+
 func (m *MockSecurityProvider) AddKey(key *MockKeyDetails) {
 	m.keys[key.id] = key
 }

service/kas/access/rewrap_test.go

@@ -67,6 +67,16 @@ type fakeKeyIndex struct {
 	err  error
 }
 
+func (f *fakeKeyIndex) String() string {
+	return "fakeKeyIndex"
+}
+
+func (f *fakeKeyIndex) LogValue() slog.Value {
+	return slog.GroupValue(
+		slog.String("Indexer", f.String()),
+	)
+}
+
 func (f *fakeKeyIndex) FindKeyByAlgorithm(context.Context, string, bool) (trust.KeyDetails, error) {
 	return nil, errors.New("not implemented")
 }

service/kas/key_indexer.go

@@ -9,6 +9,7 @@ import (
 	"encoding/pem"
 	"errors"
 	"fmt"
+	"log/slog"
 
 	"github.com/lestrrat-go/jwx/v2/jwk"
 	"github.com/opentdf/platform/lib/ocrypto"
@@ -85,6 +86,10 @@ func (p *KeyIndexer) String() string {
 	return fmt.Sprintf("PlatformKeyIndexer[%s]", p.kasURI)
 }
 
+func (p *KeyIndexer) LogValue() slog.Value {
+	return slog.StringValue(p.String())
+}
+
 func (p *KeyIndexer) FindKeyByAlgorithm(ctx context.Context, algorithm string, includeLegacy bool) (trust.KeyDetails, error) {
 	alg, err := convertAlgToEnum(algorithm)
 	if err != nil {

service/trust/delegating_key_service_test.go

@@ -3,6 +3,7 @@ package trust
 import (
 	"context"
 	"crypto/elliptic"
+	"log/slog"
 	"testing"
 
 	"github.com/opentdf/platform/lib/ocrypto"
@@ -54,6 +55,16 @@ type MockKeyIndex struct {
 	mock.Mock
 }
 
+func (m *MockKeyIndex) String() string {
+	return "mockKeyIndex"
+}
+
+func (m *MockKeyIndex) LogValue() slog.Value {
+	return slog.GroupValue(
+		slog.String("Indexer", m.String()),
+	)
+}
+
 func (m *MockKeyIndex) FindKeyByAlgorithm(ctx context.Context, algorithm string, includeLegacy bool) (KeyDetails, error) {
 	args := m.Called(ctx, algorithm, includeLegacy)
 	if a0, ok := args.Get(0).(KeyDetails); ok {

service/trust/key_index.go

@@ -2,6 +2,8 @@ package trust
 
 import (
 	"context"
+	"fmt"
+	"log/slog"
 
 	"github.com/opentdf/platform/lib/ocrypto"
 	"github.com/opentdf/platform/protocol/go/policy"
@@ -63,6 +65,8 @@ type KeyDetails interface {
 
 // KeyIndex provides methods to locate keys by various criteria
 type KeyIndex interface {
+	fmt.Stringer
+	slog.LogValuer
 	// FindKeyByAlgorithm returns a key for the specified algorithm
 	// If includeLegacy is true, legacy keys will be included in the search
 	FindKeyByAlgorithm(ctx context.Context, algorithm string, includeLegacy bool) (KeyDetails, error)