Added GPU evidence collection

.gitignore

@@ -28,4 +28,5 @@ Cargo.lock
 
 *.enc
 *.key
-*.pub
+*.pub
+.codex

cmd/attestation-service/gpu.go

@@ -0,0 +1,76 @@
+// Copyright (c) Ultraviolet
+// SPDX-License-Identifier: Apache-2.0
+
+package main
+
+import (
+	"context"
+	"crypto/sha256"
+	"fmt"
+	"strings"
+
+	attestationpb "github.com/ultravioletrs/cocos/internal/proto/attestation/v1"
+	"github.com/ultravioletrs/cocos/pkg/attestation"
+	"github.com/ultravioletrs/cocos/pkg/attestation/eat"
+	attestationgpu "github.com/ultravioletrs/cocos/pkg/attestation/gpu"
+)
+
+func newGPUCollector(cfg config) (attestationgpu.Collector, error) {
+	if strings.TrimSpace(cfg.GPUHelperPath) == "" {
+		return nil, nil
+	}
+
+	return attestationgpu.NewCommandCollector(cfg.GPUHelperPath, cfg.GPUHelperTimeout)
+}
+
+func (s *service) claimOptions(ctx context.Context, req *attestationpb.AttestationRequest, platformType attestation.PlatformType) ([]eat.ClaimsOption, error) {
+	var opts []eat.ClaimsOption
+
+	if s.gpuCollector != nil && shouldCollectGPU(platformType) {
+		sessionNonce := requestNonce(req)
+		gpuNonce := deriveComponentNonce(sessionNonce, "gpu")
+
+		evidence, err := s.gpuCollector.Collect(ctx, gpuNonce)
+		if err != nil {
+			// GPU evidence is opportunistic: if no supported CC-capable GPU is
+			// attached, or the helper cannot collect evidence, we continue with
+			// the root CPU/TEE attestation instead of failing the whole request.
+			s.logger.Warn(fmt.Sprintf("[ATTESTATION-SERVICE] Skipping optional GPU evidence collection: %s", err))
+			return opts, nil
+		}
+
+		s.logger.Info(fmt.Sprintf("[ATTESTATION-SERVICE] Collected GPU evidence: format=%s bytes=%d",
+			evidence.EvidenceFormat, len(evidence.RawEvidence)))
+
+		opts = append(opts, eat.WithGPU(&eat.GPUExtensions{
+			Vendor:         evidence.Vendor,
+			EvidenceFormat: evidence.EvidenceFormat,
+			Nonce:          evidence.Nonce,
+			EvidenceJSON:   evidence.RawEvidence,
+		}))
+	}
+
+	return opts, nil
+}
+
+func shouldCollectGPU(platformType attestation.PlatformType) bool {
+	switch platformType {
+	case attestation.SNP, attestation.SNPvTPM, attestation.TDX, attestation.Azure:
+		return true
+	default:
+		return false
+	}
+}
+
+func requestNonce(req *attestationpb.AttestationRequest) []byte {
+	if len(req.Nonce) > 0 {
+		return append([]byte(nil), req.Nonce...)
+	}
+
+	return append([]byte(nil), req.ReportData...)
+}
+
+func deriveComponentNonce(sessionNonce []byte, component string) []byte {
+	digest := sha256.Sum256(append(append([]byte(nil), sessionNonce...), []byte(":"+component)...))
+	return digest[:]
+}

cmd/attestation-service/gpu_test.go

@@ -0,0 +1,83 @@
+// Copyright (c) Ultraviolet
+// SPDX-License-Identifier: Apache-2.0
+
+package main
+
+import (
+	"context"
+	"io"
+	"log/slog"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	attestationpb "github.com/ultravioletrs/cocos/internal/proto/attestation/v1"
+	"github.com/ultravioletrs/cocos/pkg/attestation"
+	attestationgpu "github.com/ultravioletrs/cocos/pkg/attestation/gpu"
+)
+
+func TestRequestNonce(t *testing.T) {
+	req := &attestationpb.AttestationRequest{
+		ReportData: []byte("report"),
+		Nonce:      []byte("nonce"),
+	}
+
+	assert.Equal(t, []byte("nonce"), requestNonce(req))
+
+	req.Nonce = nil
+	assert.Equal(t, []byte("report"), requestNonce(req))
+}
+
+func TestDeriveComponentNonce(t *testing.T) {
+	sessionNonce := []byte("session-nonce")
+
+	gpuNonce := deriveComponentNonce(sessionNonce, "gpu")
+	gpuNonceAgain := deriveComponentNonce(sessionNonce, "gpu")
+	teeNonce := deriveComponentNonce(sessionNonce, "tee")
+
+	assert.Len(t, gpuNonce, 32)
+	assert.Equal(t, gpuNonce, gpuNonceAgain)
+	assert.NotEqual(t, gpuNonce, teeNonce)
+}
+
+func TestShouldCollectGPU(t *testing.T) {
+	assert.True(t, shouldCollectGPU(attestation.SNP))
+	assert.True(t, shouldCollectGPU(attestation.SNPvTPM))
+	assert.True(t, shouldCollectGPU(attestation.TDX))
+	assert.False(t, shouldCollectGPU(attestation.VTPM))
+	assert.False(t, shouldCollectGPU(attestation.NoCC))
+}
+
+func TestNewGPUCollector(t *testing.T) {
+	collector, err := newGPUCollector(config{})
+	assert.NoError(t, err)
+	assert.Nil(t, collector)
+
+	collector, err = newGPUCollector(config{
+		GPUHelperPath:    "/tmp/helper",
+		GPUHelperTimeout: 0,
+	})
+	assert.NoError(t, err)
+	assert.NotNil(t, collector)
+}
+
+func TestClaimOptions_SkipsOptionalGPUFailure(t *testing.T) {
+	svc := &service{
+		logger:       slog.New(slog.NewTextHandler(io.Discard, nil)),
+		gpuCollector: failingCollector{},
+	}
+
+	req := &attestationpb.AttestationRequest{
+		ReportData: []byte("report-data"),
+		Nonce:      []byte("nonce-data"),
+	}
+
+	opts, err := svc.claimOptions(context.Background(), req, attestation.TDX)
+	assert.NoError(t, err)
+	assert.Empty(t, opts)
+}
+
+type failingCollector struct{}
+
+func (failingCollector) Collect(context.Context, []byte) (*attestationgpu.Evidence, error) {
+	return nil, assert.AnError
+}

cmd/attestation-service/main.go

@@ -11,6 +11,7 @@ import (
 	"os"
 	"os/signal"
 	"syscall"
+	"time"
 
 	mglog "github.com/absmach/supermq/logger"
 	"github.com/caarlos0/env/v11"
@@ -22,6 +23,7 @@ import (
 	"github.com/ultravioletrs/cocos/pkg/attestation/azure"
 	"github.com/ultravioletrs/cocos/pkg/attestation/ccaa"
 	"github.com/ultravioletrs/cocos/pkg/attestation/eat"
+	attestationgpu "github.com/ultravioletrs/cocos/pkg/attestation/gpu"
 	"github.com/ultravioletrs/cocos/pkg/attestation/tdx"
 	"github.com/ultravioletrs/cocos/pkg/attestation/vtpm"
 	logclient "github.com/ultravioletrs/cocos/pkg/clients/grpc/log"
@@ -35,16 +37,18 @@ const (
 )
 
 type config struct {
-	LogLevel              string `env:"ATTESTATION_LOG_LEVEL"    envDefault:"debug"`
-	Vmpl                  int    `env:"ATTESTATION_VMPL"         envDefault:"2"`
-	AgentMaaURL           string `env:"AGENT_MAA_URL"            envDefault:"https://sharedeus2.eus2.attest.azure.net"`
-	AgentOSBuild          string `env:"AGENT_OS_BUILD"           envDefault:"UVC"`
-	AgentOSDistro         string `env:"AGENT_OS_DISTRO"          envDefault:"UVC"`
-	AgentOSType           string `env:"AGENT_OS_TYPE"            envDefault:"UVC"`
-	EATFormat             string `env:"ATTESTATION_EAT_FORMAT"   envDefault:"CBOR"` // JWT or CBOR
-	EATIssuer             string `env:"ATTESTATION_EAT_ISSUER"   envDefault:"cocos-attestation-service"`
-	UseCCAttestationAgent bool   `env:"USE_CC_ATTESTATION_AGENT" envDefault:"false"`
-	CCAgentAddress        string `env:"CC_AGENT_ADDRESS"         envDefault:"127.0.0.1:50002"`
+	LogLevel              string        `env:"ATTESTATION_LOG_LEVEL"    envDefault:"debug"`
+	Vmpl                  int           `env:"ATTESTATION_VMPL"         envDefault:"2"`
+	AgentMaaURL           string        `env:"AGENT_MAA_URL"            envDefault:"https://sharedeus2.eus2.attest.azure.net"`
+	AgentOSBuild          string        `env:"AGENT_OS_BUILD"           envDefault:"UVC"`
+	AgentOSDistro         string        `env:"AGENT_OS_DISTRO"          envDefault:"UVC"`
+	AgentOSType           string        `env:"AGENT_OS_TYPE"            envDefault:"UVC"`
+	EATFormat             string        `env:"ATTESTATION_EAT_FORMAT"   envDefault:"CBOR"` // JWT or CBOR
+	EATIssuer             string        `env:"ATTESTATION_EAT_ISSUER"   envDefault:"cocos-attestation-service"`
+	UseCCAttestationAgent bool          `env:"USE_CC_ATTESTATION_AGENT" envDefault:"false"`
+	CCAgentAddress        string        `env:"CC_AGENT_ADDRESS"         envDefault:"127.0.0.1:50002"`
+	GPUHelperPath         string        `env:"ATTESTATION_GPU_HELPER_PATH" envDefault:""`
+	GPUHelperTimeout      time.Duration `env:"ATTESTATION_GPU_HELPER_TIMEOUT" envDefault:"30s"`
 
 	// Future KBS Integration Configuration
 	// When KBS support is added, these fields will enable:
@@ -229,13 +233,24 @@ func main() {
 		return
 	}
 
+	gpuCollector, err := newGPUCollector(cfg)
+	if err != nil {
+		logger.Error(fmt.Sprintf("failed to configure GPU attestation collector: %s", err))
+		exitCode = 1
+		return
+	}
+	if gpuCollector != nil {
+		logger.Info(fmt.Sprintf("[ATTESTATION-SERVICE] GPU evidence collection enabled via helper %s", cfg.GPUHelperPath))
+	}
+
 	grpcServer := grpc.NewServer()
 	svc := &service{
-		provider:   provider,
-		logger:     logger,
-		signingKey: signingKey,
-		eatFormat:  cfg.EATFormat,
-		eatIssuer:  cfg.EATIssuer,
+		provider:     provider,
+		logger:       logger,
+		signingKey:   signingKey,
+		eatFormat:    cfg.EATFormat,
+		eatIssuer:    cfg.EATIssuer,
+		gpuCollector: gpuCollector,
 	}
 	attestationpb.RegisterAttestationServiceServer(grpcServer, svc)
 
@@ -267,11 +282,12 @@ func main() {
 
 type service struct {
 	attestationpb.UnimplementedAttestationServiceServer
-	provider   attestation.Provider
-	logger     *slog.Logger
-	signingKey *ecdsa.PrivateKey
-	eatFormat  string
-	eatIssuer  string
+	provider     attestation.Provider
+	logger       *slog.Logger
+	signingKey   *ecdsa.PrivateKey
+	eatFormat    string
+	eatIssuer    string
+	gpuCollector attestationgpu.Collector
 }
 
 func (s *service) FetchAttestation(ctx context.Context, req *attestationpb.AttestationRequest) (*attestationpb.AttestationResponse, error) {
@@ -330,12 +346,14 @@ func (s *service) FetchAttestation(ctx context.Context, req *attestationpb.Attes
 	}
 
 	// Create EAT claims from binary report
-	nonce := req.ReportData
-	if len(req.Nonce) > 0 {
-		nonce = req.Nonce
+	nonce := requestNonce(req)
+
+	claimOpts, err := s.claimOptions(ctx, req, platformType)
+	if err != nil {
+		return nil, err
 	}
 
-	claims, err := eat.NewEATClaims(binaryReport, nonce, platformType)
+	claims, err := eat.NewEATClaims(binaryReport, nonce, platformType, claimOpts...)
 	if err != nil {
 		s.logger.Error(fmt.Sprintf("failed to create EAT claims: %s", err))
 		return nil, fmt.Errorf("failed to create EAT claims: %w", err)

pkg/attestation/eat/eat.go

@@ -39,6 +39,7 @@ type EATClaims struct {
 	SNPExtensions  *SNPExtensions  `json:"x-cocos-sevsnp,omitempty"`
 	TDXExtensions  *TDXExtensions  `json:"x-cocos-tdx,omitempty"`
 	VTPMExtensions *VTPMExtensions `json:"x-cocos-vtpm,omitempty"`
+	GPUExtensions  *GPUExtensions  `json:"x-cocos-gpu,omitempty"`
 
 	// Original binary report (for verification)
 	RawReport []byte `json:"raw_report,omitempty"`
@@ -94,6 +95,36 @@ type VTPMExtensions struct {
 	Quote    []byte            `json:"quote,omitempty"`     // TPM quote
 }
 
+// GPUExtensions contains optional GPU attestation evidence that is bound to the
+// same attestation session as the root TEE evidence.
+type GPUExtensions struct {
+	Vendor         string `json:"vendor,omitempty" cbor:"vendor,omitempty"`
+	EvidenceFormat string `json:"evidence_format,omitempty" cbor:"evidence_format,omitempty"`
+	Nonce          []byte `json:"nonce,omitempty" cbor:"nonce,omitempty"`
+	EvidenceJSON   []byte `json:"evidence_json,omitempty" cbor:"evidence_json,omitempty"`
+}
+
+// ClaimsOption customizes EAT claims after the root platform claims are
+// extracted.
+type ClaimsOption func(*EATClaims) error
+
+// WithGPU attaches GPU evidence both as a typed extension and as an EAT submod.
+func WithGPU(gpu *GPUExtensions) ClaimsOption {
+	return func(claims *EATClaims) error {
+		if gpu == nil {
+			return nil
+		}
+
+		claims.GPUExtensions = gpu
+		if claims.Submods == nil {
+			claims.Submods = map[string]interface{}{}
+		}
+		claims.Submods["gpu"] = gpu
+
+		return nil
+	}
+}
+
 // DebugStatus constants (RFC 9711 Section 4.2.6).
 const (
 	DebugEnabled              = 0 // Debug is enabled
@@ -112,7 +143,7 @@ const (
 const MinNonceLength = 8
 
 // NewEATClaims creates EAT claims from binary attestation report.
-func NewEATClaims(report []byte, nonce []byte, platformType attestation.PlatformType) (*EATClaims, error) {
+func NewEATClaims(report []byte, nonce []byte, platformType attestation.PlatformType, opts ...ClaimsOption) (*EATClaims, error) {
 	if len(nonce) < MinNonceLength {
 		return nil, errors.New("eat_nonce must be at least 8 bytes long")
 	}
@@ -129,6 +160,12 @@ func NewEATClaims(report []byte, nonce []byte, platformType attestation.Platform
 		return nil, err
 	}
 
+	for _, opt := range opts {
+		if err := opt(claims); err != nil {
+			return nil, err
+		}
+	}
+
 	return claims, nil
 }
 

pkg/attestation/eat/eat_test.go

@@ -202,3 +202,24 @@ func TestNewEATClaims_Platforms(t *testing.T) {
 		})
 	}
 }
+
+func TestNewEATClaims_WithGPU(t *testing.T) {
+	gpuEvidence := &GPUExtensions{
+		Vendor:         "nvidia",
+		EvidenceFormat: "nvat-json",
+		Nonce:          []byte("gpu-nonce"),
+		EvidenceJSON:   []byte(`{"evidence":"gpu"}`),
+	}
+
+	claims, err := NewEATClaims(
+		[]byte("dummy report"),
+		[]byte("12345678"),
+		attestation.NoCC,
+		WithGPU(gpuEvidence),
+	)
+	assert.NoError(t, err)
+	assert.NotNil(t, claims.GPUExtensions)
+	assert.Equal(t, gpuEvidence, claims.GPUExtensions)
+	assert.Contains(t, claims.Submods, "gpu")
+	assert.Equal(t, gpuEvidence, claims.Submods["gpu"])
+}

pkg/attestation/gpu/collector.go

@@ -0,0 +1,133 @@
+// Copyright (c) Ultraviolet
+// SPDX-License-Identifier: Apache-2.0
+
+package gpu
+
+import (
+	"bytes"
+	"context"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"os/exec"
+	"strings"
+	"time"
+)
+
+const (
+	DefaultVendor         = "nvidia"
+	DefaultEvidenceFormat = "nvat-json"
+)
+
+// Collector retrieves GPU evidence for the current attestation session.
+type Collector interface {
+	Collect(ctx context.Context, nonce []byte) (*Evidence, error)
+}
+
+// Evidence contains low-level GPU evidence collected out-of-process.
+type Evidence struct {
+	Vendor         string
+	EvidenceFormat string
+	Nonce          []byte
+	RawEvidence    []byte
+}
+
+type commandCollector struct {
+	binaryPath         string
+	timeout            time.Duration
+	execCommandContext func(ctx context.Context, name string, arg ...string) *exec.Cmd
+}
+
+type helperRequest struct {
+	NonceHex string `json:"nonce_hex"`
+}
+
+type helperResponse struct {
+	Vendor         string          `json:"vendor,omitempty"`
+	EvidenceFormat string          `json:"evidence_format,omitempty"`
+	EvidenceJSON   json.RawMessage `json:"evidence_json"`
+}
+
+// NewCommandCollector creates a collector that shells out to a helper binary.
+// The helper is expected to read a JSON request on stdin and emit a JSON
+// response on stdout. See tools/nvidia-attestation-helper for the contract.
+func NewCommandCollector(binaryPath string, timeout time.Duration) (Collector, error) {
+	if strings.TrimSpace(binaryPath) == "" {
+		return nil, fmt.Errorf("gpu helper path cannot be empty")
+	}
+	if timeout <= 0 {
+		timeout = 30 * time.Second
+	}
+
+	return &commandCollector{
+		binaryPath:         binaryPath,
+		timeout:            timeout,
+		execCommandContext: exec.CommandContext,
+	}, nil
+}
+
+func (c *commandCollector) Collect(ctx context.Context, nonce []byte) (*Evidence, error) {
+	if len(nonce) == 0 {
+		return nil, fmt.Errorf("gpu nonce cannot be empty")
+	}
+
+	reqBody, err := json.Marshal(helperRequest{
+		NonceHex: hex.EncodeToString(nonce),
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal GPU helper request: %w", err)
+	}
+
+	runCtx := ctx
+	cancel := func() {}
+	if c.timeout > 0 {
+		runCtx, cancel = context.WithTimeout(ctx, c.timeout)
+	}
+	defer cancel()
+
+	stdout := &bytes.Buffer{}
+	stderr := &bytes.Buffer{}
+
+	cmd := c.execCommandContext(runCtx, c.binaryPath)
+	cmd.Stdin = bytes.NewReader(reqBody)
+	cmd.Stdout = stdout
+	cmd.Stderr = stderr
+
+	if err := cmd.Run(); err != nil {
+		errMsg := strings.TrimSpace(stderr.String())
+		if errMsg == "" {
+			errMsg = err.Error()
+		}
+		return nil, fmt.Errorf("gpu helper failed: %s", errMsg)
+	}
+
+	var resp helperResponse
+	if err := json.Unmarshal(stdout.Bytes(), &resp); err != nil {
+		return nil, fmt.Errorf("failed to decode GPU helper response: %w", err)
+	}
+	if len(resp.EvidenceJSON) == 0 {
+		return nil, fmt.Errorf("gpu helper response did not contain evidence_json")
+	}
+
+	vendor := resp.Vendor
+	if vendor == "" {
+		vendor = DefaultVendor
+	}
+
+	evidenceFormat := resp.EvidenceFormat
+	if evidenceFormat == "" {
+		evidenceFormat = DefaultEvidenceFormat
+	}
+
+	return &Evidence{
+		Vendor:         vendor,
+		EvidenceFormat: evidenceFormat,
+		Nonce:          append([]byte(nil), nonce...),
+		RawEvidence:    append([]byte(nil), resp.EvidenceJSON...),
+	}, nil
+}
+
+// SetExecCommandContext allows tests to inject a mock exec.CommandContext.
+func (c *commandCollector) SetExecCommandContext(cmdFunc func(ctx context.Context, name string, arg ...string) *exec.Cmd) {
+	c.execCommandContext = cmdFunc
+}

pkg/attestation/gpu/collector_test.go

@@ -0,0 +1,137 @@
+// Copyright (c) Ultraviolet
+// SPDX-License-Identifier: Apache-2.0
+
+package gpu
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"os/exec"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func fakeExecCommandContext(_ context.Context, name string, arg ...string) *exec.Cmd {
+	args := append([]string{"-test.run=TestGPUHelperProcess", "--", name}, arg...)
+	cmd := exec.Command(os.Args[0], args...)
+	cmd.Env = append(os.Environ(), "GO_WANT_GPU_HELPER_PROCESS=1")
+	return cmd
+}
+
+func TestGPUHelperProcess(t *testing.T) {
+	if os.Getenv("GO_WANT_GPU_HELPER_PROCESS") != "1" {
+		return
+	}
+
+	args := os.Args
+	for i := range args {
+		if args[i] == "--" {
+			args = args[i+1:]
+			break
+		}
+	}
+
+	if len(args) == 0 {
+		fmt.Fprintln(os.Stderr, "missing helper name")
+		os.Exit(2)
+	}
+
+	switch args[0] {
+	case "helper-error":
+		fmt.Fprintln(os.Stderr, "simulated helper failure")
+		os.Exit(1)
+	case "helper-invalid-json":
+		fmt.Fprintln(os.Stdout, "{not-json")
+		os.Exit(0)
+	case "helper-empty-evidence":
+		fmt.Fprintln(os.Stdout, `{"vendor":"nvidia","evidence_format":"nvat-json"}`)
+		os.Exit(0)
+	default:
+		var req helperRequest
+		if err := json.NewDecoder(os.Stdin).Decode(&req); err != nil {
+			fmt.Fprintln(os.Stderr, err.Error())
+			os.Exit(1)
+		}
+
+		resp := helperResponse{
+			Vendor:         "nvidia",
+			EvidenceFormat: "nvat-json",
+			EvidenceJSON:   json.RawMessage(fmt.Sprintf(`{"nonce_hex":"%s","evidence":"ok"}`, req.NonceHex)),
+		}
+		if err := json.NewEncoder(os.Stdout).Encode(resp); err != nil {
+			fmt.Fprintln(os.Stderr, err.Error())
+			os.Exit(1)
+		}
+		os.Exit(0)
+	}
+}
+
+func TestNewCommandCollector(t *testing.T) {
+	collector, err := NewCommandCollector("helper", time.Second)
+	assert.NoError(t, err)
+	assert.NotNil(t, collector)
+
+	collector, err = NewCommandCollector("", time.Second)
+	assert.Error(t, err)
+	assert.Nil(t, collector)
+}
+
+func TestCommandCollectorCollect(t *testing.T) {
+	collector, err := NewCommandCollector("helper-success", time.Second)
+	require.NoError(t, err)
+
+	cmdCollector, ok := collector.(*commandCollector)
+	require.True(t, ok)
+	cmdCollector.SetExecCommandContext(fakeExecCommandContext)
+
+	evidence, err := collector.Collect(context.Background(), []byte{0xaa, 0xbb, 0xcc})
+	require.NoError(t, err)
+	assert.Equal(t, DefaultVendor, evidence.Vendor)
+	assert.Equal(t, DefaultEvidenceFormat, evidence.EvidenceFormat)
+	assert.Equal(t, []byte{0xaa, 0xbb, 0xcc}, evidence.Nonce)
+	assert.JSONEq(t, `{"nonce_hex":"aabbcc","evidence":"ok"}`, string(evidence.RawEvidence))
+}
+
+func TestCommandCollectorCollectErrors(t *testing.T) {
+	tests := []struct {
+		name       string
+		helperName string
+		wantErr    string
+	}{
+		{
+			name:       "helper process failure",
+			helperName: "helper-error",
+			wantErr:    "gpu helper failed: simulated helper failure",
+		},
+		{
+			name:       "invalid json response",
+			helperName: "helper-invalid-json",
+			wantErr:    "failed to decode GPU helper response",
+		},
+		{
+			name:       "missing evidence payload",
+			helperName: "helper-empty-evidence",
+			wantErr:    "gpu helper response did not contain evidence_json",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			collector, err := NewCommandCollector(tt.helperName, time.Second)
+			require.NoError(t, err)
+
+			cmdCollector, ok := collector.(*commandCollector)
+			require.True(t, ok)
+			cmdCollector.SetExecCommandContext(fakeExecCommandContext)
+
+			_, err = collector.Collect(context.Background(), []byte{0xaa})
+			require.Error(t, err)
+			assert.Contains(t, err.Error(), tt.wantErr)
+		})
+	}
+}

tools/nvidia-attestation-helper/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "nvidia-attestation-helper"
+version = "0.1.0"
+edition = "2021"
+license = "Apache-2.0"
+
+[dependencies]
+anyhow = "1"
+nv-attestation-sdk = { git = "https://github.com/NVIDIA/attestation-sdk", branch = "main", subdirectory = "nv-attestation-sdk-rust/nv-attestation-sdk" }
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"

tools/nvidia-attestation-helper/README.md

@@ -0,0 +1,62 @@
+# NVIDIA Attestation Helper
+
+This helper wraps NVIDIA's Rust attestation SDK low-level GPU evidence
+collection flow and exposes a tiny JSON stdin/stdout protocol that the Go
+attestation service can call.
+
+## Request
+
+The helper reads a single JSON object from stdin:
+
+```json
+{
+  "nonce_hex": "aabbccdd"
+}
+```
+
+## Response
+
+On success it writes:
+
+```json
+{
+  "vendor": "nvidia",
+  "evidence_format": "nvat-json",
+  "evidence_json": { "...": "..." }
+}
+```
+
+`evidence_json` is the JSON emitted by `GpuEvidence::to_json()`.
+
+## Build
+
+Prerequisites:
+
+- Rust 1.80+
+- `libnvat.so.1`
+- Clang/LLVM
+- NVIDIA GPU driver with NVML support
+
+If you are using a system-installed NVAT library:
+
+```bash
+export NVAT_USE_SYSTEM_LIB=1
+cargo build --release
+```
+
+If you built NVAT locally, make sure the C library is installed or on
+`LD_LIBRARY_PATH` before building or running the helper.
+
+## Use With COCOS
+
+Point the attestation service at the compiled binary:
+
+```bash
+export ATTESTATION_GPU_HELPER_PATH=/path/to/nvidia-attestation-helper
+export ATTESTATION_GPU_HELPER_TIMEOUT=30s
+```
+
+When a helper path is configured, COCOS will attempt to collect GPU evidence
+opportunistically. If the host does not expose a supported CC-capable NVIDIA
+GPU, the attestation service skips GPU evidence and still returns the root
+CPU/TEE attestation.

tools/nvidia-attestation-helper/src/main.rs

@@ -0,0 +1,47 @@
+use anyhow::Context;
+use nv_attestation_sdk::{GpuEvidence, GpuEvidenceSource, Nonce, NvatSdk};
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+use std::io::{stdin, stdout, Write};
+
+#[derive(Debug, Deserialize)]
+struct Request {
+    nonce_hex: String,
+}
+
+#[derive(Debug, Serialize)]
+struct Response {
+    vendor: &'static str,
+    evidence_format: &'static str,
+    evidence_json: Value,
+}
+
+fn main() -> anyhow::Result<()> {
+    let _sdk = NvatSdk::init_default().context("failed to initialize NVIDIA attestation SDK")?;
+
+    let req: Request =
+        serde_json::from_reader(stdin().lock()).context("failed to decode helper request")?;
+    let nonce = Nonce::from_hex(&req.nonce_hex).context("failed to parse nonce")?;
+
+    let evidence_source =
+        GpuEvidenceSource::create_nvml().context("failed to create NVML evidence source")?;
+    let evidence = GpuEvidence::collect(&evidence_source, Some(&nonce))
+        .context("failed to collect evidence")?;
+    let evidence_json = evidence
+        .to_json()
+        .context("failed to serialize GPU evidence to JSON")?;
+    let evidence_json: Value =
+        serde_json::from_str(&evidence_json).context("failed to parse serialized evidence JSON")?;
+
+    let resp = Response {
+        vendor: "nvidia",
+        evidence_format: "nvat-json",
+        evidence_json,
+    };
+
+    let mut out = stdout().lock();
+    serde_json::to_writer(&mut out, &resp).context("failed to write helper response")?;
+    let _ = out.write_all(b"\n");
+
+    Ok(())
+}