control/controlclient: back out HW key attestation (#17664)

Temporarily back out the TPM-based hw attestation code while we debug
Windows exceptions.

Updates tailscale/corp#31269

Signed-off-by: Patrick O'Doherty <patrick@tailscale.com>
(cherry picked from commit a760cbe33f)

control/controlclient/direct.go

@@ -7,8 +7,6 @@ import (
 	"bytes"
 	"cmp"
 	"context"
-	"crypto"
-	"crypto/sha256"
 	"encoding/binary"
 	"encoding/json"
 	"errors"
@@ -948,26 +946,6 @@ func (c *Direct) sendMapRequest(ctx context.Context, isStreaming bool, nu Netmap
 		ConnectionHandleForTest: connectionHandleForTest,
 	}
 
-	// If we have a hardware attestation key, sign the node key with it and send
-	// the key & signature in the map request.
-	if buildfeatures.HasTPM {
-		if k := persist.AsStruct().AttestationKey; k != nil && !k.IsZero() {
-			hwPub := key.HardwareAttestationPublicFromPlatformKey(k)
-			request.HardwareAttestationKey = hwPub
-
-			t := c.clock.Now()
-			msg := fmt.Sprintf("%d|%s", t.Unix(), nodeKey.String())
-			digest := sha256.Sum256([]byte(msg))
-			sig, err := k.Sign(nil, digest[:], crypto.SHA256)
-			if err != nil {
-				c.logf("failed to sign node key with hardware attestation key: %v", err)
-			} else {
-				request.HardwareAttestationKeySignature = sig
-				request.HardwareAttestationKeySignatureTimestamp = t
-			}
-		}
-	}
-
 	var extraDebugFlags []string
 	if buildfeatures.HasAdvertiseRoutes && hi != nil && c.netMon != nil && !c.skipIPForwardingCheck &&
 		ipForwardingBroken(hi.RoutableIPs, c.netMon.InterfaceState()) {