Error out when TPM key files are used on Windows

aws_signing_helper/tpm_signer.go

@@ -1,20 +1,9 @@
 package aws_signing_helper
 
 import (
-	"crypto"
-	"crypto/ecdsa"
-	"crypto/sha1"
-	"crypto/sha256"
-	"crypto/sha512"
 	"crypto/x509"
 	"encoding/asn1"
 	"encoding/pem"
-	"errors"
-	"fmt"
-	"io"
-	"math/big"
-	"strconv"
-	"strings"
 
 	tpm2 "github.com/google/go-tpm/tpm2"
 	tpmutil "github.com/google/go-tpm/tpmutil"
@@ -79,244 +68,6 @@ var primaryParams = tpm2.Public{
 	},
 }
 
-// Returns the public key associated with this TPMv2Signer
-func (tpmv2Signer *TPMv2Signer) Public() crypto.PublicKey {
-	ret, _ := tpmv2Signer.public.Key()
-	return ret
-}
-
-// Closes this TPMv2Signer
-func (tpmv2Signer *TPMv2Signer) Close() {
-	tpmv2Signer.password = ""
-}
-
-func checkCapability(rw io.ReadWriter, algo tpm2.Algorithm) error {
-	descs, _, err := tpm2.GetCapability(rw, tpm2.CapabilityAlgs, 1, uint32(algo))
-	if err != nil {
-		errMsg := fmt.Sprintf("error trying to get capability from TPM for the algorithm (%s)", algo)
-		return errors.New(errMsg)
-	}
-	if tpm2.Algorithm(descs[0].(tpm2.AlgorithmDescription).ID) != algo {
-		errMsg := fmt.Sprintf("unsupported algorithm (%s) for TPM", algo)
-		return errors.New(errMsg)
-	}
-
-	return nil
-}
-
-// Implements the crypto.Signer interface and signs the passed in digest
-func (tpmv2Signer *TPMv2Signer) Sign(rand io.Reader, digest []byte, opts crypto.SignerOpts) (signature []byte, err error) {
-	var (
-		keyHandle tpmutil.Handle
-	)
-
-	rw, err := openTPM()
-	if err != nil {
-		return nil, err
-	}
-	defer rw.Close()
-
-	if tpmv2Signer.handle != 0 {
-		keyHandle = tpmv2Signer.handle
-	} else {
-		parentHandle := tpmutil.Handle(tpmv2Signer.tpmData.Parent)
-		if !handleIsPersistent(tpmv2Signer.tpmData.Parent) {
-			// Parent and owner passwords aren't supported currently when creating a primary given a persistent handle for the parent
-			parentHandle, _, err = tpm2.CreatePrimary(rw, tpmutil.Handle(tpmv2Signer.tpmData.Parent), tpm2.PCRSelection{}, "", "", primaryParams)
-			if err != nil {
-				return nil, err
-			}
-			defer tpm2.FlushContext(rw, parentHandle)
-		}
-
-		keyHandle, _, err = tpm2.Load(rw, parentHandle, "", tpmv2Signer.tpmData.Pubkey[2:], tpmv2Signer.tpmData.Privkey[2:])
-		if err != nil {
-			return nil, err
-		}
-		defer tpm2.FlushContext(rw, keyHandle)
-	}
-
-	var algo tpm2.Algorithm
-	var shadigest []byte
-
-	switch opts.HashFunc() {
-	case crypto.SHA256:
-		sha256digest := sha256.Sum256(digest)
-		shadigest = sha256digest[:]
-		algo = tpm2.AlgSHA256
-	case crypto.SHA384:
-		sha384digest := sha512.Sum384(digest)
-		shadigest = sha384digest[:]
-		algo = tpm2.AlgSHA384
-	case crypto.SHA512:
-		sha512digest := sha512.Sum512(digest)
-		shadigest = sha512digest[:]
-		algo = tpm2.AlgSHA512
-	}
-
-	if tpmv2Signer.public.Type == tpm2.AlgECC {
-		// Check to see that ECDSA is supported for signing
-		err = checkCapability(rw, tpm2.AlgECC)
-		if err != nil {
-			return nil, err
-		}
-
-		// For an EC key we lie to the TPM about what the hash is.
-		// It doesn't actually matter what the original digest was;
-		// the algo we feed to the TPM is *purely* based on the
-		// size of the curve itself. We truncate the actual digest,
-		// or pad with zeroes, to the byte size of the key.
-		pubKey, err := tpmv2Signer.public.Key()
-		if err != nil {
-			return nil, err
-		}
-		ecPubKey, ok := pubKey.(*ecdsa.PublicKey)
-		if !ok {
-			return nil, errors.New("failed to obtain ecdsa.PublicKey")
-		}
-		bitSize := ecPubKey.Curve.Params().BitSize
-		byteSize := (bitSize + 7) / 8
-		if byteSize > sha512.Size {
-			byteSize = sha512.Size
-		}
-		switch byteSize {
-		case sha512.Size:
-			algo = tpm2.AlgSHA512
-		case sha512.Size384:
-			algo = tpm2.AlgSHA384
-		case sha512.Size256:
-			algo = tpm2.AlgSHA256
-		case sha1.Size:
-			algo = tpm2.AlgSHA1
-		default:
-			return nil, errors.New("unsupported curve")
-		}
-
-		if len(shadigest) > byteSize {
-			shadigest = shadigest[:byteSize]
-		}
-
-		for len(shadigest) < byteSize {
-			shadigest = append([]byte{0}, shadigest...)
-		}
-
-		sig, err := tpmv2Signer.signHelper(rw, keyHandle, shadigest,
-			&tpm2.SigScheme{Alg: tpm2.AlgECDSA, Hash: algo})
-		if err != nil {
-			return nil, err
-		}
-		signature, err = asn1.Marshal(struct {
-			R *big.Int
-			S *big.Int
-		}{sig.ECC.R, sig.ECC.S})
-		if err != nil {
-			return nil, err
-		}
-	} else {
-		// Check to see that the requested hash function is supported
-		err = checkCapability(rw, algo)
-		if err != nil {
-			return nil, err
-		}
-
-		// Check to see that RSASSA is supported for signing
-		err = checkCapability(rw, tpm2.AlgRSASSA)
-		if err != nil {
-			return nil, err
-		}
-
-		sig, err := tpmv2Signer.signHelper(rw, keyHandle, shadigest,
-			&tpm2.SigScheme{Alg: tpm2.AlgRSASSA, Hash: algo})
-		if err != nil {
-			return nil, err
-		}
-		signature = sig.RSA.Signature
-	}
-	return signature, nil
-}
-
-func (tpmv2Signer *TPMv2Signer) signHelper(rw io.ReadWriter, keyHandle tpmutil.Handle, digest tpmutil.U16Bytes, sigScheme *tpm2.SigScheme) (*tpm2.Signature, error) {
-	passwordPromptInput := PasswordPromptProps{
-		InitialPassword: tpmv2Signer.password,
-		NoPassword:      tpmv2Signer.emptyAuth,
-		CheckPassword: func(password string) (interface{}, error) {
-			return tpm2.Sign(rw, keyHandle, password, digest, nil, sigScheme)
-		},
-		IncorrectPasswordMsg:               "incorrect TPM key password",
-		Prompt:                             "Please enter your TPM key password:",
-		Reprompt:                           "Incorrect TPM key password. Please try again:",
-		ParseErrMsg:                        "unable to read your TPM key password",
-		CheckPasswordAuthorizationErrorMsg: TPM_RC_AUTH_FAIL,
-	}
-
-	password, sig, err := PasswordPrompt(passwordPromptInput)
-	if err != nil {
-		return nil, err
-	}
-
-	tpmv2Signer.password = password
-	return sig.(*tpm2.Signature), err
-}
-
-// Gets the x509.Certificate associated with this TPMv2Signer
-func (tpmv2Signer *TPMv2Signer) Certificate() (*x509.Certificate, error) {
-	return tpmv2Signer.cert, nil
-}
-
-// Gets the certificate chain associated with this TPMv2Signer
-func (tpmv2Signer *TPMv2Signer) CertificateChain() (chain []*x509.Certificate, err error) {
-	return tpmv2Signer.certChain, nil
-}
-
-/*
- * DER forbids storing a BOOLEAN as anything but 0x00 or 0xFF,
- * 0x01, and the Go asn1 parser cannot be relaxed. But both
- * OpenSSL ENGINEs which produce these keys have at least in
- * the past emitted 0x01 as the value, leading to an Unmarshal
- * failure with 'asn1: syntax error: invalid boolean'. So...
- */
-func fixupEmptyAuth(tpmData *[]byte) {
-	var pos int = 0
-
-	// Skip the SEQUENCE tag and length
-	if len(*tpmData) < 2 || (*tpmData)[0] != 0x30 {
-		return
-	}
-
-	// Don't care what the SEQUENCE length is, just skip it
-	pos = 1
-	lenByte := (*tpmData)[pos]
-	if lenByte < 0x80 {
-		pos = pos + 1
-	} else if lenByte < 0x85 {
-		pos = pos + 1 + int(lenByte) - 0x80
-	} else {
-		return
-	}
-
-	if len(*tpmData) <= pos {
-		return
-	}
-
-	// Use asn1.Unmarshal to eat the OID; we care about 'rest'
-	var oid asn1.ObjectIdentifier
-	rest, err := asn1.Unmarshal((*tpmData)[pos:], &oid)
-	if err != nil || rest == nil || !oid.Equal(oidLoadableKey) || len(rest) < 5 {
-		return
-	}
-
-	// If the OPTIONAL EXPLICIT BOOLEAN [0] exists, it'll be here
-	pos = len(*tpmData) - len(rest)
-
-	if (*tpmData)[pos] == 0xa0 && // Tag
-		(*tpmData)[pos+1] == 0x03 && // length
-		(*tpmData)[pos+2] == 0x01 &&
-		(*tpmData)[pos+3] == 0x01 &&
-		(*tpmData)[pos+4] == 0x01 {
-		(*tpmData)[pos+4] = 0xff
-	}
-}
-
 type GetTPMv2SignerOpts struct {
 	certificate      *x509.Certificate
 	certificateChain []*x509.Certificate
@@ -325,120 +76,3 @@ type GetTPMv2SignerOpts struct {
 	emptyAuth        bool
 	handle           string
 }
-
-// Returns a TPMv2Signer, that can be used to sign a payload through a TPMv2-compatible
-// cryptographic device
-func GetTPMv2Signer(opts GetTPMv2SignerOpts) (signer Signer, signingAlgorithm string, err error) {
-	var (
-		certificate      *x509.Certificate
-		certificateChain []*x509.Certificate
-		keyPem           *pem.Block
-		password         string
-		emptyAuth        bool
-		tpmData          tpm2_TPMKey
-		handle           tpmutil.Handle
-		public           tpm2.Public
-		private          []byte
-	)
-
-	certificate = opts.certificate
-	certificateChain = opts.certificateChain
-	keyPem = opts.keyPem
-	password = opts.password
-	emptyAuth = opts.emptyAuth
-
-	// If a handle is provided instead of a TPM key file
-	if opts.handle != "" {
-		handleParts := strings.Split(opts.handle, ":")
-		if len(handleParts) != 2 {
-			return nil, "", errors.New("invalid TPM handle format")
-		}
-		hexHandleStr := handleParts[1]
-		if strings.HasPrefix(hexHandleStr, "0x") {
-			hexHandleStr = hexHandleStr[2:]
-		}
-		handleValue, err := strconv.ParseUint(hexHandleStr, 16, 32)
-		if err != nil {
-			return nil, "", errors.New("invalid hex TPM handle value")
-		}
-		handle = tpmutil.Handle(handleValue)
-
-		// Read the public key from the loaded key within the TPM
-		rw, err := openTPM()
-		if err != nil {
-			return nil, "", err
-		}
-		defer rw.Close()
-
-		public, _, _, err = tpm2.ReadPublic(rw, handle)
-		if err != nil {
-			return nil, "", err
-		}
-	} else {
-		fixupEmptyAuth(&keyPem.Bytes)
-		_, err = asn1.Unmarshal(keyPem.Bytes, &tpmData)
-		if err != nil {
-			return nil, "", err
-		}
-
-		emptyAuth = tpmData.EmptyAuth
-		if emptyAuth && password != "" {
-			return nil, "", errors.New("password is provided but TPM key file indicates that one isn't required")
-		}
-
-		if !tpmData.Oid.Equal(oidLoadableKey) {
-			return nil, "", errors.New("invalid OID for TPMv2 key:" + tpmData.Oid.String())
-		}
-
-		if tpmData.Policy != nil || tpmData.AuthPolicy != nil {
-			return nil, "", errors.New("TPMv2 policy not implemented yet")
-		}
-		if tpmData.Secret != nil {
-			return nil, "", errors.New("TPMv2 key has 'secret' field which should not be set")
-		}
-
-		if !handleIsPersistent(tpmData.Parent) &&
-			tpmData.Parent != int(tpm2.HandleOwner) &&
-			tpmData.Parent != int(tpm2.HandleNull) &&
-			tpmData.Parent != int(tpm2.HandleEndorsement) &&
-			tpmData.Parent != int(tpm2.HandlePlatform) {
-			return nil, "", errors.New("invalid parent for TPMv2 key")
-		}
-		if len(tpmData.Pubkey) < 2 ||
-			len(tpmData.Pubkey)-2 != (int(tpmData.Pubkey[0])<<8)+int(tpmData.Pubkey[1]) {
-			return nil, "", errors.New("invalid length for TPMv2 PUBLIC blob")
-		}
-
-		public, err = tpm2.DecodePublic(tpmData.Pubkey[2:])
-		if err != nil {
-			return nil, "", err
-		}
-
-		if len(tpmData.Privkey) < 2 ||
-			len(tpmData.Privkey)-2 != (int(tpmData.Privkey[0])<<8)+int(tpmData.Privkey[1]) {
-			return nil, "", errors.New("invalid length for TPMv2 PRIVATE blob")
-		}
-		private = tpmData.Privkey[2:]
-	}
-
-	switch public.Type {
-	case tpm2.AlgRSA:
-		signingAlgorithm = aws4_x509_rsa_sha256
-	case tpm2.AlgECC:
-		signingAlgorithm = aws4_x509_ecdsa_sha256
-	default:
-		return nil, "", errors.New("unsupported TPMv2 key type")
-	}
-
-	return &TPMv2Signer{
-			certificate,
-			certificateChain,
-			tpmData,
-			public,
-			private,
-			password,
-			emptyAuth,
-			handle,
-		},
-		signingAlgorithm, nil
-}