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Extract and return PCR digest for Quote on TPM1.2 (#16)

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go-tspi and go-tpm return different values for "quote".
In both cases we want the PCR digest so we extract it from the data
returned.
This commit is contained in:
DenisKarch 2019-04-24 11:19:18 -07:00 committed by Tom D
parent 4342561e0f
commit 3829815b47
2 changed files with 12 additions and 3 deletions
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11
attest/tpm_linux.go
View File

@ -341,14 +341,21 @@ func (k *Key) ActivateCredential(t *TPM, in EncryptedCredential) ([]byte, error)
}
func (k *Key) quote12(ctx *tspi.Context, nonce []byte) (*Quote, error) {
quote, rawSig, err := attestation.GetQuote(ctx, k.KeyBlob, nonce)
quoteInfo, rawSig, err := attestation.GetQuote(ctx, k.KeyBlob, nonce)
if err != nil {
return nil, fmt.Errorf("GetQuote() failed: %v", err)
}
// go-tspi returns TPM_QUOTE_INFO. We only want the digest of the PCRs
var version [4]byte
var quot [4]byte
var digest [20]byte
if _, err := tpmutil.Unpack(quoteInfo, &version, &quot, &digest); err != nil {
return nil, fmt.Errorf("unable to parse PCR digest from TPM_QUOTE_INFO: %v", err)
}
return &Quote{
Version: TPMVersion12,
Quote: quote,
Quote: digest[:],
Signature: rawSig,
}, nil
}

4
attest/tpm_windows.go
View File

@ -19,6 +19,7 @@ package attest
import (
"crypto"
"crypto/rand"
"crypto/sha1"
"encoding/base64"
"encoding/binary"
"encoding/json"
@ -271,10 +272,11 @@ func (k *Key) quote12(tpm io.ReadWriter, nonce []byte) (*Quote, error) {
selectedPCRs[pcr] = pcr
}
sig, quote, err := tpm1.Quote(tpm, k.hnd12, nonce, selectedPCRs[:], wellKnownAuth[:])
sig, pcrc, err := tpm1.Quote(tpm, k.hnd12, nonce, selectedPCRs[:], wellKnownAuth[:])
if err != nil {
return nil, fmt.Errorf("Quote() failed: %v", err)
}
quote := sha1.Sum(pcrc)
return &Quote{
Quote: quote,
Signature: sig,