Tpm2AttestationCertificationAuthority

Test project for Attestation CA, previously referred to as Privacy CA.

+-----+ ------ ek_rsa.cert --->  +--------------+
|     | ------ ak_rsa.pub ---->  | Attestation  |
| T P | ------ ak_rsa.name --->  | Certificate  |
| R L |                          |  Authority   |
| U A | <---- credentials -----  |              |
| S T | <---- ak_cert.enc -----  +--------------+
| T F |                       
| E O | ( Decrypt AKCert using TPM.EKpriv / TPM2_ActivateCredential )
| D R |    
|   M |    
| M   |                           +--------------+
| O   | -------- ak_cert ------>  |    Remote    |
| D   | ------ tpm2_quote ----->  | Attestation  |
| U   |                           |    Server    |
| L   |                           +--------------+
| E   |
+-----+

Attestation CA is responsible for:

• Ensuring proof of ownership, i.e. TPMs must authenticate by successfully decrypting the TPM Credential using TPM2_ActivateCredentials.
• Validating TPM Endorsement Key Certificate against trusted TPM manufacturer. (Optionally, not yet implemented: verify Endorsement Key against trusted list of specific tpm keys)
• Generating an Authentication Certificate for the TPM's Attestation Key. The certificate should reflect the privacy and identification requirements of the attestation system, and validity etc should be set appropriately.

Dependencies

• Depends on gov.niarl.his.privacyca from opencit.
• Read/write TPM2Tools 3.1.0 compatible files.

Command line

The CA can be used from command line:

java -cp bin:libs/bcpkix-jdk15on-160.jar:libs/bcprov-jdk15on-160.jar \
blaufish.test.tpm2.Tpm2AttestationCACli \
  --in-akname=test/ak_rsa.name \
  --in-akpub=test/ak_rsa.pub \
  --in-ekcert=test/nvread.1c0002.cert \
  --in-tpm-manufacturer-cert=test/OptigaRsaMfrCA022.crt \
  --out-cacert=test/temp.ca.cert \
  --out-tpm-akcert-encrypted=test/temp.akcert.encrypted \
  --out-tpm-credential=test/temp.credential

The CA will generate:

• test/temp.crediantial, a file that can be only decrypted with the TPM Endorsement Key using the tpm2_activatecredential (Proof of Ownership). In this demo, the credentials contained within is an AES-key.
• test/temp.akcert.encrypted, a file that can only be decrypted by the AES-key hidden inside the credentials.
• temp.ca.cert, the root CA certificate (just a dummy for now).

Input files are generated as follows:

tpm2_evictcontrol -Q -A o -H 0x81010007 --tcti device:/dev/tpmrm0
tpm2_evictcontrol -Q -A o -H 0x81010008 --tcti device:/dev/tpmrm0
tpm2_getpubek --tcti device:/dev/tpmrm0 -H 0x81010007 -g 0x0001 -f ek_rsa.pub
tpm2_getpubak --tcti device:/dev/tpmrm0 -E 0x81010007 -k 0x81010008 -g 0x0001 -D 0x000b -s 0x0016 -f ak_rsa.pub -n ak_rsa.name
loaded-key:
  handle: 80ffffff
  name: 000bd3dc102187be259f12f361bc0c231f5a9788a48a6a832d11d99dc8ce1b5eafca

Bugs and future improvements

• TPMT_PUBLIC parsing of TPM Authentication Key is, eh, very crude and not portable.
• Whitelisting specific TPMs Endorsement Keys is not yet implemented.
• Authentication Key Certificates generated does not include anything useful currently.
• gov.niarl.his.privacyca classes only support RSA, not ECC.