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Trusted Platform Module 2.0 » History » Version 124

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Andreas Steffen, 02.01.2021 11:38

Trusted Platform Module 2.0

Connect to a TPM 2.0 Device

Install the tpm2-tss Software Stack and the tpm2-tools Command Set

In order to connect to a TPM 2.0 hardware or firmware device a software stack implementing the TCG TSS 2.0 System Level API is needed. An excellent open source tpm2-tss library is available from the tpm2-software project which also offers a set of tpm2-tools which itself uses the TCG TSS 2.0 Enhanced System Level API.

When using the latest strongswan-5.9.1 version with a Linux 5.4 kernel or newer, we recommend these latest versions:

Support for earlier strongSwan versions and Linux kernels can be found here.

In order to test if we can connect to the TPM 2.0 device we list all persistent keys stored in the Non-Volatile (NV) RAM:

tpm2_getcap handles-persistent
- 0x81000001
- 0x81000002
- 0x81010001

A manual showing all tpm2-tools functions with their arguments can be found here. The access to the /dev/tpmrm0 TPM resource manager device requires root rights on most Linux platforms. But e.g. with Ubuntu, adding the user to the tss group enables direct access to the TPM device:

sudo usermod -a -G tss <username>

Enable the strongSwan tpm Plugin

The strongSwan libtpmtss tpm plugin and the TSS2 interface are enabled and built with the following options

./configure --enable-tss-tss2 --enable-tpm  ...

With the strongSwan pki tool we can now list the persistent key stored under the handle 0x81010001

pki --print --type priv --keyid 0x81010001 --debug 2

With debug level 2 some basic information on the TPM device is shown; A second generation Intel firmware TPM running on the Intel Management Engine is employed. Both SHA1 and SHA256 PCR banks are available:
TPM 2.0 - manufacturer: INTC (Intel) rev: 01.38 2018 
TPM 2.0 - algorithms: RSA SHA1 HMAC AES MGF1 KEYEDHASH XOR SHA256 RSASSA RSAES RSAPSS OAEP ECDSA ECDH ECDAA ECSCHNORR KDF1_SP800_56A KDF1_SP800_108 ECC SYMCIPHER CTR OFB CBC CFB ECB
TPM 2.0 - ECC curves: NIST_P256 BN_P256
TPM 2.0 - PCR banks: SHA1 SHA256

Apparently the analyzed persistent key can be used for encryption only because no signature algorithm is defined:
TPM 2.0 via TSS2 v2 available
signature algorithm is NULL with ERROR hash

Debug level 2 shows that pki extracts the public key from the TPM and converts it into a standard PKCS#1 format:
L0 - subjectPublicKeyInfo:
L1 - algorithm:
L2 - algorithmIdentifier:
L3 - algorithm:
  'rsaEncryption'
L1 - subjectPublicKey:
-- > --
L0 - RSAPublicKey:
L1 - modulus:
L1 - publicExponent:
-- < --

At the end of the output the fingerprint of the 2048 bit RSA key is listed:
  privkey:   RSA 2048 bits
  keyid:     ee:c7:bf:5a:de:0f:11:84:2c:86:2b:69:84:ba:65:b9:81:d2:a9:45
  subjkey:   df:f2:e9:e7:79:98:f0:d2:0b:62:db:c0:5c:2c:eb:45:73:85:e9:79

Derive a Persistent RSA Endorsement Key

The tpm2_createek command derives a 2048 bit RSA Endorsement Key (EK) in a deterministic way from the secret Endorsement Primary Seed unique to each TPM device and makes the key persistent in the non-volatile memory of the TPM under the object handle 0x81010002

tpm2_createek -G rsa -c 0x81010002

Using the tpm2_getcap command we can check that the newly derived Endorsement Key has been persisted in the NV RAM

tpm2_getcap handles-persistent
- 0x81000001
- 0x81000002
- 0x81010001
- 0x81010002

Listing the key properties shows that the 2048 bit Endorsement Key already exists under the handle 0x81010001 analyzed in the previous section
pki --print --type priv --keyid 0x81010002
TPM 2.0 via TSS2 v2 available
signature algorithm is NULL with ERROR hash
  privkey:   RSA 2048 bits
  keyid:     ee:c7:bf:5a:de:0f:11:84:2c:86:2b:69:84:ba:65:b9:81:d2:a9:45
  subjkey:   df:f2:e9:e7:79:98:f0:d2:0b:62:db:c0:5c:2c:eb:45:73:85:e9:79

We therefore delete the duplicate key with the following tpm2_evictcontrol command

tpm2_evictcontrol -c 0x81010002
persistent-handle: 0x81010002
action: evicted

The key removal can be verified with
tpm2_getcap handles-persistent
- 0x81000001
- 0x81000002
- 0x81010001

Derive a Persistent ECC Endorsement Key

Again using the tpm2_createek command we derive a 256 bit ECC Endorsement Key (EK) in a deterministic way from the secret Endorsement Primary Seed unique to each TPM device and make the key persistent in the non-volatile memory of the TPM under the object handle 0x81010002:

tpm2_createek -G ecc -c 0x81010002 -u ek_ecc.pub

Optionally we saved the public key in a TPM 2.0 proprietary format in the file ek_ecc.pub. The fingerprint of the ECC EK private key can be directly displayed with the command

pki --print --type priv --keyid 0x81010002
TPM 2.0 via TSS2 v2 available
signature algorithm is NULL with ERROR hash
  privkey:   ECDSA 256 bits
  keyid:     25:db:73:13:0f:c9:c8:91:68:30:8e:02:89:c1:0d:65:bd:ad:69:2a
  subjkey:   9c:b9:fb:b0:32:81:24:82:a7:07:b2:bd:bd:d3:7c:2b:22:7f:74:bf

Endorsement Key Certificates

Fetched via URL

Endorsement Key certificates issued for Intel firmware TPMs can be automatically downloaded from an Intel web server using the tpm2_getcertificate command:

tpm2_getekcertificate -o ek_ecc.crt -u ek_ecc.pub

For successful retrieval the public key ek_ecc.pub in the TPM 2.0 proprietary format is required. Using the pki tool we can list the downloaded EK certificate belonging to the ECC key:

pki --print --type x509 --in ek_ecc.crt
  subject:  "" 
  issuer:   "C=US, ST=CA, L=Santa Clara, O=Intel Corporation, OU=TPM EK intermediate for CNL_EPID_POST_B1LP_PROD_2 pid:9, CN=www.intel.com" 
  validity:  not before Sep 04 02:00:00 2019, ok
             not after  Jan 01 00:59:59 2050, ok (expires in 10600 days)
  serial:    07:99:3b:c6:88:aa:7d:72:b0:24:24:05:09:01:bb:42:55:70:1a:43
  altNames:  tcg-at-tpmManufacturer=id:494E5443, tcg-at-tpmModel=CNL, tcg-at-tpmVersion=id:00020000
  CRL URIs:  https://trustedservices.intel.com/content/CRL/ekcert/CNLEPIDPOSTB1LPPROD2_EK_Device.crl
  certificatePolicies:
             1.2.840.113741.1.5.2.1
             CPS: https://trustedservices.intel.com/content/CRL/ekcert/EKcertPolicyStatement.pdf
  authkeyId: 17:a0:05:75:d0:5e:58:e3:88:12:10:bb:98:b1:04:5b:b4:c3:06:39
  subjkeyId: 9c:b9:fb:b0:32:81:24:82:a7:07:b2:bd:bd:d3:7c:2b:22:7f:74:bf
  pubkey:    ECDSA 256 bits
  keyid:     25:db:73:13:0f:c9:c8:91:68:30:8e:02:89:c1:0d:65:bd:ad:69:2a
  subjkey:   9c:b9:fb:b0:32:81:24:82:a7:07:b2:bd:bd:d3:7c:2b:22:7f:74:bf

For the RSA 2048 Endorsement Key we first have to extract the public keyfile ek_rsa.pub in the TPM 2.0 proprietary format using the tpm2_readpublic command because we forgot to do this in the first place:

tpm2_readpublic -Q -c 0x81010001 -o ek_rsa.pub

Now we can retrieve the RSA EK certificate, too:

tpm2_getekcertificate -o ek_rsa.crt -u ek_rsa.pub

and view the contents with

pki --print --type x509 --in ek_rsa.crt
  subject:  "" 
  issuer:   "C=US, ST=CA, L=Santa Clara, O=Intel Corporation, OU=TPM EK intermediate for CNL_EPID_POST_B1LP_PROD_2 pid:9, CN=www.intel.com" 
  validity:  not before Sep 04 02:00:00 2019, ok
             not after  Jan 01 00:59:59 2050, ok (expires in 10600 days)
  serial:    14:26:0b:eb:12:a2:82:87:af:3b:75:e0:a1:a4:87:60:72:95:55:92
  altNames:  tcg-at-tpmManufacturer=id:494E5443, tcg-at-tpmModel=CNL, tcg-at-tpmVersion=id:00020000
  CRL URIs:  https://trustedservices.intel.com/content/CRL/ekcert/CNLEPIDPOSTB1LPPROD2_EK_Device.crl
  certificatePolicies:
             1.2.840.113741.1.5.2.1
             CPS: https://trustedservices.intel.com/content/CRL/ekcert/EKcertPolicyStatement.pdf
  authkeyId: 17:a0:05:75:d0:5e:58:e3:88:12:10:bb:98:b1:04:5b:b4:c3:06:39
  subjkeyId: df:f2:e9:e7:79:98:f0:d2:0b:62:db:c0:5c:2c:eb:45:73:85:e9:79
  pubkey:    RSA 2048 bits
  keyid:     ee:c7:bf:5a:de:0f:11:84:2c:86:2b:69:84:ba:65:b9:81:d2:a9:45
  subjkey:   df:f2:e9:e7:79:98:f0:d2:0b:62:db:c0:5c:2c:eb:45:73:85:e9:79

We can easily check that in both EK certificates the key fingerprints (keyid and subjkey) match with those of the EK keys persisted in the TPM.

Stored in Non-Volatile RAM

Most hardware TPMs are shipped with their Endorsement Key Certificates stored in NV RAM. E.g. on an STMicroelectronics TPM device the following data objects are stored in an NV index:

tpm2_getcap handles-nv-index
- 0x1410001
- 0x1410002
- 0x1410004
- 0x1880001
- 0x1880011
- 0x1C00002
- 0x1C0000A
- 0x1C00012
- 0x1C10102
- 0x1C10103
- 0x1C10104
- 0x1C101C0

Using the tpm2_nvreadpublic command we can look for large data objects which are prime candidates for X.509 certificates:
tpm2_nvreadpublic
  ...
0x1c00002:
  name: 000b5c112bd5f410d0abe96a50e94ff721a005c32567e4b1112ab0a8fb7e0289b7f2
  hash algorithm:
    friendly: sha256
    value: 0xB
  attributes:
    friendly: ppwrite|writedefine|write_stclear|ppread|ownerread|authread|no_da|written|platformcreate
    value: 0x1600762
  size: 1033

0x1c0000a:
  name: 000b1948300e66afad594b7a8e8368d53ddd36908fb2b46dd7b5a88051b50e4047ab
  hash algorithm:
    friendly: sha256
    value: 0xB
  attributes:
    friendly: ppwrite|writedefine|write_stclear|ppread|ownerread|authread|no_da|written|platformcreate
    value: 0x1600762
  size: 639

0x1c00012:
  name: 000cde411e123085083eedb1c9312e08dd8d229df6a5e16996035a2e3000d860b372c924de0354a6af4c7886656d2065814f
  hash algorithm:
    friendly: sha384
    value: 0xC
  attributes:
    friendly: ppwrite|writedefine|write_stclear|ppread|ownerread|authread|no_da|written|platformcreate
    value: 0x1600762
  size: 707
  ...

We can use the pki tool to directly list the properties of the EK certificates:
pki --print --type x509 --keyid 0x01c00002
TPM 2.0 via TSS2 v2 available
loaded certificate from TPM NV index 0x01c00002
  subject:  "" 
  issuer:   "C=CH, O=STMicroelectronics NV, CN=STM TPM EK Intermediate CA 06" 
  validity:  not before Feb 11 01:00:00 2020, ok
             not after  Jan 01 01:00:00 2031, ok (expires in 3650 days)
  serial:    72:78:a1:2c:87:b6:aa:45:c4:1f:57:ff:d1:3d:cf:93:42:34:b9:c9
  altNames:  tcg-at-tpmManufacturer=id:53544D20, tcg-at-tpmModel=ST33HTPHAHD4, tcg-at-tpmVersion=id:00010101
  authkeyId: fb:17:d7:0d:73:48:70:e9:19:c4:e8:e6:03:97:5e:66:4e:0e:43:de
  subjkeyId: e9:3d:51:32:04:42:73:3e:fc:bb:9e:f8:0c:21:9a:53:ec:73:80:94
  pubkey:    RSA 2048 bits
  keyid:     d3:e3:71:79:df:32:53:34:60:0f:1f:38:dc:d4:6d:53:59:1b:c5:3c
  subjkey:   e9:3d:51:32:04:42:73:3e:fc:bb:9e:f8:0c:21:9a:53:ec:73:80:94


pki --print --type x509 --keyid 0x01c0000a
TPM 2.0 via TSS2 v2 available
loaded certificate from TPM NV index 0x01c0000a
  subject:  "" 
  issuer:   "C=CH, O=STMicroelectronics NV, CN=STM TPM ECC Intermediate CA 02" 
  validity:  not before Mar 09 01:00:00 2020, ok
             not after  Jan 01 01:00:00 2031, ok (expires in 3650 days)
  serial:    51:e8:fc:b2:64:8d:1d:36:a5:bc:d7:c9:63:c1:d6:de:e7:25:09:a4
  altNames:  tcg-at-tpmManufacturer=id:53544D20, tcg-at-tpmModel=ST33HTPHAHD4, tcg-at-tpmVersion=id:00010101
  authkeyId: 66:2d:8f:1c:ec:df:f1:47:a8:b6:f0:ea:29:6a:f7:f2:4c:ad:f9:cf
  subjkeyId: d1:e8:fc:b2:64:8d:1d:36:a5:bc:d7:c9:63:c1:d6:de:e7:25:09:a4
  pubkey:    ECDSA 256 bits
  keyid:     8b:62:31:bf:08:9d:39:74:6d:05:fd:35:eb:2e:13:64:12:86:03:16
  subjkey:   d1:e8:fc:b2:64:8d:1d:36:a5:bc:d7:c9:63:c1:d6:de:e7:25:09:a4

or we can first retrieve the binary certificate blob from the NV RAM using the tpm2_nvread command:

tpm2_nvread 0x01c00012 -C o -o ek_ecc384.crt

and then list the properties of the EK certificate file:

pki --print --type x509 --in ek_ecc384.crt 
  subject:  "" 
  issuer:   "C=CH, O=STMicroelectronics NV, CN=STM TPM ECC384 Intermediate CA 01" 
  validity:  not before Feb 08 01:00:00 2020, ok
             not after  Jan 01 01:00:00 2031, ok (expires in 3650 days)
  serial:    39:ed:ae:d4:89:9e:52:08:9f:42:8a:f5:d5:58:7b:50:a6:24:f3:63
  altNames:  tcg-at-tpmManufacturer=id:53544D20, tcg-at-tpmModel=ST33HTPHAHD4, tcg-at-tpmVersion=id:00010101
  authkeyId: bd:96:3e:9a:d5:74:aa:d9:4f:ad:6c:bf:41:6d:d8:5b:4a:55:99:42
  subjkeyId: b9:ed:ae:d4:89:9e:52:08:9f:42:8a:f5:d5:58:7b:50:a6:24:f3:63
  pubkey:    ECDSA 384 bits
  keyid:     04:68:52:c4:00:ab:10:75:82:57:99:45:1e:7c:12:01:5a:8e:50:c9
  subjkey:   b9:ed:ae:d4:89:9e:52:08:9f:42:8a:f5:d5:58:7b:50:a6:24:f3:63

We see that the STMicroelectronics devices supports 384 bit ECC keys.

Generate a Persistent RSA Attestation Key

A 2048 bit RSA Attestation Key (AK) bound to the EK with handle 0x81010001 can be created with the tpm2_createak command:

tpm2_createak -C 0x81010001 -G rsa -g sha256 -s rsassa -c ak_rsa.ctx -u ak_rsa.pub -n ak_rsa.name

and made persistent under the handle 0x81010003 with the tpm2_evictcontrol command:

tpm2_evictcontrol -C o -c ak_rsa.ctx 0x81010003
persistent-handle: 0x81010003
action: persisted

The properties of the RSA AK can be displayed with the command
pki --print --type priv --keyid 0x81010003
TPM 2.0 via TSS2 v2 available
signature algorithm is RSASSA with SHA256 hash
  privkey:   RSA 2048 bits
  keyid:     df:b7:8f:95:61:8f:70:84:f4:03:e8:7e:83:a6:dd:5f:c5:ff:72:b5
  subjkey:   48:82:62:15:74:a2:10:c5:75:70:c2:d6:7d:59:9f:22:d9:4f:9c:07

Generate a Persistent ECC Attestation Key

A 256 bit ECC Attestation Key (AK) bound to the EK with handle 0x81010003 can be created and made persistent under the handle 0x81010004 with the following tpm2-tools command

tpm2_getpubak -E 0x81010003 -g ecc -D sha256 -s ecdsa -k 0x81010004 -f ak_ecc4.pub -n ak_ecc4.name

The AK public key can be exported in PKCS#1 format from the TPM using the pki tool

pki --pub --keyid 0x81010004 > ak_ecc_pub.der

The fingerprint of the ECC AK public key can be displayed with the command

pki --print --type pub --in ak_ecc_pub.der
  pubkey:    ECDSA 256 bits
  keyid:     71:49:7c:42:41:e7:c6:81:bc:31:73:f0:0f:7e:4a:e1:2d:53:00:38
  subjkey:   c7:0e:63:f8:7f:6f:f6:55:00:e5:05:7f:5a:3e:6b:6c:e7:d2:d5:13

Generate Another ECC Attestation Key

Multiple AK keys bound to a common EK key can be generated

tpm2_getpubak -E 0x81010003 -g ecc -D sha256 -s ecdsa -k 0x81010005 -f ak_ecc5.pub -n ak_ecc5.name

The fingerprint of the second ECC AK private key can be displayed with the command

pki --print --type priv --in 0x81010005
  pubkey:    ECDSA 256 bits
  keyid:     c4:b4:9c:95:27:9e:ce:81:2f:98:42:c8:1b:f0:54:ff:d4:d1:24:34
  subjkey:   cf:44:f4:f7:9d:97:09:ad:b1:09:3a:8e:6f:23:eb:9f:2c:35:94:c9

Remove a Persistent Key Object

Since the non-volatile memory of the TPM is limited any persistent key object can be removed to free storage space.
The following tpm2-tools command removes the ECC AK key with persistent handle 0x81010005

tpm2_evictcontrol -A o -H 0x81010005 -S 0x81010005

List Persistent Objects

The following tpm2-tools command lists all persistent objects stored by the TPM in non-volatile memory

tpm2_listpersistent
6 persistent objects defined.

0. Persistent handle: 0x81000001
{
        Type: 0x23
        Hash algorithm(nameAlg): 0xb
        Attributes: 0x30072
}
1. Persistent handle: 0x81000002
{
        Type: 0x23
        Hash algorithm(nameAlg): 0xb
        Attributes: 0x60072
}
2. Persistent handle: 0x81010001
{
        Type: 0x1
        Hash algorithm(nameAlg): 0xb
        Attributes: 0x300b2
}
3. Persistent handle: 0x81010002
{
        Type: 0x1
        Hash algorithm(nameAlg): 0xb
        Attributes: 0x50072
}
4. Persistent handle: 0x81010003
{
        Type: 0x23
        Hash algorithm(nameAlg): 0xb
        Attributes: 0x300b2
}
5. Persistent handle: 0x81010004
{
        Type: 0x23
        Hash algorithm(nameAlg): 0xb
        Attributes: 0x50072
}

Create a Demo Root CA

The following pki command creates a 256 bit ECDSA private key for the Demo CA

pki --gen --type ecdsa --size 256 --outform pem > demoCaKey.pem

Next we create a self-signed Root CA certificate

pki --self --ca --type ecdsa --in demoCaKey.pem --dn="C=US, O=TNC Demo, CN=TNC Demo CA" --lifetime 3652 --outform pem > demoCaCert.pem

Issue an RSA AIK Certificate

Based on the RSA AK public key exported from the TPM, the following pki command generates an Attestation Identity Key (AIK) certificate signed by the Demo CA

pki --issue --cacert demoCaCert.pem --cakey demoCaKey.pem --type pub --in ak_rsa_pub.der --dn "C=US, O=TNC Demo, OU=AIK RSA, CN=raspi5.example.com" --san raspi5.example.com --lifetime 3651 > raspi5_ak_rsa_Cert.der

Issue an ECC AIK Certificate

Based on the ECC AK public key exported from the TPM, the following pki command generates an Attestation Identity Key (AIK) certificate signed by the Demo CA

pki --issue --cacert demoCaCert.pem --cakey demoCaKey.pem --type pub --in ak_ecc_pub.der --dn "C=US, O=TNC Demo, OU=AIK ECC, CN=raspi5.example.com" --san raspi5.example.com --lifetime 3651 > raspi5_ak_ecc_Cert.der

Many certification authorities issue certificates based on PKCS#10 certificate requests. This approach is also possible. First a certificate request is generated on the host the TPM resides on

 pki --req --keyid 0x81010004 --dn "C=US, O=TNC Demo, OU=AIK ECC, CN=raspi5.example.com" --san raspi5.example.com > ak_ecc_req.der

When you are prompted for a smartcard PIN just press <enter> since this TPM private key is not protected by a PIN. In a second step the CA issues the AIK certificate based on the PKCS#10 certificate request
pki --issue --cacert demoCaCert.pem --cakey demoCaKey.pem --type pkcs10 --in ak_ecc_req.der --lifetime 3651 > raspi5_ak_ecc_Cert.der

Store the ECC AIK Certificate in the NV RAM of the TPM

A TPM 2.0 has a certain amount of Non Volatile Random Access Memory (NV RAM) that can be used to store arbitrary data, e.g. the X.509 certificates matching the persistent keys. IF both the certificates and keys are persisted in the TPM then the system disk of the host can be reformatted at any time without loosing the machine or user credentials.As with smartcards the needed amount of memory must be reserved first so we check the size of the X.509 ECC certificate

ls -l raspi5_ak_ecc_Cert.der
-rw-r--r-- 1 root root 449 Feb 17  2017 raspi5_ak_ecc_Cert.der

We then define a memory location with a size of 449 bytes that can be accessed via the handle 0x01800004 which is also called the NV index

tpm2_nvdefine -x 0x01800004 -a 0x40000001 -s 449 -t 0x2000A

Then we write the certificate file to the NV RAM destination

tpm2_nvwrite -x 0x01800004 -a 0x40000001 raspi5_ak_ecc_Cert.der

List of NV Indexes

A list of all defined NV indexes can be obtained with

tpm2_nvlist
2 NV indexes defined.

  0. NV Index: 0x1500015
  {
    Hash algorithm(nameAlg):4
     The Index attributes(attributes):0x44040004
     The size of the data area(dataSize):4
   }
  1. NV Index: 0x1800004
  {
    Hash algorithm(nameAlg):11
     The Index attributes(attributes):0x2002000a
     The size of the data area(dataSize):449
   }

Remove NV Index

The memory assigned to a given NV index can be released with the command

tpm2_nvrelease -x 0x01800001 -a 0x40000001

Configure TPM Private Key Access via VICI Interface

Configuration of TPM private key access as tokens in the secrets section of swanctl.conf

secrets {
    token_ak_rsa {
       handle = 81010002
       pin = 123456
    }
    token_ak_ecc {
       handle = 81010004
    }
}
Since the use of the RSA AK private key is password-protected, the PIN 123456 is added.

Define IPsec Connection with RSA AK Client Key

This connection configuration in swanctl.conf uses the RSA AK certificate for client authentication

connections {
   rsa {
      local_addrs  = 10.10.0.105
      remote_addrs = 10.10.0.104

      local {
         auth = pubkey 
         certs = raspi5_ak_rsa_Cert.der
      }
      remote {
         auth = pubkey 
         id = raspi4.example.com
      }
      children {
         rsa {
            mode = transport
            esp_proposals = aes128-sha256-curve25519
         }
      }
      version = 2
      proposals = aes128-sha256-curve25519
   }
}

Define IPsec Connection with ECC AK Client Key

This connection configuration in swanctl.conf references the ECC AK certificate used for client authentication via its handle, i.e. the NV index

connections {
   ecc {
      local_addrs  = 10.10.0.105
      remote_addrs = 10.10.0.104

      local {
         auth = pubkey
         cert-tpm {
            handle = 0x01800004
         }
      }
      remote {
         auth = pubkey
         id = raspi4.example.com
      }
      children {
         ecc {
            mode = transport
            esp_proposals = aes128-sha256-curve25519
         }
      }
      version = 2
      proposals = aes128-sha256-curve25519
   }
}

Starting the strongSwan Daemon

systemctl start strongswan-swanctl

Feb 19 10:52:01 raspi5 systemd[1]: Starting strongSwan IPsec IKEv1/IKEv2 daemon using swanctl...
Feb 19 10:52:01 raspi5 charon-systemd[21165]: loaded plugins: charon-systemd charon-systemd random nonce x509 constraints openssl pem pkcs1 pkcs8 pkcs12 pubkey mgf1 ntru curve25519 eap-identity eap-ttls eap-tnc tnc-tnccs tnc-imc tnccs-20 socket-default kernel-netlink vici tpm
Feb 19 10:52:01 raspi5 charon-systemd[21165]: spawning 16 worker threads
Feb 19 10:52:01 raspi5 charon-systemd[21165]: loaded certificate 'C=US, O=TNC Demo, OU=AIK RSA, CN=raspi5.example.com'
Feb 19 10:52:01 raspi5 charon-systemd[21165]: loaded certificate 'C=US, O=TNC Demo, CN=TNC Demo CA'

The RSA AK private key is attached to the charon-systemd daemon via the TPM 2.0 resource manager

Feb 19 10:52:01 raspi5 charon-systemd[21165]: TPM 2.0 - manufacturer: IFX (SLB9670) rev: 01.16 2015
Feb 19 10:52:01 raspi5 charon-systemd[21165]: TPM 2.0 - algorithms: RSA SHA1 HMAC AES KEYEDHASH XOR SHA256 RSASSA RSAES RSAPSS OAEP ECDSA ECDH SM2 KDF1_SP800_56A KDF1_SP800_108 ECC SYMCIPHER CFB
Feb 19 10:52:01 raspi5 charon-systemd[21165]: TPM 2.0 - ECC curves: NIST_P256 BN_P256
Feb 19 10:52:01 raspi5 charon-systemd[21165]: TPM 2.0 via TSS2 v2 available
Feb 19 10:52:01 raspi5 charon-systemd[21165]: AIK signature algorithm is RSASSA with SHA256 hash
Feb 19 10:52:01 raspi5 charon-systemd[21165]: loaded RSA private key from token
F

The ECC AK private key is attached to the charon-systemd daemon via the TPM 2.0 resource manager

Feb 19 10:52:01 raspi5 charon-systemd[21165]: TPM 2.0 - manufacturer: IFX (SLB9670) rev: 01.16 2015
Feb 19 10:52:01 raspi5 charon-systemd[21165]: TPM 2.0 - algorithms: RSA SHA1 HMAC AES KEYEDHASH XOR SHA256 RSASSA RSAES RSAPSS OAEP ECDSA ECDH SM2 KDF1_SP800_56A KDF1_SP800_108 ECC SYMCIPHER CFB
Feb 19 10:52:02 raspi5 charon-systemd[21165]: TPM 2.0 - ECC curves: NIST_P256 BN_P256
Feb 19 10:52:02 raspi5 charon-systemd[21165]: TPM 2.0 via TSS2 v2 available
Feb 19 10:52:02 raspi5 charon-systemd[21165]: AIK signature algorithm is ECDSA with SHA256 hash
Feb 19 10:52:02 raspi5 charon-systemd[21165]: loaded ECDSA private key from token

The ECC AIK certificate is loaded by the charon-systemd daemon via the TPM 2.0 resource manager

Feb 19 10:52:02 raspi5 charon-systemd[21165]: TPM 2.0 - manufacturer: IFX (SLB9670) rev: 01.16 2015
Feb 19 10:52:02 raspi5 charon-systemd[21165]: TPM 2.0 - algorithms: RSA SHA1 HMAC AES KEYEDHASH XOR SHA256 RSASSA RSAES RSAPSS OAEP ECDSA ECDH SM2 KDF1_SP800_56A KDF1_SP800_108 ECC SYMCIPHER CFB
Feb 19 10:52:02 raspi5 charon-systemd[21165]: TPM 2.0 - ECC curves: NIST_P256 BN_P256
Feb 19 10:52:02 raspi5 charon-systemd[21165]: TPM 2.0 via TSS2 v2 available
Feb 19 10:52:02 raspi5 charon-systemd[21165]: loaded certificate from TPM NV index 0x01800004

The two connection definitions are received by the charon-systemd daemon from the swanctl command line tool via the VICI interface

Feb 19 10:52:02 raspi5 charon-systemd[21165]:   id not specified, defaulting to cert subject 'C=US, O=TNC Demo, OU=AIK RSA, CN=raspi5.example.com'
Feb 19 10:52:02 raspi5 charon-systemd[21165]: added vici connection: rsa
Feb 19 10:52:02 raspi5 charon-systemd[21165]:   id not specified, defaulting to cert subject 'C=US, O=TNC Demo, OU=AIK ECC, CN=raspi5.example.com'
Feb 19 10:52:02 raspi5 charon-systemd[21165]: added vici connection: ecc

The swanctl command line tool reports its actions

Feb 19 10:52:02 raspi5 swanctl[21183]: loaded certificate from '/etc/swanctl/x509/raspi5_ak_rsa_Cert.der'
Feb 19 10:52:02 raspi5 swanctl[21183]: loaded certificate from '/etc/swanctl/x509ca/demoCaCert.pem'
Feb 19 10:52:02 raspi5 swanctl[21183]: loaded key token_ak_rsa from token [keyid: f49e857dde4e67f5fb870398673f207cf33f2b66]
Feb 19 10:52:02 raspi5 swanctl[21183]: loaded key token_ak_ecc from token [keyid: c70e63f87f6ff65500e5057f5a3e6b6ce7d2d513]
Feb 19 10:52:02 raspi5 swanctl[21183]: loaded connection 'rsa'
Feb 19 10:52:02 raspi5 swanctl[21183]: loaded connection 'ecc'
Feb 19 10:52:02 raspi5 swanctl[21183]: successfully loaded 2 connections, 0 unloaded


Feb 19 10:52:02 raspi5 systemd[1]: Started strongSwan IPsec IKEv1/IKEv2 daemon using swanctl.

The following swanctl command shows the two loaded connections

swanctl --list-conns


rsa: IKEv2, reauthentication every 10800s, no rekeying
  local:  10.10.0.105
  remote: 10.10.0.104
  local public key authentication:
    id: C=US, O=TNC Demo, OU=AIK RSA, CN=raspi5.example.com
    certs: C=US, O=TNC Demo, OU=AIK RSA, CN=raspi5.example.com
  remote public key authentication:
    id: raspi4.example.com
  rsa: TRANSPORT, rekeying every 3600s or 300000000 bytes or 500000 packets
    local:  dynamic
    remote: dynamic

ecc: IKEv2, reauthentication every 10800s, no rekeying
  local:  10.10.0.105
  remote: 10.10.0.104
  local public key authentication:
    id: C=US, O=TNC Demo, OU=AIK ECC, CN=raspi5.example.com
    certs: C=US, O=TNC Demo, OU=AIK ECC, CN=raspi5.example.com
  remote public key authentication:
    id: raspi4.example.com
  ecc: TRANSPORT, rekeying every 3600s or 300000000 bytes or 500000 packets
    local:  dynamic
    remote: dynamic

The loaded certificates can also be displayed

swanctl --list-certs

You can clearly see that the connection between the AK certificates and their matching AK private key has been established (..., has private key)

List of X.509 End Entity Certificates

  subject:  "C=US, O=TNC Demo, OU=AIK RSA, CN=raspi5.example.com" 
  issuer:   "C=US, O=TNC Demo, CN=TNC Demo CA" 
  validity:  not before Feb 19 09:33:43 2017, ok
             not after  Aug 29 10:33:43 2026, ok (expires in 3477 days)
  serial:    11:57:33:3e:2a:8e:8a:32
  altNames:  raspi5.example.com
  authkeyId: 21:02:7e:2d:de:8b:77:48:75:de:56:2f:b5:d4:62:ec:c3:09:15:f2
  subjkeyId: f4:9e:85:7d:de:4e:67:f5:fb:87:03:98:67:3f:20:7c:f3:3f:2b:66
  pubkey:    RSA 2048 bits, has private key
  keyid:     71:21:f5:d4:7e:59:4a:88:16:ca:57:85:98:3d:36:a7:b1:d5:75:fa
  subjkey:   f4:9e:85:7d:de:4e:67:f5:fb:87:03:98:67:3f:20:7c:f3:3f:2b:66

  subject:  "C=US, O=TNC Demo, OU=AIK ECC, CN=raspi5.example.com" 
  issuer:   "C=US, O=TNC Demo, CN=TNC Demo CA" 
  validity:  not before Feb 17 23:17:19 2017, ok
             not after  Aug 30 00:17:19 2026, ok (expires in 3478 days)
  serial:    52:9d:3e:42:6f:71:63:3d
  altNames:  raspi5.example.com
  authkeyId: 21:02:7e:2d:de:8b:77:48:75:de:56:2f:b5:d4:62:ec:c3:09:15:f2
  subjkeyId: c7:0e:63:f8:7f:6f:f6:55:00:e5:05:7f:5a:3e:6b:6c:e7:d2:d5:13
  pubkey:    ECDSA 256 bits, has private key
  keyid:     71:49:7c:42:41:e7:c6:81:bc:31:73:f0:0f:7e:4a:e1:2d:53:00:38
  subjkey:   c7:0e:63:f8:7f:6f:f6:55:00:e5:05:7f:5a:3e:6b:6c:e7:d2:d5:13


List of X.509 CA Certificates

  subject:  "C=US, O=TNC Demo, CN=TNC Demo CA" 
  issuer:   "C=US, O=TNC Demo, CN=TNC Demo CA" 
  validity:  not before Aug 31 10:29:27 2016, ok
             not after  Aug 31 10:29:27 2026, ok (expires in 3479 days)
  serial:    02:c8:85:e1:ef:fa:8f:20
  flags:     CA CRLSign self-signed 
  subjkeyId: 21:02:7e:2d:de:8b:77:48:75:de:56:2f:b5:d4:62:ec:c3:09:15:f2
  pubkey:    ECDSA 256 bits
  keyid:     a1:b5:e0:29:d0:4c:a7:62:bd:ca:a3:b4:af:18:42:2c:4a:01:55:9a
  subjkey:   21:02:7e:2d:de:8b:77:48:75:de:56:2f:b5:d4:62:ec:c3:09:15:f2

IKEv2 Authentication with RSA AIK Certificate

With the following swanctl command the "rsa" connection is established

swanctl --initiate --child rsa


Feb 19 10:52:21 raspi5 charon-systemd[21165]: vici initiate 'rsa'
Feb 19 10:52:21 raspi5 charon-systemd[21165]: initiating IKE_SA rsa[1] to 10.10.0.104
Feb 19 10:52:21 raspi5 charon-systemd[21165]: generating IKE_SA_INIT request 0 [ SA KE No N(NATD_S_IP) N(NATD_D_IP) N(FRAG_SUP) N(HASH_ALG) N(REDIR_SUP) V ]
Feb 19 10:52:21 raspi5 charon-systemd[21165]: sending packet: from 10.10.0.105[500] to 10.10.0.104[500] (1257 bytes)
Feb 19 10:52:21 raspi5 charon-systemd[21165]: received packet: from 10.10.0.104[500] to 10.10.0.105[500] (1259 bytes)
Feb 19 10:52:21 raspi5 charon-systemd[21165]: parsed IKE_SA_INIT response 0 [ SA KE No N(NATD_S_IP) N(NATD_D_IP) CERTREQ N(HASH_ALG) V ]
Feb 19 10:52:21 raspi5 charon-systemd[21165]: received strongSwan vendor ID
Feb 19 10:52:21 raspi5 charon-systemd[21165]: received cert request for "C=US, O=TNC Demo, CN=TNC Demo CA" 
Feb 19 10:52:21 raspi5 charon-systemd[21165]: sending cert request for "C=US, O=TNC Demo, CN=TNC Demo CA"

The RSA AK private key stored in the TPM 2.0 is used to generate an RSA_EMSA_PKCS1_SHA2_256 signature which is sent in the AUTH payload of the IKE_AUTH request. The matching client certificate is sent int the CERT payload.

Feb 19 10:52:24 raspi5 charon-systemd[21165]: authentication of 'C=US, O=TNC Demo, OU=AIK RSA, CN=raspi5.example.com' (myself) with RSA_EMSA_PKCS1_SHA2_256 successful
Feb 19 10:52:24 raspi5 charon-systemd[21165]: sending end entity cert "C=US, O=TNC Demo, OU=AIK RSA, CN=raspi5.example.com" 


Feb 19 10:52:24 raspi5 charon-systemd[21165]: establishing CHILD_SA rsa
Feb 19 10:52:24 raspi5 charon-systemd[21165]: generating IKE_AUTH request 1 [ IDi CERT CERTREQ IDr AUTH N(USE_TRANSP) SA TSi TSr N(MOBIKE_SUP) N(ADD_6_ADDR) N(EAP_ONLY) N(MSG_ID_SYN_SUP) ]
Feb 19 10:52:24 raspi5 charon-systemd[21165]: sending packet: from 10.10.0.105[4500] to 10.10.0.104[4500] (1296 bytes)
Feb 19 10:52:24 raspi5 charon-systemd[21165]: received packet: from 10.10.0.104[4500] to 10.10.0.105[4500] (752 bytes)
Feb 19 10:52:24 raspi5 charon-systemd[21165]: parsed IKE_AUTH response 1 [ IDr CERT AUTH N(USE_TRANSP) SA TSi TSr N(AUTH_LFT) N(MOBIKE_SUP) N(NO_ADD_ADDR) ]
Feb 19 10:52:24 raspi5 charon-systemd[21165]: received end entity cert "C=US, O=TNC Demo, CN=raspi4.example.com" 
Feb 19 10:52:24 raspi5 charon-systemd[21165]:   using certificate "C=US, O=TNC Demo, CN=raspi4.example.com" 
Feb 19 10:52:24 raspi5 charon-systemd[21165]:   using trusted ca certificate "C=US, O=TNC Demo, CN=TNC Demo CA" 
Feb 19 10:52:24 raspi5 charon-systemd[21165]:   reached self-signed root ca with a path length of 0
Feb 19 10:52:24 raspi5 charon-systemd[21165]: authentication of 'raspi4.example.com' with ECDSA_WITH_SHA256_DER successful
Feb 19 10:52:24 raspi5 charon-systemd[21165]: IKE_SA rsa[1] established between 10.10.0.105[C=US, O=TNC Demo, OU=AIK RSA, CN=raspi5.example.com]...10.10.0.104[raspi4.example.com]
Feb 19 10:52:24 raspi5 charon-systemd[21165]: scheduling reauthentication in 10507s
Feb 19 10:52:24 raspi5 charon-systemd[21165]: maximum IKE_SA lifetime 11587s
Feb 19 10:52:24 raspi5 charon-systemd[21165]: CHILD_SA rsa{1} established with SPIs c23deb9d_i ce48d08e_o and TS 10.10.0.105/32 === 10.10.0.104/32
Feb 19 10:52:24 raspi5 charon-systemd[21165]: received AUTH_LIFETIME of 10103s, scheduling reauthentication in 9023s
Feb 19 10:52:24 raspi5 charon-systemd[21165]: peer supports MOBIKE

The following swanctl command shows the established IPsec connection

 swanctl --list-sas


rsa: #1, ESTABLISHED, IKEv2, 7ba3b4d06c051ecb_i* 14e1769a8aeb7f28_r
  local  'C=US, O=TNC Demo, OU=AIK RSA, CN=raspi5.example.com' @ 10.10.0.105[4500]
  remote 'raspi4.example.com' @ 10.10.0.104[4500]
  AES_CBC-128/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/CURVE_25519
  established 252s ago, reauth in 8771s
  rsa: #1, reqid 1, INSTALLED, TRANSPORT, ESP:AES_CBC-128/HMAC_SHA2_256_128
    installed 252s ago, rekeying in 3258s, expires in 3708s
    in  c23deb9d,    640 bytes,    10 packets,     3s ago
    out ce48d08e,    640 bytes,    10 packets,     3s ago
    local  10.10.0.105/32
    remote 10.10.0.104/32

With this swanctl command the "rsa" connection is terminated

swanctl --terminate --ike rsa


Feb 19 10:59:16 raspi5 charon-systemd[21165]: vici terminate IKE_SA 'rsa'
Feb 19 10:59:16 raspi5 charon-systemd[21165]: deleting IKE_SA rsa[1] between 10.10.0.105[C=US, O=TNC Demo, OU=AIK RSA, CN=raspi5.example.com]...10.10.0.104[raspi4.example.com]
Feb 19 10:59:16 raspi5 charon-systemd[21165]: sending DELETE for IKE_SA rsa[1]
Feb 19 10:59:16 raspi5 charon-systemd[21165]: generating INFORMATIONAL request 2 [ D ]
Feb 19 10:59:16 raspi5 charon-systemd[21165]: sending packet: from 10.10.0.105[4500] to 10.10.0.104[4500] (80 bytes)
Feb 19 10:59:16 raspi5 charon-systemd[21165]: received packet: from 10.10.0.104[4500] to 10.10.0.105[4500] (80 bytes)
Feb 19 10:59:16 raspi5 charon-systemd[21165]: parsed INFORMATIONAL response 2 [ ]
Feb 19 10:59:16 raspi5 charon-systemd[21165]: IKE_SA deleted

IKEv2 Authentication with ECC AIK Certificate

Next we initiate the "ecc" connection

swanctl --initiate --child ecc


Feb 19 11:00:32 raspi5 charon-systemd[21165]: vici initiate 'ecc'
Feb 19 11:00:32 raspi5 charon-systemd[21165]: initiating IKE_SA ecc[2] to 10.10.0.104
Feb 19 11:00:32 raspi5 charon-systemd[21165]: generating IKE_SA_INIT request 0 [ SA KE No N(NATD_S_IP) N(NATD_D_IP) N(FRAG_SUP) N(HASH_ALG) N(REDIR_SUP) V ]
Feb 19 11:00:32 raspi5 charon-systemd[21165]: sending packet: from 10.10.0.105[500] to 10.10.0.104[500] (1257 bytes)
Feb 19 11:00:32 raspi5 charon-systemd[21165]: received packet: from 10.10.0.104[500] to 10.10.0.105[500] (1259 bytes)
Feb 19 11:00:32 raspi5 charon-systemd[21165]: parsed IKE_SA_INIT response 0 [ SA KE No N(NATD_S_IP) N(NATD_D_IP) CERTREQ N(HASH_ALG) V ]
Feb 19 11:00:32 raspi5 charon-systemd[21165]: received strongSwan vendor ID
Feb 19 11:00:32 raspi5 charon-systemd[21165]: received cert request for "C=US, O=TNC Demo, CN=TNC Demo CA" 
Feb 19 11:00:32 raspi5 charon-systemd[21165]: sending cert request for "C=US, O=TNC Demo, CN=TNC Demo CA"

The ECC AK private key stored in the TPM 2.0 is used to generate an ECDSA_WITH_SHA256_DER signature which is sent in the AUTH payload of the IKE_AUTH request. The matching client certificate is sent int the CERT payload.

Feb 19 11:00:34 raspi5 charon-systemd[21165]: authentication of 'C=US, O=TNC Demo, OU=AIK ECC, CN=raspi5.example.com' (myself) with ECDSA_WITH_SHA256_DER successful
Feb 19 11:00:34 raspi5 charon-systemd[21165]: sending end entity cert "C=US, O=TNC Demo, OU=AIK ECC, CN=raspi5.example.com" 


Feb 19 11:00:34 raspi5 charon-systemd[21165]: establishing CHILD_SA ecc
Feb 19 11:00:34 raspi5 charon-systemd[21165]: generating IKE_AUTH request 1 [ IDi CERT CERTREQ IDr AUTH N(USE_TRANSP) SA TSi TSr N(MOBIKE_SUP) N(ADD_6_ADDR) N(EAP_ONLY) N(MSG_ID_SYN_SUP) ]
Feb 19 11:00:34 raspi5 charon-systemd[21165]: sending packet: from 10.10.0.105[4500] to 10.10.0.104[4500] (912 bytes)
Feb 19 11:00:34 raspi5 charon-systemd[21165]: received packet: from 10.10.0.104[4500] to 10.10.0.105[4500] (752 bytes)
Feb 19 11:00:34 raspi5 charon-systemd[21165]: parsed IKE_AUTH response 1 [ IDr CERT AUTH N(USE_TRANSP) SA TSi TSr N(AUTH_LFT) N(MOBIKE_SUP) N(NO_ADD_ADDR) ]
Feb 19 11:00:34 raspi5 charon-systemd[21165]: received end entity cert "C=US, O=TNC Demo, CN=raspi4.example.com" 
Feb 19 11:00:34 raspi5 charon-systemd[21165]:   using certificate "C=US, O=TNC Demo, CN=raspi4.example.com" 
Feb 19 11:00:34 raspi5 charon-systemd[21165]:   using trusted ca certificate "C=US, O=TNC Demo, CN=TNC Demo CA" 
Feb 19 11:00:34 raspi5 charon-systemd[21165]:   reached self-signed root ca with a path length of 0
Feb 19 11:00:34 raspi5 charon-systemd[21165]: authentication of 'raspi4.example.com' with ECDSA_WITH_SHA256_DER successful
Feb 19 11:00:34 raspi5 charon-systemd[21165]: IKE_SA ecc[2] established between 10.10.0.105[C=US, O=TNC Demo, OU=AIK ECC, CN=raspi5.example.com]...10.10.0.104[raspi4.example.com]
Feb 19 11:00:34 raspi5 charon-systemd[21165]: scheduling reauthentication in 10180s
Feb 19 11:00:34 raspi5 charon-systemd[21165]: maximum IKE_SA lifetime 11260s
Feb 19 11:00:34 raspi5 charon-systemd[21165]: CHILD_SA ecc{2} established with SPIs c2c16cd0_i c47ea6f6_o and TS 10.10.0.105/32 === 10.10.0.104/32
Feb 19 11:00:34 raspi5 charon-systemd[21165]: received AUTH_LIFETIME of 9880s, scheduling reauthentication in 8800s
Feb 19 11:00:34 raspi5 charon-systemd[21165]: peer supports MOBIKE

The establed IKE and CHILD SAs are displayed

 swanctl --list-sas


ecc: #2, ESTABLISHED, IKEv2, b7f2652777b0996a_i* 12282b5964ff0658_r
  local  'C=US, O=TNC Demo, OU=AIK ECC, CN=raspi5.example.com' @ 10.10.0.105[4500]
  remote 'raspi4.example.com' @ 10.10.0.104[4500]
  AES_CBC-128/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/CURVE_25519
  established 126s ago, reauth in 8674s
  ecc: #2, reqid 2, INSTALLED, TRANSPORT, ESP:AES_CBC-128/HMAC_SHA2_256_128
    installed 126s ago, rekeying in 3252s, expires in 3834s
    in  c2c16cd0,    320 bytes,     5 packets,     2s ago
    out c47ea6f6,    320 bytes,     5 packets,     2s ago
    local  10.10.0.105/32
    remote 10.10.0.104/32

The IKE and CHILD SAs are terminated

swanctl --terminate --ike ecc


Feb 19 11:04:32 raspi5 charon-systemd[21165]: vici terminate IKE_SA 'ecc'
Feb 19 11:04:32 raspi5 charon-systemd[21165]: deleting IKE_SA ecc[2] between 10.10.0.105[C=US, O=TNC Demo, OU=AIK ECC, CN=raspi5.example.com]...10.10.0.104[raspi4.example.com]
Feb 19 11:04:32 raspi5 charon-systemd[21165]: sending DELETE for IKE_SA ecc[2]
Feb 19 11:04:32 raspi5 charon-systemd[21165]: generating INFORMATIONAL request 2 [ D ]
Feb 19 11:04:32 raspi5 charon-systemd[21165]: sending packet: from 10.10.0.105[4500] to 10.10.0.104[4500] (80 bytes)
Feb 19 11:04:32 raspi5 charon-systemd[21165]: received packet: from 10.10.0.104[4500] to 10.10.0.105[4500] (80 bytes)
Feb 19 11:04:32 raspi5 charon-systemd[21165]: parsed INFORMATIONAL response 2 [ ]
Feb 19 11:04:32 raspi5 charon-systemd[21165]: IKE_SA deleted