fapi-profile(5) File Formats Manual fapi-profile(5)
SEE ALSO
fapi-config(5)
DESCRIPTION
FAPI Cryptographic Profile
Cryptographic profiles determine the cryptographic algorithms and para-
meters for all keys and operations of a specific TPM interaction. The
values affected by these profiles are:
• the name hash algorithm
• asymmetric signature algorithm, scheme and parameters (such as curve,
keysize, default padding, hash, etc)
• PCR bank selection (which PCR banks shall be extended, quoted and
read)
Two exemplary profiles for RSA and ECC are installed with the TSS. By
default, the RSA cryptographic profile is activated. The user is free
to create own cryptographic profiles according to his needs.
Specific profiles are activated in the FAPI configuration file. If not
otherwise specified during TSS installation, the default location for
the exemplary profiles is /etc/tpm2-tss/profiles/ and /etc/tpm2-tss/ for
the FAPI configuration file.
The parameters of the profile are:
• type: The asymmetric algorithm used for this profile.
• nameAlg: The hash algorithm which will be used for sessions and keys.
• srk_template: The type definition for the /SRK object. See the type
parameter of Fapi_CreateKey.
• srk_description: The description to be set for the /EK object. See
Fapi_GetDescription.
• ek_template: The type definition for the /EK object. See the type pa-
rameter of Fapi_CreateKey.
• ek_description: The description to be set for the /SRK object. See
Fapi_GetDescription.
• ecc_signing_scheme: The signing scheme used for ECC keys.
• rsa_signing_scheme: The signing scheme used for RSA keys.
• keyBits: The key size for RSA keys.
• exponent: The exponent of RSA keys.
• sym_mode: The block cipher mode for symmetric encryption.
• sym_parameters: The algorithm and parameters used for symmetric en-
cryption.
• sym_block_size: The block size used for symmetric encryption.
• session_symmetric: The algorithm and parameters used for parameter en-
cryption of a session (The same format and default as sym_parameters).
• pcr_selection: The PCR registers and banks used by FAPI.
• curveID: The curve ID for ECC keys.
• ek_policy: The JSON encoded policy for the /EK object.
• srk_policy: The JSON encoded policy for the /SRK object.
• eh_policy: The JSON encoded policy for the endorsement hierarchy /HE.
• sh_policy: The JSON encoded policy for the owner hierarchy /HS.
• lockout_policy: The JSON encoded policy for the lockout hierarchy
/LOCKOUT.
• newMaxTries: Count of authorization failures before the lockout is im-
posed. If not set the default is 5.
• newRecoveryTime: Time in seconds before the authorization failure
count is automatically decremented. A value of zero indicates that DA
protection is disabled. If not set the default is 1000.
• lockoutRecovery: Time in seconds after a lockoutAuth failure before
use of lockoutAuth is allowed A value of zero indicates that a reboot
is required. If not set the default is 1000.
• ignore_ek_template: Ignore EK template stored in NV ram. If not set
the default is "no".
EXAMPLES
The following JSON encoded example shows the standard profile for ECC
keys:
{
"type": "TPM2_ALG_ECC",
"nameAlg":"TPM2_ALG_SHA256",
"srk_template": "system,restricted,decrypt,0x81000001",
"srk_description": "Storage root key SRK",
"ek_template": "system,restricted,decrypt",
"ek_description": "Endorsement key EK",
"ecc_signing_scheme": {
"scheme":"TPM2_ALG_ECDSA",
"details":{
"hashAlg":"TPM2_ALG_SHA256"
},
},
"sym_mode":"TPM2_ALG_CFB",
"sym_parameters": {
"algorithm":"TPM2_ALG_AES",
"keyBits":"128",
"mode":"TPM2_ALG_CFB"
},
"sym_block_size": 16,
"pcr_selection": [
{ "hash": "TPM2_ALG_SHA1",
"pcrSelect": [ ],
},
{ "hash": "TPM2_ALG_SHA256",
"pcrSelect": [ 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 ]
}
],
"curveID": "TPM2_ECC_NIST_P256",
"ek_policy": {
"description": "Endorsement hierarchy used for policy secret.",
"policy":[
{
"type":"POLICYSECRET",
"objectName": "4000000b",
}
]
}
}
Beside the cryptographic parameters descriptions for the storage root
key and the endorsement key can be set. For the endorsement hierarchy
the policy "ek_policy" is set according to the TCG Credential profile EK
2.0. The values of the constants are the same as the constants defined
in the TSS header files, where the prefix TPM2_ can be omitted.
The key type of the storage root key and the endorsement key is defined
by the JSON fields srk_template and ek_template. The type consists of a
list of comma and/or space separated keywords. If a keyword is not
present the inverse of the reference TPM attribute bits SHALL be set or
cleared. The keywords are:
• sign: Sets the sign attribute of a key.
• decrypt: Sets the decrypt attribute of a key.
• If neither sign nor decrypt are provided, both attributes SHALL be
set.
• restricted: Sets the restricted attribute of a key.
• If restricted is set, either sign or decrypt (but not both) SHALL be
set.
• noda: Sets the noda attribute of a key or NV index.
• A hexadecimal number: Marks a key object to be made persistent and
sets the persistent object handle to this value.
The RSA profile has specific values for the signing scheme and the de-
crypt scheme:
"rsa_signing_scheme": {
"scheme":"TPM2_ALG_RSAPSS",
"details":{
"hashAlg":"TPM2_ALG_SHA256"
}
"rsa_decrypt_scheme": {
"scheme":"TPM2_ALG_OAEP",
"details":{
"hashAlg":"TPM2_ALG_SHA256"
}
},
Possible values for the signing schemes are:
• RSA: RSASSA, RSAPSS
• ECC: ECDSA, ECDAA
Possible modes for symmetric encryption are:
• CTR, OFB, CBC, CFB, ECB, NULL
Possible modes for the RSA decrypt scheme are:
• RSAES, OAEP
The following curve ids can be used:
• ECC_NIST_P192, ECC_NIST_P224, ECC_NIST_P256, ECC_NIST_P384,
ECC_NIST_P521, ECC_BN_P256, ECC_BN_P638, ECC_SM2_P256
If the PCR registers 0 to 10 are extended by BIOS and IMA in the SHA1 bank the following PCR selection should
be used to enable the use of FAPI quote and verify quote:
"pcr_selection": [
{ "hash": "TPM2_ALG_SHA1",
"pcrSelect": [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ],
},
{ "hash": "TPM2_ALG_SHA256",
"pcrSelect": [ 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 ]
}
],
COLOPHON
This page is part of release 4.1.3 of Open Source implementation of the
TCG TPM2 Software Stack (TSS2). A description of the project, informa-
tion about reporting bugs, and the latest version of this page can be
found at https://github.com/tpm2-software/tpm2-tss/.
TPM2 Software Stack JULI 2020 fapi-profile(5)
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