-----Original Message----- From: Roberts, William C Sent: Monday, November 5, 2018 2:14 PM To: 'Marco De Benedictis' <marco.debenedictis(a)polito.it&gt;; tpm2(a)lists.01.org Subject: RE: [tpm2] Generate restricted signing key under owner hierarchy > -----Original Message----- > From: tpm2 [mailto:tpm2-bounces@lists.01.org] On Behalf Of Marco De > Benedictis > Sent: Monday, November 5, 2018 1:20 PM > To: tpm2(a)lists.01.org > Subject: [tpm2] Generate restricted signing key under owner hierarchy > > Hi all, > > I am using tpm2-tools on master (commit > a9fbf1879a8b008f89dc90f32b4ac701ac5ce2dd) and I am unable to generate > a restricted signing key under the owner hierarchy. > > First, I have generated a primary key on the owner hierarchy: > > tpm2_createprimary -a o -g sha256 -G ecc -o primary/context.ctx > > and then I run: > > tpm2_create -C primary/context.ctx \ > -g sha256-G ecc \ > -u child.pub \ > -r child.priv \ > -A > "fixedtpm|fixedparent|sensitivedataorigin|userwithauth|restricted|sign" > > I get an error: > > "ERROR: Tss2_Sys_Create(0x2D2) - tpm:parameter(2):unsupported or > incompatible scheme" > > If I run the same command without the "restricted" object attribute, it works. > Any idea on this behavior? Does this comply with the specs? I see the same behavior on the simulator, your failing at the following check: TPM_RC SchemeChecks( OBJECT *parentObject, // IN: parent (null if primary seed) TPMT_PUBLIC *publicArea // IN: public area of the object ) { <snip> // signing key that does not have a proper signing scheme. // This is OK if the key is not restricted and its scheme // is TPM_ALG_NULL if(attributes.restricted || scheme != TPM_ALG_NULL) return TPM_RCS_SCHEME; <snip> } Which was added in Revision 101 of the spec (see the change log): https://trustedcomputinggroup.org/wp-content/uploads/TPM-Rev-2.0-Part-1- Architecture-01.38.pdf If you apply this patch: diff --git a/lib/tpm2_alg_util.c b/lib/tpm2_alg_util.c index f109ca98e520..b018b1cbd9f0 100644 --- a/lib/tpm2_alg_util.c +++ b/lib/tpm2_alg_util.c @@ -302,11 +302,11 @@ static bool handle_asym_scheme_common(const char *ext, TPM2B_PUBLIC *public) { } } - if (is_restricted && s->scheme.scheme != TPM2_ALG_NULL) { - LOG_ERR("Restricted objects require a NULL scheme"); - /* don't print another error message */ - return false; - } +// if (is_restricted && s->scheme.scheme != TPM2_ALG_NULL) { +// LOG_ERR("Restricted objects require a NULL scheme"); +// /* don't print another error message */ +// return false; +// } /* * If the scheme is set, both the encrypt and decrypt attributes cannot be set, --- It should work if you do (note I changed file names): tpm2_create -C primary.ctx -g sha256 -G ecc256:ecdsa:null -u child.pub -r child.priv -A "fixedtpm|fixedparent|sensitivedataorigin|userwithauth|restricted|sign" The important takeaway is that you need a full algorithm specified for a restricted key, as restricted keys MUST have a signing scheme and MUST have a NULL symmetric details.

> > Thanks, > Marco > > > -- > MARCO DE BENEDICTIS > Department of Control and Computer Engineering Politecnico di Torino > E-mail: marco.debenedictis(a)polito.it - Phone: +39 (011) 090 7192