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/********************************************************************************/
/* */
/* Functions used for ticket computations. */
/* Written by Ken Goldman */
/* IBM Thomas J. Watson Research Center */
/* $Id: Ticket.c 1594 2020-03-26 22:15:48Z kgoldman $ */
/* */
/* Licenses and Notices */
/* */
/* 1. Copyright Licenses: */
/* */
/* - Trusted Computing Group (TCG) grants to the user of the source code in */
/* this specification (the "Source Code") a worldwide, irrevocable, */
/* nonexclusive, royalty free, copyright license to reproduce, create */
/* derivative works, distribute, display and perform the Source Code and */
/* derivative works thereof, and to grant others the rights granted herein. */
/* */
/* - The TCG grants to the user of the other parts of the specification */
/* (other than the Source Code) the rights to reproduce, distribute, */
/* display, and perform the specification solely for the purpose of */
/* developing products based on such documents. */
/* */
/* 2. Source Code Distribution Conditions: */
/* */
/* - Redistributions of Source Code must retain the above copyright licenses, */
/* this list of conditions and the following disclaimers. */
/* */
/* - Redistributions in binary form must reproduce the above copyright */
/* licenses, this list of conditions and the following disclaimers in the */
/* documentation and/or other materials provided with the distribution. */
/* */
/* 3. Disclaimers: */
/* */
/* - THE COPYRIGHT LICENSES SET FORTH ABOVE DO NOT REPRESENT ANY FORM OF */
/* LICENSE OR WAIVER, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, WITH */
/* RESPECT TO PATENT RIGHTS HELD BY TCG MEMBERS (OR OTHER THIRD PARTIES) */
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/* (c) Copyright IBM Corp. and others, 2016 - 2020 */
/* */
/********************************************************************************/
/* 10.2.23 Ticket.c */
/* 10.2.23.1 Introduction */
/* This clause contains the functions used for ticket computations. */
/* 10.2.23.2 Includes */
#include "Tpm.h"
/* 10.2.23.3 Functions */
/* 10.2.23.3.1 TicketIsSafe() */
/* This function indicates if producing a ticket is safe. It checks if the leading bytes of an input
buffer is TPM_GENERATED_VALUE or its substring of canonical form. If so, it is not safe to
produce ticket for an input buffer claiming to be TPM generated buffer */
/* Return Values Meaning */
/* TRUE It is safe to produce ticket */
/* FALSE It is not safe to produce ticket */
BOOL
TicketIsSafe(
TPM2B *buffer
)
{
TPM_CONSTANTS32 valueToCompare = TPM_GENERATED_VALUE;
BYTE bufferToCompare[sizeof(valueToCompare)];
BYTE *marshalBuffer;
//
// If the buffer size is less than the size of TPM_GENERATED_VALUE, assume
// it is not safe to generate a ticket
if(buffer->size < sizeof(valueToCompare))
return FALSE;
marshalBuffer = bufferToCompare;
TPM_CONSTANTS32_Marshal(&valueToCompare, &marshalBuffer, NULL);
if(MemoryEqual(buffer->buffer, bufferToCompare, sizeof(valueToCompare)))
return FALSE;
else
return TRUE;
}
/* 10.2.23.3.2 TicketComputeVerified() */
/* This function creates a TPMT_TK_VERIFIED ticket. */
void
TicketComputeVerified(
TPMI_RH_HIERARCHY hierarchy, // IN: hierarchy constant for ticket
TPM2B_DIGEST *digest, // IN: digest
TPM2B_NAME *keyName, // IN: name of key that signed the values
TPMT_TK_VERIFIED *ticket // OUT: verified ticket
)
{
TPM2B_PROOF *proof;
HMAC_STATE hmacState;
//
// Fill in ticket fields
ticket->tag = TPM_ST_VERIFIED;
ticket->hierarchy = hierarchy;
proof = HierarchyGetProof(hierarchy);
// Start HMAC using the proof value of the hierarchy as the HMAC key
ticket->digest.t.size = CryptHmacStart2B(&hmacState, CONTEXT_INTEGRITY_HASH_ALG,
&proof->b);
// TPM_ST_VERIFIED
CryptDigestUpdateInt(&hmacState, sizeof(TPM_ST), ticket->tag);
// digest
CryptDigestUpdate2B(&hmacState.hashState, &digest->b);
// key name
CryptDigestUpdate2B(&hmacState.hashState, &keyName->b);
// done
CryptHmacEnd2B(&hmacState, &ticket->digest.b);
return;
}
/* 10.2.23.3.3 TicketComputeAuth() */
/* This function creates a TPMT_TK_AUTH ticket. */
void
TicketComputeAuth(
TPM_ST type, // IN: the type of ticket.
TPMI_RH_HIERARCHY hierarchy, // IN: hierarchy constant for ticket
UINT64 timeout, // IN: timeout
BOOL expiresOnReset,// IN: flag to indicate if ticket expires on
// TPM Reset
TPM2B_DIGEST *cpHashA, // IN: input cpHashA
TPM2B_NONCE *policyRef, // IN: input policyRef
TPM2B_NAME *entityName, // IN: name of entity
TPMT_TK_AUTH *ticket // OUT: Created ticket
)
{
TPM2B_PROOF *proof;
HMAC_STATE hmacState;
//
// Get proper proof
proof = HierarchyGetProof(hierarchy);
// Fill in ticket fields
ticket->tag = type;
ticket->hierarchy = hierarchy;
// Start HMAC with hierarchy proof as the HMAC key
ticket->digest.t.size = CryptHmacStart2B(&hmacState, CONTEXT_INTEGRITY_HASH_ALG,
&proof->b);
// TPM_ST_AUTH_SECRET or TPM_ST_AUTH_SIGNED,
CryptDigestUpdateInt(&hmacState, sizeof(UINT16), ticket->tag);
// cpHash
CryptDigestUpdate2B(&hmacState.hashState, &cpHashA->b);
// policyRef
CryptDigestUpdate2B(&hmacState.hashState, &policyRef->b);
// keyName
CryptDigestUpdate2B(&hmacState.hashState, &entityName->b);
// timeout
CryptDigestUpdateInt(&hmacState, sizeof(timeout), timeout);
if(timeout != 0)
{
// epoch
CryptDigestUpdateInt(&hmacState.hashState, sizeof(CLOCK_NONCE),
g_timeEpoch);
// reset count
if(expiresOnReset)
CryptDigestUpdateInt(&hmacState.hashState, sizeof(gp.totalResetCount),
gp.totalResetCount);
}
// done
CryptHmacEnd2B(&hmacState, &ticket->digest.b);
return;
}
/* 10.2.23.3.4 TicketComputeHashCheck() */
/* This function creates a TPMT_TK_HASHCHECK ticket. */
void
TicketComputeHashCheck(
TPMI_RH_HIERARCHY hierarchy, // IN: hierarchy constant for ticket
TPM_ALG_ID hashAlg, // IN: the hash algorithm for 'digest'
TPM2B_DIGEST *digest, // IN: input digest
TPMT_TK_HASHCHECK *ticket // OUT: Created ticket
)
{
TPM2B_PROOF *proof;
HMAC_STATE hmacState;
//
// Get proper proof
proof = HierarchyGetProof(hierarchy);
// Fill in ticket fields
ticket->tag = TPM_ST_HASHCHECK;
ticket->hierarchy = hierarchy;
// Start HMAC using hierarchy proof as HMAC key
ticket->digest.t.size = CryptHmacStart2B(&hmacState, CONTEXT_INTEGRITY_HASH_ALG,
&proof->b);
// TPM_ST_HASHCHECK
CryptDigestUpdateInt(&hmacState, sizeof(TPM_ST), ticket->tag);
// hash algorithm
CryptDigestUpdateInt(&hmacState, sizeof(hashAlg), hashAlg);
// digest
CryptDigestUpdate2B(&hmacState.hashState, &digest->b);
// done
CryptHmacEnd2B(&hmacState, &ticket->digest.b);
return;
}
/* 10.2.23.3.5 TicketComputeCreation() */
/* This function creates a TPMT_TK_CREATION ticket. */
void
TicketComputeCreation(
TPMI_RH_HIERARCHY hierarchy, // IN: hierarchy for ticket
TPM2B_NAME *name, // IN: object name
TPM2B_DIGEST *creation, // IN: creation hash
TPMT_TK_CREATION *ticket // OUT: created ticket
)
{
TPM2B_PROOF *proof;
HMAC_STATE hmacState;
// Get proper proof
proof = HierarchyGetProof(hierarchy);
// Fill in ticket fields
ticket->tag = TPM_ST_CREATION;
ticket->hierarchy = hierarchy;
// Start HMAC using hierarchy proof as HMAC key
ticket->digest.t.size = CryptHmacStart2B(&hmacState, CONTEXT_INTEGRITY_HASH_ALG,
&proof->b);
// TPM_ST_CREATION
CryptDigestUpdateInt(&hmacState, sizeof(TPM_ST), ticket->tag);
// name if provided
if(name != NULL)
CryptDigestUpdate2B(&hmacState.hashState, &name->b);
// creation hash
CryptDigestUpdate2B(&hmacState.hashState, &creation->b);
// Done
CryptHmacEnd2B(&hmacState, &ticket->digest.b);
return;
}
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