1// This file was extracted from the TCG Published
2// Trusted Platform Module Library
3// Part 3: Commands
4// Family "2.0"
5// Level 00 Revision 01.16
6// October 30, 2014
7
8#include "InternalRoutines.h"
9#include "HMAC_fp.h"
10//
11//
12//     Error Returns                     Meaning
13//
14//     TPM_RC_ATTRIBUTES                 key referenced by handle is not a signing key or is a restricted key
15//     TPM_RC_TYPE                       key referenced by handle is not an HMAC key
16//     TPM_RC_VALUE                      hashAlg is not compatible with the hash algorithm of the scheme of
17//                                       the object referenced by handle
18//
19TPM_RC
20TPM2_HMAC(
21   HMAC_In           *in,                 // IN: input parameter list
22   HMAC_Out          *out                 // OUT: output parameter list
23   )
24{
25   HMAC_STATE                 hmacState;
26   OBJECT                    *hmacObject;
27   TPMI_ALG_HASH              hashAlg;
28   TPMT_PUBLIC               *publicArea;
29
30// Input Validation
31
32   // Get HMAC key object and public area pointers
33   hmacObject = ObjectGet(in->handle);
34   publicArea = &hmacObject->publicArea;
35
36   // Make sure that the key is an HMAC key
37   if(publicArea->type != TPM_ALG_KEYEDHASH)
38       return TPM_RC_TYPE + RC_HMAC_handle;
39
40   // and that it is unrestricted
41   if(publicArea->objectAttributes.restricted == SET)
42       return TPM_RC_ATTRIBUTES + RC_HMAC_handle;
43
44   // and that it is a signing key
45   if(publicArea->objectAttributes.sign != SET)
46       return TPM_RC_KEY + RC_HMAC_handle;
47
48   // See if the key has a default
49   if(publicArea->parameters.keyedHashDetail.scheme.scheme == TPM_ALG_NULL)
50       // it doesn't so use the input value
51       hashAlg = in->hashAlg;
52   else
53   {
54       // key has a default so use it
55       hashAlg
56           = publicArea->parameters.keyedHashDetail.scheme.details.hmac.hashAlg;
57       // and verify that the input was either the TPM_ALG_NULL or the default
58       if(in->hashAlg != TPM_ALG_NULL && in->hashAlg != hashAlg)
59           hashAlg = TPM_ALG_NULL;
60   }
61   // if we ended up without a hash algorith then return an error
62   if(hashAlg == TPM_ALG_NULL)
63       return TPM_RC_VALUE + RC_HMAC_hashAlg;
64
65// Command Output
66
67  // Start HMAC stack
68  out->outHMAC.t.size = CryptStartHMAC2B(hashAlg,
69                                         &hmacObject->sensitive.sensitive.bits.b,
70                                         &hmacState);
71  // Adding HMAC data
72  CryptUpdateDigest2B(&hmacState, &in->buffer.b);
73
74  // Complete HMAC
75  CryptCompleteHMAC2B(&hmacState, &out->outHMAC.b);
76
77   return TPM_RC_SUCCESS;
78}
79