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// This file was extracted from the TCG Published
// Trusted Platform Module Library
// Part 3: Commands
// Family "2.0"
// Level 00 Revision 01.16
// October 30, 2014
#include "InternalRoutines.h"
#include "StartAuthSession_fp.h"
//
//
// Error Returns Meaning
//
// TPM_RC_ATTRIBUTES tpmKey does not reference a decrypt key
// TPM_RC_CONTEXT_GAP the difference between the most recently created active context and
// the oldest active context is at the limits of the TPM
// TPM_RC_HANDLE input decrypt key handle only has public portion loaded
// TPM_RC_MODE symmetric specifies a block cipher but the mode is not
// TPM_ALG_CFB.
// TPM_RC_SESSION_HANDLES no session handle is available
// TPM_RC_SESSION_MEMORY no more slots for loading a session
// TPM_RC_SIZE nonce less than 16 octets or greater than the size of the digest
// produced by authHash
// TPM_RC_VALUE secret size does not match decrypt key type; or the recovered secret
// is larger than the digest size of the nameAlg of tpmKey; or, for an
// RSA decrypt key, if encryptedSecret is greater than the public
// exponent of tpmKey.
//
TPM_RC
TPM2_StartAuthSession(
StartAuthSession_In *in, // IN: input parameter buffer
StartAuthSession_Out *out // OUT: output parameter buffer
)
{
TPM_RC result = TPM_RC_SUCCESS;
OBJECT *tpmKey; // TPM key for decrypt salt
SESSION *session; // session internal data
TPM2B_DATA salt;
// Input Validation
// Check input nonce size. IT should be at least 16 bytes but not larger
// than the digest size of session hash.
if( in->nonceCaller.t.size < 16
|| in->nonceCaller.t.size > CryptGetHashDigestSize(in->authHash))
return TPM_RC_SIZE + RC_StartAuthSession_nonceCaller;
// If an decrypt key is passed in, check its validation
if(in->tpmKey != TPM_RH_NULL)
{
// secret size cannot be 0
if(in->encryptedSalt.t.size == 0)
return TPM_RC_VALUE + RC_StartAuthSession_encryptedSalt;
// Get pointer to loaded decrypt key
tpmKey = ObjectGet(in->tpmKey);
// Decrypting salt requires accessing the private portion of a key.
// Therefore, tmpKey can not be a key with only public portion loaded
if(tpmKey->attributes.publicOnly)
return TPM_RC_HANDLE + RC_StartAuthSession_tpmKey;
// HMAC session input handle check.
// tpmKey should be a decryption key
if(tpmKey->publicArea.objectAttributes.decrypt != SET)
return TPM_RC_ATTRIBUTES + RC_StartAuthSession_tpmKey;
// Secret Decryption. A TPM_RC_VALUE, TPM_RC_KEY or Unmarshal errors
// may be returned at this point
result = CryptSecretDecrypt(in->tpmKey, &in->nonceCaller, "SECRET",
&in->encryptedSalt, &salt);
if(result != TPM_RC_SUCCESS)
return TPM_RC_VALUE + RC_StartAuthSession_encryptedSalt;
}
else
{
// secret size must be 0
if(in->encryptedSalt.t.size != 0)
return TPM_RC_VALUE + RC_StartAuthSession_encryptedSalt;
salt.t.size = 0;
}
// If the bind handle references a transient object, make sure that the
// sensitive area is loaded so that the authValue can be accessed.
if( HandleGetType(in->bind) == TPM_HT_TRANSIENT
&& ObjectGet(in->bind)->attributes.publicOnly == SET)
return TPM_RC_HANDLE + RC_StartAuthSession_bind;
// If 'symmetric' is a symmetric block cipher (not TPM_ALG_NULL or TPM_ALG_XOR)
// then the mode must be CFB.
if( in->symmetric.algorithm != TPM_ALG_NULL
&& in->symmetric.algorithm != TPM_ALG_XOR
&& in->symmetric.mode.sym != TPM_ALG_CFB)
return TPM_RC_MODE + RC_StartAuthSession_symmetric;
// Internal Data Update
// Create internal session structure. TPM_RC_CONTEXT_GAP, TPM_RC_NO_HANDLES
// or TPM_RC_SESSION_MEMORY errors may be returned returned at this point.
//
// The detailed actions for creating the session context are not shown here
// as the details are implementation dependent
// SessionCreate sets the output handle
result = SessionCreate(in->sessionType, in->authHash,
&in->nonceCaller, &in->symmetric,
in->bind, &salt, &out->sessionHandle);
if(result != TPM_RC_SUCCESS)
return result;
// Command Output
// Get session pointer
session = SessionGet(out->sessionHandle);
// Copy nonceTPM
out->nonceTPM = session->nonceTPM;
return TPM_RC_SUCCESS;
}
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