TSS_RESULT LIBTPMCALL TCS_Unseal(UINT32 locality, TPM_KEY_HANDLE hParent, TPM_AUTHDATA * parentSecret, BYTE * sealedData, UINT32 sealedDataSize, TPM_AUTHDATA * dataSecret, TPM_AUTH * parentAuth, TPM_AUTH * dataAuth, BYTE ** data, UINT32 * dataSize) {
UINT64 offset = 0;
TSS_RESULT result;
UINT32 paramSize;
BYTE txBlob[TSS_TPM_TXBLOB_SIZE];
TPM_COMMAND_CODE ordinal = TPM_ORD_Unseal;
BYTE bigendian_ordinal[sizeof(ordinal)];
BYTE bigendian_outDataSize[sizeof(*dataSize)];
TPM_NONCE h1;
TPM_NONCE h1Check;
struct USHAContext ctx_sha1;
if(LIBTPM_IsInit() == false) {
LOGERROR("libtpm not initialized");
return TCSERR(TSS_E_INTERNAL_ERROR);
}
LOGDEBUG("Entering TCS_Unseal");
// Generate H1
USHAReset(&ctx_sha1, SHA1);
UINT32ToArray(ordinal, bigendian_ordinal);
USHAInput(&ctx_sha1, bigendian_ordinal, sizeof(bigendian_ordinal));
USHAInput(&ctx_sha1, sealedData, sealedDataSize);
USHAResult(&ctx_sha1, (uint8_t *) &h1);
memset(&ctx_sha1, 0, sizeof(ctx_sha1));
// Compute Auth (OSAP & OIAP)
result = tcs_compute_auth(locality, parentAuth, &h1, parentSecret);
if(result) {
return result;
}
result = tcs_compute_auth(locality, dataAuth, &h1, dataSecret);
if(result) {
return result;
}
// Communication with TPM
result = tpm_rqu_build(TPM_ORD_Unseal, &offset, txBlob, hParent, sealedDataSize, sealedData, parentAuth, dataAuth);
if(result) {
LOGDEBUG("tpm_rqu_build returns %x", result);
return result;
}
UnloadBlob_Header(txBlob, ¶mSize);
result = tpm_io(locality, txBlob, paramSize, txBlob, sizeof(txBlob));
if(result) {
result = TDDLERR(result);
LOGERROR("tpm_io returns %x", result);
return result;
}
result = UnloadBlob_Header(txBlob, ¶mSize);
if(! result) {
result = tpm_rsp_parse(TPM_ORD_Unseal, txBlob, paramSize, dataSize, data, parentAuth, dataAuth);
}
if(!result) {
//Check auth values
UINT32ToArray(*dataSize, bigendian_outDataSize);
USHAReset(&ctx_sha1, SHA1);
USHAInput(&ctx_sha1, (uint8_t *) &result, sizeof(TPM_RESULT));
USHAInput(&ctx_sha1, bigendian_ordinal, sizeof(bigendian_ordinal));
USHAInput(&ctx_sha1, bigendian_outDataSize, sizeof(bigendian_outDataSize));
USHAInput(&ctx_sha1, *data, (int) *dataSize);
USHAResult(&ctx_sha1, (uint8_t *) &h1Check);
memset(&ctx_sha1, 0, sizeof(ctx_sha1));
result = tcs_check_auth(parentAuth, &h1Check, parentSecret);
if(! result) {
result = tcs_check_auth(dataAuth, &h1Check, dataSecret);
if(result) {
free(*data);
*data = 0;
}
} else {
free(*data);
*data = 0;
}
}
LOGDEBUG("Exiting TCS_Unseal : %x", result);
return result;
}
/*
* hmacReset
*
* Description:
* This function will initialize the hmacContext in preparation
* for computing a new HMAC message digest.
*
* Parameters:
* context: [in/out]
* The context to reset.
* whichSha: [in]
* One of SHA1, SHA224, SHA256, SHA384, SHA512
* key: [in]
* The secret shared key.
* key_len: [in]
* The length of the secret shared key.
*
* Returns:
* sha Error Code.
*
*/
int hmacReset(HMACContext *ctx, enum SHAversion whichSha,
const unsigned char *key, int key_len)
{
int i, blocksize, hashsize;
/* inner padding - key XORd with ipad */
unsigned char k_ipad[USHA_Max_Message_Block_Size];
/* temporary buffer when keylen > blocksize */
unsigned char tempkey[USHAMaxHashSize];
if (!ctx) return shaNull;
blocksize = ctx->blockSize = USHABlockSize(whichSha);
hashsize = ctx->hashSize = USHAHashSize(whichSha);
ctx->whichSha = whichSha;
/*
* If key is longer than the hash blocksize,
* reset it to key = HASH(key).
*/
if (key_len > blocksize) {
USHAContext tctx;
int err = USHAReset(&tctx, whichSha) ||
USHAInput(&tctx, key, key_len) ||
USHAResult(&tctx, tempkey);
if (err != shaSuccess) return err;
key = tempkey;
key_len = hashsize;
}
/*
* The HMAC transform looks like:
*
* SHA(K XOR opad, SHA(K XOR ipad, text))
*
* where K is an n byte key.
* ipad is the byte 0x36 repeated blocksize times
* opad is the byte 0x5c repeated blocksize times
* and text is the data being protected.
*/
/* store key into the pads, XOR'd with ipad and opad values */
for (i = 0; i < key_len; i++) {
k_ipad[i] = key[i] ^ 0x36;
ctx->k_opad[i] = key[i] ^ 0x5c;
}
/* remaining pad bytes are '\0' XOR'd with ipad and opad values */
for (; i < blocksize; i++) {
k_ipad[i] = 0x36;
ctx->k_opad[i] = 0x5c;
}
/* perform inner hash */
/* init context for 1st pass */
return USHAReset(&ctx->shaContext, whichSha) ||
/* and start with inner pad */
USHAInput(&ctx->shaContext, k_ipad, blocksize);
}
