More sealing/unsealing examples

.gitignore

@@ -65,12 +65,15 @@ examples/keygen/external_import
 examples/nvram/store
 examples/nvram/read
 examples/nvram/counter
+examples/nvram/seal_policy_auth_nv
+examples/nvram/seal_policy_auth_nv_external
 examples/gpio/gpio_config
 examples/gpio/gpio_set
 examples/gpio/gpio_read
 examples/gpio/gpio_nuvoton
 examples/seal/seal
 examples/seal/unseal
+examples/seal/seal_policy_auth
 examples/attestation/make_credential
 examples/attestation/activate_credential
 examples/boot/secure_rot

examples/README.md

@@ -453,6 +453,47 @@ After a successful unsealing, the data is stored into a new file. If no filename
 See [examples/boot/README.md](/examples/boot/README.md)
 
 
+### Sealing data to the TPM with policy authorization
+
+Data can also be sealed to the TPM, either to NVM or regular, with policy authorization. ./examples/seal/seal\_policy\_auth.c shows an example of how to seal data to the TPM using the wolfTPM2\_SealWithAuthKey function and unseal with wolfTPM2\_UnsealWithAuthSig. These functions call wolfTPM2\_PolicyPCR to add the PCR values to the policyDigest and TPM2\_PolicyAuthorize to sign the digest with either an ecc or rsa key. ./examples/nvram/seal\_policy\_auth\_nv.c is similar but seals to the data to NVM and uses TPM2\_PolicyAuthorizeNV to keep the policyDigest in NVM so it persists in between boots. ./examples/nvram/seal\_policy\_auth\_nv\_external.c works the same way but it shows how to use a key generated from outside wolfTPM, currently only supports ecc256 keys
+
+```
+$ ./examples/seal/seal_policy_auth -ecc -aes 16
+Example for sealing data to the TPM with policy authorization
+	PCR Indicies:16
+	Use Parameter Encryption: CFB
+wolfTPM2_Init: success
+TPM2_StartAuthSession: sessionHandle 0x3000000
+Loading SRK: Storage 0x81000200 (282 bytes)
+ECC template
+Loaded sealBlob to 0x80000002
+TPM2_StartAuthSession: sessionHandle 0x3000000
+Unsealed secret matches!
+
+$ ./examples/nvram/seal_policy_auth_nv -ecc -aes 16
+Example for sealing data to NV memory with policy authorization
+	PCR Indicies:16
+	Use Parameter Encryption: CFB
+wolfTPM2_Init: success
+TPM2_StartAuthSession: sessionHandle 0x3000000
+Loading SRK: Storage 0x81000200 (282 bytes)
+ECC template
+TPM2_StartAuthSession: sessionHandle 0x3000000
+Unsealed secret matches!
+
+$ ./examples/nvram/seal_policy_auth_nv_external -ecc -aes 16
+Warning: Unrecognized option: -ecc
+Example for sealing data to NV memory with policy authorization
+	PCR Indicies:16
+	Use Parameter Encryption: CFB
+wolfTPM2_Init: success
+Loading SRK: Storage 0x81000200 (282 bytes)
+TPM2_StartAuthSession: sessionHandle 0x3000000
+TPM2_StartAuthSession: sessionHandle 0x3000000
+Unsealed secret matches!
+```
+
+
 ## Secure Boot
 
 ### TPM based root of trust

examples/nvram/include.am

@@ -21,13 +21,28 @@ examples_nvram_counter_SOURCES      = examples/nvram/counter.c \
                                    examples/tpm_test_keys.c
 examples_nvram_counter_LDADD        = src/libwolftpm.la $(LIB_STATIC_ADD)
 examples_nvram_counter_DEPENDENCIES = src/libwolftpm.la
+
+noinst_PROGRAMS += examples/nvram/seal_policy_auth_nv
+examples_nvram_seal_policy_auth_nv_SOURCES      = examples/nvram/seal_policy_auth_nv.c \
+                                                  examples/tpm_test_keys.c
+examples_nvram_seal_policy_auth_nv_LDADD        = src/libwolftpm.la $(LIB_STATIC_ADD)
+examples_nvram_seal_policy_auth_nv_DEPENDENCIES = src/libwolftpm.la
+
+noinst_PROGRAMS += examples/nvram/seal_policy_auth_nv_external
+examples_nvram_seal_policy_auth_nv_external_SOURCES      = examples/nvram/seal_policy_auth_nv_external.c \
+                                                  examples/tpm_test_keys.c
+examples_nvram_seal_policy_auth_nv_external_LDADD        = src/libwolftpm.la $(LIB_STATIC_ADD)
+examples_nvram_seal_policy_auth_nv_external_DEPENDENCIES = src/libwolftpm.la
+
 endif
 
 example_nvramdir = $(exampledir)/nvram
 dist_example_nvram_DATA = \
   examples/nvram/store.c \
   examples/nvram/read.c \
-  examples/nvram/counter.c
+  examples/nvram/counter.c \
+  examples/nvram/seal_policy_auth_nv.c \
+  examples/nvram/seal_policy_auth_nv_external.c
 
 DISTCLEANFILES+= examples/nvram/.libs/store
 DISTCLEANFILES+= examples/nvram/.libs/read

examples/nvram/seal_policy_auth_nv.c

@@ -0,0 +1,294 @@
+/* seal_policy_auth_nv.c
+ *
+ * Copyright (C) 2006-2023 wolfSSL Inc.
+ *
+ * This file is part of wolfTPM.
+ *
+ * wolfTPM is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * wolfTPM is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+/* This is a helper tool for setting policies on a TPM 2.0 PCR */
+
+#include <wolftpm/tpm2_wrap.h>
+
+#include <stdio.h>
+
+#if !defined(WOLFTPM2_NO_WRAPPER) && !defined(WOLFTPM2_NO_WOLFCRYPT)
+
+#include <examples/nvram/nvram.h>
+#include <hal/tpm_io.h>
+#include <examples/tpm_test.h>
+#include <examples/tpm_test_keys.h>
+#include <wolfssl/wolfcrypt/hash.h>
+
+/******************************************************************************/
+/* --- BEGIN TPM2.0 PCR Policy example tool  -- */
+/******************************************************************************/
+
+static void usage(void)
+{
+    printf("Expected usage:\n");
+    printf("./examples/nvram/seal_policy_auth_nv [-aes/xor] [-rsa/ecc] [pcr]\n");
+    printf("* -aes/xor: Use Parameter Encryption\n");
+    printf("* -rsa/ecc: Pick sealing key type, (default rsa)\n");
+    printf("* pcr: PCR index between 0-23 (default %d)\n", TPM2_DEMO_PCR_INDEX);
+}
+
+static const word32 sealNvIndex = TPM2_DEMO_NV_TEST_INDEX;
+static const word32 policyDigestNvIndex = TPM2_DEMO_NV_TEST_INDEX + 1;
+
+int TPM2_PCR_Seal_With_Policy_Auth_NV_Test(void* userCtx, int argc, char *argv[])
+{
+    int i;
+    int rc = -1;
+    WOLFTPM2_NV nv;
+    WOLFTPM2_DEV dev;
+    WOLFTPM2_KEY storage;
+    WOLFTPM2_SESSION tpmSession;
+    WOLFTPM2_KEYBLOB authKey;
+    TPMT_PUBLIC authTemplate;
+    /* default to aes since parm encryption is required */
+    TPM_ALG_ID paramEncAlg = TPM_ALG_CFB;
+    word32 pcrIndex = TPM2_DEMO_PCR_INDEX;
+    byte pcrArray[PCR_SELECT_MAX*2];
+    word32 pcrArraySz = 0;
+    byte secret[16];
+    byte secretOut[16];
+    word32 secretOutSz = (word32)sizeof(secretOut);
+    byte policySignedSig[MAX_RSA_KEY_BYTES];
+    word32 policySignedSigSz = MAX_RSA_KEY_BYTES;
+    TPM_ALG_ID alg = TPM_ALG_RSA;
+
+    XMEMSET(&dev, 0, sizeof(WOLFTPM2_DEV));
+    XMEMSET(&storage, 0, sizeof(WOLFTPM2_KEY));
+    XMEMSET(&tpmSession, 0, sizeof(WOLFTPM2_SESSION));
+    XMEMSET(&nv, 0, sizeof(nv));
+    XMEMSET(&authTemplate, 0, sizeof(TPMT_PUBLIC));
+
+    /* set the secret */
+    for (i = 0; i < (int)sizeof(secret); i++) {
+        secret[i] = i;
+    }
+
+    if (argc >= 2) {
+        if (XSTRCMP(argv[1], "-?") == 0 ||
+            XSTRCMP(argv[1], "-h") == 0 ||
+            XSTRCMP(argv[1], "--help") == 0) {
+            usage();
+            return 0;
+        }
+    }
+    while (argc > 1) {
+        if (XSTRCMP(argv[argc-1], "-aes") == 0) {
+            paramEncAlg = TPM_ALG_CFB;
+        }
+        else if (XSTRCMP(argv[argc-1], "-xor") == 0) {
+            paramEncAlg = TPM_ALG_XOR;
+        }
+        else if (XSTRCMP(argv[argc-1], "-rsa") == 0) {
+            alg = TPM_ALG_RSA;
+        }
+        else if (XSTRCMP(argv[argc-1], "-ecc") == 0) {
+            alg = TPM_ALG_ECC;
+        }
+        else if (argv[argc-1][0] != '-') {
+            /* TODO: Allow selection of multiple PCR's SHA-1 or SHA2-256 */
+            pcrIndex = XATOI(argv[argc-1]);
+            if (pcrIndex > PCR_LAST) {
+                printf("PCR index is out of range (0-23)\n");
+                usage();
+                return 0;
+            }
+            pcrArray[pcrArraySz] = pcrIndex;
+            pcrArraySz++;
+        }
+        else {
+            printf("Warning: Unrecognized option: %s\n", argv[argc-1]);
+        }
+        argc--;
+    }
+
+    if (pcrArraySz == 0) {
+        pcrArray[pcrArraySz] = pcrIndex;
+        pcrArraySz++;
+    }
+
+    printf("Example for sealing data to NV memory with policy authorization\n");
+    printf("\tPCR Indicies:");
+
+    for (i = 0; i < (int)pcrArraySz; i++) {
+        printf("%d ", pcrArray[i]);
+    }
+
+    printf("\n");
+
+    printf("\tUse Parameter Encryption: %s\n", TPM2_GetAlgName(paramEncAlg));
+
+    rc = wolfTPM2_Init(&dev, TPM2_IoCb, userCtx);
+    if (rc != TPM_RC_SUCCESS) {
+        printf("wolfTPM2_Init failed 0x%x: %s\n", rc, TPM2_GetRCString(rc));
+        goto exit;
+    }
+    printf("wolfTPM2_Init: success\n");
+
+    /* session is required for pcr authorization */
+    /* Start an authenticated policy session (salted / unbound) */
+    rc = wolfTPM2_StartSession(&dev, &tpmSession, NULL, NULL,
+        TPM_SE_POLICY, paramEncAlg);
+    if (rc != 0) goto exit;
+    printf("TPM2_StartAuthSession: sessionHandle 0x%x\n",
+        (word32)tpmSession.handle.hndl);
+
+    /* set session for authorization of the storage key */
+    rc = wolfTPM2_SetAuthSession(&dev, 0, &tpmSession,
+        (TPMA_SESSION_decrypt | TPMA_SESSION_encrypt |
+        TPMA_SESSION_continueSession));
+    if (rc != 0) goto exit;
+
+    /* get SRK */
+    rc = getPrimaryStoragekey(&dev, &storage, TPM_ALG_RSA);
+    if (rc != 0) goto exit;
+
+    /* create the auth key template */
+    if (alg == TPM_ALG_RSA) {
+        printf("RSA template\n");
+        rc = wolfTPM2_GetKeyTemplate_RSA(&authTemplate,
+                 TPMA_OBJECT_sensitiveDataOrigin | TPMA_OBJECT_userWithAuth |
+                 TPMA_OBJECT_decrypt | TPMA_OBJECT_sign | TPMA_OBJECT_noDA);
+    }
+    else if (alg == TPM_ALG_ECC) {
+        printf("ECC template\n");
+        rc = wolfTPM2_GetKeyTemplate_ECC(&authTemplate,
+                 TPMA_OBJECT_sensitiveDataOrigin | TPMA_OBJECT_userWithAuth |
+                 TPMA_OBJECT_sign | TPMA_OBJECT_noDA,
+                 TPM_ECC_NIST_P256, TPM_ALG_ECDSA);
+    }
+    if (rc != TPM_RC_SUCCESS) {
+        printf("create template failed failed\n");
+        goto exit;
+    }
+
+    /* generate the authorized key, this auth key can also generated and */
+    /* loaded externally */
+    rc = wolfTPM2_CreateKey(&dev, &authKey, &storage.handle,
+                            &authTemplate, NULL, 0);
+    if (rc != TPM_RC_SUCCESS) {
+        printf("wolfTPM2_CreateKey failed\n");
+        goto exit;
+    }
+
+    rc = wolfTPM2_LoadKey(&dev, &authKey, &storage.handle);
+    if (rc != TPM_RC_SUCCESS) {
+        printf("wolfTPM2_LoadKey failed\n");
+        goto exit;
+    }
+
+    /* seal the secret */
+    rc = wolfTPM2_SealWithAuthKeyNV(&dev, (WOLFTPM2_KEY*)&authKey,
+        &tpmSession, TPM_ALG_SHA256, TPM_ALG_SHA256, pcrArray,
+        pcrArraySz, secret, sizeof(secret),
+        NULL, 0, sealNvIndex, policyDigestNvIndex, policySignedSig,
+        &policySignedSigSz);
+    if (rc != TPM_RC_SUCCESS) {
+        printf("wolfTPM2_SealWithAuthPolicyNV failed 0x%x: %s\n", rc,
+            TPM2_GetRCString(rc));
+        goto exit;
+    }
+
+    /* reset our session */
+    wolfTPM2_UnloadHandle(&dev, &tpmSession.handle);
+    XMEMSET(&tpmSession, 0, sizeof(WOLFTPM2_SESSION));
+
+    rc = wolfTPM2_StartSession(&dev, &tpmSession, NULL, NULL,
+        TPM_SE_POLICY, paramEncAlg);
+    if (rc != 0) goto exit;
+    printf("TPM2_StartAuthSession: sessionHandle 0x%x\n",
+        (word32)tpmSession.handle.hndl);
+
+    /* set session for authorization of the storage key */
+    rc = wolfTPM2_SetAuthSession(&dev, 0, &tpmSession,
+        (TPMA_SESSION_decrypt | TPMA_SESSION_encrypt |
+        TPMA_SESSION_continueSession));
+    if (rc != 0) goto exit;
+
+    nv.handle.hndl = sealNvIndex;
+
+    /* try to unseal with the regular command, should fail */
+    rc = wolfTPM2_NVReadAuth(&dev, &nv, sealNvIndex,
+        secretOut, &secretOutSz, 0);
+    if (rc == TPM_RC_SUCCESS) {
+        printf("wolfTPM2_NVReadAuth failed, it should not have allowed a read"
+            " without PolicyAuthorizeNV 0x%x: %s\n", rc, TPM2_GetRCString(rc));
+        goto exit;
+    }
+
+    /* unseal the secret */
+    rc = wolfTPM2_UnsealWithAuthSigNV(&dev, (WOLFTPM2_KEY*)&authKey,
+        &tpmSession, TPM_ALG_SHA256, pcrArray,
+        pcrArraySz, NULL, 0, policySignedSig, policySignedSigSz, sealNvIndex,
+        policyDigestNvIndex, secretOut, &secretOutSz);
+    if (rc != TPM_RC_SUCCESS) {
+        printf("wolfTPM2_UnsealWithAuthSigNV failed 0x%x: %s\n", rc,
+            TPM2_GetRCString(rc));
+        goto exit;
+    }
+
+    if (XMEMCMP(secret, secretOut, sizeof(secret)) != 0) {
+        printf("Unsealed secret does not match\n");
+        goto exit;
+    }
+    else {
+        printf("Unsealed secret matches!\n");
+    }
+
+exit:
+    if (rc != 0) {
+        printf("Failure 0x%x: %s\n", rc, wolfTPM2_GetRCString(rc));
+    }
+
+    wolfTPM2_SetAuthPassword(&dev, 0, NULL);
+
+    wolfTPM2_UnloadHandle(&dev, &authKey.handle);
+    wolfTPM2_UnloadHandle(&dev, &storage.handle);
+    wolfTPM2_UnloadHandle(&dev, &tpmSession.handle);
+
+    wolfTPM2_Cleanup(&dev);
+
+    return rc;
+}
+
+/******************************************************************************/
+/* --- END TPM2.0 PCR Policy example tool -- */
+/******************************************************************************/
+
+#endif /* !WOLFTPM2_NO_WRAPPER && !WOLFTPM2_NO_WOLFCRYPT */
+
+
+#ifndef NO_MAIN_DRIVER
+int main(int argc, char *argv[])
+{
+    int rc = -1;
+
+#if !defined(WOLFTPM2_NO_WRAPPER) && !defined(WOLFTPM2_NO_WOLFCRYPT)
+    rc = TPM2_PCR_Seal_With_Policy_Auth_NV_Test(NULL, argc, argv);
+#else
+    printf("Wrapper code not compiled in\n");
+    (void)argc;
+    (void)argv;
+#endif /* !WOLFTPM2_NO_WRAPPER && !WOLFTPM2_NO_WOLFCRYPT */
+
+    return rc;
+}
+#endif