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wolfTPM
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Minor changes based on peer feedback 

Signed-off-by: Dimitar Tomov <dimi@wolfssl.com>
pull/157/head
Dimitar Tomov 2021-04-20 15:07:32 +03:00
parent f1f4de5739
commit 474ddb4d01
3 changed files with 22 additions and 7 deletions
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7
examples/README.md
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@ -379,7 +379,7 @@ After successful key extraction using "read", the NV Index is destroyed. Therefo
## Seal / Unseal
TPM 2.0 can protect secrets using a standard Seal/Unseal procedure. Seal can be created using a TPM 2.0 key or against a set of PCR values.
TPM 2.0 can protect secrets using a standard Seal/Unseal procedure. Seal can be created using a TPM 2.0 key or against a set of PCR values. Note: Secret data sealed in a key is limited to a maximum size of 128 bytes.
There are two examples available: `seal/seal` and `seal/unseal`.
@ -392,6 +392,7 @@ Using the `seal` example we store securely our data in a newly generated TPM 2.0
Please find example output from sealing and unsealing a secret message:
```
$ ./examples/seal/seal keyblob.bin mySecretMessage
TPM2.0 Simple Seal example
Key Blob: keyblob.bin
@ -402,6 +403,7 @@ Created new TPM seal key (pub 46, priv 141 bytes)
Wrote 193 bytes to keyblob.bin
Key Public Blob 46
Key Private Blob 141
$ ./examples/keygen/keyload -persistent
TPM2.0 Key load example
Key Blob: keyblob.bin
@ -411,13 +413,16 @@ Reading 193 bytes from keyblob.bin
Reading the private part of the key
Loaded key to 0x80000001
Key was made persistent at 0x81000202
$ ./examples/seal/unseal message.raw
Example how to unseal data using TPM2.0
wolfTPM2_Init: success
Unsealing succeeded
Stored unsealed data to file = message.raw
$ cat message.raw
mySecretMessage
```
After a successful unsealing, the data is stored into a new file. If no filename is provided, the `unseal` tool stores the data in `unseal.bin`.

9
examples/seal/seal.c
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@ -137,12 +137,13 @@ int TPM2_Seal_Example(void* userCtx, int argc, char *argv[])
#if !defined(WOLFTPM2_NO_WOLFCRYPT) && !defined(NO_FILESYSTEM)
rc = writeKeyBlob(outputFile, &newKey);
#endif
//#else
printf("Key Public Blob %d\n", newKey.pub.size);
#ifdef DEBUG_WOLFTPM
printf("Key Seal, Public Blob %d\n", newKey.pub.size);
TPM2_PrintBin((const byte*)&newKey.pub.publicArea, newKey.pub.size);
printf("Key Private Blob %d\n", newKey.priv.size);
printf("Key Seal, Private Blob %d\n", newKey.priv.size);
TPM2_PrintBin(newKey.priv.buffer, newKey.priv.size);
//#endif
#endif
exit:

13
src/tpm2_wrap.c
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@ -4007,6 +4007,15 @@ int wolfTPM2_CreateKeySeal(WOLFTPM2_DEV* dev, WOLFTPM2_KEYBLOB* keyBlob,
if (dev == NULL || keyBlob == NULL || parent == NULL || publicTemplate == NULL)
return BAD_FUNC_ARG;
/* Seal size is limited to TCG defined MAX_SYM_DATA, which is 128 bytes */
if (sealSize < 0 || sealSize > 128) {
printf("wolfTPM2_CreateKeySeal failed. Seal size is invalid.\n");
#ifdef DEBUG_WOLFTPM
printf("Seal size %d should not be larger than 128 bytes\n", sealSize);
#endif
return BAD_FUNC_ARG;
}
/* clear output key buffer */
XMEMSET(keyBlob, 0, sizeof(WOLFTPM2_KEYBLOB));
XMEMSET(&createOut, 0, sizeof(createOut)); /* make sure pub struct is zero init */
@ -4031,13 +4040,13 @@ int wolfTPM2_CreateKeySeal(WOLFTPM2_DEV* dev, WOLFTPM2_KEYBLOB* keyBlob,
rc = TPM2_Create(&createIn, &createOut);
if (rc != TPM_RC_SUCCESS) {
#ifdef DEBUG_WOLFTPM
printf("TPM2_Create key failed %d: %s\n", rc, wolfTPM2_GetRCString(rc));
printf("wolfTPM2_CreateKeySeal failed %d: %s\n", rc, wolfTPM2_GetRCString(rc));
#endif
return rc;
}
#ifdef DEBUG_WOLFTPM
printf("TPM2_Create key: pub %d, priv %d\n",
printf("wolfTPM2_CreateKeySeal generated key with: pub %d, priv %d\n",
createOut.outPublic.size, createOut.outPrivate.size);
TPM2_PrintPublicArea(&createOut.outPublic);
#endif