void ExternalKeyImportSample(Tpm2 tpm, TestContext testCtx)
{
// Create a software key (external to any TPM).
int keySize = 2048;
var externalRsaKey = new RawRsa(keySize);
// When an external key comes from a cert, one would need to extract the key size and
// byte buffers representing public and private parts of the key from the cert, an use
// them directly in the call to ImportExternalRsaKey() below (i.e. no RawRsa object is
// necessary).
// Signing scheme to use (it may come from the key's cert)
TpmAlgId sigHashAlg = Substrate.Random(TpmCfg.HashAlgs);
var sigScheme = new SchemeRsassa(sigHashAlg);
// An arbitrary external key would not have TPM key attributes associated with it.
// Yet some of them may be inferred from the cert based on the declared key purpose
// (ObjectAttr.Sign below). The others are defined by the intended TPM key usage
// scenarios, e.g. ObjectAttr.UserWithAuth tells TPM to allow key usage authorization
// using an auth value (random byte buffer) in a password or an HMAC session.
ObjectAttr keyAttrs = ObjectAttr.Sign | ObjectAttr.UserWithAuth;
// Generate an auth value for the imported matching in strength the signing scheme
byte[] authVal = Substrate.RandomAuth(sigHashAlg);
// We need a storage key to use as a parent of the imported key.
// The following helper creates an RSA primary storage key.
TpmHandle hParent = Substrate.CreateRsaPrimary(tpm);
TssObject importedKey = ImportExternalRsaKey(tpm, hParent,
keySize, sigScheme,
externalRsaKey.Public, externalRsaKey.Private,
keyAttrs, authVal);
// Now we can load the newly imported key into the TPM, ...
TpmHandle hImportedKey = tpm.Load(hParent, importedKey.Private, importedKey.Public);
// ... let the TSS know the auth value associated with this handle, ...
hImportedKey.SetAuth(authVal);
// ... and use it to sign something to check if import was OK
TpmHash toSign = TpmHash.FromRandom(sigHashAlg);
ISignatureUnion sig = tpm.Sign(hImportedKey, toSign, null, new TkHashcheck());
// Verify that the signature is correct using the public part of the imported key
bool sigOk = importedKey.Public.VerifySignatureOverHash(toSign, sig);
testCtx.Assert("Signature.OK", sigOk);
// Cleanup
tpm.FlushContext(hImportedKey);
// The parent key handle can be flushed immediately after it was used in the Load() command
tpm.FlushContext(hParent);
// Imported private/public key pair (in the TssObject) can be stored on disk, in the cloud,
// etc. (no additional protection is necessary), and loaded into the TPM as above whenever
// the key is needed.
// Alternatively the key can be persisted in the TPM using the EvictControl() command
} // ExternalKeyImportSample
} // SimpleDuplicateImportRsaSample
TssObject ImportExternalRsaKey(Tpm2 tpm, TpmHandle hParent,
int keySizeInBits, IAsymSchemeUnion scheme,
byte[] publicPart, byte[] privatePart,
ObjectAttr keyAttrs,
byte[] authVal = null, byte[] policyDigest = null)
{
TpmAlgId sigHashAlg = TpmHelper.GetSchemeHash(scheme),
nameAlg = sigHashAlg;
// TPM signing key template with the actual public key bits
var inPub = new TpmPublic(nameAlg,
keyAttrs,
policyDigest,
new RsaParms(new SymDefObject(), scheme as IAsymSchemeUnion,
(ushort)keySizeInBits, 0),
new Tpm2bPublicKeyRsa(publicPart));
// Wrap the key in a TSS helper class
TssObject swKey = TssObject.Create(inPub, authVal, privatePart);
// Get a key duplication blob in TPM 2.0 compatibale format
TpmPrivate dupBlob = swKey.GetPlaintextDuplicationBlob();
// Importing a duplication blob creates a new TPM private key blob protected
// with its new parent key.
swKey.Private = tpm.Import(hParent, null, swKey.Public, dupBlob, null, new SymDefObject());
return(swKey);
} // ImportExternalRsaKey
internal static TpmHandle CreateEncryptionDecryptionKey(Tpm2 tpm, TpmHandle parent)
{
var sensCreate = new SensitiveCreate(null, null);
var sym = new SymDefObject(TpmAlgId.Aes, 128, TpmAlgId.Cfb);
var pub = new TpmPublic(TpmAlgId.Sha256,
ObjectAttr.Decrypt | ObjectAttr.UserWithAuth,
null,
sym,
new Tpm2bDigestSymcipher());
TssObject swKey = TssObject.Create(pub);
var innerWrapKey = sym == null ? null : SymCipher.Create(sym);
byte[] name, qname;
TpmPublic pubParent = tpm.ReadPublic(parent, out name, out qname);
byte[] encSecret;
TpmPrivate dupBlob = swKey.GetDuplicationBlob(pubParent, innerWrapKey, out encSecret);
TpmPrivate privImp = tpm.Import(parent, innerWrapKey, swKey.Public, dupBlob,
encSecret, sym ?? new SymDefObject());
TpmHandle hKey = tpm.Load(parent, privImp, swKey.Public)
.SetAuth(swKey.Sensitive.authValue);
return(hKey);
}
} // QuotePcrs()
/// <summary>
/// This sample demonstrates the creation and use of a storage root key that
/// behaves like the Storage Root Key (SRK) defined in TPM1.2.
/// To do this we need to create a new primary, and then use EvictControl
/// to make it NV-resident.
/// </summary>
/// <param name="tpm">Reference to TPM object</param>
static void StorageRootKey(Tpm2 tpm)
{
Console.WriteLine("\nStorageRootKey sample started.");
//
// This template asks the TPM to create an 2048 bit RSA storage key
// with an associated AES key for symmetric protection of its child keys.
// NOTE - The term SRK is not used in TPM 2.0 spec, but is widely used
// in other documents.
//
var srkTemplate = new TpmPublic(TpmAlgId.Sha256, // Name algorithm
ObjectAttr.Restricted | // Storage keys must be restricted
ObjectAttr.Decrypt | // Storage keys are Decrypt keys
ObjectAttr.FixedParent | ObjectAttr.FixedTPM | // Non-duplicable (like 1.2)
ObjectAttr.UserWithAuth | ObjectAttr.SensitiveDataOrigin,
null, // No policy
new RsaParms(new SymDefObject(TpmAlgId.Aes, 128, TpmAlgId.Cfb),
new NullAsymScheme(), // No signing or decryption scheme
2048, 0), // 2048-bit RSA
new Tpm2bPublicKeyRsa());
AuthValue childAuthVal = AuthValue.FromRandom(8);
TssObject swKey = TssObject.Create(srkTemplate, childAuthVal);
TpmPublic srkPublic;
CreationData srkCreationData;
TkCreation srkCreationTicket;
byte[] srkCreationHash;
//
// Ask the TPM to create a new primary RSA/AES primary storage key
//
TpmHandle keyHandle = tpm.CreatePrimary(TpmRh.Owner, // In the owner-hierarchy
new SensitiveCreate(null, null), // Empty auth-value
srkTemplate, // Key template (params)
null, // For creation ticket
new PcrSelection[0], // For creation ticket
out srkPublic, // Out pubKey and attrs
out srkCreationData, // Not used here
out srkCreationHash, // Ibid
out srkCreationTicket); // Ibid
//
// print out text-versions of the public key just created
//
Console.WriteLine("New SRK public key\n" + srkPublic.ToString());
//
// The caller provides the handle for persistent keys
//
TpmHandle srkHandle = TpmHandle.Persistent(0x5000);
//
// Ae will make the "SRK" persistent in an NV-slot, so clean up anything
// that is already there
//
tpm._AllowErrors()
.EvictControl(TpmRh.Owner, srkHandle, srkHandle);
if (tpm._LastCommandSucceeded())
{
Console.WriteLine("Removed previous persistent SRK.");
}
//
// Make the SRK NV-resident
//
tpm.EvictControl(TpmRh.Owner, keyHandle, srkHandle);
Console.WriteLine("SRK is persistent now.");
Console.WriteLine("\nStorageRootKey sample finished.");
} // StorageRootKey()
/// <summary>
/// This sample demonstrates the creation and use of a storage root key that
/// behaves like the Storage Root Key (SRK) defined in TPM1.2.
/// To do this we need to create a new primary, and then use EvictControl
/// to make it NV-resident.
/// </summary>
/// <param name="tpm">Reference to TPM object</param>
static void StorageRootKey(Tpm2 tpm)
{
//
// This template asks the TPM to create an 2048 bit RSA storage key
// with an associated AES key for symmetric data protection. The term
// "SRKs" is not used in TPM2.0, but we use it here to
// not
//
var srkTemplate = new TpmPublic(TpmAlgId.Sha1, // Name algorithm
ObjectAttr.Restricted | // Storage keys must be restricted
ObjectAttr.Decrypt | // Storage keys are Decrypt keys
ObjectAttr.FixedParent | ObjectAttr.FixedTPM | // Non-duplicable (like 1.2)
ObjectAttr.UserWithAuth | ObjectAttr.SensitiveDataOrigin,
new byte[0], // No policy
new RsaParms(new SymDefObject(TpmAlgId.Aes, 128, TpmAlgId.Cfb),
new NullAsymScheme(), // No signature
2048, 0), // 2048-bit RSA
new Tpm2bPublicKeyRsa());
//
// Authorization for the key we are about to create
//
var srkAuth = new byte[0];
AuthValue childAuthVal = AuthValue.FromRandom(8);
TssObject swKey = TssObject.CreateStorageParent(srkTemplate, childAuthVal);
TpmPublic srkPublic;
CreationData srkCreationData;
TkCreation srkCreationTicket;
byte[] srkCreationHash;
//
// Ask the TPM to create a new primary RSA/AES primary storage key
//
TpmHandle keyHandle = tpm[_ownerAuth].CreatePrimary(
TpmHandle.RhOwner, // In the owner-hierarchy
new SensitiveCreate(srkAuth, new byte[0]), // With this auth-value
srkTemplate, // Describes key
new byte[0], // For creation ticket
new PcrSelection[0], // For creation ticket
out srkPublic, // Out pubKey and attrs
out srkCreationData, // Not used here
out srkCreationHash, // Ibid
out srkCreationTicket); // Ibid
//
// print out text-versions of the public key just created
//
Console.WriteLine("New SRK public key\n" + srkPublic.ToString());
//
// The caller provides the handle for persistent keys
//
TpmHandle srkHandle = TpmHandle.Persistent(0x5000);
//
// Ae will make the "SRK" persistent in an NV-slot, so clean up anything
// that is already there
//
tpm[_ownerAuth]._AllowErrors().EvictControl(TpmHandle.RhOwner, srkHandle, srkHandle);
TpmRc lastError = tpm._GetLastResponseCode();
//
// Make the SRK NV-resident
//
tpm[_ownerAuth].EvictControl(TpmHandle.RhOwner, keyHandle, srkHandle);
Console.WriteLine("SRK is persistent now.");
}
/// <summary>
/// Performs the following operations:
/// - Generates in software (using TSS.net helpers) a key with the given template,
/// - Creates TPM-compatible dupliction blob for the given TPM based parent key,
/// - Import the duplication blob into TPM
/// - Loads the imported key into the TPM
/// - Makes sure that the imported key works.
/// </summary>
/// <param name="tpm">TPM instance to use</param>
/// <param name="keyPub">Template for the software generated key.</param>
/// <param name="hParent">Intended TPM based parent key for the software generated key.</param>
/// <param name="innerSymDef">Specification of the optional inner wrapper for the duplication blob.</param>
static void GenerateAndImport(Tpm2 tpm, TpmPublic keyPub, TpmHandle hParent,
SymDefObject innerSymDef = null)
{
//
// Create a software key with the given template
//
// Generate a random auth value for the key to be created (though we could
// use an empty buffer, too).
var keyAuth = AuthValue.FromRandom(CryptoLib.DigestSize(keyPub.nameAlg));
// Generate the key
TssObject swKey = TssObject.Create(keyPub, keyAuth);
//
// Create duplication blob for the new key with the SRK as the new parent
//
// Create a symmetric software key if an inner wrapper is requested.
var innerWrapKey = innerSymDef == null ? null : SymCipher.Create(innerSymDef);
// Retrieve the public area of the intended parent key from the TPM
// We do not need the name (and qualified name) of the key here, but
// the TPM command returns them anyway.
// NOTE - Alternatively we could get the public area from the overloaded
// form of the CreateRsaPrimaryStorageKey() helper used to create the parent
// key, as all TPM key creation commands (TPM2_CreatePrimary(), TPM2_Create()
// and TPM2_CreateLoaded()) return it.
byte[] name, qname;
TpmPublic pubParent = tpm.ReadPublic(hParent, out name, out qname);
byte[] encSecret;
TpmPrivate dupBlob = swKey.GetDuplicationBlob(pubParent, innerWrapKey, out encSecret);
// Import the duplication blob into the TPM
TpmPrivate privImp = tpm.Import(hParent, innerWrapKey, swKey.Public, dupBlob,
encSecret, innerSymDef ?? new SymDefObject());
// Load the imported key ...
TpmHandle hKey = tpm.Load(hParent, privImp, swKey.Public)
.SetAuth(swKey.Sensitive.authValue);
// ... and validate that it works
byte[] message = Globs.GetRandomBytes(32);
if (keyPub.objectAttributes.HasFlag(ObjectAttr.Decrypt))
{
// Encrypt something
if (keyPub.type == TpmAlgId.Symcipher)
{
// Only need software symcypher here to query IV size.
// Normally, when you use a fixed algorithm, you can hardcode it.
var swSym = SymCipher.Create(keyPub.parameters as SymDefObject);
byte[] ivIn = Globs.GetRandomBytes(swSym.IVSize),
ivOut = null;
byte[] cipher = swKey.Encrypt(message, ref ivIn, out ivOut);
// Not all TPMs implement TPM2_EncryptDecrypt() command
tpm._ExpectResponses(TpmRc.Success, TpmRc.TbsCommandBlocked);
byte[] decrypted = tpm.EncryptDecrypt(hKey, 1, TpmAlgId.Null, ivIn,
cipher, out ivOut);
if (tpm._LastCommandSucceeded())
{
bool decOk = Globs.ArraysAreEqual(message, decrypted);
Console.WriteLine("Imported symmetric key validation {0}",
decOk ? "SUCCEEDED" : "FAILED");
}
}
}
else
{
// Sign something (works for both asymmetric and MAC keys)
string keyType = keyPub.type == TpmAlgId.Rsa ? "RSA"
: keyPub.type == TpmAlgId.Keyedhash ? "HMAC"
: "UNKNOWN"; // Should not happen in this sample
TpmAlgId sigHashAlg = GetSchemeHash(keyPub);
TpmHash toSign = TpmHash.FromData(sigHashAlg, message);
var proofx = new TkHashcheck(TpmRh.Null, null);
ISignatureUnion sig = tpm.Sign(hKey, toSign, null, proofx);
bool sigOk = swKey.VerifySignatureOverHash(toSign, sig);
Console.WriteLine("Imported {0} key validation {1}", keyType,
sigOk ? "SUCCEEDED" : "FAILED");
}
// Free TPM resources taken by the loaded imported key
tpm.FlushContext(hKey);
} // GenerateAndImport
