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NAMEtpm2_loadexternal(1) - Load an external object into the TPM.SYNOPSIStpm2_loadexternal [OPTIONS]DESCRIPTIONtpm2_loadexternal(1) - This command loads an external object into the TPM, forgoing TPM protections. Ie, the key material is not protected by the parent object’s seed. The command allows loading of just the public portion of an object or both the public and private portions of an object.The tool outputs the name of the loaded object in a YAML dictionary format with the key name where the value for that key is the name of the object in hex format, for example:
It also saves a context file for future interactions with the object. OPTIONS
Hierarchy to use for the ticket, optional. Defaults to
n, null. Supported options are:
The algorithm used by the key to be imported. Supports:
The public portion of the object, this can be one of the
following file formats:
The sensitive portion of the object, optional. If one
wishes to use the private portion of a key, this must be specified. Like
option -u, this command takes files in the following format:
Note: The private portion does not respect TSS formats as it’s impossible to get a TPM2B_SENSITIVE output from a previous command. They are always protected by the TPM as TPM2B_PRIVATE blobs.
The authorization value for the key, optional.
The input policy file, optional. A file containing the hash of a policy derived from tpm2_createpolicy.
The hash algorithm for generating the objects name. This is optional and defaults to sha256 when not specified. However, load external supports having a null name algorithm. In this case, no cryptographic binding checks between the public and private portions are performed.
The object attributes, optional. The default for created objects is: TPMA_OBJECT_SIGN_ENCRYPT|TPMA_OBJECT_DECRYPT. Optionally, if -p is specified or no -p or -L is specified then TPMA_OBJECT_USERWITHAUTH is added to the default attribute set. Note: If specifying attributes, the TPM will reject certain attributes like TPMA_OBJECT_FIXEDTPM, as those guarantees cannot be made.
The file name to save the object context, required.
An optional file to save the object name, which is in a binary hash format. The size of the hash is based on name algorithm or the -g option.
An optional password for an Open SSL (OSSL) provided input file. It mirrors the -passin option of OSSL and is known to support the pass, file, env, fd and plain password formats of openssl. (see man(1) openssl) for more. ReferencesContext Object FormatThe type of a context object, whether it is a handle or file name, is determined according to the following logic in-order:
Authorization FormattingAuthorization for use of an object in TPM2.0 can come in 3 different forms: 1. Password 2. HMAC 3. SessionsNOTE: “Authorizations default to the EMPTY PASSWORD when not specified”. PasswordsPasswords are interpreted in the following forms below using prefix identifiers.Note: By default passwords are assumed to be in the string form when they do not have a prefix. StringA string password, specified by prefix “str:” or it’s absence (raw string without prefix) is not interpreted, and is directly used for authorization.Examples
Hex-stringA hex-string password, specified by prefix “hex:” is converted from a hexidecimal form into a byte array form, thus allowing passwords with non-printable and/or terminal un-friendly characters.Example
FileA file based password, specified be prefix “file:” should be the path of a file containing the password to be read by the tool or a “-” to use stdin. Storing passwords in files prevents information leakage, passwords passed as options can be read from the process list or common shell history features.Examples
SessionsWhen using a policy session to authorize the use of an object, prefix the option argument with the session keyword. Then indicate a path to a session file that was created with tpm2_startauthsession(1). Optionally, if the session requires an auth value to be sent with the session handle (eg policy password), then append a + and a string as described in the Passwords section.ExamplesTo use a session context file called session.ctx.
To use a session context file called session.ctx AND send the authvalue mypassword.
To use a session context file called session.ctx AND send the HEX authvalue 0x11223344.
PCR AuthorizationsYou can satisfy a PCR policy using the “pcr:” prefix and the PCR minilanguage. The PCR minilanguage is as follows: <pcr-spec>=<raw-pcr-file>The PCR spec is documented in in the section “PCR bank specifiers”. The raw-pcr-file is an optional argument that contains the output of the raw PCR contents as returned by tpm2_pcrread(1). PCR bank specifiers (pcr.md) ExamplesTo satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifier of:
specifying AUTH. Algorithm SpecifiersOptions that take algorithms support “nice-names”.There are two major algorithm specification string classes, simple and complex. Only certain algorithms will be accepted by the TPM, based on usage and conditions. Simple specifiersThese are strings with no additional specification data. When creating objects, non-specified portions of an object are assumed to defaults. You can find the list of known “Simple Specifiers Below”.Asymmetric
Symmetric
Hashing Algorithms
Keyed Hash
Signing Schemes
Asymmetric Encryption Schemes
Modes
Misc
Complex SpecifiersObjects, when specified for creation by the TPM, have numerous algorithms to populate in the public data. Things like type, scheme and asymmetric details, key size, etc. Below is the general format for specifying this data: <type>:<scheme>:<symmetric-details>Type SpecifiersThis portion of the complex algorithm specifier is required. The remaining scheme and symmetric details will default based on the type specified and the type of the object being created.
Scheme SpecifiersNext, is an optional field, it can be skipped.Schemes are usually Signing Schemes or Asymmetric Encryption Schemes. Most signing schemes take a hash algorithm directly following the signing scheme. If the hash algorithm is missing, it defaults to sha256. Some take no arguments, and some take multiple arguments. Hash Optional Scheme SpecifiersThese scheme specifiers are followed by a dash and a valid hash algorithm, For example: oaep-sha256.
Multiple Option Scheme SpecifiersThis scheme specifier is followed by a count (max size UINT16) then followed by a dash(-) and a valid hash algorithm. * ecdaa For example, ecdaa4-sha256. If no count is specified, it defaults to 4.No Option Scheme SpecifiersThis scheme specifier takes NO arguments. * rsaesSymmetric Details SpecifiersThis field is optional, and defaults based on the type of object being created and it’s attributes. Generally, any valid Symmetric specifier from the Type Specifiers list should work. If not specified, an asymmetric objects symmetric details defaults to aes128cfb.ExamplesCreate an rsa2048 key with an rsaes asymmetric encryption schemetpm2_create -C parent.ctx -G rsa2048:rsaes -u key.pub -r key.privCreate an ecc256 key with an ecdaa signing scheme with a count of 4 and sha384 hash/tpm2_create -C parent.ctx -G ecc256:ecdaa4-sha384 -u key.pub -r key.priv cryptographic algorithms ALGORITHM.Object AttributesObject Attributes are used to control various properties of created objects. When specified as an option, either the raw bitfield mask or “nice-names” may be used. The values can be found in Table 31 Part 2 of the TPM2.0 specification, which can be found here:<https://trustedcomputinggroup.org/wp-content/uploads/TPM-Rev-2.0-Part-2-Structures-01.38.pdf> Nice names are calculated by taking the name field of table 31 and removing the prefix TPMA_OBJECT_ and lowercasing the result. Thus, TPMA_OBJECT_FIXEDTPM becomes fixedtpm. Nice names can be joined using the bitwise or “|” symbol. For instance, to set The fields TPMA_OBJECT_FIXEDTPM, TPMA_OBJECT_NODA, and TPMA_OBJECT_SIGN_ENCRYPT, the argument would be: fixedtpm|noda|sign specifying the object attributes ATTRIBUTES. COMMON OPTIONSThis collection of options are common to many programs and provide information that many users may expect.
To successfully use the manpages feature requires the manpages to be installed or on MANPATH, See man(1) for more details.
TCTI ConfigurationThe TCTI or “Transmission Interface” is the communication mechanism with the TPM. TCTIs can be changed for communication with TPMs across different mediums.To control the TCTI, the tools respect:
Note: The command line option always overrides the environment variable. The current known TCTIs are:
The arguments to either the command line option or the environment variable are in the form: <tcti-name>:<tcti-option-config> Specifying an empty string for either the <tcti-name> or <tcti-option-config> results in the default being used for that portion respectively. TCTI DefaultsWhen a TCTI is not specified, the default TCTI is searched for using dlopen(3) semantics. The tools will search for tabrmd, device and mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query what TCTI will be chosen as the default by using the -v option to print the version information. The “default-tcti” key-value pair will indicate which of the aforementioned TCTIs is the default.Custom TCTIsAny TCTI that implements the dynamic TCTI interface can be loaded. The tools internally use dlopen(3), and the raw tcti-name value is used for the lookup. Thus, this could be a path to the shared library, or a library name as understood by dlopen(3) semantics.TCTI OPTIONSThis collection of options are used to configure the various known TCTI modules available:
Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI=“device:/dev/tpm0”
Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TCTI=“mssim:host=localhost,port=2321”
Specify the tabrmd tcti name and a config string of bus_name=com.example.FooBar:
Specify the default (abrmd) tcti and a config string of bus_type=session:
NOTE: abrmd and tabrmd are synonymous. the various known TCTI modules. NOTES
EXAMPLESLoad a TPM generated public key into the owner hierarchy
Load an RSA public key into the owner hierarchy
Load an RSA key-pair into the null hierarchy
Load an AES key into the null hierarchy
ReturnsTools can return any of the following codes:
BUGSGithub Issues (https://github.com/tpm2-software/tpm2-tools/issues)HELPSee the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
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