1tpm2_ecdhkeygen(1) General Commands Manual tpm2_ecdhkeygen(1)
2
6 tpm2_ecdhkeygen(1) - Creates an ephemeral key and uses it to generate
7 the shared secret value using the parameters from a ECC public key.
8
10 tpm2_ecdhkeygen [OPTIONS]
11
13 tpm2_ecdhkeygen(1) - Creates an ephemeral key and uses it to generate
14 the shared secret value using the parameters from a ECC public key.
15
17 • -c, --context=FILE:
18 Context object pointing to ECC public key. Either a file or a handle
20 number. See section “Context Object Format”.
21 • -u, --public=FILE:
23 Output ECC point Q.
25 • -o, --output=FILE
27 Specify file path to save the calculated ecdh secret or Z point.
29 • --cphash=FILE
31 File path to record the hash of the command parameters. This is com‐
33 monly termed as cpHash. NOTE: When this option is selected, The tool
34 will not actually execute the command, it simply returns a cpHash.
35 References
38 Options that take algorithms support “nice-names”.
39 There are two major algorithm specification string classes, simple and
41 complex. Only certain algorithms will be accepted by the TPM, based on
42 usage and conditions.
43 Simple specifiers
45 These are strings with no additional specification data. When creating
46 objects, non-specified portions of an object are assumed to defaults.
47 You can find the list of known “Simple Specifiers” below.
48 Asymmetric
50 • rsa
51 • ecc
53 Symmetric
55 • aes
56 • camellia
58 • sm4
60 Hashing Algorithms
62 • sha1
63 • sha256
65 • sha384
67 • sha512
69 • sm3_256
71 • sha3_256
73 • sha3_384
75 • sha3_512
77 Keyed Hash
79 • hmac
80 • xor
82 Signing Schemes
84 • rsassa
85 • rsapss
87 • ecdsa
89 • ecdaa
91 • ecschnorr
93 • sm2
95 Asymmetric Encryption Schemes
97 • oaep
98 • rsaes
100 • ecdh
102 Modes
104 • ctr
105 • ofb
107 • cbc
109 • cfb
111 • ecb
113 Misc
115 • null
116 Complex Specifiers
118 Objects, when specified for creation by the TPM, have numerous algo‐
119 rithms to populate in the public data. Things like type, scheme and
120 asymmetric details, key size, etc. Below is the general format for
121 specifying this data: <type>:<scheme>:<symmetric-details>
122 Type Specifiers
124 This portion of the complex algorithm specifier is required. The re‐
125 maining scheme and symmetric details will default based on the type
126 specified and the type of the object being created.
127 • aes - Default AES: aes128
129 • aes128<mode> - 128 bit AES with optional mode (ctr|ofb|cbc|cfb|ecb).
131 If mode is not specified, defaults to null.
132 • aes192<mode> - Same as aes128<mode>, except for a 192 bit key size.
134 • aes256<mode> - Same as aes128<mode>, except for a 256 bit key size.
136 • sm4 - Default SM4: sm4128
138 • sm4128 or sm4_128 <mode> - 128 bit SM4 with optional mode
140 (ctr|ofb|cbc|cfb|ecb). If mode is not specified, defaults to null.
141 • ecc - Elliptical Curve, defaults to ecc256.
143 • ecc192 or ecc_nist_p192 - 192 bit ECC NIST curve
145 • ecc224 or ecc_nist_p224 - 224 bit ECC NIST curve
147 • ecc256 or ecc_nist_p256 - 256 bit ECC NIST curve
149 • ecc384 or ecc_nist_p384 - 384 bit ECC NIST curve
151 • ecc521 or ecc_nist_p521 - 521 bit ECC NIST curve
153 • ecc_sm2 or ecc_sm2_p256 - 256 bit SM2 curve
155 • rsa - Default RSA: rsa2048
157 • rsa1024 - RSA with 1024 bit keysize.
159 • rsa2048 - RSA with 2048 bit keysize.
161 • rsa3072 - RSA with 3072 bit keysize.
163 • rsa4096 - RSA with 4096 bit keysize.
165 Scheme Specifiers
167 Next, is an optional field, it can be skipped.
168 Schemes are usually Signing Schemes or Asymmetric Encryption Schemes.
170 Most signing schemes take a hash algorithm directly following the sign‐
171 ing scheme. If the hash algorithm is missing, it defaults to sha256.
172 Some take no arguments, and some take multiple arguments.
173 Hash Optional Scheme Specifiers
175 These scheme specifiers are followed by a dash and a valid hash algo‐
176 rithm, For example: oaep-sha256.
177 • oaep
179 • ecdh
181 • rsassa
183 • rsapss
185 • ecdsa
187 • ecschnorr
189 • sm2
191 Multiple Option Scheme Specifiers
193 This scheme specifier is followed by a count (max size UINT16) then
194 followed by a dash(-) and a valid hash algorithm. * ecdaa For example,
195 ecdaa4-sha256. If no count is specified, it defaults to 4.
196 No Option Scheme Specifiers
198 This scheme specifier takes NO arguments. * rsaes
199 Symmetric Details Specifiers
201 This field is optional, and defaults based on the type of object being
202 created and it’s attributes. Generally, any valid Symmetric specifier
203 from the Type Specifiers list should work. If not specified, an asym‐
204 metric objects symmetric details defaults to aes128cfb.
205 Examples
207 Create an rsa2048 key with an rsaes asymmetric encryption scheme
208 tpm2_create -C parent.ctx -G rsa2048:rsaes -u key.pub -r key.priv
209 Create an ecc256 key with an ecdaa signing scheme with a count of 4 and
211 sha384 hash
212 /tpm2_create -C parent.ctx -G ecc256:ecdaa4-sha384 -u key.pub -r
213 key.priv cryptographic algorithms ALGORITHM.
214
216 This collection of options are common to many programs and provide in‐
217 formation that many users may expect.
218 • -h, --help=[man|no-man]: Display the tools manpage. By default, it
220 attempts to invoke the manpager for the tool, however, on failure
221 will output a short tool summary. This is the same behavior if the
222 “man” option argument is specified, however if explicit “man” is re‐
223 quested, the tool will provide errors from man on stderr. If the
224 “no-man” option if specified, or the manpager fails, the short op‐
225 tions will be output to stdout.
226 To successfully use the manpages feature requires the manpages to be
228 installed or on MANPATH, See man(1) for more details.
229 • -v, --version: Display version information for this tool, supported
231 tctis and exit.
232 • -V, --verbose: Increase the information that the tool prints to the
234 console during its execution. When using this option the file and
235 line number are printed.
236 • -Q, --quiet: Silence normal tool output to stdout.
238 • -Z, --enable-errata: Enable the application of errata fixups. Useful
240 if an errata fixup needs to be applied to commands sent to the TPM.
241 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
242 formation many users may expect.
243
245 The TCTI or “Transmission Interface” is the communication mechanism
246 with the TPM. TCTIs can be changed for communication with TPMs across
247 different mediums.
248 To control the TCTI, the tools respect:
250 1. The command line option -T or --tcti
252 2. The environment variable: TPM2TOOLS_TCTI.
254 Note: The command line option always overrides the environment vari‐
256 able.
257 The current known TCTIs are:
259 • tabrmd - The resource manager, called tabrmd
261 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
262 abrmd as a tcti name are synonymous.
263 • mssim - Typically used for communicating to the TPM software simula‐
265 tor.
266 • device - Used when talking directly to a TPM device file.
268 • none - Do not initalize a connection with the TPM. Some tools allow
270 for off-tpm options and thus support not using a TCTI. Tools that do
271 not support it will error when attempted to be used without a TCTI
272 connection. Does not support ANY options and MUST BE presented as
273 the exact text of “none”.
274 The arguments to either the command line option or the environment
276 variable are in the form:
277 <tcti-name>:<tcti-option-config>
279 Specifying an empty string for either the <tcti-name> or <tcti-op‐
281 tion-config> results in the default being used for that portion respec‐
282 tively.
283 TCTI Defaults
285 When a TCTI is not specified, the default TCTI is searched for using
286 dlopen(3) semantics. The tools will search for tabrmd, device and
287 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
288 what TCTI will be chosen as the default by using the -v option to print
289 the version information. The “default-tcti” key-value pair will indi‐
290 cate which of the aforementioned TCTIs is the default.
291 Custom TCTIs
293 Any TCTI that implements the dynamic TCTI interface can be loaded. The
294 tools internally use dlopen(3), and the raw tcti-name value is used for
295 the lookup. Thus, this could be a path to the shared library, or a li‐
296 brary name as understood by dlopen(3) semantics.
297
299 This collection of options are used to configure the various known TCTI
300 modules available:
301 • device: For the device TCTI, the TPM character device file for use by
303 the device TCTI can be specified. The default is /dev/tpm0.
304 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI=“de‐
306 vice:/dev/tpm0”
307 • mssim: For the mssim TCTI, the domain name or IP address and port
309 number used by the simulator can be specified. The default are
310 127.0.0.1 and 2321.
311 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
313 TI=“mssim:host=localhost,port=2321”
314 • abrmd: For the abrmd TCTI, the configuration string format is a se‐
316 ries of simple key value pairs separated by a `,' character. Each
317 key and value string are separated by a `=' character.
318 • TCTI abrmd supports two keys:
320 1. `bus_name' : The name of the tabrmd service on the bus (a
322 string).
323 2. `bus_type' : The type of the dbus instance (a string) limited to
325 `session' and `system'.
326 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
328 ample.FooBar:
329 \--tcti=tabrmd:bus_name=com.example.FooBar
331 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
333 sion:
334 \--tcti:bus_type=session
336 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
338 ules.
339
341 tpm2_createprimary -C o -c prim.ctx -Q
342 tpm2_create -C prim.ctx -c key.ctx -u key.pub -r key.priv -G ecc256:ecdaa
344 tpm2_ecdhkeygen -u ecdh.pub -o ecdh.priv -c key.ctx
346
348 Tools can return any of the following codes:
349 • 0 - Success.
351 • 1 - General non-specific error.
353 • 2 - Options handling error.
355 • 3 - Authentication error.
357 • 4 - TCTI related error.
359 • 5 - Non supported scheme. Applicable to tpm2_testparams.
361
363 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
364
366 See the Mailing List (https://lists.linuxfoundation.org/mailman/listin‐
367 fo/tpm2)
368tpm2-tools tpm2_ecdhkeygen(1)