1tpm2_ecdhzgen(1) General Commands Manual tpm2_ecdhzgen(1)
2
6 tpm2_ecdhzgen(1) - Recovers the shared secret value (Z) from a public
7 point and a specified private key.
8
10 tpm2_ecdhzgen [OPTIONS]
11
13 tpm2_ecdhzgen(1) - Recovers the shared secret value (Z) from a public
14 point and a specified private key. It will perform the multiplication
15 of the provided inPoint (QB) with the private key (ds) and return the
16 coordinates of the resultant point (Z = (xZ , yZ) ≔ [hds]QB; where h is
17 the cofactor of the curve).
18
20 • -c, --key-context=FILE:
21 Context object pointing to ECC key. Either a file or a handle num‐
23 ber. See section “Context Object Format”.
24 • -p, --key-auth=AUTH:
26 The authorization value for the ECC key object.
28 • -u, --public=FILE:
30 Output ECC point Q.
32 • -o, --output=FILE
34 Specify file path to save the calculated ecdh secret or Z point.
36 References
39 Options that take algorithms support “nice-names”.
40 There are two major algorithm specification string classes, simple and
42 complex. Only certain algorithms will be accepted by the TPM, based on
43 usage and conditions.
44 Simple specifiers
46 These are strings with no additional specification data. When creating
47 objects, non-specified portions of an object are assumed to defaults.
48 You can find the list of known “Simple Specifiers Below”.
49 Asymmetric
51 • rsa
52 • ecc
54 Symmetric
56 • aes
57 • camellia
59 Hashing Algorithms
61 • sha1
62 • sha256
64 • sha384
66 • sha512
68 • sm3_256
70 • sha3_256
72 • sha3_384
74 • sha3_512
76 Keyed Hash
78 • hmac
79 • xor
81 Signing Schemes
83 • rsassa
84 • rsapss
86 • ecdsa
88 • ecdaa
90 • ecschnorr
92 Asymmetric Encryption Schemes
94 • oaep
95 • rsaes
97 • ecdh
99 Modes
101 • ctr
102 • ofb
104 • cbc
106 • cfb
108 • ecb
110 Misc
112 • null
113 Complex Specifiers
115 Objects, when specified for creation by the TPM, have numerous algo‐
116 rithms to populate in the public data. Things like type, scheme and
117 asymmetric details, key size, etc. Below is the general format for
118 specifying this data: <type>:<scheme>:<symmetric-details>
119 Type Specifiers
121 This portion of the complex algorithm specifier is required. The re‐
122 maining scheme and symmetric details will default based on the type
123 specified and the type of the object being created.
124 • aes - Default AES: aes128
126 • aes128<mode> - 128 bit AES with optional mode (ctr|ofb|cbc|cfb|ecb).
128 If mode is not specified, defaults to null.
129 • aes192<mode> - Same as aes128<mode>, except for a 192 bit key size.
131 • aes256<mode> - Same as aes128<mode>, except for a 256 bit key size.
133 • ecc - Elliptical Curve, defaults to ecc256.
135 • ecc192 - 192 bit ECC
137 • ecc224 - 224 bit ECC
139 • ecc256 - 256 bit ECC
141 • ecc384 - 384 bit ECC
143 • ecc521 - 521 bit ECC
145 • rsa - Default RSA: rsa2048
147 • rsa1024 - RSA with 1024 bit keysize.
149 • rsa2048 - RSA with 2048 bit keysize.
151 • rsa4096 - RSA with 4096 bit keysize.
153 Scheme Specifiers
155 Next, is an optional field, it can be skipped.
156 Schemes are usually Signing Schemes or Asymmetric Encryption Schemes.
158 Most signing schemes take a hash algorithm directly following the sign‐
159 ing scheme. If the hash algorithm is missing, it defaults to sha256.
160 Some take no arguments, and some take multiple arguments.
161 Hash Optional Scheme Specifiers
163 These scheme specifiers are followed by a dash and a valid hash algo‐
164 rithm, For example: oaep-sha256.
165 • oaep
167 • ecdh
169 • rsassa
171 • rsapss
173 • ecdsa
175 • ecschnorr
177 Multiple Option Scheme Specifiers
179 This scheme specifier is followed by a count (max size UINT16) then
180 followed by a dash(-) and a valid hash algorithm. * ecdaa For example,
181 ecdaa4-sha256. If no count is specified, it defaults to 4.
182 No Option Scheme Specifiers
184 This scheme specifier takes NO arguments. * rsaes
185 Symmetric Details Specifiers
187 This field is optional, and defaults based on the type of object being
188 created and it’s attributes. Generally, any valid Symmetric specifier
189 from the Type Specifiers list should work. If not specified, an asym‐
190 metric objects symmetric details defaults to aes128cfb.
191 Examples
193 Create an rsa2048 key with an rsaes asymmetric encryption scheme
194 tpm2_create -C parent.ctx -G rsa2048:rsaes -u key.pub -r key.priv
195 Create an ecc256 key with an ecdaa signing scheme with a count of 4 and
197 sha384 hash
198 /tpm2_create -C parent.ctx -G ecc256:ecdaa4-sha384 -u key.pub -r
199 key.priv cryptographic algorithms ALGORITHM.
200
202 This collection of options are common to many programs and provide in‐
203 formation that many users may expect.
204 • -h, --help=[man|no-man]: Display the tools manpage. By default, it
206 attempts to invoke the manpager for the tool, however, on failure
207 will output a short tool summary. This is the same behavior if the
208 “man” option argument is specified, however if explicit “man” is re‐
209 quested, the tool will provide errors from man on stderr. If the
210 “no-man” option if specified, or the manpager fails, the short op‐
211 tions will be output to stdout.
212 To successfully use the manpages feature requires the manpages to be
214 installed or on MANPATH, See man(1) for more details.
215 • -v, --version: Display version information for this tool, supported
217 tctis and exit.
218 • -V, --verbose: Increase the information that the tool prints to the
220 console during its execution. When using this option the file and
221 line number are printed.
222 • -Q, --quiet: Silence normal tool output to stdout.
224 • -Z, --enable-errata: Enable the application of errata fixups. Useful
226 if an errata fixup needs to be applied to commands sent to the TPM.
227 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
228 formation many users may expect.
229
231 The TCTI or “Transmission Interface” is the communication mechanism
232 with the TPM. TCTIs can be changed for communication with TPMs across
233 different mediums.
234 To control the TCTI, the tools respect:
236 1. The command line option -T or --tcti
238 2. The environment variable: TPM2TOOLS_TCTI.
240 Note: The command line option always overrides the environment vari‐
242 able.
243 The current known TCTIs are:
245 • tabrmd - The resource manager, called tabrmd
247 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
248 abrmd as a tcti name are synonymous.
249 • mssim - Typically used for communicating to the TPM software simula‐
251 tor.
252 • device - Used when talking directly to a TPM device file.
254 • none - Do not initalize a connection with the TPM. Some tools allow
256 for off-tpm options and thus support not using a TCTI. Tools that do
257 not support it will error when attempted to be used without a TCTI
258 connection. Does not support ANY options and MUST BE presented as
259 the exact text of “none”.
260 The arguments to either the command line option or the environment
262 variable are in the form:
263 <tcti-name>:<tcti-option-config>
265 Specifying an empty string for either the <tcti-name> or <tcti-op‐
267 tion-config> results in the default being used for that portion respec‐
268 tively.
269 TCTI Defaults
271 When a TCTI is not specified, the default TCTI is searched for using
272 dlopen(3) semantics. The tools will search for tabrmd, device and
273 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
274 what TCTI will be chosen as the default by using the -v option to print
275 the version information. The “default-tcti” key-value pair will indi‐
276 cate which of the aforementioned TCTIs is the default.
277 Custom TCTIs
279 Any TCTI that implements the dynamic TCTI interface can be loaded. The
280 tools internally use dlopen(3), and the raw tcti-name value is used for
281 the lookup. Thus, this could be a path to the shared library, or a li‐
282 brary name as understood by dlopen(3) semantics.
283
285 This collection of options are used to configure the various known TCTI
286 modules available:
287 • device: For the device TCTI, the TPM character device file for use by
289 the device TCTI can be specified. The default is /dev/tpm0.
290 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI=“de‐
292 vice:/dev/tpm0”
293 • mssim: For the mssim TCTI, the domain name or IP address and port
295 number used by the simulator can be specified. The default are
296 127.0.0.1 and 2321.
297 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
299 TI=“mssim:host=localhost,port=2321”
300 • abrmd: For the abrmd TCTI, the configuration string format is a se‐
302 ries of simple key value pairs separated by a `,' character. Each
303 key and value string are separated by a `=' character.
304 • TCTI abrmd supports two keys:
306 1. `bus_name' : The name of the tabrmd service on the bus (a
308 string).
309 2. `bus_type' : The type of the dbus instance (a string) limited to
311 `session' and `system'.
312 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
314 ample.FooBar:
315 \--tcti=tabrmd:bus_name=com.example.FooBar
317 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
319 sion:
320 \--tcti:bus_type=session
322 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
324 ules.
325
327 tpm2_createprimary -C o -c prim.ctx -Q
328 tpm2_create -C prim.ctx -c key.ctx -u key.pub -r key.priv -G ecc256:ecdh
330 tpm2_ecdhkeygen -u ecdh.pub -o ecdh.priv -c key.ctx
332 tpm2_ecdhzgen -u ecdh.pub -o ecdh.dat -c key.ctx
334
336 Tools can return any of the following codes:
337 • 0 - Success.
339 • 1 - General non-specific error.
341 • 2 - Options handling error.
343 • 3 - Authentication error.
345 • 4 - TCTI related error.
347 • 5 - Non supported scheme. Applicable to tpm2_testparams.
349
351 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
352
354 See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
355tpm2-tools tpm2_ecdhzgen(1)