1 ========================== 1 ==========================
2 Trusted and Encrypted Keys 2 Trusted and Encrypted Keys
3 ========================== 3 ==========================
4 4
5 Trusted and Encrypted Keys are two new key typ 5 Trusted and Encrypted Keys are two new key types added to the existing kernel
6 key ring service. Both of these new types are 6 key ring service. Both of these new types are variable length symmetric keys,
7 and in both cases all keys are created in the 7 and in both cases all keys are created in the kernel, and user space sees,
8 stores, and loads only encrypted blobs. Trust 8 stores, and loads only encrypted blobs. Trusted Keys require the availability
9 of a Trust Source for greater security, while 9 of a Trust Source for greater security, while Encrypted Keys can be used on any
10 system. All user level blobs, are displayed an 10 system. All user level blobs, are displayed and loaded in hex ASCII for
11 convenience, and are integrity verified. 11 convenience, and are integrity verified.
12 12
13 13
14 Trust Source 14 Trust Source
15 ============ 15 ============
16 16
17 A trust source provides the source of security 17 A trust source provides the source of security for Trusted Keys. This
18 section lists currently supported trust source 18 section lists currently supported trust sources, along with their security
19 considerations. Whether or not a trust source 19 considerations. Whether or not a trust source is sufficiently safe depends
20 on the strength and correctness of its impleme 20 on the strength and correctness of its implementation, as well as the threat
21 environment for a specific use case. Since th 21 environment for a specific use case. Since the kernel doesn't know what the
22 environment is, and there is no metric of trus 22 environment is, and there is no metric of trust, it is dependent on the
23 consumer of the Trusted Keys to determine if t 23 consumer of the Trusted Keys to determine if the trust source is sufficiently
24 safe. 24 safe.
25 25
26 * Root of trust for storage 26 * Root of trust for storage
27 27
28 (1) TPM (Trusted Platform Module: hardwar 28 (1) TPM (Trusted Platform Module: hardware device)
29 29
30 Rooted to Storage Root Key (SRK) whic 30 Rooted to Storage Root Key (SRK) which never leaves the TPM that
31 provides crypto operation to establis 31 provides crypto operation to establish root of trust for storage.
32 32
33 (2) TEE (Trusted Execution Environment: O 33 (2) TEE (Trusted Execution Environment: OP-TEE based on Arm TrustZone)
34 34
35 Rooted to Hardware Unique Key (HUK) w 35 Rooted to Hardware Unique Key (HUK) which is generally burnt in on-chip
36 fuses and is accessible to TEE only. 36 fuses and is accessible to TEE only.
37 37
38 (3) CAAM (Cryptographic Acceleration and <<
39 <<
40 When High Assurance Boot (HAB) is ena <<
41 mode, trust is rooted to the OTPMK, a <<
42 randomly generated and fused into eac <<
43 Otherwise, a common fixed test key is <<
44 <<
45 (4) DCP (Data Co-Processor: crypto accele <<
46 <<
47 Rooted to a one-time programmable key <<
48 in the on-chip fuses and is accessibl <<
49 DCP provides two keys that can be use <<
50 and the UNIQUE key. Default is to use <<
51 the OTP key can be done via a module <<
52 <<
53 * Execution isolation 38 * Execution isolation
54 39
55 (1) TPM 40 (1) TPM
56 41
57 Fixed set of operations running in is 42 Fixed set of operations running in isolated execution environment.
58 43
59 (2) TEE 44 (2) TEE
60 45
61 Customizable set of operations runnin 46 Customizable set of operations running in isolated execution
62 environment verified via Secure/Trust 47 environment verified via Secure/Trusted boot process.
63 48
64 (3) CAAM <<
65 <<
66 Fixed set of operations running in is <<
67 <<
68 (4) DCP <<
69 <<
70 Fixed set of cryptographic operations <<
71 environment. Only basic blob key encr <<
72 The actual key sealing/unsealing is d <<
73 <<
74 * Optional binding to platform integrity sta 49 * Optional binding to platform integrity state
75 50
76 (1) TPM 51 (1) TPM
77 52
78 Keys can be optionally sealed to spec 53 Keys can be optionally sealed to specified PCR (integrity measurement)
79 values, and only unsealed by the TPM, 54 values, and only unsealed by the TPM, if PCRs and blob integrity
80 verifications match. A loaded Trusted 55 verifications match. A loaded Trusted Key can be updated with new
81 (future) PCR values, so keys are easi 56 (future) PCR values, so keys are easily migrated to new PCR values,
82 such as when the kernel and initramfs 57 such as when the kernel and initramfs are updated. The same key can
83 have many saved blobs under different 58 have many saved blobs under different PCR values, so multiple boots are
84 easily supported. 59 easily supported.
85 60
86 (2) TEE 61 (2) TEE
87 62
88 Relies on Secure/Trusted boot process 63 Relies on Secure/Trusted boot process for platform integrity. It can
89 be extended with TEE based measured b 64 be extended with TEE based measured boot process.
90 65
91 (3) CAAM <<
92 <<
93 Relies on the High Assurance Boot (HA <<
94 for platform integrity. <<
95 <<
96 (4) DCP <<
97 <<
98 Relies on Secure/Trusted boot process <<
99 platform integrity. <<
100 <<
101 * Interfaces and APIs 66 * Interfaces and APIs
102 67
103 (1) TPM 68 (1) TPM
104 69
105 TPMs have well-documented, standardiz 70 TPMs have well-documented, standardized interfaces and APIs.
106 71
107 (2) TEE 72 (2) TEE
108 73
109 TEEs have well-documented, standardiz 74 TEEs have well-documented, standardized client interface and APIs. For
110 more details refer to ``Documentation !! 75 more details refer to ``Documentation/staging/tee.rst``.
111 <<
112 (3) CAAM <<
113 <<
114 Interface is specific to silicon vend <<
115 76
116 (4) DCP <<
117 <<
118 Vendor-specific API that is implement <<
119 ``drivers/crypto/mxs-dcp.c``. <<
120 77
121 * Threat model 78 * Threat model
122 79
123 The strength and appropriateness of a par !! 80 The strength and appropriateness of a particular TPM or TEE for a given
124 purpose must be assessed when using them 81 purpose must be assessed when using them to protect security-relevant data.
125 82
126 83
127 Key Generation 84 Key Generation
128 ============== 85 ==============
129 86
130 Trusted Keys 87 Trusted Keys
131 ------------ 88 ------------
132 89
133 New keys are created from random numbers. They 90 New keys are created from random numbers. They are encrypted/decrypted using
134 a child key in the storage key hierarchy. Encr 91 a child key in the storage key hierarchy. Encryption and decryption of the
135 child key must be protected by a strong access 92 child key must be protected by a strong access control policy within the
136 trust source. The random number generator in u 93 trust source. The random number generator in use differs according to the
137 selected trust source: 94 selected trust source:
138 95
139 * TPM: hardware device based RNG 96 * TPM: hardware device based RNG
140 97
141 Keys are generated within the TPM. Streng 98 Keys are generated within the TPM. Strength of random numbers may vary
142 from one device manufacturer to another. 99 from one device manufacturer to another.
143 100
144 * TEE: OP-TEE based on Arm TrustZone based 101 * TEE: OP-TEE based on Arm TrustZone based RNG
145 102
146 RNG is customizable as per platform needs 103 RNG is customizable as per platform needs. It can either be direct output
147 from platform specific hardware RNG or a 104 from platform specific hardware RNG or a software based Fortuna CSPRNG
148 which can be seeded via multiple entropy 105 which can be seeded via multiple entropy sources.
149 106
150 * CAAM: Kernel RNG <<
151 <<
152 The normal kernel random number generator <<
153 CAAM HWRNG, enable CRYPTO_DEV_FSL_CAAM_RN <<
154 is probed. <<
155 <<
156 * DCP (Data Co-Processor: crypto accelerato <<
157 <<
158 The DCP hardware device itself does not p <<
159 so the kernel default RNG is used. SoCs w <<
160 a dedicated hardware RNG that is independ <<
161 to back the kernel RNG. <<
162 <<
163 Users may override this by specifying ``truste 107 Users may override this by specifying ``trusted.rng=kernel`` on the kernel
164 command-line to override the used RNG with the 108 command-line to override the used RNG with the kernel's random number pool.
165 109
166 Encrypted Keys 110 Encrypted Keys
167 -------------- 111 --------------
168 112
169 Encrypted keys do not depend on a trust source 113 Encrypted keys do not depend on a trust source, and are faster, as they use AES
170 for encryption/decryption. New keys are create !! 114 for encryption/decryption. New keys are created from kernel-generated random
171 random numbers or user-provided decrypted data !! 115 numbers, and are encrypted/decrypted using a specified ‘master’ key. The
172 using a specified ‘master’ key. The ‘mas !! 116 ‘master’ key can either be a trusted-key or user-key type. The main disadvantage
173 user-key type. The main disadvantage of encryp !! 117 of encrypted keys is that if they are not rooted in a trusted key, they are only
174 rooted in a trusted key, they are only as secu !! 118 as secure as the user key encrypting them. The master user key should therefore
175 them. The master user key should therefore be !! 119 be loaded in as secure a way as possible, preferably early in boot.
176 possible, preferably early in boot. <<
177 120
178 121
179 Usage 122 Usage
180 ===== 123 =====
181 124
182 Trusted Keys usage: TPM 125 Trusted Keys usage: TPM
183 ----------------------- 126 -----------------------
184 127
185 TPM 1.2: By default, trusted keys are sealed u 128 TPM 1.2: By default, trusted keys are sealed under the SRK, which has the
186 default authorization value (20 bytes of 0s). 129 default authorization value (20 bytes of 0s). This can be set at takeownership
187 time with the TrouSerS utility: "tpm_takeowner 130 time with the TrouSerS utility: "tpm_takeownership -u -z".
188 131
189 TPM 2.0: The user must first create a storage 132 TPM 2.0: The user must first create a storage key and make it persistent, so the
190 key is available after reboot. This can be don 133 key is available after reboot. This can be done using the following commands.
191 134
192 With the IBM TSS 2 stack:: 135 With the IBM TSS 2 stack::
193 136
194 #> tsscreateprimary -hi o -st 137 #> tsscreateprimary -hi o -st
195 Handle 80000000 138 Handle 80000000
196 #> tssevictcontrol -hi o -ho 80000000 -hp 81 139 #> tssevictcontrol -hi o -ho 80000000 -hp 81000001
197 140
198 Or with the Intel TSS 2 stack:: 141 Or with the Intel TSS 2 stack::
199 142
200 #> tpm2_createprimary --hierarchy o -G rsa20 143 #> tpm2_createprimary --hierarchy o -G rsa2048 -c key.ctxt
201 [...] 144 [...]
202 #> tpm2_evictcontrol -c key.ctxt 0x81000001 145 #> tpm2_evictcontrol -c key.ctxt 0x81000001
203 persistentHandle: 0x81000001 146 persistentHandle: 0x81000001
204 147
205 Usage:: 148 Usage::
206 149
207 keyctl add trusted name "new keylen [optio 150 keyctl add trusted name "new keylen [options]" ring
208 keyctl add trusted name "load hex_blob [pc 151 keyctl add trusted name "load hex_blob [pcrlock=pcrnum]" ring
209 keyctl update key "update [options]" 152 keyctl update key "update [options]"
210 keyctl print keyid 153 keyctl print keyid
211 154
212 options: 155 options:
213 keyhandle= ascii hex value of sealin 156 keyhandle= ascii hex value of sealing key
214 TPM 1.2: default 0x4000 157 TPM 1.2: default 0x40000000 (SRK)
215 TPM 2.0: no default; mu 158 TPM 2.0: no default; must be passed every time
216 keyauth= ascii hex auth for sealin 159 keyauth= ascii hex auth for sealing key default 0x00...i
217 (40 ascii zeros) 160 (40 ascii zeros)
218 blobauth= ascii hex auth for sealed 161 blobauth= ascii hex auth for sealed data default 0x00...
219 (40 ascii zeros) 162 (40 ascii zeros)
220 pcrinfo= ascii hex of PCR_INFO or 163 pcrinfo= ascii hex of PCR_INFO or PCR_INFO_LONG (no default)
221 pcrlock= pcr number to be extended 164 pcrlock= pcr number to be extended to "lock" blob
222 migratable= 0|1 indicating permission 165 migratable= 0|1 indicating permission to reseal to new PCR values,
223 default 1 (resealing allo 166 default 1 (resealing allowed)
224 hash= hash algorithm name as a 167 hash= hash algorithm name as a string. For TPM 1.x the only
225 allowed value is sha1. Fo 168 allowed value is sha1. For TPM 2.x the allowed values
226 are sha1, sha256, sha384, 169 are sha1, sha256, sha384, sha512 and sm3-256.
227 policydigest= digest for the authorizat 170 policydigest= digest for the authorization policy. must be calculated
228 with the same hash algori 171 with the same hash algorithm as specified by the 'hash='
229 option. 172 option.
230 policyhandle= handle to an authorizatio 173 policyhandle= handle to an authorization policy session that defines the
231 same policy and with the 174 same policy and with the same hash algorithm as was used to
232 seal the key. 175 seal the key.
233 176
234 "keyctl print" returns an ascii hex copy of th 177 "keyctl print" returns an ascii hex copy of the sealed key, which is in standard
235 TPM_STORED_DATA format. The key length for ne 178 TPM_STORED_DATA format. The key length for new keys are always in bytes.
236 Trusted Keys can be 32 - 128 bytes (256 - 1024 179 Trusted Keys can be 32 - 128 bytes (256 - 1024 bits), the upper limit is to fit
237 within the 2048 bit SRK (RSA) keylength, with 180 within the 2048 bit SRK (RSA) keylength, with all necessary structure/padding.
238 181
239 Trusted Keys usage: TEE 182 Trusted Keys usage: TEE
240 ----------------------- 183 -----------------------
241 184
242 Usage:: 185 Usage::
243 186
244 keyctl add trusted name "new keylen" ring 187 keyctl add trusted name "new keylen" ring
245 keyctl add trusted name "load hex_blob" ri 188 keyctl add trusted name "load hex_blob" ring
246 keyctl print keyid 189 keyctl print keyid
247 190
248 "keyctl print" returns an ASCII hex copy of th 191 "keyctl print" returns an ASCII hex copy of the sealed key, which is in format
249 specific to TEE device implementation. The ke 192 specific to TEE device implementation. The key length for new keys is always
250 in bytes. Trusted Keys can be 32 - 128 bytes ( 193 in bytes. Trusted Keys can be 32 - 128 bytes (256 - 1024 bits).
251 194
252 Trusted Keys usage: CAAM <<
253 ------------------------ <<
254 <<
255 Usage:: <<
256 <<
257 keyctl add trusted name "new keylen" ring <<
258 keyctl add trusted name "load hex_blob" ri <<
259 keyctl print keyid <<
260 <<
261 "keyctl print" returns an ASCII hex copy of th <<
262 CAAM-specific format. The key length for new <<
263 Trusted Keys can be 32 - 128 bytes (256 - 1024 <<
264 <<
265 Trusted Keys usage: DCP <<
266 ----------------------- <<
267 <<
268 Usage:: <<
269 <<
270 keyctl add trusted name "new keylen" ring <<
271 keyctl add trusted name "load hex_blob" ri <<
272 keyctl print keyid <<
273 <<
274 "keyctl print" returns an ASCII hex copy of th <<
275 specific to this DCP key-blob implementation. <<
276 always in bytes. Trusted Keys can be 32 - 128 <<
277 <<
278 Encrypted Keys usage 195 Encrypted Keys usage
279 -------------------- 196 --------------------
280 197
281 The decrypted portion of encrypted keys can co 198 The decrypted portion of encrypted keys can contain either a simple symmetric
282 key or a more complex structure. The format of 199 key or a more complex structure. The format of the more complex structure is
283 application specific, which is identified by ' 200 application specific, which is identified by 'format'.
284 201
285 Usage:: 202 Usage::
286 203
287 keyctl add encrypted name "new [format] ke 204 keyctl add encrypted name "new [format] key-type:master-key-name keylen"
288 ring 205 ring
289 keyctl add encrypted name "new [format] ke <<
290 decrypted-data" ring <<
291 keyctl add encrypted name "load hex_blob" 206 keyctl add encrypted name "load hex_blob" ring
292 keyctl update keyid "update key-type:maste 207 keyctl update keyid "update key-type:master-key-name"
293 208
294 Where:: 209 Where::
295 210
296 format:= 'default | ecryptfs | enc32' 211 format:= 'default | ecryptfs | enc32'
297 key-type:= 'trusted' | 'user' 212 key-type:= 'trusted' | 'user'
298 213
299 Examples of trusted and encrypted key usage 214 Examples of trusted and encrypted key usage
300 ------------------------------------------- 215 -------------------------------------------
301 216
302 Create and save a trusted key named "kmk" of l 217 Create and save a trusted key named "kmk" of length 32 bytes.
303 218
304 Note: When using a TPM 2.0 with a persistent k 219 Note: When using a TPM 2.0 with a persistent key with handle 0x81000001,
305 append 'keyhandle=0x81000001' to statements be 220 append 'keyhandle=0x81000001' to statements between quotes, such as
306 "new 32 keyhandle=0x81000001". 221 "new 32 keyhandle=0x81000001".
307 222
308 :: 223 ::
309 224
310 $ keyctl add trusted kmk "new 32" @u 225 $ keyctl add trusted kmk "new 32" @u
311 440502848 226 440502848
312 227
313 $ keyctl show 228 $ keyctl show
314 Session Keyring 229 Session Keyring
315 -3 --alswrv 500 500 keyring: 230 -3 --alswrv 500 500 keyring: _ses
316 97833714 --alswrv 500 -1 \_ keyri 231 97833714 --alswrv 500 -1 \_ keyring: _uid.500
317 440502848 --alswrv 500 500 \_ t 232 440502848 --alswrv 500 500 \_ trusted: kmk
318 233
319 $ keyctl print 440502848 234 $ keyctl print 440502848
320 0101000000000000000001005d01b7e3f4a6be5709 235 0101000000000000000001005d01b7e3f4a6be5709930f3b70a743cbb42e0cc95e18e915
321 3f60da455bbf1144ad12e4f92b452f966929f6105f 236 3f60da455bbf1144ad12e4f92b452f966929f6105fd29ca28e4d4d5a031d068478bacb0b
322 27351119f822911b0a11ba3d3498ba6a32e50dac7f 237 27351119f822911b0a11ba3d3498ba6a32e50dac7f32894dd890eb9ad578e4e292c83722
323 a52e56a097e6a68b3f56f7a52ece0cdccba1eb62ca 238 a52e56a097e6a68b3f56f7a52ece0cdccba1eb62cad7d817f6dc58898b3ac15f36026fec
324 d568bd4a706cb60bb37be6d8f1240661199d640b66 239 d568bd4a706cb60bb37be6d8f1240661199d640b66fb0fe3b079f97f450b9ef9c22c6d5d
325 dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471 240 dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471dc6d13ecf8298b946f65345faa5ef0
326 f1f8fff03ad0acb083725535636addb08d73dedb98 241 f1f8fff03ad0acb083725535636addb08d73dedb9832da198081e5deae84bfaf0409c22b
327 e4a8aea2b607ec96931e6f4d4fe563ba 242 e4a8aea2b607ec96931e6f4d4fe563ba
328 243
329 $ keyctl pipe 440502848 > kmk.blob 244 $ keyctl pipe 440502848 > kmk.blob
330 245
331 Load a trusted key from the saved blob:: 246 Load a trusted key from the saved blob::
332 247
333 $ keyctl add trusted kmk "load `cat kmk.bl 248 $ keyctl add trusted kmk "load `cat kmk.blob`" @u
334 268728824 249 268728824
335 250
336 $ keyctl print 268728824 251 $ keyctl print 268728824
337 0101000000000000000001005d01b7e3f4a6be5709 252 0101000000000000000001005d01b7e3f4a6be5709930f3b70a743cbb42e0cc95e18e915
338 3f60da455bbf1144ad12e4f92b452f966929f6105f 253 3f60da455bbf1144ad12e4f92b452f966929f6105fd29ca28e4d4d5a031d068478bacb0b
339 27351119f822911b0a11ba3d3498ba6a32e50dac7f 254 27351119f822911b0a11ba3d3498ba6a32e50dac7f32894dd890eb9ad578e4e292c83722
340 a52e56a097e6a68b3f56f7a52ece0cdccba1eb62ca 255 a52e56a097e6a68b3f56f7a52ece0cdccba1eb62cad7d817f6dc58898b3ac15f36026fec
341 d568bd4a706cb60bb37be6d8f1240661199d640b66 256 d568bd4a706cb60bb37be6d8f1240661199d640b66fb0fe3b079f97f450b9ef9c22c6d5d
342 dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471 257 dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471dc6d13ecf8298b946f65345faa5ef0
343 f1f8fff03ad0acb083725535636addb08d73dedb98 258 f1f8fff03ad0acb083725535636addb08d73dedb9832da198081e5deae84bfaf0409c22b
344 e4a8aea2b607ec96931e6f4d4fe563ba 259 e4a8aea2b607ec96931e6f4d4fe563ba
345 260
346 Reseal (TPM specific) a trusted key under new 261 Reseal (TPM specific) a trusted key under new PCR values::
347 262
348 $ keyctl update 268728824 "update pcrinfo= 263 $ keyctl update 268728824 "update pcrinfo=`cat pcr.blob`"
349 $ keyctl print 268728824 264 $ keyctl print 268728824
350 010100000000002c0002800093c35a09b70fff26e7 265 010100000000002c0002800093c35a09b70fff26e7a98ae786c641e678ec6ffb6b46d805
351 77c8a6377aed9d3219c6dfec4b23ffe3000001005d 266 77c8a6377aed9d3219c6dfec4b23ffe3000001005d37d472ac8a44023fbb3d18583a4f73
352 d3a076c0858f6f1dcaa39ea0f119911ff03f5406df 267 d3a076c0858f6f1dcaa39ea0f119911ff03f5406df4f7f27f41da8d7194f45c9f4e00f2e
353 df449f266253aa3f52e55c53de147773e00f0f9aca 268 df449f266253aa3f52e55c53de147773e00f0f9aca86c64d94c95382265968c354c5eab4
354 9638c5ae99c89de1e0997242edfb0b501744e11ff9 269 9638c5ae99c89de1e0997242edfb0b501744e11ff9762dfd951cffd93227cc513384e7e6
355 e782c29435c7ec2edafaa2f4c1fe6e7a781b59549f 270 e782c29435c7ec2edafaa2f4c1fe6e7a781b59549ff5296371b42133777dcc5b8b971610
356 94bc67ede19e43ddb9dc2baacad374a36feaf0314d 271 94bc67ede19e43ddb9dc2baacad374a36feaf0314d700af0a65c164b7082401740e489c9
357 7ef6a24defe4846104209bf0c3eced7fa1a672ed5b 272 7ef6a24defe4846104209bf0c3eced7fa1a672ed5b125fc9d8cd88b476a658a4434644ef
358 df8ae9a178e9f83ba9f08d10fa47e4226b98b0702f 273 df8ae9a178e9f83ba9f08d10fa47e4226b98b0702f06b3b8
359 274
360 275
361 The initial consumer of trusted keys is EVM, w 276 The initial consumer of trusted keys is EVM, which at boot time needs a high
362 quality symmetric key for HMAC protection of f 277 quality symmetric key for HMAC protection of file metadata. The use of a
363 trusted key provides strong guarantees that th 278 trusted key provides strong guarantees that the EVM key has not been
364 compromised by a user level problem, and when 279 compromised by a user level problem, and when sealed to a platform integrity
365 state, protects against boot and offline attac 280 state, protects against boot and offline attacks. Create and save an
366 encrypted key "evm" using the above trusted ke 281 encrypted key "evm" using the above trusted key "kmk":
367 282
368 option 1: omitting 'format':: 283 option 1: omitting 'format'::
369 284
370 $ keyctl add encrypted evm "new trusted:km 285 $ keyctl add encrypted evm "new trusted:kmk 32" @u
371 159771175 286 159771175
372 287
373 option 2: explicitly defining 'format' as 'def 288 option 2: explicitly defining 'format' as 'default'::
374 289
375 $ keyctl add encrypted evm "new default tr 290 $ keyctl add encrypted evm "new default trusted:kmk 32" @u
376 159771175 291 159771175
377 292
378 $ keyctl print 159771175 293 $ keyctl print 159771175
379 default trusted:kmk 32 2375725ad57798846a9 294 default trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b3
380 82dbbc55be2a44616e4959430436dc4f2a7a9659aa 295 82dbbc55be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e0
381 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc 296 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc
382 297
383 $ keyctl pipe 159771175 > evm.blob 298 $ keyctl pipe 159771175 > evm.blob
384 299
385 Load an encrypted key "evm" from saved blob:: 300 Load an encrypted key "evm" from saved blob::
386 301
387 $ keyctl add encrypted evm "load `cat evm. 302 $ keyctl add encrypted evm "load `cat evm.blob`" @u
388 831684262 303 831684262
389 304
390 $ keyctl print 831684262 305 $ keyctl print 831684262
391 default trusted:kmk 32 2375725ad57798846a9 306 default trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b3
392 82dbbc55be2a44616e4959430436dc4f2a7a9659aa 307 82dbbc55be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e0
393 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc 308 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc
394 309
395 Instantiate an encrypted key "evm" using user- <<
396 <<
397 $ evmkey=$(dd if=/dev/urandom bs=1 count=3 <<
398 $ keyctl add encrypted evm "new default us <<
399 794890253 <<
400 <<
401 $ keyctl print 794890253 <<
402 default user:kmk 32 2375725ad57798846a9bbd <<
403 bbc55be2a44616e4959430436dc4f2a7a9659aa60b <<
404 17c64 5972dcb82ab2dde83376d82b2e3c09ffc <<
405 <<
406 Other uses for trusted and encrypted keys, suc 310 Other uses for trusted and encrypted keys, such as for disk and file encryption
407 are anticipated. In particular the new format 311 are anticipated. In particular the new format 'ecryptfs' has been defined
408 in order to use encrypted keys to mount an eCr 312 in order to use encrypted keys to mount an eCryptfs filesystem. More details
409 about the usage can be found in the file 313 about the usage can be found in the file
410 ``Documentation/security/keys/ecryptfs.rst``. 314 ``Documentation/security/keys/ecryptfs.rst``.
411 315
412 Another new format 'enc32' has been defined in 316 Another new format 'enc32' has been defined in order to support encrypted keys
413 with payload size of 32 bytes. This will initi 317 with payload size of 32 bytes. This will initially be used for nvdimm security
414 but may expand to other usages that require 32 318 but may expand to other usages that require 32 bytes payload.
415 319
416 320
417 TPM 2.0 ASN.1 Key Format 321 TPM 2.0 ASN.1 Key Format
418 ------------------------ 322 ------------------------
419 323
420 The TPM 2.0 ASN.1 key format is designed to be 324 The TPM 2.0 ASN.1 key format is designed to be easily recognisable,
421 even in binary form (fixing a problem we had w 325 even in binary form (fixing a problem we had with the TPM 1.2 ASN.1
422 format) and to be extensible for additions lik 326 format) and to be extensible for additions like importable keys and
423 policy:: 327 policy::
424 328
425 TPMKey ::= SEQUENCE { 329 TPMKey ::= SEQUENCE {
426 type OBJECT IDENTIFIER 330 type OBJECT IDENTIFIER
427 emptyAuth [0] EXPLICIT BOOLEAN O 331 emptyAuth [0] EXPLICIT BOOLEAN OPTIONAL
428 parent INTEGER 332 parent INTEGER
429 pubkey OCTET STRING 333 pubkey OCTET STRING
430 privkey OCTET STRING 334 privkey OCTET STRING
431 } 335 }
432 336
433 type is what distinguishes the key even in bin 337 type is what distinguishes the key even in binary form since the OID
434 is provided by the TCG to be unique and thus f 338 is provided by the TCG to be unique and thus forms a recognizable
435 binary pattern at offset 3 in the key. The OI 339 binary pattern at offset 3 in the key. The OIDs currently made
436 available are:: 340 available are::
437 341
438 2.23.133.10.1.3 TPM Loadable key. This is 342 2.23.133.10.1.3 TPM Loadable key. This is an asymmetric key (Usually
439 RSA2048 or Elliptic Curve) 343 RSA2048 or Elliptic Curve) which can be imported by a
440 TPM2_Load() operation. 344 TPM2_Load() operation.
441 345
442 2.23.133.10.1.4 TPM Importable Key. This 346 2.23.133.10.1.4 TPM Importable Key. This is an asymmetric key (Usually
443 RSA2048 or Elliptic Curve) 347 RSA2048 or Elliptic Curve) which can be imported by a
444 TPM2_Import() operation. 348 TPM2_Import() operation.
445 349
446 2.23.133.10.1.5 TPM Sealed Data. This is 350 2.23.133.10.1.5 TPM Sealed Data. This is a set of data (up to 128
447 bytes) which is sealed by 351 bytes) which is sealed by the TPM. It usually
448 represents a symmetric key 352 represents a symmetric key and must be unsealed before
449 use. 353 use.
450 354
451 The trusted key code only uses the TPM Sealed 355 The trusted key code only uses the TPM Sealed Data OID.
452 356
453 emptyAuth is true if the key has well known au 357 emptyAuth is true if the key has well known authorization "". If it
454 is false or not present, the key requires an e 358 is false or not present, the key requires an explicit authorization
455 phrase. This is used by most user space consu 359 phrase. This is used by most user space consumers to decide whether
456 to prompt for a password. 360 to prompt for a password.
457 361
458 parent represents the parent key handle, eithe 362 parent represents the parent key handle, either in the 0x81 MSO space,
459 like 0x81000001 for the RSA primary storage ke 363 like 0x81000001 for the RSA primary storage key. Userspace programmes
460 also support specifying the primary handle in 364 also support specifying the primary handle in the 0x40 MSO space. If
461 this happens the Elliptic Curve variant of the 365 this happens the Elliptic Curve variant of the primary key using the
462 TCG defined template will be generated on the 366 TCG defined template will be generated on the fly into a volatile
463 object and used as the parent. The current ke 367 object and used as the parent. The current kernel code only supports
464 the 0x81 MSO form. 368 the 0x81 MSO form.
465 369
466 pubkey is the binary representation of TPM2B_P 370 pubkey is the binary representation of TPM2B_PRIVATE excluding the
467 initial TPM2B header, which can be reconstruct 371 initial TPM2B header, which can be reconstructed from the ASN.1 octet
468 string length. 372 string length.
469 373
470 privkey is the binary representation of TPM2B_ 374 privkey is the binary representation of TPM2B_PUBLIC excluding the
471 initial TPM2B header which can be reconstructe 375 initial TPM2B header which can be reconstructed from the ASN.1 octed
472 string length. 376 string length.
473 <<
474 DCP Blob Format <<
475 --------------- <<
476 <<
477 .. kernel-doc:: security/keys/trusted-keys/tru <<
478 :doc: dcp blob format <<
479 <<
480 .. kernel-doc:: security/keys/trusted-keys/tru <<
481 :identifiers: struct dcp_blob_fmt <<
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