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 76
112 (3) CAAM <<
113 <<
114 Interface is specific to silicon vend <<
115 <<
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 generated in the trust source. They
134 a child key in the storage key hierarchy. Encr !! 91 are encrypted/decrypted using a child key in the storage key hierarchy.
135 child key must be protected by a strong access !! 92 Encryption and decryption of the child key must be protected by a strong
136 trust source. The random number generator in u !! 93 access control policy within the trust source.
137 selected trust source: <<
138 94
139 * TPM: hardware device based RNG !! 95 * TPM (hardware device) based RNG
140 96
141 Keys are generated within the TPM. Streng !! 97 Strength of random numbers may vary from one device manufacturer to
142 from one device manufacturer to another. !! 98 another.
143 99
144 * TEE: OP-TEE based on Arm TrustZone based !! 100 * TEE (OP-TEE based on Arm TrustZone) based RNG
145 101
146 RNG is customizable as per platform needs 102 RNG is customizable as per platform needs. It can either be direct output
147 from platform specific hardware RNG or a 103 from platform specific hardware RNG or a software based Fortuna CSPRNG
148 which can be seeded via multiple entropy 104 which can be seeded via multiple entropy sources.
149 105
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 <<
164 command-line to override the used RNG with the <<
165 <<
166 Encrypted Keys 106 Encrypted Keys
167 -------------- 107 --------------
168 108
169 Encrypted keys do not depend on a trust source 109 Encrypted keys do not depend on a trust source, and are faster, as they use AES
170 for encryption/decryption. New keys are create !! 110 for encryption/decryption. New keys are created from kernel-generated random
171 random numbers or user-provided decrypted data !! 111 numbers, and are encrypted/decrypted using a specified ‘master’ key. The
172 using a specified ‘master’ key. The ‘mas !! 112 ‘master’ key can either be a trusted-key or user-key type. The main disadvantage
173 user-key type. The main disadvantage of encryp !! 113 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 !! 114 as secure as the user key encrypting them. The master user key should therefore
175 them. The master user key should therefore be !! 115 be loaded in as secure a way as possible, preferably early in boot.
176 possible, preferably early in boot. <<
177 116
178 117
179 Usage 118 Usage
180 ===== 119 =====
181 120
182 Trusted Keys usage: TPM 121 Trusted Keys usage: TPM
183 ----------------------- 122 -----------------------
184 123
185 TPM 1.2: By default, trusted keys are sealed u 124 TPM 1.2: By default, trusted keys are sealed under the SRK, which has the
186 default authorization value (20 bytes of 0s). 125 default authorization value (20 bytes of 0s). This can be set at takeownership
187 time with the TrouSerS utility: "tpm_takeowner 126 time with the TrouSerS utility: "tpm_takeownership -u -z".
188 127
189 TPM 2.0: The user must first create a storage 128 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 129 key is available after reboot. This can be done using the following commands.
191 130
192 With the IBM TSS 2 stack:: 131 With the IBM TSS 2 stack::
193 132
194 #> tsscreateprimary -hi o -st 133 #> tsscreateprimary -hi o -st
195 Handle 80000000 134 Handle 80000000
196 #> tssevictcontrol -hi o -ho 80000000 -hp 81 135 #> tssevictcontrol -hi o -ho 80000000 -hp 81000001
197 136
198 Or with the Intel TSS 2 stack:: 137 Or with the Intel TSS 2 stack::
199 138
200 #> tpm2_createprimary --hierarchy o -G rsa20 139 #> tpm2_createprimary --hierarchy o -G rsa2048 -c key.ctxt
201 [...] 140 [...]
202 #> tpm2_evictcontrol -c key.ctxt 0x81000001 141 #> tpm2_evictcontrol -c key.ctxt 0x81000001
203 persistentHandle: 0x81000001 142 persistentHandle: 0x81000001
204 143
205 Usage:: 144 Usage::
206 145
207 keyctl add trusted name "new keylen [optio 146 keyctl add trusted name "new keylen [options]" ring
208 keyctl add trusted name "load hex_blob [pc 147 keyctl add trusted name "load hex_blob [pcrlock=pcrnum]" ring
209 keyctl update key "update [options]" 148 keyctl update key "update [options]"
210 keyctl print keyid 149 keyctl print keyid
211 150
212 options: 151 options:
213 keyhandle= ascii hex value of sealin 152 keyhandle= ascii hex value of sealing key
214 TPM 1.2: default 0x4000 153 TPM 1.2: default 0x40000000 (SRK)
215 TPM 2.0: no default; mu 154 TPM 2.0: no default; must be passed every time
216 keyauth= ascii hex auth for sealin 155 keyauth= ascii hex auth for sealing key default 0x00...i
217 (40 ascii zeros) 156 (40 ascii zeros)
218 blobauth= ascii hex auth for sealed 157 blobauth= ascii hex auth for sealed data default 0x00...
219 (40 ascii zeros) 158 (40 ascii zeros)
220 pcrinfo= ascii hex of PCR_INFO or 159 pcrinfo= ascii hex of PCR_INFO or PCR_INFO_LONG (no default)
221 pcrlock= pcr number to be extended 160 pcrlock= pcr number to be extended to "lock" blob
222 migratable= 0|1 indicating permission 161 migratable= 0|1 indicating permission to reseal to new PCR values,
223 default 1 (resealing allo 162 default 1 (resealing allowed)
224 hash= hash algorithm name as a 163 hash= hash algorithm name as a string. For TPM 1.x the only
225 allowed value is sha1. Fo 164 allowed value is sha1. For TPM 2.x the allowed values
226 are sha1, sha256, sha384, 165 are sha1, sha256, sha384, sha512 and sm3-256.
227 policydigest= digest for the authorizat 166 policydigest= digest for the authorization policy. must be calculated
228 with the same hash algori 167 with the same hash algorithm as specified by the 'hash='
229 option. 168 option.
230 policyhandle= handle to an authorizatio 169 policyhandle= handle to an authorization policy session that defines the
231 same policy and with the 170 same policy and with the same hash algorithm as was used to
232 seal the key. 171 seal the key.
233 172
234 "keyctl print" returns an ascii hex copy of th 173 "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 174 TPM_STORED_DATA format. The key length for new keys are always in bytes.
236 Trusted Keys can be 32 - 128 bytes (256 - 1024 175 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 176 within the 2048 bit SRK (RSA) keylength, with all necessary structure/padding.
238 177
239 Trusted Keys usage: TEE 178 Trusted Keys usage: TEE
240 ----------------------- 179 -----------------------
241 180
242 Usage:: 181 Usage::
243 182
244 keyctl add trusted name "new keylen" ring 183 keyctl add trusted name "new keylen" ring
245 keyctl add trusted name "load hex_blob" ri 184 keyctl add trusted name "load hex_blob" ring
246 keyctl print keyid 185 keyctl print keyid
247 186
248 "keyctl print" returns an ASCII hex copy of th 187 "keyctl print" returns an ASCII hex copy of the sealed key, which is in format
249 specific to TEE device implementation. The ke 188 specific to TEE device implementation. The key length for new keys is always
250 in bytes. Trusted Keys can be 32 - 128 bytes ( 189 in bytes. Trusted Keys can be 32 - 128 bytes (256 - 1024 bits).
251 190
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 191 Encrypted Keys usage
279 -------------------- 192 --------------------
280 193
281 The decrypted portion of encrypted keys can co 194 The decrypted portion of encrypted keys can contain either a simple symmetric
282 key or a more complex structure. The format of 195 key or a more complex structure. The format of the more complex structure is
283 application specific, which is identified by ' 196 application specific, which is identified by 'format'.
284 197
285 Usage:: 198 Usage::
286 199
287 keyctl add encrypted name "new [format] ke 200 keyctl add encrypted name "new [format] key-type:master-key-name keylen"
288 ring 201 ring
289 keyctl add encrypted name "new [format] ke <<
290 decrypted-data" ring <<
291 keyctl add encrypted name "load hex_blob" 202 keyctl add encrypted name "load hex_blob" ring
292 keyctl update keyid "update key-type:maste 203 keyctl update keyid "update key-type:master-key-name"
293 204
294 Where:: 205 Where::
295 206
296 format:= 'default | ecryptfs | enc32' 207 format:= 'default | ecryptfs | enc32'
297 key-type:= 'trusted' | 'user' 208 key-type:= 'trusted' | 'user'
298 209
299 Examples of trusted and encrypted key usage 210 Examples of trusted and encrypted key usage
300 ------------------------------------------- 211 -------------------------------------------
301 212
302 Create and save a trusted key named "kmk" of l 213 Create and save a trusted key named "kmk" of length 32 bytes.
303 214
304 Note: When using a TPM 2.0 with a persistent k 215 Note: When using a TPM 2.0 with a persistent key with handle 0x81000001,
305 append 'keyhandle=0x81000001' to statements be 216 append 'keyhandle=0x81000001' to statements between quotes, such as
306 "new 32 keyhandle=0x81000001". 217 "new 32 keyhandle=0x81000001".
307 218
308 :: 219 ::
309 220
310 $ keyctl add trusted kmk "new 32" @u 221 $ keyctl add trusted kmk "new 32" @u
311 440502848 222 440502848
312 223
313 $ keyctl show 224 $ keyctl show
314 Session Keyring 225 Session Keyring
315 -3 --alswrv 500 500 keyring: 226 -3 --alswrv 500 500 keyring: _ses
316 97833714 --alswrv 500 -1 \_ keyri 227 97833714 --alswrv 500 -1 \_ keyring: _uid.500
317 440502848 --alswrv 500 500 \_ t 228 440502848 --alswrv 500 500 \_ trusted: kmk
318 229
319 $ keyctl print 440502848 230 $ keyctl print 440502848
320 0101000000000000000001005d01b7e3f4a6be5709 231 0101000000000000000001005d01b7e3f4a6be5709930f3b70a743cbb42e0cc95e18e915
321 3f60da455bbf1144ad12e4f92b452f966929f6105f 232 3f60da455bbf1144ad12e4f92b452f966929f6105fd29ca28e4d4d5a031d068478bacb0b
322 27351119f822911b0a11ba3d3498ba6a32e50dac7f 233 27351119f822911b0a11ba3d3498ba6a32e50dac7f32894dd890eb9ad578e4e292c83722
323 a52e56a097e6a68b3f56f7a52ece0cdccba1eb62ca 234 a52e56a097e6a68b3f56f7a52ece0cdccba1eb62cad7d817f6dc58898b3ac15f36026fec
324 d568bd4a706cb60bb37be6d8f1240661199d640b66 235 d568bd4a706cb60bb37be6d8f1240661199d640b66fb0fe3b079f97f450b9ef9c22c6d5d
325 dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471 236 dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471dc6d13ecf8298b946f65345faa5ef0
326 f1f8fff03ad0acb083725535636addb08d73dedb98 237 f1f8fff03ad0acb083725535636addb08d73dedb9832da198081e5deae84bfaf0409c22b
327 e4a8aea2b607ec96931e6f4d4fe563ba 238 e4a8aea2b607ec96931e6f4d4fe563ba
328 239
329 $ keyctl pipe 440502848 > kmk.blob 240 $ keyctl pipe 440502848 > kmk.blob
330 241
331 Load a trusted key from the saved blob:: 242 Load a trusted key from the saved blob::
332 243
333 $ keyctl add trusted kmk "load `cat kmk.bl 244 $ keyctl add trusted kmk "load `cat kmk.blob`" @u
334 268728824 245 268728824
335 246
336 $ keyctl print 268728824 247 $ keyctl print 268728824
337 0101000000000000000001005d01b7e3f4a6be5709 248 0101000000000000000001005d01b7e3f4a6be5709930f3b70a743cbb42e0cc95e18e915
338 3f60da455bbf1144ad12e4f92b452f966929f6105f 249 3f60da455bbf1144ad12e4f92b452f966929f6105fd29ca28e4d4d5a031d068478bacb0b
339 27351119f822911b0a11ba3d3498ba6a32e50dac7f 250 27351119f822911b0a11ba3d3498ba6a32e50dac7f32894dd890eb9ad578e4e292c83722
340 a52e56a097e6a68b3f56f7a52ece0cdccba1eb62ca 251 a52e56a097e6a68b3f56f7a52ece0cdccba1eb62cad7d817f6dc58898b3ac15f36026fec
341 d568bd4a706cb60bb37be6d8f1240661199d640b66 252 d568bd4a706cb60bb37be6d8f1240661199d640b66fb0fe3b079f97f450b9ef9c22c6d5d
342 dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471 253 dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471dc6d13ecf8298b946f65345faa5ef0
343 f1f8fff03ad0acb083725535636addb08d73dedb98 254 f1f8fff03ad0acb083725535636addb08d73dedb9832da198081e5deae84bfaf0409c22b
344 e4a8aea2b607ec96931e6f4d4fe563ba 255 e4a8aea2b607ec96931e6f4d4fe563ba
345 256
346 Reseal (TPM specific) a trusted key under new 257 Reseal (TPM specific) a trusted key under new PCR values::
347 258
348 $ keyctl update 268728824 "update pcrinfo= 259 $ keyctl update 268728824 "update pcrinfo=`cat pcr.blob`"
349 $ keyctl print 268728824 260 $ keyctl print 268728824
350 010100000000002c0002800093c35a09b70fff26e7 261 010100000000002c0002800093c35a09b70fff26e7a98ae786c641e678ec6ffb6b46d805
351 77c8a6377aed9d3219c6dfec4b23ffe3000001005d 262 77c8a6377aed9d3219c6dfec4b23ffe3000001005d37d472ac8a44023fbb3d18583a4f73
352 d3a076c0858f6f1dcaa39ea0f119911ff03f5406df 263 d3a076c0858f6f1dcaa39ea0f119911ff03f5406df4f7f27f41da8d7194f45c9f4e00f2e
353 df449f266253aa3f52e55c53de147773e00f0f9aca 264 df449f266253aa3f52e55c53de147773e00f0f9aca86c64d94c95382265968c354c5eab4
354 9638c5ae99c89de1e0997242edfb0b501744e11ff9 265 9638c5ae99c89de1e0997242edfb0b501744e11ff9762dfd951cffd93227cc513384e7e6
355 e782c29435c7ec2edafaa2f4c1fe6e7a781b59549f 266 e782c29435c7ec2edafaa2f4c1fe6e7a781b59549ff5296371b42133777dcc5b8b971610
356 94bc67ede19e43ddb9dc2baacad374a36feaf0314d 267 94bc67ede19e43ddb9dc2baacad374a36feaf0314d700af0a65c164b7082401740e489c9
357 7ef6a24defe4846104209bf0c3eced7fa1a672ed5b 268 7ef6a24defe4846104209bf0c3eced7fa1a672ed5b125fc9d8cd88b476a658a4434644ef
358 df8ae9a178e9f83ba9f08d10fa47e4226b98b0702f 269 df8ae9a178e9f83ba9f08d10fa47e4226b98b0702f06b3b8
359 270
360 271
361 The initial consumer of trusted keys is EVM, w 272 The initial consumer of trusted keys is EVM, which at boot time needs a high
362 quality symmetric key for HMAC protection of f 273 quality symmetric key for HMAC protection of file metadata. The use of a
363 trusted key provides strong guarantees that th 274 trusted key provides strong guarantees that the EVM key has not been
364 compromised by a user level problem, and when 275 compromised by a user level problem, and when sealed to a platform integrity
365 state, protects against boot and offline attac 276 state, protects against boot and offline attacks. Create and save an
366 encrypted key "evm" using the above trusted ke 277 encrypted key "evm" using the above trusted key "kmk":
367 278
368 option 1: omitting 'format':: 279 option 1: omitting 'format'::
369 280
370 $ keyctl add encrypted evm "new trusted:km 281 $ keyctl add encrypted evm "new trusted:kmk 32" @u
371 159771175 282 159771175
372 283
373 option 2: explicitly defining 'format' as 'def 284 option 2: explicitly defining 'format' as 'default'::
374 285
375 $ keyctl add encrypted evm "new default tr 286 $ keyctl add encrypted evm "new default trusted:kmk 32" @u
376 159771175 287 159771175
377 288
378 $ keyctl print 159771175 289 $ keyctl print 159771175
379 default trusted:kmk 32 2375725ad57798846a9 290 default trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b3
380 82dbbc55be2a44616e4959430436dc4f2a7a9659aa 291 82dbbc55be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e0
381 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc 292 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc
382 293
383 $ keyctl pipe 159771175 > evm.blob 294 $ keyctl pipe 159771175 > evm.blob
384 295
385 Load an encrypted key "evm" from saved blob:: 296 Load an encrypted key "evm" from saved blob::
386 297
387 $ keyctl add encrypted evm "load `cat evm. 298 $ keyctl add encrypted evm "load `cat evm.blob`" @u
388 831684262 299 831684262
389 300
390 $ keyctl print 831684262 301 $ keyctl print 831684262
391 default trusted:kmk 32 2375725ad57798846a9 302 default trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b3
392 82dbbc55be2a44616e4959430436dc4f2a7a9659aa 303 82dbbc55be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e0
393 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc 304 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc
394 305
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 306 Other uses for trusted and encrypted keys, such as for disk and file encryption
407 are anticipated. In particular the new format 307 are anticipated. In particular the new format 'ecryptfs' has been defined
408 in order to use encrypted keys to mount an eCr 308 in order to use encrypted keys to mount an eCryptfs filesystem. More details
409 about the usage can be found in the file 309 about the usage can be found in the file
410 ``Documentation/security/keys/ecryptfs.rst``. 310 ``Documentation/security/keys/ecryptfs.rst``.
411 311
412 Another new format 'enc32' has been defined in 312 Another new format 'enc32' has been defined in order to support encrypted keys
413 with payload size of 32 bytes. This will initi 313 with payload size of 32 bytes. This will initially be used for nvdimm security
414 but may expand to other usages that require 32 314 but may expand to other usages that require 32 bytes payload.
415 315
416 316
417 TPM 2.0 ASN.1 Key Format 317 TPM 2.0 ASN.1 Key Format
418 ------------------------ 318 ------------------------
419 319
420 The TPM 2.0 ASN.1 key format is designed to be 320 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 321 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 322 format) and to be extensible for additions like importable keys and
423 policy:: 323 policy::
424 324
425 TPMKey ::= SEQUENCE { 325 TPMKey ::= SEQUENCE {
426 type OBJECT IDENTIFIER 326 type OBJECT IDENTIFIER
427 emptyAuth [0] EXPLICIT BOOLEAN O 327 emptyAuth [0] EXPLICIT BOOLEAN OPTIONAL
428 parent INTEGER 328 parent INTEGER
429 pubkey OCTET STRING 329 pubkey OCTET STRING
430 privkey OCTET STRING 330 privkey OCTET STRING
431 } 331 }
432 332
433 type is what distinguishes the key even in bin 333 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 334 is provided by the TCG to be unique and thus forms a recognizable
435 binary pattern at offset 3 in the key. The OI 335 binary pattern at offset 3 in the key. The OIDs currently made
436 available are:: 336 available are::
437 337
438 2.23.133.10.1.3 TPM Loadable key. This is 338 2.23.133.10.1.3 TPM Loadable key. This is an asymmetric key (Usually
439 RSA2048 or Elliptic Curve) 339 RSA2048 or Elliptic Curve) which can be imported by a
440 TPM2_Load() operation. 340 TPM2_Load() operation.
441 341
442 2.23.133.10.1.4 TPM Importable Key. This 342 2.23.133.10.1.4 TPM Importable Key. This is an asymmetric key (Usually
443 RSA2048 or Elliptic Curve) 343 RSA2048 or Elliptic Curve) which can be imported by a
444 TPM2_Import() operation. 344 TPM2_Import() operation.
445 345
446 2.23.133.10.1.5 TPM Sealed Data. This is 346 2.23.133.10.1.5 TPM Sealed Data. This is a set of data (up to 128
447 bytes) which is sealed by 347 bytes) which is sealed by the TPM. It usually
448 represents a symmetric key 348 represents a symmetric key and must be unsealed before
449 use. 349 use.
450 350
451 The trusted key code only uses the TPM Sealed 351 The trusted key code only uses the TPM Sealed Data OID.
452 352
453 emptyAuth is true if the key has well known au 353 emptyAuth is true if the key has well known authorization "". If it
454 is false or not present, the key requires an e 354 is false or not present, the key requires an explicit authorization
455 phrase. This is used by most user space consu 355 phrase. This is used by most user space consumers to decide whether
456 to prompt for a password. 356 to prompt for a password.
457 357
458 parent represents the parent key handle, eithe 358 parent represents the parent key handle, either in the 0x81 MSO space,
459 like 0x81000001 for the RSA primary storage ke 359 like 0x81000001 for the RSA primary storage key. Userspace programmes
460 also support specifying the primary handle in 360 also support specifying the primary handle in the 0x40 MSO space. If
461 this happens the Elliptic Curve variant of the 361 this happens the Elliptic Curve variant of the primary key using the
462 TCG defined template will be generated on the 362 TCG defined template will be generated on the fly into a volatile
463 object and used as the parent. The current ke 363 object and used as the parent. The current kernel code only supports
464 the 0x81 MSO form. 364 the 0x81 MSO form.
465 365
466 pubkey is the binary representation of TPM2B_P 366 pubkey is the binary representation of TPM2B_PRIVATE excluding the
467 initial TPM2B header, which can be reconstruct 367 initial TPM2B header, which can be reconstructed from the ASN.1 octet
468 string length. 368 string length.
469 369
470 privkey is the binary representation of TPM2B_ 370 privkey is the binary representation of TPM2B_PUBLIC excluding the
471 initial TPM2B header which can be reconstructe 371 initial TPM2B header which can be reconstructed from the ASN.1 octed
472 string length. 372 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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