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 38 (3) CAAM (Cryptographic Acceleration and Assurance Module: IP on NXP SoCs)
39 39
40 When High Assurance Boot (HAB) is ena 40 When High Assurance Boot (HAB) is enabled and the CAAM is in secure
41 mode, trust is rooted to the OTPMK, a 41 mode, trust is rooted to the OTPMK, a never-disclosed 256-bit key
42 randomly generated and fused into eac 42 randomly generated and fused into each SoC at manufacturing time.
43 Otherwise, a common fixed test key is 43 Otherwise, a common fixed test key is used instead.
44 44
45 (4) DCP (Data Co-Processor: crypto accele 45 (4) DCP (Data Co-Processor: crypto accelerator of various i.MX SoCs)
46 46
47 Rooted to a one-time programmable key 47 Rooted to a one-time programmable key (OTP) that is generally burnt
48 in the on-chip fuses and is accessibl 48 in the on-chip fuses and is accessible to the DCP encryption engine only.
49 DCP provides two keys that can be use 49 DCP provides two keys that can be used as root of trust: the OTP key
50 and the UNIQUE key. Default is to use 50 and the UNIQUE key. Default is to use the UNIQUE key, but selecting
51 the OTP key can be done via a module 51 the OTP key can be done via a module parameter (dcp_use_otp_key).
52 52
53 * Execution isolation 53 * Execution isolation
54 54
55 (1) TPM 55 (1) TPM
56 56
57 Fixed set of operations running in is 57 Fixed set of operations running in isolated execution environment.
58 58
59 (2) TEE 59 (2) TEE
60 60
61 Customizable set of operations runnin 61 Customizable set of operations running in isolated execution
62 environment verified via Secure/Trust 62 environment verified via Secure/Trusted boot process.
63 63
64 (3) CAAM 64 (3) CAAM
65 65
66 Fixed set of operations running in is 66 Fixed set of operations running in isolated execution environment.
67 67
68 (4) DCP 68 (4) DCP
69 69
70 Fixed set of cryptographic operations 70 Fixed set of cryptographic operations running in isolated execution
71 environment. Only basic blob key encr 71 environment. Only basic blob key encryption is executed there.
72 The actual key sealing/unsealing is d 72 The actual key sealing/unsealing is done on main processor/kernel space.
73 73
74 * Optional binding to platform integrity sta 74 * Optional binding to platform integrity state
75 75
76 (1) TPM 76 (1) TPM
77 77
78 Keys can be optionally sealed to spec 78 Keys can be optionally sealed to specified PCR (integrity measurement)
79 values, and only unsealed by the TPM, 79 values, and only unsealed by the TPM, if PCRs and blob integrity
80 verifications match. A loaded Trusted 80 verifications match. A loaded Trusted Key can be updated with new
81 (future) PCR values, so keys are easi 81 (future) PCR values, so keys are easily migrated to new PCR values,
82 such as when the kernel and initramfs 82 such as when the kernel and initramfs are updated. The same key can
83 have many saved blobs under different 83 have many saved blobs under different PCR values, so multiple boots are
84 easily supported. 84 easily supported.
85 85
86 (2) TEE 86 (2) TEE
87 87
88 Relies on Secure/Trusted boot process 88 Relies on Secure/Trusted boot process for platform integrity. It can
89 be extended with TEE based measured b 89 be extended with TEE based measured boot process.
90 90
91 (3) CAAM 91 (3) CAAM
92 92
93 Relies on the High Assurance Boot (HA 93 Relies on the High Assurance Boot (HAB) mechanism of NXP SoCs
94 for platform integrity. 94 for platform integrity.
95 95
96 (4) DCP 96 (4) DCP
97 97
98 Relies on Secure/Trusted boot process 98 Relies on Secure/Trusted boot process (called HAB by vendor) for
99 platform integrity. 99 platform integrity.
100 100
101 * Interfaces and APIs 101 * Interfaces and APIs
102 102
103 (1) TPM 103 (1) TPM
104 104
105 TPMs have well-documented, standardiz 105 TPMs have well-documented, standardized interfaces and APIs.
106 106
107 (2) TEE 107 (2) TEE
108 108
109 TEEs have well-documented, standardiz 109 TEEs have well-documented, standardized client interface and APIs. For
110 more details refer to ``Documentation 110 more details refer to ``Documentation/driver-api/tee.rst``.
111 111
112 (3) CAAM 112 (3) CAAM
113 113
114 Interface is specific to silicon vend 114 Interface is specific to silicon vendor.
115 115
116 (4) DCP 116 (4) DCP
117 117
118 Vendor-specific API that is implement 118 Vendor-specific API that is implemented as part of the DCP crypto driver in
119 ``drivers/crypto/mxs-dcp.c``. 119 ``drivers/crypto/mxs-dcp.c``.
120 120
121 * Threat model 121 * Threat model
122 122
123 The strength and appropriateness of a par 123 The strength and appropriateness of a particular trust source for a given
124 purpose must be assessed when using them 124 purpose must be assessed when using them to protect security-relevant data.
125 125
126 126
127 Key Generation 127 Key Generation
128 ============== 128 ==============
129 129
130 Trusted Keys 130 Trusted Keys
131 ------------ 131 ------------
132 132
133 New keys are created from random numbers. They 133 New keys are created from random numbers. They are encrypted/decrypted using
134 a child key in the storage key hierarchy. Encr 134 a child key in the storage key hierarchy. Encryption and decryption of the
135 child key must be protected by a strong access 135 child key must be protected by a strong access control policy within the
136 trust source. The random number generator in u 136 trust source. The random number generator in use differs according to the
137 selected trust source: 137 selected trust source:
138 138
139 * TPM: hardware device based RNG 139 * TPM: hardware device based RNG
140 140
141 Keys are generated within the TPM. Streng 141 Keys are generated within the TPM. Strength of random numbers may vary
142 from one device manufacturer to another. 142 from one device manufacturer to another.
143 143
144 * TEE: OP-TEE based on Arm TrustZone based 144 * TEE: OP-TEE based on Arm TrustZone based RNG
145 145
146 RNG is customizable as per platform needs 146 RNG is customizable as per platform needs. It can either be direct output
147 from platform specific hardware RNG or a 147 from platform specific hardware RNG or a software based Fortuna CSPRNG
148 which can be seeded via multiple entropy 148 which can be seeded via multiple entropy sources.
149 149
150 * CAAM: Kernel RNG 150 * CAAM: Kernel RNG
151 151
152 The normal kernel random number generator 152 The normal kernel random number generator is used. To seed it from the
153 CAAM HWRNG, enable CRYPTO_DEV_FSL_CAAM_RN 153 CAAM HWRNG, enable CRYPTO_DEV_FSL_CAAM_RNG_API and ensure the device
154 is probed. 154 is probed.
155 155
156 * DCP (Data Co-Processor: crypto accelerato 156 * DCP (Data Co-Processor: crypto accelerator of various i.MX SoCs)
157 157
158 The DCP hardware device itself does not p 158 The DCP hardware device itself does not provide a dedicated RNG interface,
159 so the kernel default RNG is used. SoCs w 159 so the kernel default RNG is used. SoCs with DCP like the i.MX6ULL do have
160 a dedicated hardware RNG that is independ 160 a dedicated hardware RNG that is independent from DCP which can be enabled
161 to back the kernel RNG. 161 to back the kernel RNG.
162 162
163 Users may override this by specifying ``truste 163 Users may override this by specifying ``trusted.rng=kernel`` on the kernel
164 command-line to override the used RNG with the 164 command-line to override the used RNG with the kernel's random number pool.
165 165
166 Encrypted Keys 166 Encrypted Keys
167 -------------- 167 --------------
168 168
169 Encrypted keys do not depend on a trust source 169 Encrypted keys do not depend on a trust source, and are faster, as they use AES
170 for encryption/decryption. New keys are create 170 for encryption/decryption. New keys are created either from kernel-generated
171 random numbers or user-provided decrypted data 171 random numbers or user-provided decrypted data, and are encrypted/decrypted
172 using a specified ‘master’ key. The ‘mas 172 using a specified ‘master’ key. The ‘master’ key can either be a trusted-key or
173 user-key type. The main disadvantage of encryp 173 user-key type. The main disadvantage of encrypted keys is that if they are not
174 rooted in a trusted key, they are only as secu 174 rooted in a trusted key, they are only as secure as the user key encrypting
175 them. The master user key should therefore be 175 them. The master user key should therefore be loaded in as secure a way as
176 possible, preferably early in boot. 176 possible, preferably early in boot.
177 177
178 178
179 Usage 179 Usage
180 ===== 180 =====
181 181
182 Trusted Keys usage: TPM 182 Trusted Keys usage: TPM
183 ----------------------- 183 -----------------------
184 184
185 TPM 1.2: By default, trusted keys are sealed u 185 TPM 1.2: By default, trusted keys are sealed under the SRK, which has the
186 default authorization value (20 bytes of 0s). 186 default authorization value (20 bytes of 0s). This can be set at takeownership
187 time with the TrouSerS utility: "tpm_takeowner 187 time with the TrouSerS utility: "tpm_takeownership -u -z".
188 188
189 TPM 2.0: The user must first create a storage 189 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 190 key is available after reboot. This can be done using the following commands.
191 191
192 With the IBM TSS 2 stack:: 192 With the IBM TSS 2 stack::
193 193
194 #> tsscreateprimary -hi o -st 194 #> tsscreateprimary -hi o -st
195 Handle 80000000 195 Handle 80000000
196 #> tssevictcontrol -hi o -ho 80000000 -hp 81 196 #> tssevictcontrol -hi o -ho 80000000 -hp 81000001
197 197
198 Or with the Intel TSS 2 stack:: 198 Or with the Intel TSS 2 stack::
199 199
200 #> tpm2_createprimary --hierarchy o -G rsa20 200 #> tpm2_createprimary --hierarchy o -G rsa2048 -c key.ctxt
201 [...] 201 [...]
202 #> tpm2_evictcontrol -c key.ctxt 0x81000001 202 #> tpm2_evictcontrol -c key.ctxt 0x81000001
203 persistentHandle: 0x81000001 203 persistentHandle: 0x81000001
204 204
205 Usage:: 205 Usage::
206 206
207 keyctl add trusted name "new keylen [optio 207 keyctl add trusted name "new keylen [options]" ring
208 keyctl add trusted name "load hex_blob [pc 208 keyctl add trusted name "load hex_blob [pcrlock=pcrnum]" ring
209 keyctl update key "update [options]" 209 keyctl update key "update [options]"
210 keyctl print keyid 210 keyctl print keyid
211 211
212 options: 212 options:
213 keyhandle= ascii hex value of sealin 213 keyhandle= ascii hex value of sealing key
214 TPM 1.2: default 0x4000 214 TPM 1.2: default 0x40000000 (SRK)
215 TPM 2.0: no default; mu 215 TPM 2.0: no default; must be passed every time
216 keyauth= ascii hex auth for sealin 216 keyauth= ascii hex auth for sealing key default 0x00...i
217 (40 ascii zeros) 217 (40 ascii zeros)
218 blobauth= ascii hex auth for sealed 218 blobauth= ascii hex auth for sealed data default 0x00...
219 (40 ascii zeros) 219 (40 ascii zeros)
220 pcrinfo= ascii hex of PCR_INFO or 220 pcrinfo= ascii hex of PCR_INFO or PCR_INFO_LONG (no default)
221 pcrlock= pcr number to be extended 221 pcrlock= pcr number to be extended to "lock" blob
222 migratable= 0|1 indicating permission 222 migratable= 0|1 indicating permission to reseal to new PCR values,
223 default 1 (resealing allo 223 default 1 (resealing allowed)
224 hash= hash algorithm name as a 224 hash= hash algorithm name as a string. For TPM 1.x the only
225 allowed value is sha1. Fo 225 allowed value is sha1. For TPM 2.x the allowed values
226 are sha1, sha256, sha384, 226 are sha1, sha256, sha384, sha512 and sm3-256.
227 policydigest= digest for the authorizat 227 policydigest= digest for the authorization policy. must be calculated
228 with the same hash algori 228 with the same hash algorithm as specified by the 'hash='
229 option. 229 option.
230 policyhandle= handle to an authorizatio 230 policyhandle= handle to an authorization policy session that defines the
231 same policy and with the 231 same policy and with the same hash algorithm as was used to
232 seal the key. 232 seal the key.
233 233
234 "keyctl print" returns an ascii hex copy of th 234 "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 235 TPM_STORED_DATA format. The key length for new keys are always in bytes.
236 Trusted Keys can be 32 - 128 bytes (256 - 1024 236 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 237 within the 2048 bit SRK (RSA) keylength, with all necessary structure/padding.
238 238
239 Trusted Keys usage: TEE 239 Trusted Keys usage: TEE
240 ----------------------- 240 -----------------------
241 241
242 Usage:: 242 Usage::
243 243
244 keyctl add trusted name "new keylen" ring 244 keyctl add trusted name "new keylen" ring
245 keyctl add trusted name "load hex_blob" ri 245 keyctl add trusted name "load hex_blob" ring
246 keyctl print keyid 246 keyctl print keyid
247 247
248 "keyctl print" returns an ASCII hex copy of th 248 "keyctl print" returns an ASCII hex copy of the sealed key, which is in format
249 specific to TEE device implementation. The ke 249 specific to TEE device implementation. The key length for new keys is always
250 in bytes. Trusted Keys can be 32 - 128 bytes ( 250 in bytes. Trusted Keys can be 32 - 128 bytes (256 - 1024 bits).
251 251
252 Trusted Keys usage: CAAM 252 Trusted Keys usage: CAAM
253 ------------------------ 253 ------------------------
254 254
255 Usage:: 255 Usage::
256 256
257 keyctl add trusted name "new keylen" ring 257 keyctl add trusted name "new keylen" ring
258 keyctl add trusted name "load hex_blob" ri 258 keyctl add trusted name "load hex_blob" ring
259 keyctl print keyid 259 keyctl print keyid
260 260
261 "keyctl print" returns an ASCII hex copy of th 261 "keyctl print" returns an ASCII hex copy of the sealed key, which is in a
262 CAAM-specific format. The key length for new 262 CAAM-specific format. The key length for new keys is always in bytes.
263 Trusted Keys can be 32 - 128 bytes (256 - 1024 263 Trusted Keys can be 32 - 128 bytes (256 - 1024 bits).
264 264
265 Trusted Keys usage: DCP 265 Trusted Keys usage: DCP
266 ----------------------- 266 -----------------------
267 267
268 Usage:: 268 Usage::
269 269
270 keyctl add trusted name "new keylen" ring 270 keyctl add trusted name "new keylen" ring
271 keyctl add trusted name "load hex_blob" ri 271 keyctl add trusted name "load hex_blob" ring
272 keyctl print keyid 272 keyctl print keyid
273 273
274 "keyctl print" returns an ASCII hex copy of th 274 "keyctl print" returns an ASCII hex copy of the sealed key, which is in format
275 specific to this DCP key-blob implementation. 275 specific to this DCP key-blob implementation. The key length for new keys is
276 always in bytes. Trusted Keys can be 32 - 128 276 always in bytes. Trusted Keys can be 32 - 128 bytes (256 - 1024 bits).
277 277
278 Encrypted Keys usage 278 Encrypted Keys usage
279 -------------------- 279 --------------------
280 280
281 The decrypted portion of encrypted keys can co 281 The decrypted portion of encrypted keys can contain either a simple symmetric
282 key or a more complex structure. The format of 282 key or a more complex structure. The format of the more complex structure is
283 application specific, which is identified by ' 283 application specific, which is identified by 'format'.
284 284
285 Usage:: 285 Usage::
286 286
287 keyctl add encrypted name "new [format] ke 287 keyctl add encrypted name "new [format] key-type:master-key-name keylen"
288 ring 288 ring
289 keyctl add encrypted name "new [format] ke 289 keyctl add encrypted name "new [format] key-type:master-key-name keylen
290 decrypted-data" ring 290 decrypted-data" ring
291 keyctl add encrypted name "load hex_blob" 291 keyctl add encrypted name "load hex_blob" ring
292 keyctl update keyid "update key-type:maste 292 keyctl update keyid "update key-type:master-key-name"
293 293
294 Where:: 294 Where::
295 295
296 format:= 'default | ecryptfs | enc32' 296 format:= 'default | ecryptfs | enc32'
297 key-type:= 'trusted' | 'user' 297 key-type:= 'trusted' | 'user'
298 298
299 Examples of trusted and encrypted key usage 299 Examples of trusted and encrypted key usage
300 ------------------------------------------- 300 -------------------------------------------
301 301
302 Create and save a trusted key named "kmk" of l 302 Create and save a trusted key named "kmk" of length 32 bytes.
303 303
304 Note: When using a TPM 2.0 with a persistent k 304 Note: When using a TPM 2.0 with a persistent key with handle 0x81000001,
305 append 'keyhandle=0x81000001' to statements be 305 append 'keyhandle=0x81000001' to statements between quotes, such as
306 "new 32 keyhandle=0x81000001". 306 "new 32 keyhandle=0x81000001".
307 307
308 :: 308 ::
309 309
310 $ keyctl add trusted kmk "new 32" @u 310 $ keyctl add trusted kmk "new 32" @u
311 440502848 311 440502848
312 312
313 $ keyctl show 313 $ keyctl show
314 Session Keyring 314 Session Keyring
315 -3 --alswrv 500 500 keyring: 315 -3 --alswrv 500 500 keyring: _ses
316 97833714 --alswrv 500 -1 \_ keyri 316 97833714 --alswrv 500 -1 \_ keyring: _uid.500
317 440502848 --alswrv 500 500 \_ t 317 440502848 --alswrv 500 500 \_ trusted: kmk
318 318
319 $ keyctl print 440502848 319 $ keyctl print 440502848
320 0101000000000000000001005d01b7e3f4a6be5709 320 0101000000000000000001005d01b7e3f4a6be5709930f3b70a743cbb42e0cc95e18e915
321 3f60da455bbf1144ad12e4f92b452f966929f6105f 321 3f60da455bbf1144ad12e4f92b452f966929f6105fd29ca28e4d4d5a031d068478bacb0b
322 27351119f822911b0a11ba3d3498ba6a32e50dac7f 322 27351119f822911b0a11ba3d3498ba6a32e50dac7f32894dd890eb9ad578e4e292c83722
323 a52e56a097e6a68b3f56f7a52ece0cdccba1eb62ca 323 a52e56a097e6a68b3f56f7a52ece0cdccba1eb62cad7d817f6dc58898b3ac15f36026fec
324 d568bd4a706cb60bb37be6d8f1240661199d640b66 324 d568bd4a706cb60bb37be6d8f1240661199d640b66fb0fe3b079f97f450b9ef9c22c6d5d
325 dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471 325 dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471dc6d13ecf8298b946f65345faa5ef0
326 f1f8fff03ad0acb083725535636addb08d73dedb98 326 f1f8fff03ad0acb083725535636addb08d73dedb9832da198081e5deae84bfaf0409c22b
327 e4a8aea2b607ec96931e6f4d4fe563ba 327 e4a8aea2b607ec96931e6f4d4fe563ba
328 328
329 $ keyctl pipe 440502848 > kmk.blob 329 $ keyctl pipe 440502848 > kmk.blob
330 330
331 Load a trusted key from the saved blob:: 331 Load a trusted key from the saved blob::
332 332
333 $ keyctl add trusted kmk "load `cat kmk.bl 333 $ keyctl add trusted kmk "load `cat kmk.blob`" @u
334 268728824 334 268728824
335 335
336 $ keyctl print 268728824 336 $ keyctl print 268728824
337 0101000000000000000001005d01b7e3f4a6be5709 337 0101000000000000000001005d01b7e3f4a6be5709930f3b70a743cbb42e0cc95e18e915
338 3f60da455bbf1144ad12e4f92b452f966929f6105f 338 3f60da455bbf1144ad12e4f92b452f966929f6105fd29ca28e4d4d5a031d068478bacb0b
339 27351119f822911b0a11ba3d3498ba6a32e50dac7f 339 27351119f822911b0a11ba3d3498ba6a32e50dac7f32894dd890eb9ad578e4e292c83722
340 a52e56a097e6a68b3f56f7a52ece0cdccba1eb62ca 340 a52e56a097e6a68b3f56f7a52ece0cdccba1eb62cad7d817f6dc58898b3ac15f36026fec
341 d568bd4a706cb60bb37be6d8f1240661199d640b66 341 d568bd4a706cb60bb37be6d8f1240661199d640b66fb0fe3b079f97f450b9ef9c22c6d5d
342 dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471 342 dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471dc6d13ecf8298b946f65345faa5ef0
343 f1f8fff03ad0acb083725535636addb08d73dedb98 343 f1f8fff03ad0acb083725535636addb08d73dedb9832da198081e5deae84bfaf0409c22b
344 e4a8aea2b607ec96931e6f4d4fe563ba 344 e4a8aea2b607ec96931e6f4d4fe563ba
345 345
346 Reseal (TPM specific) a trusted key under new 346 Reseal (TPM specific) a trusted key under new PCR values::
347 347
348 $ keyctl update 268728824 "update pcrinfo= 348 $ keyctl update 268728824 "update pcrinfo=`cat pcr.blob`"
349 $ keyctl print 268728824 349 $ keyctl print 268728824
350 010100000000002c0002800093c35a09b70fff26e7 350 010100000000002c0002800093c35a09b70fff26e7a98ae786c641e678ec6ffb6b46d805
351 77c8a6377aed9d3219c6dfec4b23ffe3000001005d 351 77c8a6377aed9d3219c6dfec4b23ffe3000001005d37d472ac8a44023fbb3d18583a4f73
352 d3a076c0858f6f1dcaa39ea0f119911ff03f5406df 352 d3a076c0858f6f1dcaa39ea0f119911ff03f5406df4f7f27f41da8d7194f45c9f4e00f2e
353 df449f266253aa3f52e55c53de147773e00f0f9aca 353 df449f266253aa3f52e55c53de147773e00f0f9aca86c64d94c95382265968c354c5eab4
354 9638c5ae99c89de1e0997242edfb0b501744e11ff9 354 9638c5ae99c89de1e0997242edfb0b501744e11ff9762dfd951cffd93227cc513384e7e6
355 e782c29435c7ec2edafaa2f4c1fe6e7a781b59549f 355 e782c29435c7ec2edafaa2f4c1fe6e7a781b59549ff5296371b42133777dcc5b8b971610
356 94bc67ede19e43ddb9dc2baacad374a36feaf0314d 356 94bc67ede19e43ddb9dc2baacad374a36feaf0314d700af0a65c164b7082401740e489c9
357 7ef6a24defe4846104209bf0c3eced7fa1a672ed5b 357 7ef6a24defe4846104209bf0c3eced7fa1a672ed5b125fc9d8cd88b476a658a4434644ef
358 df8ae9a178e9f83ba9f08d10fa47e4226b98b0702f 358 df8ae9a178e9f83ba9f08d10fa47e4226b98b0702f06b3b8
359 359
360 360
361 The initial consumer of trusted keys is EVM, w 361 The initial consumer of trusted keys is EVM, which at boot time needs a high
362 quality symmetric key for HMAC protection of f 362 quality symmetric key for HMAC protection of file metadata. The use of a
363 trusted key provides strong guarantees that th 363 trusted key provides strong guarantees that the EVM key has not been
364 compromised by a user level problem, and when 364 compromised by a user level problem, and when sealed to a platform integrity
365 state, protects against boot and offline attac 365 state, protects against boot and offline attacks. Create and save an
366 encrypted key "evm" using the above trusted ke 366 encrypted key "evm" using the above trusted key "kmk":
367 367
368 option 1: omitting 'format':: 368 option 1: omitting 'format'::
369 369
370 $ keyctl add encrypted evm "new trusted:km 370 $ keyctl add encrypted evm "new trusted:kmk 32" @u
371 159771175 371 159771175
372 372
373 option 2: explicitly defining 'format' as 'def 373 option 2: explicitly defining 'format' as 'default'::
374 374
375 $ keyctl add encrypted evm "new default tr 375 $ keyctl add encrypted evm "new default trusted:kmk 32" @u
376 159771175 376 159771175
377 377
378 $ keyctl print 159771175 378 $ keyctl print 159771175
379 default trusted:kmk 32 2375725ad57798846a9 379 default trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b3
380 82dbbc55be2a44616e4959430436dc4f2a7a9659aa 380 82dbbc55be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e0
381 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc 381 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc
382 382
383 $ keyctl pipe 159771175 > evm.blob 383 $ keyctl pipe 159771175 > evm.blob
384 384
385 Load an encrypted key "evm" from saved blob:: 385 Load an encrypted key "evm" from saved blob::
386 386
387 $ keyctl add encrypted evm "load `cat evm. 387 $ keyctl add encrypted evm "load `cat evm.blob`" @u
388 831684262 388 831684262
389 389
390 $ keyctl print 831684262 390 $ keyctl print 831684262
391 default trusted:kmk 32 2375725ad57798846a9 391 default trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b3
392 82dbbc55be2a44616e4959430436dc4f2a7a9659aa 392 82dbbc55be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e0
393 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc 393 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc
394 394
395 Instantiate an encrypted key "evm" using user- 395 Instantiate an encrypted key "evm" using user-provided decrypted data::
396 396
397 $ evmkey=$(dd if=/dev/urandom bs=1 count=3 397 $ evmkey=$(dd if=/dev/urandom bs=1 count=32 | xxd -c32 -p)
398 $ keyctl add encrypted evm "new default us 398 $ keyctl add encrypted evm "new default user:kmk 32 $evmkey" @u
399 794890253 399 794890253
400 400
401 $ keyctl print 794890253 401 $ keyctl print 794890253
402 default user:kmk 32 2375725ad57798846a9bbd 402 default user:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b382d
403 bbc55be2a44616e4959430436dc4f2a7a9659aa60b 403 bbc55be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e0247
404 17c64 5972dcb82ab2dde83376d82b2e3c09ffc 404 17c64 5972dcb82ab2dde83376d82b2e3c09ffc
405 405
406 Other uses for trusted and encrypted keys, suc 406 Other uses for trusted and encrypted keys, such as for disk and file encryption
407 are anticipated. In particular the new format 407 are anticipated. In particular the new format 'ecryptfs' has been defined
408 in order to use encrypted keys to mount an eCr 408 in order to use encrypted keys to mount an eCryptfs filesystem. More details
409 about the usage can be found in the file 409 about the usage can be found in the file
410 ``Documentation/security/keys/ecryptfs.rst``. 410 ``Documentation/security/keys/ecryptfs.rst``.
411 411
412 Another new format 'enc32' has been defined in 412 Another new format 'enc32' has been defined in order to support encrypted keys
413 with payload size of 32 bytes. This will initi 413 with payload size of 32 bytes. This will initially be used for nvdimm security
414 but may expand to other usages that require 32 414 but may expand to other usages that require 32 bytes payload.
415 415
416 416
417 TPM 2.0 ASN.1 Key Format 417 TPM 2.0 ASN.1 Key Format
418 ------------------------ 418 ------------------------
419 419
420 The TPM 2.0 ASN.1 key format is designed to be 420 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 421 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 422 format) and to be extensible for additions like importable keys and
423 policy:: 423 policy::
424 424
425 TPMKey ::= SEQUENCE { 425 TPMKey ::= SEQUENCE {
426 type OBJECT IDENTIFIER 426 type OBJECT IDENTIFIER
427 emptyAuth [0] EXPLICIT BOOLEAN O 427 emptyAuth [0] EXPLICIT BOOLEAN OPTIONAL
428 parent INTEGER 428 parent INTEGER
429 pubkey OCTET STRING 429 pubkey OCTET STRING
430 privkey OCTET STRING 430 privkey OCTET STRING
431 } 431 }
432 432
433 type is what distinguishes the key even in bin 433 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 434 is provided by the TCG to be unique and thus forms a recognizable
435 binary pattern at offset 3 in the key. The OI 435 binary pattern at offset 3 in the key. The OIDs currently made
436 available are:: 436 available are::
437 437
438 2.23.133.10.1.3 TPM Loadable key. This is 438 2.23.133.10.1.3 TPM Loadable key. This is an asymmetric key (Usually
439 RSA2048 or Elliptic Curve) 439 RSA2048 or Elliptic Curve) which can be imported by a
440 TPM2_Load() operation. 440 TPM2_Load() operation.
441 441
442 2.23.133.10.1.4 TPM Importable Key. This 442 2.23.133.10.1.4 TPM Importable Key. This is an asymmetric key (Usually
443 RSA2048 or Elliptic Curve) 443 RSA2048 or Elliptic Curve) which can be imported by a
444 TPM2_Import() operation. 444 TPM2_Import() operation.
445 445
446 2.23.133.10.1.5 TPM Sealed Data. This is 446 2.23.133.10.1.5 TPM Sealed Data. This is a set of data (up to 128
447 bytes) which is sealed by 447 bytes) which is sealed by the TPM. It usually
448 represents a symmetric key 448 represents a symmetric key and must be unsealed before
449 use. 449 use.
450 450
451 The trusted key code only uses the TPM Sealed 451 The trusted key code only uses the TPM Sealed Data OID.
452 452
453 emptyAuth is true if the key has well known au 453 emptyAuth is true if the key has well known authorization "". If it
454 is false or not present, the key requires an e 454 is false or not present, the key requires an explicit authorization
455 phrase. This is used by most user space consu 455 phrase. This is used by most user space consumers to decide whether
456 to prompt for a password. 456 to prompt for a password.
457 457
458 parent represents the parent key handle, eithe 458 parent represents the parent key handle, either in the 0x81 MSO space,
459 like 0x81000001 for the RSA primary storage ke 459 like 0x81000001 for the RSA primary storage key. Userspace programmes
460 also support specifying the primary handle in 460 also support specifying the primary handle in the 0x40 MSO space. If
461 this happens the Elliptic Curve variant of the 461 this happens the Elliptic Curve variant of the primary key using the
462 TCG defined template will be generated on the 462 TCG defined template will be generated on the fly into a volatile
463 object and used as the parent. The current ke 463 object and used as the parent. The current kernel code only supports
464 the 0x81 MSO form. 464 the 0x81 MSO form.
465 465
466 pubkey is the binary representation of TPM2B_P 466 pubkey is the binary representation of TPM2B_PRIVATE excluding the
467 initial TPM2B header, which can be reconstruct 467 initial TPM2B header, which can be reconstructed from the ASN.1 octet
468 string length. 468 string length.
469 469
470 privkey is the binary representation of TPM2B_ 470 privkey is the binary representation of TPM2B_PUBLIC excluding the
471 initial TPM2B header which can be reconstructe 471 initial TPM2B header which can be reconstructed from the ASN.1 octed
472 string length. 472 string length.
473 473
474 DCP Blob Format 474 DCP Blob Format
475 --------------- 475 ---------------
476 476
477 .. kernel-doc:: security/keys/trusted-keys/tru 477 .. kernel-doc:: security/keys/trusted-keys/trusted_dcp.c
478 :doc: dcp blob format 478 :doc: dcp blob format
479 479
480 .. kernel-doc:: security/keys/trusted-keys/tru 480 .. kernel-doc:: security/keys/trusted-keys/trusted_dcp.c
481 :identifiers: struct dcp_blob_fmt 481 :identifiers: struct dcp_blob_fmt
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