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Diffstat (limited to 'Documentation/keys-trusted-encrypted.txt')
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diff --git a/Documentation/keys-trusted-encrypted.txt b/Documentation/keys-trusted-encrypted.txt deleted file mode 100644 index 8fb79bc1ac4b..000000000000 --- a/Documentation/keys-trusted-encrypted.txt +++ /dev/null @@ -1,145 +0,0 @@ - Trusted and Encrypted Keys - -Trusted and Encrypted Keys are two new key types added to the existing kernel -key ring service. Both of these new types are variable length symmetic keys, -and in both cases all keys are created in the kernel, and user space sees, -stores, and loads only encrypted blobs. Trusted Keys require the availability -of a Trusted Platform Module (TPM) chip for greater security, while Encrypted -Keys can be used on any system. All user level blobs, are displayed and loaded -in hex ascii for convenience, and are integrity verified. - -Trusted Keys use a TPM both to generate and to seal the keys. Keys are sealed -under a 2048 bit RSA key in the TPM, and optionally sealed to specified PCR -(integrity measurement) values, and only unsealed by the TPM, if PCRs and blob -integrity verifications match. A loaded Trusted Key can be updated with new -(future) PCR values, so keys are easily migrated to new pcr values, such as -when the kernel and initramfs are updated. The same key can have many saved -blobs under different PCR values, so multiple boots are easily supported. - -By default, trusted keys are sealed under the SRK, which has the default -authorization value (20 zeros). This can be set at takeownership time with the -trouser's utility: "tpm_takeownership -u -z". - -Usage: - keyctl add trusted name "new keylen [options]" ring - keyctl add trusted name "load hex_blob [pcrlock=pcrnum]" ring - keyctl update key "update [options]" - keyctl print keyid - - options: - keyhandle= ascii hex value of sealing key default 0x40000000 (SRK) - keyauth= ascii hex auth for sealing key default 0x00...i - (40 ascii zeros) - blobauth= ascii hex auth for sealed data default 0x00... - (40 ascii zeros) - blobauth= ascii hex auth for sealed data default 0x00... - (40 ascii zeros) - pcrinfo= ascii hex of PCR_INFO or PCR_INFO_LONG (no default) - pcrlock= pcr number to be extended to "lock" blob - migratable= 0|1 indicating permission to reseal to new PCR values, - default 1 (resealing allowed) - -"keyctl print" returns an ascii hex copy of the sealed key, which is in standard -TPM_STORED_DATA format. The key length for new keys are always in bytes. -Trusted Keys can be 32 - 128 bytes (256 - 1024 bits), the upper limit is to fit -within the 2048 bit SRK (RSA) keylength, with all necessary structure/padding. - -Encrypted keys do not depend on a TPM, and are faster, as they use AES for -encryption/decryption. New keys are created from kernel generated random -numbers, and are encrypted/decrypted using a specified 'master' key. The -'master' key can either be a trusted-key or user-key type. The main -disadvantage of encrypted keys is that if they are not rooted in a trusted key, -they are only as secure as the user key encrypting them. The master user key -should therefore be loaded in as secure a way as possible, preferably early in -boot. - -Usage: - keyctl add encrypted name "new key-type:master-key-name keylen" ring - keyctl add encrypted name "load hex_blob" ring - keyctl update keyid "update key-type:master-key-name" - -where 'key-type' is either 'trusted' or 'user'. - -Examples of trusted and encrypted key usage: - -Create and save a trusted key named "kmk" of length 32 bytes: - - $ keyctl add trusted kmk "new 32" @u - 440502848 - - $ keyctl show - Session Keyring - -3 --alswrv 500 500 keyring: _ses - 97833714 --alswrv 500 -1 \_ keyring: _uid.500 - 440502848 --alswrv 500 500 \_ trusted: kmk - - $ keyctl print 440502848 - 0101000000000000000001005d01b7e3f4a6be5709930f3b70a743cbb42e0cc95e18e915 - 3f60da455bbf1144ad12e4f92b452f966929f6105fd29ca28e4d4d5a031d068478bacb0b - 27351119f822911b0a11ba3d3498ba6a32e50dac7f32894dd890eb9ad578e4e292c83722 - a52e56a097e6a68b3f56f7a52ece0cdccba1eb62cad7d817f6dc58898b3ac15f36026fec - d568bd4a706cb60bb37be6d8f1240661199d640b66fb0fe3b079f97f450b9ef9c22c6d5d - dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471dc6d13ecf8298b946f65345faa5ef0 - f1f8fff03ad0acb083725535636addb08d73dedb9832da198081e5deae84bfaf0409c22b - e4a8aea2b607ec96931e6f4d4fe563ba - - $ keyctl pipe 440502848 > kmk.blob - -Load a trusted key from the saved blob: - - $ keyctl add trusted kmk "load `cat kmk.blob`" @u - 268728824 - - $ keyctl print 268728824 - 0101000000000000000001005d01b7e3f4a6be5709930f3b70a743cbb42e0cc95e18e915 - 3f60da455bbf1144ad12e4f92b452f966929f6105fd29ca28e4d4d5a031d068478bacb0b - 27351119f822911b0a11ba3d3498ba6a32e50dac7f32894dd890eb9ad578e4e292c83722 - a52e56a097e6a68b3f56f7a52ece0cdccba1eb62cad7d817f6dc58898b3ac15f36026fec - d568bd4a706cb60bb37be6d8f1240661199d640b66fb0fe3b079f97f450b9ef9c22c6d5d - dd379f0facd1cd020281dfa3c70ba21a3fa6fc2471dc6d13ecf8298b946f65345faa5ef0 - f1f8fff03ad0acb083725535636addb08d73dedb9832da198081e5deae84bfaf0409c22b - e4a8aea2b607ec96931e6f4d4fe563ba - -Reseal a trusted key under new pcr values: - - $ keyctl update 268728824 "update pcrinfo=`cat pcr.blob`" - $ keyctl print 268728824 - 010100000000002c0002800093c35a09b70fff26e7a98ae786c641e678ec6ffb6b46d805 - 77c8a6377aed9d3219c6dfec4b23ffe3000001005d37d472ac8a44023fbb3d18583a4f73 - d3a076c0858f6f1dcaa39ea0f119911ff03f5406df4f7f27f41da8d7194f45c9f4e00f2e - df449f266253aa3f52e55c53de147773e00f0f9aca86c64d94c95382265968c354c5eab4 - 9638c5ae99c89de1e0997242edfb0b501744e11ff9762dfd951cffd93227cc513384e7e6 - e782c29435c7ec2edafaa2f4c1fe6e7a781b59549ff5296371b42133777dcc5b8b971610 - 94bc67ede19e43ddb9dc2baacad374a36feaf0314d700af0a65c164b7082401740e489c9 - 7ef6a24defe4846104209bf0c3eced7fa1a672ed5b125fc9d8cd88b476a658a4434644ef - df8ae9a178e9f83ba9f08d10fa47e4226b98b0702f06b3b8 - -Create and save an encrypted key "evm" using the above trusted key "kmk": - - $ keyctl add encrypted evm "new trusted:kmk 32" @u - 159771175 - - $ keyctl print 159771175 - trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b382dbbc55 - be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e024717c64 - 5972dcb82ab2dde83376d82b2e3c09ffc - - $ keyctl pipe 159771175 > evm.blob - -Load an encrypted key "evm" from saved blob: - - $ keyctl add encrypted evm "load `cat evm.blob`" @u - 831684262 - - $ keyctl print 831684262 - trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b382dbbc55 - be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e024717c64 - 5972dcb82ab2dde83376d82b2e3c09ffc - - -The initial consumer of trusted keys is EVM, which at boot time needs a high -quality symmetric key for HMAC protection of file metadata. The use of a -trusted key provides strong guarantees that the EVM key has not been -compromised by a user level problem, and when sealed to specific boot PCR -values, protects against boot and offline attacks. Other uses for trusted and -encrypted keys, such as for disk and file encryption are anticipated. |
