[lkml]   [2010]   [Nov]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    Subject[PATCH v1.3 0/4] keys: trusted and encrypted keys
    The previous posting added serveral new trusted-key options (migratable,
    pcrlock, keyhandle, keyauth, blobauth), described below, based on
    suggestions by Jason Gunthorpe. This patch requires the pcrlock option
    be executed with CAP_SYS_ADMIN privileges. By default, trusted keys
    work as previously described.

    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".

    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

    keyhandle= ascii hex value of sealing key default 0x40000000 (SRK)
    keyauth= ascii hex auth for sealing key 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)

    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

    keyctl add encrypted name "new master-key-name keylen" ring
    keyctl add encrypted name "load master-key-name keylen hex_blob" ring
    keyctl update keyid "update master-key-name"

    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.

    Mimi Zohar
    David Safford

    Mimi Zohar (4):
    lib: hex2bin converts ascii hexadecimal string to binary
    key: add tpm_send command
    keys: add new trusted key-type
    keys: add new key-type encrypted

    drivers/char/tpm/tpm.c | 17 +
    include/keys/encrypted-type.h | 30 +
    include/keys/trusted-type.h | 32 ++
    include/linux/kernel.h | 1 +
    include/linux/tpm.h | 3 +
    lib/hexdump.c | 16 +
    security/Kconfig | 31 +
    security/keys/Makefile | 2 +
    security/keys/encrypted_defined.c | 816 +++++++++++++++++++++++++++
    security/keys/encrypted_defined.h | 52 ++
    security/keys/trusted_defined.c | 1101 +++++++++++++++++++++++++++++++++++++
    security/keys/trusted_defined.h | 147 +++++
    12 files changed, 2248 insertions(+), 0 deletions(-)
    create mode 100644 include/keys/encrypted-type.h
    create mode 100644 include/keys/trusted-type.h
    create mode 100644 security/keys/encrypted_defined.c
    create mode 100644 security/keys/encrypted_defined.h
    create mode 100644 security/keys/trusted_defined.c
    create mode 100644 security/keys/trusted_defined.h


     \ /
      Last update: 2010-11-10 16:55    [W:0.047 / U:7.928 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site