The sign operation can operate in a non-hashed mode by running the RSA
sign operation directly on the input. This assumes that the input is
less than key_size_in_bytes - 11. Since the TPM performs its own PKCS1
padding, it isn't possible to support 'raw' mode, only 'pkcs1'.
Alternatively, a hashed version is also possible. In this variant the
input is hashed (by userspace) via the selected hash function first.
Then this implementation takes care of converting the hash to ASN.1
format and the sign operation is performed on the result. This is
similar to the implementation inside crypto/rsa-pkcs1pad.c.
ASN1 templates were copied from crypto/rsa-pkcs1pad.c. There seems to
be no easy way to expose that functionality, but likely the templates
should be shared somehow.
The sign operation is implemented via TPM_Sign operation on the TPM.
It is assumed that the TPM wrapped key provided uses
TPM_SS_RSASSAPKCS1v15_DER signature scheme. This allows the TPM_Sign
operation to work on data up to key_len_in_bytes - 11 bytes long.
In theory, we could also use TPM_Unbind instead of TPM_Sign, but we would
have to manually pkcs1 pad the digest first.
Signed-off-by: Denis Kenzior <denkenz@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: James Morris <james.morris@microsoft.com>
This patch implements the verify_signature operation. The public key
portion extracted from the TPM key blob is used. The operation is
performed entirely in software using the crypto API.
Signed-off-by: Denis Kenzior <denkenz@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: James Morris <james.morris@microsoft.com>
This patch implements the pkey_decrypt operation using the private key
blob. The blob is first loaded into the TPM via tpm_loadkey2. Once the
handle is obtained, tpm_unbind operation is used to decrypt the data on
the TPM and the result is returned. The key loaded by tpm_loadkey2 is
then evicted via tpm_flushspecific operation.
This patch assumes that the SRK authorization is a well known 20-byte of
zeros and the same holds for the key authorization of the provided key.
Signed-off-by: Denis Kenzior <denkenz@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: James Morris <james.morris@microsoft.com>
This patch impelements the pkey_encrypt operation. The public key
portion extracted from the TPM key blob is used. The operation is
performed entirely in software using the crypto API.
Signed-off-by: Denis Kenzior <denkenz@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: James Morris <james.morris@microsoft.com>
This commit implements the pkey_query operation. This is accomplished
by utilizing the public key portion to obtain max encryption size
information for the operations that utilize the public key (encrypt,
verify). The private key size extracted from the TPM_Key data structure
is used to fill the information where the private key is used (decrypt,
sign).
The kernel uses a DER/BER format for public keys and does not support
setting the key via the raw binary form. To get around this a simple
DER/BER formatter is implemented which stores the DER/BER formatted key
and exponent in a temporary buffer for use by the crypto API.
The only exponent supported currently is 65537. This holds true for
other Linux TPM tools such as 'create_tpm_key' and
trousers-openssl_tpm_engine.
Signed-off-by: Denis Kenzior <denkenz@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: James Morris <james.morris@microsoft.com>
The parsed BER/DER blob obtained from user space contains a TPM_Key
structure. This structure has some information about the key as well as
the public key portion.
This patch extracts this information for future use.
Signed-off-by: Denis Kenzior <denkenz@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marcel Holtmann <marcel@holtmann.org>
Reviewed-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: James Morris <james.morris@microsoft.com>
