This commit is contained in:
Nicolas Williams 2021-05-14 14:40:55 -05:00
parent 63f5e96b0f
commit ca4b14f5a2

View file

@ -52,8 +52,7 @@ TPMs have a very rich set of options for authorization. It's not just
restricted keys to allow access only to applications that also have restricted keys to allow access only to applications that also have
other access. other access.
Where to start? Let's start with hash extension, which may be the only Where to start? Let's start with hash extension.
trivial concept in the world of TPMs!
## Hash Extension ## Hash Extension
@ -282,8 +281,8 @@ the platform's, and even the platform's user(s)' identities.
## Key Wrapping ## Key Wrapping
The primary key is always a decrypt-only asymmetric private key, and its The primary key is generally a decrypt-only asymmetric private key, and
corresponding public key is therefore encrypt-only. This is largely its corresponding public key is therefore encrypt-only. This is largely
because of _key wrapping_, where a secret or private key is encrypted to because of _key wrapping_, where a secret or private key is encrypted to
a TPM's EKpub so that it can be safely sent to that TPM so that that TPM a TPM's EKpub so that it can be safely sent to that TPM so that that TPM
can then decrypt and use that secret. can then decrypt and use that secret.
@ -455,7 +454,8 @@ An unrestricted signing key can be used to sign arbitrary content.
A restricted signing key can be used to sign only TPM-generated content A restricted signing key can be used to sign only TPM-generated content
as part of specific TPM restricted signing commands. Such content as part of specific TPM restricted signing commands. Such content
always begins with a magic byte sequence. always begins with a magic byte sequence, and the TPM refuses to sign
externally generated content that starts with that magic byte sequence.
A restricted decryption key can only be used to decrypt ciphertexts A restricted decryption key can only be used to decrypt ciphertexts
whose plaintexts have a certain structure. In particular these are used whose plaintexts have a certain structure. In particular these are used