On 11/15/2013 4:24 AM, Thomas Habets wrote: > > I'm concerned with any cryptography done in software, including > generating keys that actually matter in the trust chain or for key > storage. Storing on disk is just the biggest concern. Even having them > in RAM seems wrong.
The TPM key is not generated in software. The key pair is generated on the TPM. The private key is returned encrypted. > I'm also concerned about *any* way to extract the keys from the TPM, > even for attackers that have the user or SO PIN, or even the owner > password and SRK (and the SRK needs to be well known for pkcs11, it > seems). The key is always 'extracted from the TPM' when it is created, then loaded for use by the TPM. > Yes, but encrypted with what key? Each TPM private key is encrypted by its parent, sometimes called a key encrypting key. When you go up the key hierarchy, you eventually get to the root parent, called the SRK, storage root key. The SRK is created on the TPM and never leaves the device. > So in other words: How do "migratable" keys not enable a bypass of the > whole reason for having a TPM chip in the first place? There are controls on migration. It requires the authorization password of the parent and the migration authorization password of the key. The owner password authorizes where it can be migrated. All these controls are certainly far better than just having the private key on your disk. But yes, if everyone cooperates, you could migrate the key to a software TPM and get the private key. That's the price you pay for backups. If you don't want the key to be migrated ever, create a non-migratable key. You must, however, have a plan that's better than, "If the TPM fails, my business fails." ------------------------------------------------------------------------------ DreamFactory - Open Source REST & JSON Services for HTML5 & Native Apps OAuth, Users, Roles, SQL, NoSQL, BLOB Storage and External API Access Free app hosting. Or install the open source package on any LAMP server. Sign up and see examples for AngularJS, jQuery, Sencha Touch and Native! http://pubads.g.doubleclick.net/gampad/clk?id=63469471&iu=/4140/ostg.clktrk _______________________________________________ TrouSerS-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/trousers-users
