ssh-tpm-agent

ssh-agent for TPMs

MIT License

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Ecosystems: Go
ssh-tpm-agent - v0.6.0 Latest Release

Published by Foxboron 2 months ago

The release is signed with C100 3466 7663 4E80 C940 FB9E 9C02 FF41 9FEC BE16.

New Features

Support for SSH certificates

ssh-tpm-add will now look for cert.pub files in the working directory when adding new files to the agent. The agent has also learned how to show the certificates to the ssh client.

Support for ssh-tpm-ca-authority

ssh-tpm-ca-authority is a project to try and provision short-lived device and identity bound SSH certificates. It's currently POC quality, but ssh-tpm-add has learned how to fetch these certificates for demo purposes.

Misc fixes

  • The askpass prompt will now be the standard openssh prompt string. This is to enable caching implemented by some agents.

Bug fixes

  • askpass programs will now be looked for in the SSH_ASKPASS environment flag as intended.
  • ssh-tpm-agent would not report any errors if it failed to find an askpass binary. This has been fixed

Full Changelog: https://github.com/Foxboron/ssh-tpm-agent/compare/v0.5.0...v0.6.0

ssh-tpm-agent - v0.5.0

Published by Foxboron 4 months ago

The release is signed with C100 3466 7663 4E80 C940 FB9E 9C02 FF41 9FEC BE16.

⚠️ Breaking Changes ⚠️

With the continued development of go-tpm-keyfiles there was several issues
with the key format that ssh-tpm-keygen previously generated.

This has been corrected however supporting older keys is going to be hard. So
please recreate any keys you have made with previous releases.

Sorry for the bother, but as the keys are now properly compatible with the other
tss keys this should not happen in the future.

Changes

The pinentry usage in ssh-tpm-agent has been replaced with askpass. This
requires you to have a askpass binary installed for GUI password prompts to
display.

This also features a rework of all the prompts in ssh-tpm-keygen.

The TPM interaction in ssh-tpm-keygen has now fully moved to go-tpm-keyfiles.

https://github.com/Foxboron/go-tpm-keyfiles

Beware, dragons.

New Features

Better support for ssh-add in ssh-tpm-agent

Previously there was several stubbed functions in ssh-tpm-agent that made for
a broken support when flags like ssh-add -d was used. This has been fixed and
ssh-tpm-agent should now properly support, and with the proxy support should
forward, all ssh-agent commands properly.

Creating and importing wrapped keys

ssh-tpm-keygen has learned how to create wrapped keys. Wrapped keys are keys
that can be created remotely and can be imported by the client. The wrapped keys
are only importable by the given TPM and can't be recovered by anyone else.

The way this work is that the client shares the public key of a given TPM
hierarchy, created by tpm2_createprimary, which is shared. The remote machine
can then create a SSH key with ssh-keygen, or a key with openssl, which is
wrapped by ssh-tpm-keygen.

Creation of the shared secret under the owner hierarchy with a SRK, this needs
to be done on the client and shared with the remote machine.

$ tpm2_createprimary -C o -G ecc -g sha256 -c prim.ctx -a 'restricted|decrypt|fixedtpm|fixedparent|sensitivedataorigin|userwithauth|noda' -f pem -o srk.pem

Creation of a key on the remote end:

$ ssh-keygen -t ecdsa -b 256 -N "" -f ./ecdsa.key
# OR with openssl
$ openssl genpkey -algorithm EC -pkeyopt ec_paramgen_curve:prime256v1 -out ecdsa.key

# Wrap with ssh-tpm-keygen
$ ssh-tpm-keygen --wrap-with srk.pub --wrap ecdsa.key -f wrapped_id_ecdsa

Which can then be imported on the client side through ssh-tpm-keygen --import:

$ ssh-tpm-keygen --import ./wrapped_id_ecdsa.tpm --output id_ecdsa.tpm

A usecase for this can be for provisioning purposes in an enterprise setting
where the clients are under central control and you want to provision with a
centrally controlled SSH key that can only be used by a single machine.

Please note that establishing some sort of trust between the remote and client
is a non-trivial problem.

Initial support for key creation under a given parent handle

With the support for importing wrapped keys, ssh-tpm-keygen has gotten
--parent-handle to create ssh keys under a given TPM hierarchy.

Support for persistent handles is not fully implemented yet.

Support for ssh-tpm-keygen --print-pubkey

With the support for using wrapped and/or imported keys, ssh-tpm-keygen has
now learned a new flag --print-pubkey that will list the authorized keys
version of a given TPM key.

ssh-tpm-agent - v0.4.0

Published by Foxboron 5 months ago

The release is signed with C100 3466 7663 4E80 C940 FB9E 9C02 FF41 9FEC BE16.

New Features

Owner password support

Passing --owner-password to ssh-tpm-agent or ssh-tpm-add will query for the owner password for the SRK.

Stubbing out missing ssh-agent functions

Fixed a bug where using ssh-add with ssh-tpm-agent would fail as the proxy operations where not implemented.

What's Changed

New Contributors

Full Changelog: https://github.com/Foxboron/ssh-tpm-agent/compare/v0.3.1...v0.4.0

ssh-tpm-agent - v0.3.1

Published by Foxboron 8 months ago

Bugfix release

  • Missing go-tpm-keyfile update meant the key descriptions where not included in the keys.
  • Ensure we are always setting a minimum bitlength value for keys.
  • Ensure -f is treated as an aboslute path, and not have the ssh path appended.

What's Changed

New Contributors

Full Changelog: https://github.com/Foxboron/ssh-tpm-agent/compare/v0.3.0...v0.3.1

ssh-tpm-agent - v0.3.0

Published by Foxboron 8 months ago

The release is signed with C100 3466 7663 4E80 C940 FB9E 9C02 FF41 9FEC BE16.

⚠️ Breaking Changes ⚠️

The key format has been changed from the custom binary format to the TPM 2.0 Key
files specification. Keys from v0.1.0 and v0.2.0 are no longer supported and
ssh-tpm-agent will give you a warning when it finds such a key.

The reason for this change is that the older format was a custom binary format
that doesn't support TPM key policies and authpolicies that will be needed in
the future. The format would have to be versioned at some point so using an
established format makes more sense.

This change also creates incompatible TPM keys without a hardcoded signature
schemes. This allows us to support other hashing algorithms instead of always
relying on sha256.

This change also changes the TPM primary key from being RSA or ECDSA to
always standardizing on a NIST-P256 primary key.

For the spec:
https://www.hansenpartnership.com/draft-bottomley-tpm2-keys.html

The library for the key format:
https://github.com/Foxboron/go-tpm-keyfiles

New Features

Support for ecdsa 384 and 521 bit lengths

ECDSA p384 and p521 keys are now supported. They can be created with a the
-b switch.

λ ~ » ssh-tpm-keygen -t ecdsa -b 384
λ ~ » ssh-tpm-keygen -t ecdsa -b 521

Note that the availability of the different bit lengths depends on the TPM
available on the system. Use ssh-tpm-keygen --supported to list supported bit
lengths.

λ ~ » ssh-tpm-keygen --supported
ecdsa bit lengths: 256 384
rsa bit lengths: 2048

What's Changed

Full Changelog: https://github.com/Foxboron/ssh-tpm-agent/compare/v0.2.0...v0.3.0

ssh-tpm-agent - ssh-tpm-agent v0.2.0

Published by Foxboron about 1 year ago

The release is signed with C100 3466 7663 4E80 C940 FB9E 9C02 FF41 9FEC BE16.

New Features

Agent proxying

ssh-tpm-agent now allows ssh-agent proxying through the -A option. This allows ssh-tpm-agent to forward signing requests to other agents that supports other key types then the TPM keys. This is practical to keep one socket as a main socket while still not having to abandon non-TPM sealed keys.

Key import

ssh-tpm-keygen has gotten an --import command to allows people to import RSA2048 and ecdsa keys created by ssh-keygen.

RSA key support

ssh-tpm-agent now supports rsa2048 keys. TPMs usually do not support anything above 2048 bit strength, I recommend the ecdsa keys instead but someone might want RSA keys I guess.

Host Key support

This release implements support for TPM sealed host keys. ssh-tpm-hostkeys shows host keys and installs system global services, and configuration for sshd, to use ssh-tpm-agent as a system daemon. ssh-tpm-keygen -A creates ecdsa and RSA host keys.

What's Changed

New Contributors

Full Changelog: https://github.com/Foxboron/ssh-tpm-agent/compare/v0.1.0...v0.2.0

ssh-tpm-agent - v1.0.0-rc2

Published by Foxboron about 1 year ago

Full Changelog: https://github.com/Foxboron/ssh-tpm-agent/compare/v1.0.0-rc1...v1.0.0-rc2

ssh-tpm-agent - v1.0.0-rc1

Published by Foxboron about 1 year ago

Release candidate.

What's Changed

New Contributors

Full Changelog: https://github.com/Foxboron/ssh-tpm-agent/compare/v0.1.0...v1.0.0-rc1

ssh-tpm-agent - ssh-tpm-agent v0.1.0

Published by Foxboron about 1 year ago

This is the initial release of ssh-tpm-agent.

It provides an ssh-agent compatible agent that serves TPM sealed keys to ssh servers.

Still WIP/experimental, please do not package.

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