JOSEVirtualHSM

Virtual JOSE HSM for signing JWSes and decrypting JWEs

Installation

def deps do
  [
    {:jose_virtual_hsm, "~> 0.2.0"}
  ]
end

Description

It is a virtual HSM in the sense that keys private keys for signing and decrypting are not available to other processes, and are particularly protected against leaking:

there are stored in a private ETS
processes dealing with these keys are marked as sensitive
keys loaded from the disk or the environment can be deleted after loading (ideal for container deployment)

Other features include:

keys can be generated automatically given a specification, so that there no secret to handle during deployment
it is automatically clusterized: any node can sign a JWS or decrypt a JWE with any key in the cluster. Nodes don't share keys (they can't) but can work with each other in a transparent fashion
key ID is automatically generated using RFC7638 - JSON Web Key (JWK) Thumbprint
- however, note that due to a limitation in the underlying JOSE library, JWSes do not include the kid in their header

Launching `JOSEVirtualHSM`

JOSEVirtualHSM is a GenServer that must be launched in a supervised manner at application startup. In your app/application.ex file, add:

children = [
  JOSEVirtualHSM
]

children = [
  {JOSEVirtualHSM, opts...}
]

where opts is a Keyword to the list of children.

Options

:delete_on_load: when loading a private key from a file or the environment, this options, when set to true, deletes the key after loading. Defaults to true
:keys: the list of keys to load. See t:key_load_specs/0 for the different methods to load keys

Environment options

The key specification can also be retrieved from the environment options:

config/config.exs:

config :jose_virtual_hsm, :keys, [
  {:auto_gen, {:ec, "P-256"}, %{"use" => "sig"}},
  {:auto_gen, {:rsa, 2048}, %{"use" => "sig"}},
  {:auto_gen, {:okp, :Ed25519}, %{"use" => "sig"}},
  {:auto_gen, {:ec, "P-256"}, %{"use" => "enc"}},
  {:auto_gen, {:rsa, 2048}, %{"use" => "enc"}},
  {:auto_gen, {:okp, :X25519}, %{"use" => "enc"}}
]

This key specification is used i nthe following examples.

Example

Retrieving public keys

iex> JOSEVirtualHSM.public_keys()
[
  %{
    "crv" => "X25519",
    "kid" => "NqYw6_wlorTvDqae3HaI79i_k_Q61l0jESQNvgT0Ku4",
    "kty" => "OKP",
    "use" => "enc",
    "x" => "lY2nopV03NTsSqCVgfyr_VNjTBkUhGHcHjIHJNrlaKQ"
  },
  %{
    "crv" => "Ed25519",
    "kid" => "Hq3_i8UWJ1FqokUqTQRDLw4GvvBQCKiMjSoQ4Ng6CY0",
    "kty" => "OKP",
    "use" => "sig",
    "x" => "XxHceRoVym7hsb5W-T2RqTzgoz_DEmCZKHBjy6MWsZA"
  },
  %{
    "e" => "AQAB",
    "kid" => "5A5Z3JxpYNO4pqbfC4wSFUk2cpkcAxwZsH0yev3zXpk",
    "kty" => "RSA",
    "n" => "7Rwb2l4ORycxCPAMK2B_p1FqKqrBpmcjklqazucAiJtNPtY2n-yEziD05-urwutIN2-wfaKIGg51-8KIQN5x_PTXUxje2oK3GOHHWaSWGpd1kJVEe-owSKGQxoga5rQDTk4j3MMA0brbgoJM2v32lKiv5CgV6E-wgCXb8QlrvIpwhnIN9CPEHuxo9Izpw8WqIj4d8Uu7LohxUM0eFfBkdbmgt5xL4Xm5MV6eDRhYq9agRLGNbBIHK2T5Xyq6-YB5URtWCeizA8hongk6nZAzy19wvz88pj4CsBy73UuP0jdT-wlGGvTpGx9AEFLv1p_RXzVgfZMGn2z3Q8Mhf0mxVQ",
    "use" => "sig"
  },
  %{
    "e" => "AQAB",
    "kid" => "szhiyrpeKBtQOr6cSEj3TbJ87vqvvGuk3Is6cPBYNm0",
    "kty" => "RSA",
    "n" => "5GX4GERxJ2rV-w5T2G00D3-HLEriXjriL-w7TkCB9H8zhiljHH0SxmbxBMT5HksJMWQyiDZEKp6ilrZCjsvOAJCpvh0SrPnIRzu95Wt1VlGOlp0C2BnL0wuPnkrUHbGZAzE-ux4ISpw9LqTi6KlL1dWQei6-_ihs0E37iTpFJy2EbEVXG6ydsH0FnoJv0_dgf3P4Yy8kIoNx5f4czLSWhK-psoPVKxxAN3mlY7iRGQHxOdgEyrsANj8uSQehzO87T5IVmMDtoBBx6PUn9awDW5emoU_mfXy3hlR3S67pjbjfNA5A3QZBs39-hCU92EtA7CS0IQ_rvvAfvlLV3T-tjQ",
    "use" => "enc"
  },
  %{
    "crv" => "P-256",
    "kid" => "ltu_BZFFssJhqlTdKvf3VWu7z9dFKhwFxXSx8Q-bpw4",
    "kty" => "EC",
    "use" => "enc",
    "x" => "jopq4PgS4w9721MwJppxw7niV-1zqgtBd-JeVWPuBcU",
    "y" => "Eo1xbm0g5AsB8GSiXKHRynXH2OwRcMO9i-6PTi-k-GE"
  },
  %{
    "crv" => "P-256",
    "kid" => "SiuAFPXstUhUzhmc__1mybX1ZJcJ6F2llEeb-LaAjIo",
    "kty" => "EC",
    "use" => "sig",
    "x" => "2PXy4aIbWUHzkRksSITO1ws9Y1AI14fBAtsvr1UDwXQ",
    "y" => "hPtgSkKH6DXzh18Ym_jh9bzcJir5mKp_skj9oKI5ydA"
  }
]

These public keys can obviously be shared with third parties. They can be used:

to verify signature of a JWS signed by JOSEVirtualHSM
to encrypt a JWE to be sent to the server using JOSEVirtualHSM

JOSEVirtualHSM doesn't support JWS verification and JWE encryption. For that, use JOSE or JOSEUtils instead.

Signing:

iex> JOSEVirtualHSM.sign(%{"hello" => "world"})
{:ok,
 {"eyJhbGciOiJSUzI1NiJ9.eyJoZWxsbyI6IndvcmxkIn0.nFP2GBJdsKzgUMR7g55pMmtNckXB9F9C83jhfAW0qOake7AmpZb3eLZhGi3OrTB7CRI2x9MHtA1qQMdOY0u8R_VovYfv5fGLVRJLe8uICGIq1NojO_66lMMoxmtMxIhVcX1FZfWR9Z_Ez4KGVm4eJvTuO33ds115Ik8Vh3aGFBorW74rYqjYZPgEHyjO4RqbzexBodq-z5rGOqAvFgz9C6X_xkMwiI6mNI4XIQ-5jzLPKMP5t94QwJGZ4EEc9QyFbNqmh2OlUaY0NTthP6MAzler7K5oz2S_6mQvt6K4Fmk1C-HIR3nad_s_z-PLvj6tEJnmIiEcFHTxfRcceUQ_QA",
  %{
    "e" => "AQAB",
    "kid" => "5A5Z3JxpYNO4pqbfC4wSFUk2cpkcAxwZsH0yev3zXpk",
    "kty" => "RSA",
    "n" => "7Rwb2l4ORycxCPAMK2B_p1FqKqrBpmcjklqazucAiJtNPtY2n-yEziD05-urwutIN2-wfaKIGg51-8KIQN5x_PTXUxje2oK3GOHHWaSWGpd1kJVEe-owSKGQxoga5rQDTk4j3MMA0brbgoJM2v32lKiv5CgV6E-wgCXb8QlrvIpwhnIN9CPEHuxo9Izpw8WqIj4d8Uu7LohxUM0eFfBkdbmgt5xL4Xm5MV6eDRhYq9agRLGNbBIHK2T5Xyq6-YB5URtWCeizA8hongk6nZAzy19wvz88pj4CsBy73UuP0jdT-wlGGvTpGx9AEFLv1p_RXzVgfZMGn2z3Q8Mhf0mxVQ",
    "use" => "sig"
  }}}
iex> JOSEVirtualHSM.sign(%{"hello" => "world"})
{:ok,
 {"eyJhbGciOiJFZERTQSJ9.eyJoZWxsbyI6IndvcmxkIn0.WVRgyl4Pen0nieJF7cmGXQnkOocP4B6i78VgkKxcu_-gADSIM5Cg_mL2T-cU1ZY1ib91bQnHALdNoXqVSi66DQ",
  %{
    "crv" => "Ed25519",
    "kid" => "Hq3_i8UWJ1FqokUqTQRDLw4GvvBQCKiMjSoQ4Ng6CY0",
    "kty" => "OKP",
    "use" => "sig",
    "x" => "XxHceRoVym7hsb5W-T2RqTzgoz_DEmCZKHBjy6MWsZA"
  }}}
iex> JOSEVirtualHSM.sign(%{"hello" => "world"})
{:ok,
 {"eyJhbGciOiJFZERTQSJ9.eyJoZWxsbyI6IndvcmxkIn0.WVRgyl4Pen0nieJF7cmGXQnkOocP4B6i78VgkKxcu_-gADSIM5Cg_mL2T-cU1ZY1ib91bQnHALdNoXqVSi66DQ",
  %{
    "crv" => "Ed25519",
    "kid" => "Hq3_i8UWJ1FqokUqTQRDLw4GvvBQCKiMjSoQ4Ng6CY0",
    "kty" => "OKP",
    "use" => "sig",
    "x" => "XxHceRoVym7hsb5W-T2RqTzgoz_DEmCZKHBjy6MWsZA"
  }}}
iex> JOSEVirtualHSM.sign(%{"hello" => "world"})
{:ok,
 {"eyJhbGciOiJFUzI1NiJ9.eyJoZWxsbyI6IndvcmxkIn0.1viHUsVOseF1eJ0nZAOXbo0RfHGP5H1U8lfV9qLijf4EnDbaPI7NkRdFQIHvbYVTYakm0dHdF2YPlNfKOrGMbg",
  %{
    "crv" => "P-256",
    "kid" => "SiuAFPXstUhUzhmc__1mybX1ZJcJ6F2llEeb-LaAjIo",
    "kty" => "EC",
    "use" => "sig",
    "x" => "2PXy4aIbWUHzkRksSITO1ws9Y1AI14fBAtsvr1UDwXQ",
    "y" => "hPtgSkKH6DXzh18Ym_jh9bzcJir5mKp_skj9oKI5ydA"
  }}}

Notice how keys where chosen randomly from all the available keys. JOSEVirtualHSM always prefers keys on local node, when available. It's possible to specify how to sign using t:JOSEUtils.JWK.key_selector/0:

iex> JOSEVirtualHSM.sign(%{"hello" => "world"}, alg: ["ES256", "ES384", "ES512"])
{:ok,
 {"eyJhbGciOiJFUzI1NiJ9.eyJoZWxsbyI6IndvcmxkIn0.ooZ8pRuhp20K8s7k0xkNGCb47nE8sW_JrjHtsb_w5PEFFGR1F7wysJGfg2tTU7kT0QzQQEeWUg0FJgkqsowbTw",
  %{
    "crv" => "P-256",
    "kid" => "SiuAFPXstUhUzhmc__1mybX1ZJcJ6F2llEeb-LaAjIo",
    "kty" => "EC",
    "use" => "sig",
    "x" => "2PXy4aIbWUHzkRksSITO1ws9Y1AI14fBAtsvr1UDwXQ",
    "y" => "hPtgSkKH6DXzh18Ym_jh9bzcJir5mKp_skj9oKI5ydA"
  }}}
iex> JOSEVirtualHSM.sign(%{"hello" => "world"}, kty: "OKP")
{:ok,
 {"eyJhbGciOiJFZERTQSJ9.eyJoZWxsbyI6IndvcmxkIn0.WVRgyl4Pen0nieJF7cmGXQnkOocP4B6i78VgkKxcu_-gADSIM5Cg_mL2T-cU1ZY1ib91bQnHALdNoXqVSi66DQ",
  %{
    "crv" => "Ed25519",
    "kid" => "Hq3_i8UWJ1FqokUqTQRDLw4GvvBQCKiMjSoQ4Ng6CY0",
    "kty" => "OKP",
    "use" => "sig",
    "x" => "XxHceRoVym7hsb5W-T2RqTzgoz_DEmCZKHBjy6MWsZA"
  }}}

Decryption

With RSA:

iex> jwk_pub = JOSEVirtualHSM.public_keys() |> Enum.find(&(&1["kty"] == "RSA" and &1["use"] == "enc"))
%{
  "e" => "AQAB",
  "kid" => "szhiyrpeKBtQOr6cSEj3TbJ87vqvvGuk3Is6cPBYNm0",
  "kty" => "RSA",
  "n" => "5GX4GERxJ2rV-w5T2G00D3-HLEriXjriL-w7TkCB9H8zhiljHH0SxmbxBMT5HksJMWQyiDZEKp6ilrZCjsvOAJCpvh0SrPnIRzu95Wt1VlGOlp0C2BnL0wuPnkrUHbGZAzE-ux4ISpw9LqTi6KlL1dWQei6-_ihs0E37iTpFJy2EbEVXG6ydsH0FnoJv0_dgf3P4Yy8kIoNx5f4czLSWhK-psoPVKxxAN3mlY7iRGQHxOdgEyrsANj8uSQehzO87T5IVmMDtoBBx6PUn9awDW5emoU_mfXy3hlR3S67pjbjfNA5A3QZBs39-hCU92EtA7CS0IQ_rvvAfvlLV3T-tjQ",
  "use" => "enc"
}
iex> jwe = JOSEUtils.JWE.encrypt!(%{"very" => "secret"}, jwk_pub, "RSA-OAEP", "A128GCM")
"eyJhbGciOiJSU0EtT0FFUCIsImVuYyI6IkExMjhHQ00ifQ.0odG-8i5DL-SB1h4_DeGbavEZhACbVKqvnz2MCoSUyCW84U7ejqn2HqLh8Te03_yIlR9jC8raJ4OI75fbsK9bKrSf_RubJIYjVto0GaBIJzREujjS2fVACe5UUPQ9lVkYplXiT-wqm3wvtX9GkaBz4FL-fmftgtdW9zdYC9U2D_AfFG5hhO4BnAUaI7x1wDdnVMCPjbg5B21x6IPGSma0H6YgCyBf26BRIuNNRbaly89CAam3oqzTn3t0UrDb-Hrx8jEC4a9RxmL44RIdFVAjijcWLjorSd8qq8qGrDa7gpcFEGAYrX7U5XDawjyJnWzWD1g-LDn6H0IbAn5LEorEA.rTMjuaYevaacZbzt.6t7IpuvqFe2nt94httLzpjk.Cc5UcgwZBhkuUFsDeKpQBA"
iex> JOSEVirtualHSM.decrypt(jwe)
{:ok,
 {"{\\"very\\":\\"secret\\"}",
  %{
    "e" => "AQAB",
    "kid" => "szhiyrpeKBtQOr6cSEj3TbJ87vqvvGuk3Is6cPBYNm0",
    "kty" => "RSA",
    "n" => "5GX4GERxJ2rV-w5T2G00D3-HLEriXjriL-w7TkCB9H8zhiljHH0SxmbxBMT5HksJMWQyiDZEKp6ilrZCjsvOAJCpvh0SrPnIRzu95Wt1VlGOlp0C2BnL0wuPnkrUHbGZAzE-ux4ISpw9LqTi6KlL1dWQei6-_ihs0E37iTpFJy2EbEVXG6ydsH0FnoJv0_dgf3P4Yy8kIoNx5f4czLSWhK-psoPVKxxAN3mlY7iRGQHxOdgEyrsANj8uSQehzO87T5IVmMDtoBBx6PUn9awDW5emoU_mfXy3hlR3S67pjbjfNA5A3QZBs39-hCU92EtA7CS0IQ_rvvAfvlLV3T-tjQ",
    "use" => "enc"
  }}}

With ECDH-ES:

iex> jwk_pub = JOSEVirtualHSM.public_keys() |> Enum.find(&(&1["kty"] == "EC" and &1["use"] == "enc"))
%{
  "crv" => "P-256",
  "kid" => "ltu_BZFFssJhqlTdKvf3VWu7z9dFKhwFxXSx8Q-bpw4",
  "kty" => "EC",
  "use" => "enc",
  "x" => "jopq4PgS4w9721MwJppxw7niV-1zqgtBd-JeVWPuBcU",
  "y" => "Eo1xbm0g5AsB8GSiXKHRynXH2OwRcMO9i-6PTi-k-GE"
}
iex> my_jwk_priv = JOSE.JWK.generate_key({:ec, "P-256"}) |> JOSE.JWK.to_map() |> elem(1)
%{
  "crv" => "P-256",
  "d" => "TsfNgJq_UEWdf0rqp2W5OQJQMbtANMMWwguNO4VrZkM",
  "kty" => "EC",
  "x" => "UIZ5br7q2li5NzcZePOiK4Wi3jV4xATVT4Yie8xMRT8",
  "y" => "eiLF2EUWFbPX2MTchz_h-VbiEjnJ9koB-6kVqWF3kBo"
}
iex> jwe = JOSEUtils.JWE.encrypt!(%{"very" => "secret"}, {jwk_pub, my_jwk_priv}, "ECDH-ES", "A128GCM")
"eyJhbGciOiJFQ0RILUVTIiwiZW5jIjoiQTEyOEdDTSIsImVwayI6eyJjcnYiOiJQLTI1NiIsImt0eSI6IkVDIiwieCI6IlVJWjVicjdxMmxpNU56Y1plUE9pSzRXaTNqVjR4QVRWVDRZaWU4eE1SVDgiLCJ5IjoiZWlMRjJFVVdGYlBYMk1UY2h6X2gtVmJpRWpuSjlrb0ItNmtWcVdGM2tCbyJ9fQ..16AhXI2qu9cw7A6e.dG_TaBdpAJHgR962LxThdWo.uBtZ3N55sztIRgCFwzC5hw"
iex> JOSEVirtualHSM.decrypt(jwe)
{:ok,
 {"{\\"very\\":\\"secret\\"}",
  %{
    "crv" => "P-256",
    "kid" => "ltu_BZFFssJhqlTdKvf3VWu7z9dFKhwFxXSx8Q-bpw4",
    "kty" => "EC",
    "use" => "enc",
    "x" => "jopq4PgS4w9721MwJppxw7niV-1zqgtBd-JeVWPuBcU",
    "y" => "Eo1xbm0g5AsB8GSiXKHRynXH2OwRcMO9i-6PTi-k-GE"
  }}}

Clustering

The JOSEVirtualHSM of the current node listens to other JOSEVirtualHSM on joining and leaving of other nodes, and registers their public keys and deletes them when needed.

This is based on BEAM distribution. Other distribution methods (such as using Redis as an intermediary) are not supported.

Architecture

Each node runs its own instance of JOSEVirtualHSM, which is a GenServer. This GenServer has the following roles:

on startup, it loads the keys from the key specification
it stores local private keys in a private ETS
it listens for joining and leaving nodes to gain knowledge of available keys

When an operation is requested for a local key, the local instance of JOSEVirtualHSM launches a worker process and sends it the required private keys to perform the signing or decryption operation. This process is in charge of:

performing the signing or decryption operation
answer to the original process

The JOSEVirtualHSM instance keeps track of the launched process and responds with an error to the calling process if the worker process died in an abnormal manner.

The number of worker processes is not limited. No queueing or pooling method is implemented. As a consequence, a server could become unresponsive and overwhelmed should too many signing or decryption requests arrive at the same time. Any PR implementing it is welcome :)