Support for ECDH / EC-based encryption in Vault Transit (beyond ECDSA)?

Vault
1

Hello HashiCorp community,

I’m exploring how to use elliptic curve (EC) keys not just for signing (ECDSA) but also for encryption / key agreement (ECDH-ES style encryption) within Vault. The specific use case is supporting OpenID-4 Verifiable Credential issuance, which mandates alg = ECDH-ES with enc = A128GCM (on curve P-256).

I’m aware that Vault Transit supports:

  • ECDSA keys (ecdsa-p256, ecdsa-p384, ecdsa-p521) for signing and verification.

  • RSA keys for encryption, decryption, signing, verification.

  • Symmetric AES / GCM keys for encryption/decryption.

But I haven’t found documentation or examples showing that Vault can perform EC key agreement / ECDH-ES encryption. The typical JWE flow is:

  1. Client picks ephemeral EC key (epk).

  2. Client and server derive a shared secret via ECDH.

  3. Use that shared secret (via KDF) to derive a CEK.

  4. Encrypt payload with CEK using AES-GCM.

I have a few questions:

  1. Does Vault Transit support ECDH / EC key agreement (i.e. can Vault internally perform the ECDH and wrap/unwrap CEK) as part of JWE encryption or decryption?

  2. If not currently supported, is there a roadmap or feature request to enable EC-based encryption in Transit?

  3. If partial support exists (e.g. in Enterprise or via plugin), what is the mechanism / API?

  4. Does anyone have a workaround for using EC keys for encryption with Vault — e.g. exporting private key or bridging to external crypto engine — while preserving some security guarantees?

The goal is to allow EC keys stored in Vault to be used for full JWE ECDH-ES (not just ECDSA). I’d love to hear from maintainers or users who have tried this.

Thanks in advance for any guidance!