soft_signer changelog

All notable changes are documented here. The format follows Keep a Changelog, and this project adheres to Semantic Versioning.

[Unreleased]

SoftSigner.PKCS12 and SoftSigner.PKCS8 do_sign/3 surface typed atom errors for well-known sign-side failure modes. EC key with PSS opts, missing OTP padding combos, and similar :public_key.sign/3 failures now return {:error, :incompatible_alg} instead of {:error, {:soft_sign_failed, "..."}}. Anything else still falls back to the stringified message wrapper for debugging.
Both signer moduledocs now spell out the BEAM-heap threat model. Implementation unchanged; the doc makes it explicit that the decoded RSA private key is BEAM-resident for the lifetime of any reference to the struct, and that the package boundary between :soft_signer and :pkcs11ex is the deployment-topology mitigation.

Initial release. Software-key implementations of the SignCore.Signer protocol.

SoftSigner.PKCS12 — load PKCS#12 (.p12 / .pfx) bundles via the openssl pkcs12 CLI, sign via :public_key.sign/3. Cert chain extraction (cert_chain/1) returns the leaf + intermediates leaf-first for direct use in :x5c. Friendly errors for :bundle_not_found, {:openssl, "PKCS#12 password incorrect"}, etc.
SoftSigner.PKCS8 — load PKCS#8 PEM private keys (encrypted or unencrypted) plus a separately supplied certificate (single or chain). Both file-path opts (:key_path / :cert_path) and in-memory PEM string opts (:key_pem / :cert_pem) supported. Distinguishes encrypted-without-password (:password_required) from wrong-password (:wrong_password) via the OTP-28 PEM-decode failure mode classification.
SignCore.Signer protocol implementations for both structs — RSASSA-PSS (:PS256) and RSASSA-PKCS1-v1_5 (:RS256) signature math.

Requires :sign_core ~> 0.1.
Requires openssl CLI on PATH for PKCS#12 decryption (no pure-Erlang PKCS#12 decode — the format's encryption variants are too vendor-specific to roll safely).

The boundary between pkcs11ex (hardware) and soft_signer (software) is enforced by the Hex dep tree: deployments that omit :soft_signer from their mix.lock cannot software-sign by package boundary, not just by configuration.