OpenSSL

Setup

Platform/OpenSsl/ wraps OpenSSL for TLS transport and keyed at-rest cryptography on hosted targets. It fills the Stream role with TLS and the SecurityPolicy role for at-rest integrity and confidentiality.

What a TLS stream must do is the same whichever library provides it, and is stated once under TLS obligations. This page covers what this adapter needs, how credentials reach it, and where it does not yet meet that contract.

What it ships

Header	What it is
SolidSyslogOpenSslAesGcmPolicy.h	A keyed AES-256-GCM security policy (OpenSSL reference integration) that encrypts and authenticates each stored record - confidentiality plus tamper-detection for store-and-forward.
SolidSyslogOpenSslAesGcmPolicyErrors.h	Source identity for the OpenSslAesGcmPolicy adapter; the detail codes it reports are the portable ones in SolidSyslogAesGcmPolicyErrors.h.
SolidSyslogOpenSslCredentialsDefinition.h	The OpenSSL credentials vtable (Install / Release) - where a TLS stream's trust anchors, client credential and pinned peer fingerprints come from, and the extension point an implementor fills in.
SolidSyslogOpenSslHmacSha256Policy.h	A keyed HMAC-SHA256 security policy (OpenSSL reference integration) that authenticates each stored record - tamper-detection for store-and-forward without encryption.
SolidSyslogOpenSslHmacSha256PolicyErrors.h	Source identity for the OpenSslHmacSha256Policy adapter; the detail codes it reports are the portable ones in SolidSyslogHmacSha256PolicyErrors.h.
SolidSyslogOpenSslNullCredentials.h	The no-op OpenSSL credentials Null object: installs nothing and releases nothing.
SolidSyslogOpenSslPemFileCredentials.h	An OpenSSL credentials backend that names its material by file path, and hands those paths to OpenSSL to open and parse.
SolidSyslogOpenSslPemFileCredentialsErrors.h	Source identity for the OpenSslPemFileCredentials adapter; the detail codes it reports are the portable ones in SolidSyslogTlsCredentialsErrors.h.
SolidSyslogOpenSslStream.h	TLS over an injected byte-transport Stream (OpenSSL reference integration), for a StreamSender that needs an encrypted channel.
SolidSyslogOpenSslStreamErrors.h	Source identity for the OpenSslStream adapter; the detail codes it reports are the portable ones in SolidSyslogTlsStreamErrors.h.

Requirements

OpenSSL 3.0 or later. The CMake configure fails below that rather than the build, so an older libssl is caught before anything compiles.

A SolidSyslogSleepFunction is required and has no default.

Credentials come from a credentials source

Where trust anchors, pinned peer fingerprints and the mutual-TLS client credential come from is the integrator's choice rather than this adapter's. The stream is wired to a SolidSyslogOpenSslCredentials, asked once per connection to install its material on the SSL_CTX and told once per connection when that material is no longer needed. A source backed by a hardware key store, a keyring or an encrypted store is a class implementing that role, and needs no change here.

One source ships with the pack: SolidSyslogOpenSslPemFileCredentials, which names its material by file path. It performs no file handling of its own - the paths go to OpenSSL, which opens and parses them, so PEM bytes never pass through this library. The key must not be encrypted: a passphrase is never prompted for, so an encrypted key fails to load and is reported as CLIENT_CREDENTIAL_NOT_INSTALLED.

The SSL_CTX is rebuilt on every open and freed on close, and the credentials source is asked again each time. Nothing is held between connections. Rotation is therefore a replacement and a reconnection: put the new material in place, and it is in force on the next connection, either through ordinary reconnection after an outage or immediately by moving the stream's configuration version. Nothing has to be freed to rotate the shipped source, which names a path that OpenSSL reads afresh on each connection, so the version is the whole of it.

What it reports

Every class in this pack reports portable detail codes, so a handler written against them keeps working if the crypto backend underneath changes. What stays specific to this pack is event->Source, which names the class that reported.

Each role's codes are the whole vocabulary that role can express, so some describe faults this pack cannot have and it never raises them.

From the TLS-stream codes it does not raise DEFAULTS_NOT_APPLIED, because nothing here applies a library preset, or NULL_RNG, because OpenSSL carries its own entropy source and the configuration asks for none. Nor LIBRARY_OUT_OF_MEMORY: OpenSSL's handshake raises an allocation failure as the same generic error its other crypto failures use, so this pack cannot tell one from the other and does not guess.

From the credentials codes it does not raise NULL_RNG for the same reason, nor PEM_NOT_TERMINATED, TRUST_ANCHORS_NOT_PARSED or CLIENT_CREDENTIAL_NOT_PARSED: the shipped source names a path and hands it to OpenSSL, which reads and parses the file itself, so a failure there arrives as TRUST_ANCHORS_NOT_LOADED or CLIENT_CREDENTIAL_NOT_INSTALLED rather than as a parse of its own. Nor ALREADY_IN_USE: the shipped source holds nothing between connections, so two streams may share one.

The at-rest policies raise every code their roles define.

What a connection is made with

The stream asks for a profile once per connection, and takes the expected peer name and the cipher policy from it. Nothing is stored between connections, so a change is a matter of returning something different and moving the stream's version.

Both of OpenSSL's cipher lists are selectable, because it keeps two: one governs TLS 1.2 and below, the other TLS 1.3, and since no protocol ceiling is pinned the second is usually the one in force. Leave either unset and OpenSSL's own default stands - for TLS 1.3 that is the suite RFC 8446 makes mandatory plus the two it recommends. A list OpenSSL rejects fails Open before any handshake and is reported as CIPHER_POLICY_REJECTED, rather than falling back. An empty CipherSuites is not rejected: it is OpenSSL's way of turning TLS 1.3 off.

The security level is pinned at 2 after the policy is applied, so a list carrying @SECLEVEL=n cannot lower it.

Key-exchange groups and signature algorithms are not selectable here. TLS 1.3 moved both out of the ciphersuite, so a policy naming a curve has nowhere to go yet.

Each connection is a fresh session with none supplied to resume, and the stream never writes early data, so it meets the contract's resumption and early-data obligations by construction. It refuses a request from the collector to renegotiate.

An expected identity given as an address literal is matched against the certificate's iPAddress entries only, never against a DNS name or Common Name spelling the same digits. Refusing a TLS 1.2 peer that does not acknowledge secure renegotiation is OpenSSL's own default from 3.0, which the stream relies on rather than sets.

A send first reads what the collector has sent, so that a session the collector has closed refuses the record rather than taking it, as the Stream contract requires. A write alone would not notice: OpenSSL takes the record into the session regardless of the close_notify waiting unread. When the read meets the close, or the transport beneath has gone, the send fails, the stream closes itself, and your store replays the record on the next connection. Syslog over TLS carries nothing from collector to device, so the read normally finds nothing; application data it does meet is discarded, not kept for a later read, and the probe makes at most eight reads of up to 16 bytes each, so a close behind more than that goes unnoticed.

Where it falls short of the contract

Every obligation under TLS obligations is met by this pack as shipped.