Revision history for Mail::DKIM2

0.20    2026-10-14
        DKIM2 for stock Mailman, with dkim2-milter and Postfix routing only.
        - New: dkim2-milter --wrap-single-part (inbound mode, needs
          --snapshot-dir). A single-part post is wrapped as a one-part
          multipart/mixed (its Content-* fields and body unchanged), the
          wrap recorded as its own unsigned Message-Instance, and the
          wrapped message kept as the snapshot the outbound milter diffs
          against. Stock Mailman then adds its footer as an extra part
          rather than re-encoding the body. See
          docs/dkim2-postfix-stock-mailman-guide.md in the interop repository.
        - New: Mail::DKIM2::Wrap (wrap_single_part).
        - Behaviour change: dkim2-milter in outbound mode adds no
          Message-Instance to mail it does not sign (no key for the sender,
          a refused chain, a signer failure), and removes every
          Message-Instance no DKIM2-Signature covers -- instances hops on
          this host added for a signature that is not going to be made --
          recording it as X-DKIM2-Info: action=removed-unsigned-mi=...;.
          It used to add an unsigned Message-Instance and leave the others,
          which receivers report as permerror ("m=N is not signed"). An
          unsigned post now leaves with no DKIM2 at all, and a signed one
          fails honestly against the sender's signature. DKIM2Sign does the
          same on a refusal, a domain with no signing configuration, or a
          Signer failure.
        - Fix: dkim2-milter in outbound mode computes its own
          Message-Instance (the diff against the snapshot) before checking
          the upstream chain, and checks the message as it will be signed.
          It used to check first, so a list manager that changed a message
          without recording an instance of its own -- every list copy
          whose changes only the snapshot diff records -- was refused.
        - Security fix: dkim2-milter no longer finds snapshots by
          Message-Instance value. A post that replayed a sender's genuine
          m=1 over an edited body found the genuine post's snapshot, and
          the edit was recorded and signed as this host's own change. The
          inbound milter now snapshots only a message it stamps m=1 or
          whose top instance matches the content, stores the snapshot under
          a random token and names it in a new X-DKIM2-Snapshot header; the
          outbound milter diffs only against the snapshot that token names.
          Every mode strips X-DKIM2-Snapshot from the mail it sees, so a
          token neither comes from outside nor leaves the host. The inbound
          and outbound milters must share --snapshot-dir (as before) and be
          upgraded together. The authentication_milter handlers do the same:
          DKIM2Verify names its snapshot in X-DKIM2-Snapshot (and removes
          any that arrives), DKIM2Sign finds it only through that token, and
          both must be upgraded together.
        - Behaviour change: since the outbound milter's own diff instance is
          now gated as an unsigned instance, a diff that falls back to a null
          body Recipe is signed only with --allow-null-body-recipe.
        - Fix: dkim2-milter registers SMFIF_CHGHDRS, so removing a broken
          intermediate Message-Instance (which calls chgheader) no longer
          dies in Sendmail::PMilter. The removals now go out before the new
          Message-Instance is inserted, so an MTA that counts inserted
          fields in a header index still removes the right one.

0.19    2026-10-09
        Fixes from a follow-up review of 0.18. Malformed fields that used to
        verify are now errors; well-formed mail verifies as before, and
        signatures fold where they did, except as below.
        - Behaviour change: a DKIM2-Signature or Message-Instance must parse
          as a whole tag list (spec-06 sections 7, 8, 11.2). A fragment that
          is not name=value ("junk", "9bad=foo"), or a value with a byte
          outside printable ASCII or a ";", is PERMERROR "syntax error"; it
          used to be dropped and the rest verified. Well-formed unknown tags
          are still ignored and still signed.
          Mail::DKIM2::TagValueList gains split_tag_list() and syntax_error().
        - Behaviour change: whitespace inside an s= selector or algorithm, or
          an h= hash name, is a syntax error. "rsa- sha256" used to be read
          as rsa-sha256. FWS around the item's colons and commas and inside
          base64 is still accepted. An h= hash-set missing a digest is a
          syntax error rather than skipped; parse_hash_sets() returns undef
          for a malformed value.
        - Behaviour change: every value in a key record, unknown tags'
          included, must fit the tag-list grammar; a NUL, DEL or 8-bit byte
          makes the record a syntax error.
        - Fix: the signer split a long d= domain (two 40-character labels)
          across lines, and the verifier then failed the MAIL FROM/d= match.
          fold_header() now folds a DKIM2 field only where its grammar allows
          FWS -- base64 interiors, beside s= and h= item colons, list commas
          other than in s= -- leaving an unbreakable token whole on a longer
          line, and croaks rather than emit a line over 998 characters.
        - Fix: header recipe generation was quadratic in repeated identical
          fields (16,000 took ~3s); it is linear, with identical recipes.
        - Fix: load() rethrows a host's exception object from the input's
          can() instead of replacing it with a "cannot read" croak.
        - Docs: Signature.pm comments describe the empty s= value and
          spec-06 9.6's WSP deletion.

0.18    2026-10-09
        Fixes from an external review against spec-06. Several are
        behaviour changes for messages that are malformed or adversarial;
        well-formed mail verifies as before.
        - Behaviour change: only the signature algorithms rsa-sha256 and
          ed25519-sha256, matched exactly, are verified. An s= item naming
          anything else is ignored before its key is fetched (spec-06 §3.4);
          it used to be fetched and verified as RSA, so a correctly
          RSA-signed item declaring an unknown algorithm passed, and many
          distinct unknown names meant as many sequential DNS lookups. s= is
          parsed once, not once per item accessed. A signature whose items
          all name unknown algorithms is FAIL "has no signature with a
          supported algorithm"; a known item whose value is not a padded
          base64string is PERMERROR "syntax error"; a key of the wrong type
          for the algorithm is PERMERROR "algorithm mismatch".
        - Behaviour change: key records are validated whole
          (Mail::DKIM2::Common::parse_dkim_key_record, new): a repeated tag,
          v= not first or not exactly DKIM1, a missing, unpadded or
          non-base64 p=, or a p= that is not a key make the record a syntax
          error; an empty p= is revoked; k= other than rsa or ed25519 is no
          longer read as RSA. More than one TXT record for a selector is an
          error (one record in several strings is joined). The verifier
          reports these as spec-06 §11.5's PERMERRORs naming the selector, and
          a key absent for every item as PERMERROR "public key <sel> does not
          exist". parse_dkim_pubkey keeps its key-or-undef contract.
        - Behaviour change: Message-Instance tag names are case insignificant
          (spec-06 §7): M= and H= are read as m= and h= everywhere, and a tag
          repeated in any case is PERMERROR "syntax error" -- a wrong h= ahead
          of the right one used to be overwritten and pass.
        - Behaviour change: t= must be 1*DIGIT; anything else is PERMERROR
          "syntax error", even with SkipTimestampCheck, and t=0 is subject to
          the age check.
        - Behaviour change: a failed signature item reads "DKIM2-Signature
          i=N <selector> incorrect signature" (spec-06 §11.6).
        - Body Recipes come from a built-in capped Myers diff, the same
          algorithm as this repository's C, Python, Go and Mailman
          generators (vectors/body-diff.json); Algorithm::Diff is no longer a
          prerequisite. Repeated-line bodies no longer take quadratic time.
          A Recipe carries at most MaxRecipeLiterals literal lines (new
          calculate option, default 1000); over that the default path gives
          the null body Recipe, and EpilogueThreshold (no longer capped) the
          epilogue. dkim2-milter --max-recipe-literals and the DKIM2Sign
          handler's max_recipe_literals set it. An unchanged body under
          EpilogueThreshold gets no Recipe instead of an epilogue copy.
        - Behaviour change: every public constructor and class method that
          takes named options croaks on one it does not know, as the
          CONVENTIONS always said (Signature->new, MessageInstance
          calculate/verify/undo/chain_verifies, Gate->check, DSN
          generate/authenticate/propagate, MessageStore->new,
          Validate::report, fold_header).
        - Mail::DKIM2::DSN: authenticate and propagate take keys from DNS
          through Resolver when no PubkeyCallback is given, as documented;
          propagate croaks unless ForwarderDomain is the d= of the hop it
          strips; the POD says what ok means for an unsigned DSN.
        - Every eval in the library, Validate, Reflector and Split included,
          rethrows a host's exception object.
        - TagValueList/Signature parse() always returns a new object.
        - The README and Mail::DKIM2 SYNOPSIS sign and verify correctly, and
          t/synopsis.t runs them.

0.17    2026-10-08
        - Mail::DKIM2::Gate: when the Gate runs the Verifier itself and it
          passes, the Verifier has already walked the whole Message-Instance
          chain, so the Gate no longer walks it a second time. It still does
          when there are no signatures, when the caller supplied VerifyResult,
          or when the Verifier did not pass.
        - The Gate's null-body refusal now names the library option
          (AllowNullBodyRecipe), not the CLI flag. dkim2sign and dkim2-milter
          still show --allow-null-body-recipe, and the authentication_milter
          DKIM2Sign handler shows allow_null_body_recipe.
        - authentication_milter DKIM2Verify: for a message that already has
          Message-Instance headers, skip the MessageInstance verify that only
          picked the snapshot key when snapshot_directory is not set.

0.16    2026-10-08
        - Mail::DKIM2::Gate's null body rule: a DKIM2-Signature with m=k
          covers Message-Instances 1..k, so without AllowNullBodyRecipe the
          gate refuses when any instance with a null body Recipe has m=
          above the highest m= of the valid upstream signatures -- the top,
          or one with another unsigned instance added over it: a null this
          hop is the first to sign. A null an upstream domain already
          declared and signed (a list post forwarded unchanged) is extended
          without the option; the upstream chain must still verify and the
          header history below the null must still check out. In 0.15 any
          null top was refused, signed or not, and a null under an unsigned
          top was never looked at (so the DKIM2Sign handler, recomputing
          its own instance over a snapshot keyed by the null one, signed it
          without the option). The refusal reads "unsigned top
          Message-Instance m=N has a null body Recipe", or "unsigned
          Message-Instance m=N ..." when it is not the top. The result gains
          top_signed, covered_m and unsigned_null. bin/dkim2sign,
          bin/dkim2-milter and the DKIM2Sign handler follow the Gate and add
          the informational X-DKIM2-Info action=null-body-recipe when they
          sign over either kind of null. (t/gate-null-top.t,
          t/milter-sign-gate.t, t/sign-cli.t, t/milter-script.t;
          signer-gate fixtures null-top-signed, null-below-unsigned-top,
          null-below-signed)
        - Behaviour change: Mail::DKIM2::Verifier reports a DKIM2-Signature
          it cannot key -- no i=, an i= that is not a positive integer
          (i=, i=0, i=abc, i=-1), or one that does not parse -- as
          permerror, "PERMERROR DKIM2-Signature has a missing or malformed
          i= tag", as the Python, Go, C and JS verifiers now all do. It used
          to ignore such a field and verify the rest, so a junk
          "DKIM2-Signature: m=2" prepended to a valid chain passed -- and
          the Gate, counting coverage by m=, took it as signing an unsigned
          null top. Mail::DKIM2::Signer likewise refuses to sign over such
          a field (result fail with the same message), and only a signature
          with a valid i= counts towards the Gate's coverage.
          (t/verifier-unkeyable.t, t/gate-null-top.t)
        - Behaviour change: every DKIM2-Signature i= and m=, and every
          Message-Instance m=, must be a chain number: 1*DIGIT in ASCII
          (else "PERMERROR <field> has a malformed <tag>= tag", or the
          unkeyable message above for i=), at most three digits naming
          1..MAX_CHAIN_NUMBER (100) (else "PERMERROR <field> <tag>= exceeds
          the maximum chain number of 100"), and no more than
          MAX_CHAIN_LENGTH (32) (else "... exceeds the maximum chain length
          of 32"). "01" and "001" are 1, in all five verifiers and four
          signers. Found while the header fields are read, before any gap
          check: i=99999999999999999999 used to kill the Verifier ("Range
          iterator outside integer range"), and m=4294967297x was read as
          its digit prefix. The Signer refuses to sign over such a field.
          Common exports chain_number_error(), MAX_CHAIN_NUMBER and
          mi_version_tag() (the raw m= value, from any position in the
          field); extract_mi_version() is now numeric and returns undef
          unless the whole m= is ASCII digits. (t/chain-number-bound.t)
        - The Verifier keyed Message-Instances by the m= string, so an
          instance written m=01 read as "missing Message-Instance m=1" in
          Perl alone; instances and the donotmodify check are keyed by
          number now. (t/chain-number-bound.t)
        - A duplicate key anywhere in a Recipe's JSON (at the top level or
          inside "h") is invalid JSON: "PERMERROR Message-Instance m=N
          contains invalid JSON". Parsers disagree on which value wins (C's
          kept the first, the others the last), so {"b":[...],"b":null} was
          a real body Recipe to some verifiers and gates and a null one to
          others. Common::decode_tag_json refuses it, so the Verifier, the
          Gate and the signers all do. (t/invalid-json.t; negative vectors
          recipe-duplicate-*, signer-gate fixture recipe-duplicate-key)
        - bin/dkim2-milter fails closed. Outbound, an exception in the Gate,
          in computing the Message-Instance or in the Signer is logged and
          the message goes on unsigned. Inbound, a Verifier exception gives
          dkim2=temperror in Authentication-Results (never pass), and an
          exception computing the Message-Instance is logged and adds no
          Message-Instance; the message goes on with its
          Authentication-Results. An out-of-range Message-Instance m= is
          never used as a bound when stripping instances above a snapshot
          (m=99999999999999999999 died there, m=4294967297 ran out of
          memory). A Signer that declines is logged too. (t/milter-script.t)
        - The DKIM2Sign handler (authentication_milter) follows the Gate, on
          the message as it would sign it (its own Message-Instance
          included), replacing its own chain_verifies() check. New config
          allow_null_body_recipe (default 0) is the milter's
          --allow-null-body-recipe. A refusal signs nothing and adds or
          strips no Message-Instance; it is logged, counted in
          dkim2_sign_total by reason, and (broken-mi-chain,
          null-body-recipe) marked with X-DKIM2-Info
          action=not-signed=<reason>. Upstream keys come from the milter's
          resolver (dns_overrides and skip_timestamp_check for tests).
          Mail is signed exactly as before when there is no upstream chain.
          Gate->check takes Resolver and IgnorePrefixes. The test mock of
          Mail::Milter::Authentication moved to t/lib/MockAuthMilter.pm.
          (t/milter-sign-gate.t)
        - Behaviour change: the DKIM2Sign and DKIM2Verify handlers apply
          their own default_config() to any option the configuration leaves
          out (or sets to null); an explicit 0 still wins.
          authentication_milter only uses default_config() to generate a
          sample config, so before this DKIM2Sign's sign_local,
          sign_authenticated, add_message_instance and record_smtp_params,
          and DKIM2Verify's add_message_instance, were off unless set. A
          deployment that relied on leaving them out to keep them off must
          now set them to 0. (t/milter-sign-gate.t, t/milter.t)
        - The DKIM2Sign handler deletes the broken intermediate
          Message-Instances it strips through the framework's
          change_header() (SMFIR_CHGHEADER). It used to push them onto the
          handler's remove_headers, which authentication_milter never
          reads, so they stayed on the wire. (t/milter.t)
        - Mail::DKIM2::Common exports valid_sequence() and
          UNKEYABLE_SIGNATURE_ERROR.
        - Signer POD: result() lists every fail cause.
        - bin/validate.pl reports the header-level PERMERRORs (a
          DKIM2-Signature with no usable i=, an i=/m= that is not a chain
          number) before its walk. It used to pass a message whose only
          DKIM2-Signature was junk. It also reads i=/m= with the tag-list
          parser, so FWS around "=" no longer breaks its walk.
          (t/validate-cli.t)
        - DKIM2_DATE 2026-10-08.

0.15    2026-10-08
        - MessageInstance->calculate takes BodyRecipe ('none', 'null' or a
          Recipe) and then skips the body diff; body_hash accessor;
          body_digest_raw(). For list managers that build the Recipe from
          their own layout (Sympa always-wrap). (t/mi-body-recipe-option.t)
        - MessageInstance->calculate takes BodyHash (a base64 sha256 hash, or
          a hashref per algorithm, from body_digest_raw) with BodyRecipe or
          for m=1: the body is not hashed or read, so the message passed may
          be its header block alone. A list manager sending many copies of a
          large body no longer has each one parsed and hashed twice.
          body_digest_raw hashes the body a megabyte at a time instead of
          copying it whole. (t/mi-body-recipe-option.t)
        - calculate validates both: a BodyHash value must be the base64 of a
          digest of its algorithm's length (it goes into h= verbatim); a
          string message without a final line break gets a CRLF; a
          BodyRecipe of undef, with an undefined step or a literal holding
          CR or LF, or with no previous message croaks; BodyRecipe 'none'
          with BodyHash croaks unless the hash is the previous instance's
          body hash. (t/mi-body-recipe-option.t)
        - The body diff finds the common prefix and suffix a 4 KB block at a
          time instead of a character at a time: about 5x faster for a list
          manager's per-recipient Recipe (2 MB body: 104 ms to 21 ms), the
          same Recipes. (t/mi-flat-common-len.t)

0.14    2026-10-07
        - The Verifier and MessageInstance->chain_verifies walk the header
          history past an instance whose body Recipe is null: the body is
          unrecoverable there, but every lower instance's header hashes
          are still checked down to m=1. (t/mi-null-header-history.t)
        - Validate (and bin/validate.pl): a null body Recipe no longer fails
          the chain; the header history below it is checked, and the lower
          levels report body_hash 'not-checked'. (t/validate-null-body.t)
        - dkim2-milter --allow-null-body-recipe (default off): a message
          whose top Message-Instance has a null body Recipe is no longer
          signed silently; it is refused (X-DKIM2-Info
          not-signed=null-body-recipe) unless the option is set, and signed
          with X-DKIM2-Info null-body-recipe when it is.
        - bin/dkim2sign no longer signs blindly over an existing chain: like
          dkim2-milter it verifies the upstream DKIM2-Signatures (an unsigned
          top Message-Instance is allowed) and that the Message-Instance chain
          undoes cleanly, and refuses (exit 1, nothing on stdout) otherwise.
          A top null body Recipe is refused unless --allow-null-body-recipe.
          New --dns-json (default $DKIM2_DNS_JSON) and --ignore-timestamps.
          The decision is the new Mail::DKIM2::Gate, shared with the milter;
          the Signer library itself still signs ungated. (t/sign-cli.t)
        - nd= bridge: when the top DKIM2-Signature carries nd=, the Gate
          (and so dkim2sign and dkim2-milter) signs only if nd= equals the
          signing d= (case-insensitive) and otherwise refuses with "top
          signature nd=X names another domain". Verifier gains
          next_domain_ok($d) / NextDomainOK; Gate->check takes
          SigningDomain. Every non-nd case behaves as before.
          (t/sign-cli.t, t/milter-script.t)
        - A Message-Instance whose r= has a "b" that is neither null nor an
          array (e.g. 5, "x", {}) is now a PERMERROR instead of being read
          as a null body Recipe; likewise an "h" that is not an object.
          (t/mi-null-recipe.t)
        - A body Recipe's structure (integer bounds, ascending, no overlap)
          is validated even when a null body Recipe above it means it is
          never applied; a malformed one below a null now fails the chain.
          (t/mi-null-header-history.t)
        - DKIM2_DATE is 2026-10-07: what the milter signs and how the
          Verifier judges a null body Recipe changed.

0.13    2026-10-04
        - The header Recipe builder treated "no instances" and "one empty
          instance" of a field as the same, so removing an empty header
          (a bare "Bcc:", which Sympa's egress now removes) went unrecorded
          and the Message-Instance did not verify. (t/recipe-empty-header.t)

0.12    2026-10-04
        - undo() rebuilt a base64 or quoted-printable body encoded twice:
          Recipes work on wire lines, so the rebuilt body is already in its
          transfer encoding, and Email::MIME->body_set encoded it again.
          Every such message a list re-encoded (footer appended, body
          re-wrapped) failed "m=1 does not match content" and the milter
          refused to sign it -- 17 of 88 charset-corpus samples through
          Mailman, while the Python undo rebuilt them byte for byte. The
          body is now set as raw octets. (t/undo-encoded-body.t)
        - DKIM2_DATE is 2026-10-04: the Message-Instance headers this
          library emits changed shape in 0.11 ("b" literals, integer copy
          ranges), and the X-DKIM2-Info date stamp follows emitted-header
          changes.

0.11    2026-10-04
        Fixes found by replaying public-archive mail in assorted charsets
        (ISO-2022-JP, GB2312/GB18030, Big5, EUC-KR, Latin-1, raw 8-bit
        headers) through the signers, verifiers and list managers
        (interop util/charset-corpus.sh).
        - Recipe literals carrying any octet >= 0x80 are emitted as a new
          {"b": [base64, ...]} step instead of {"d": [...]}. A literal is
          the raw octets of a header value or body line; JSON text is
          UTF-8, so the old encoder wrote ISO-2022-JP, GB18030, Big5 and
          Latin-1 octets into the JSON as they were, which no strict JSON
          parser reads back. The decoder rejects a "b" item that is not
          RFC 4648 base64 or decodes to something containing CR or LF.
          Agreed extension to spec-06 §5, proposed to the WG.
          (t/recipe-base64.t)
        - Recipe copy ranges must ascend (spec-06 §5.1): each "c" step
          starts after the one before it ends. undo() used to sort the
          ranges and reject only overlap; it now rejects an out-of-order
          range too, for body and header Recipes alike. The header Recipe
          builder in calculate() no longer emits one: a header instance a
          hop moved above one it left alone is recorded literally.
          (t/recipe-order.t, t/undo-bounds.t)
        - Two more Recipe schema rules the other verifiers already hold, so
          every implementation gives the same verdict: a "c" bound must be
          a JSON integer (a string such as "2" is malformed; told apart by
          the scalar's flags, not its text), an empty "d" or "b" array is
          malformed (minItems 1), and so is a "d" string containing CR or
          LF (§5.1/§5.2 MUST NOT). (t/recipe-order.t, t/recipe-base64.t)
        - Recipe copy ranges are emitted as JSON integers. An index used as
          a hash key while de-duplicating header copies was stringified in
          place, so every Sympa Message-Instance carried {"c":["2","2"]},
          which the spec-06 schema forbids and strict verifiers reject.
          (t/recipe-integers.t)
        - A broken Content-Type (`text/plain; Windows-1252`) no longer makes
          every verification print Email::MIME's "Illegal parameter" warning:
          the library parses with parameter checking relaxed, for the parse
          only, since DKIM2 never reads a MIME parameter.
          (t/malformed-content-type.t)
        - The test suite is self-contained: the test keys and dns.json ship
          under t/data/ (t/data-in-sync.t keeps them equal to the interop
          repository's shared copies), bin/validate.pl takes --dns-json and
          defaults to that copy, and the tests that cross-check the other
          implementations or the deployment templates skip outside the
          repository. 0.10's tests could not run from the tarball.

0.10    2026-10-02
        API cleanup ahead of a CPAN release. Incompatible changes are marked *.
        - New top-level Mail::DKIM2 module documenting the conventions every
          module follows; every module now carries the distribution $VERSION.
        - Constructor options are CamelCase and validated: an unknown option
          croaks. Verifier options (SkipTimestampCheck, AllowUnsignedMI,
          MidProcess, HeadersOnly, PubkeyCallback, Resolver, IgnorePrefixes)
          can be given to new() and are no longer silently discarded.
        - load($input): one-shot PRINT+CLOSE taking a string, scalar ref,
          filehandle or Email::MIME, normalising LF to CRLF. TIEHANDLE lets a
          Signer or Verifier be tied to a filehandle.
        - Verifier->signatures and ->top_signature for Authentication-Results
          writers.
        * Ignore prefixes are per instance: Common::ignore_header_prefixes is
          gone; pass IgnorePrefixes to Verifier->new and to
          MessageInstance->calculate/verify/chain_verifies instead.
          should_skip takes the prefixes as a second argument.
        * Key fetching moves to the Verifier: Signature->fetch_public_key is
          replaced by Verifier->fetch_public_key($signature, $idx), driven by
          the Resolver option. Only NXDOMAIN/NOERROR/NODATA are permanent; any
          other resolver error is temperror. The pubkey callback receives the
          verifier as a third argument.
        * Signer no longer dies from inside PRINT on a chain it cannot
          extend: result() is 'fail' and details() says why. result() is
          undef (not '?') before CLOSE. details() and result_detail() added.
        * Signature: mail_from(), rcpt_to() and flags() are get/set like the
          other tag accessors; set_rcpt_to is removed.
        * Mail::DKIM2::DSN methods take CamelCase named arguments (Message,
          Signer, To, ReportingMTA, Status, Reason, PubkeyCallback,
          ForwarderDomain, SkipAuthentication, SkipTimestampCheck) instead of
          a hashref. Validate::report takes PubkeyCallback, DnsPath,
          SkipTimestampCheck.
        * Command-line tools: dkim2sign (was dkim2sign.pl) and the new
          dkim2verify are installed; verify-sig.pl, calculate-dkim2.pl and
          the *-mailversion tools are removed.
        - POD rewritten for spec-06 (the previous text described
          draft-clayton-08 tags); Net::DNS declared as a prerequisite.
        - dkim2-milter and dkim2-split-lmtp are installed programs (were
          bin/*.pl, run from the checkout). X-DKIM2-Info sw= says
          dkim2-milter.

0.01    2026-03-08
        - Initial release
        - Implements draft-clayton-dkim2-spec-08
        - Signer: streaming DKIM2-Signature generation with SMTP param recording
        - Verifier: full chain verification (all signatures, not just outermost)
        - MessageInstance: calculate, verify, and undo with header/body diff recipes
        - Signature: tag-value parser with base64-encoded JSON tags
        - HeaderParser: thin streaming base class replacing Mail::DKIM::Common
        - Common: shared canonicalization, hashing, domain matching utilities