Add OpenSSL 4.0.x support

OpenSSL 4.0.0 was released in April 2026, and a shared-docker builder image
(`shared-docker-ci-standard-builder-with-openssl-4.0.0`) is now available.
The builder configures OpenSSL with `--api=3.0.0`, preserving the 3.0
application API — so extending every `openssl_3.0.x` compile guard to also
list `openssl_4.0.x` is sufficient to support the new backend at the FFI
boundary.

Also drops "supported on..." docstrings that listed every supported
backend — tautological prose that's better omitted. Version qualifiers
remain where they express a real subset (SHAKE variable-length output).

Incidentally corrects a pre-existing docstring in `ssl/crypto/crypto.pony`
that listed PBKDF2 as requiring OpenSSL only, though LibreSSL has been
supported since first-class LibreSSL landed.

Closes #44

Author: SeanTAllen

.github/workflows/breakage-against-linux-ponyc-latest.yml

@@ -92,3 +92,24 @@ jobs:
           type: stream
           topic: ${{ github.repository }} scheduled job failure
           content: ${{ github.server_url}}/${{ github.repository }}/actions/runs/${{ github.run_id }} failed.
+
+  test-openssl-4-vs-ponyc-latest:
+    name: OpenSSL 4.x with ponyc main
+    runs-on: ubuntu-latest
+    container:
+      image: ghcr.io/ponylang/shared-docker-ci-standard-builder-with-openssl-4.0.0:nightly
+    steps:
+      - uses: actions/checkout@v6.0.2
+      - name: Test
+        run: make test config=debug ssl=4.0.x
+      - name: Send alert on failure
+        if: ${{ failure() }}
+        uses: zulip/github-actions-zulip/send-message@e4c8f27c732ba9bd98ac6be0583096dea82feea5
+        with:
+          api-key: ${{ secrets.ZULIP_SCHEDULED_JOB_FAILURE_API_KEY }}
+          email: ${{ secrets.ZULIP_SCHEDULED_JOB_FAILURE_EMAIL }}
+          organization-url: 'https://ponylang.zulipchat.com/'
+          to: notifications
+          type: stream
+          topic: ${{ github.repository }} scheduled job failure
+          content: ${{ github.server_url}}/${{ github.repository }}/actions/runs/${{ github.run_id }} failed.

.github/workflows/pr.yml

@@ -57,6 +57,16 @@ jobs:
       - name: Test
         run: make test config=debug ssl=3.0.x
 
+  test-openssl-4-vs-ponyc-release:
+    name: OpenSSL 4.x with most recent ponyc release
+    runs-on: ubuntu-latest
+    container:
+      image: ghcr.io/ponylang/shared-docker-ci-standard-builder-with-openssl-4.0.0:release
+    steps:
+      - uses: actions/checkout@v6.0.2
+      - name: Test
+        run: make test config=debug ssl=4.0.x
+
   test-x86-64-windows-vs-ponyc-release:
     name: Windows x86-64 (LibreSSL) with most recent ponyc release
     runs-on: windows-2025

.release-notes/add-openssl-4.0.x-support.md

@@ -0,0 +1,4 @@
+## Add OpenSSL 4.0.x support
+
+OpenSSL 4.0.x is now a supported backend. Select it at compile time with `-Dopenssl_4.0.x`, or pass `ssl=4.0.x` to `make` when building the library itself. The library's API is unchanged; existing code continues to work without modification.
+

CLAUDE.md

@@ -15,6 +15,7 @@ SSL version is **required**. Valid values:
 
 | `ssl=` value | Define passed to ponyc | Backend |
 |---|---|---|
+| `4.0.x` | `-Dopenssl_4.0.x` | OpenSSL 4.x |
 | `3.0.x` | `-Dopenssl_3.0.x` | OpenSSL 3.x |
 | `1.1.x` | `-Dopenssl_1.1.x` | OpenSSL 1.1.x |
 | `libressl` | `-Dlibressl` | LibreSSL |
@@ -37,12 +38,12 @@ Version-specific code uses two patterns:
 
 **FFI declarations** use `if` guards on the `use` statement:
 ```pony
-use @TLS_method[Pointer[None]]() if "openssl_1.1.x" or "openssl_3.0.x" or "libressl"
+use @TLS_method[Pointer[None]]() if "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl"
 ```
 
 **Code blocks** use `ifdef` with `elseif` chains and a compile_error catch-all:
 ```pony
-ifdef "openssl_1.1.x" or "openssl_3.0.x" then
+ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" then
   // OpenSSL path
 elseif "libressl" then
   // LibreSSL path (when it diverges from OpenSSL)

Makefile

@@ -24,7 +24,9 @@ else
 endif
 
 ifeq (,$(filter $(MAKECMDGOALS),clean docs realclean TAGS))
-  ifeq ($(ssl), 3.0.x)
+  ifeq ($(ssl), 4.0.x)
+	  SSL = -Dopenssl_4.0.x
+  else ifeq ($(ssl), 3.0.x)
 	  SSL = -Dopenssl_3.0.x
   else ifeq ($(ssl), 1.1.x)
 	  SSL = -Dopenssl_1.1.x

README.md

@@ -17,7 +17,7 @@ Production ready.
 
 ## Supported SSL versions
 
-OpenSSL 1.1.x, OpenSSL 3.0.x, and LibreSSL are supported. Select the library version at compile-time using Pony's compile time definition functionality.
+OpenSSL 1.1.x, OpenSSL 3.0.x, OpenSSL 4.0.x, and LibreSSL are supported. Select the library version at compile-time using Pony's compile time definition functionality.
 
 ### Using OpenSSL 1.1.x
 
@@ -31,6 +31,12 @@ corral run -- ponyc -Dopenssl_1.1.x
 corral run -- ponyc -Dopenssl_3.0.x
 ```
 
+### Using OpenSSL 4.0.x
+
+```bash
+corral run -- ponyc -Dopenssl_4.0.x
+```
+
 ### Using LibreSSL
 
 ```bash

examples/digest-example/digest-example.pony

@@ -14,8 +14,8 @@ actor Main
       env.out.print("Error computing hash")
     end
 
-    // SHAKE256 with variable-length output (OpenSSL 3.0.x only)
-    ifdef "openssl_3.0.x" then
+    // SHAKE256 with variable-length output (OpenSSL 3.0.x or 4.0.x)
+    ifdef "openssl_3.0.x" or "openssl_4.0.x" then
       let shake: Digest = Digest.shake256(64)
       try
         shake.append("Hello ")?

ssl/crypto/_test.pony

@@ -23,13 +23,13 @@ actor \nodoc\ Main is TestList
     test(Property1UnitTest[USize](_TestHmacSha256Deterministic))
     test(Property1UnitTest[USize](_TestRandBytesOutputLength))
     test(Property1UnitTest[USize](_TestRandBytesNonConstant))
-    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "libressl" then
+    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl" then
       test(_TestPbkdf2Sha256Rfc7914)
       test(_TestPbkdf2Sha256Scram)
       test(Property1UnitTest[USize](_TestPbkdf2Sha256OutputLength))
       test(Property1UnitTest[USize](_TestPbkdf2Sha256Deterministic))
     end
-    ifdef "openssl_3.0.x" then
+    ifdef "openssl_3.0.x" or "openssl_4.0.x" then
       test(Property1UnitTest[USize](_TestShake128OutputLength))
       test(Property1UnitTest[USize](_TestShake256OutputLength))
       test(Property1UnitTest[USize](_TestShake128XofPrefix))
@@ -179,7 +179,7 @@ class \nodoc\ iso _TestDigest is UnitTest
       "cd945c6a77006272322f911c9be31fa970043daa4b61cee607566cbfa2c69b09",
       ToHexString(sha512.final()))
 
-    ifdef "openssl_1.1.x" or "openssl_3.0.x" then
+    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" then
       let shake128 = Digest.shake128()
       shake128.append("message1")?
       shake128.append("message2")?
@@ -326,7 +326,7 @@ class \nodoc\ iso _TestPbkdf2Sha256Rfc7914 is UnitTest
   fun name(): String => "crypto/Pbkdf2Sha256/RFC7914"
 
   fun apply(h: TestHelper) ? =>
-    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "libressl" then
+    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl" then
       // Test Vector 1: Password "passwd", Salt "salt", c=1, dkLen=64
       h.assert_eq[String](
         "55ac046e56e3089fec1691c22544b605f94185216dde0465e68b9d57c20dacbc" +
@@ -349,7 +349,7 @@ class \nodoc\ iso _TestPbkdf2Sha256Scram is UnitTest
   fun name(): String => "crypto/Pbkdf2Sha256/SCRAM"
 
   fun apply(h: TestHelper) ? =>
-    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "libressl" then
+    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl" then
       // Salt: decoded bytes of base64 "W22ZaJ0SNY7soEsUEjb6gQ=="
       let salt = recover val [as U8:
         0x5b; 0x6d; 0x99; 0x68; 0x9d; 0x12; 0x35; 0x8e
@@ -408,7 +408,7 @@ class \nodoc\ iso _TestPbkdf2Sha256OutputLength is Property1[USize]
     Generators.usize(1, 128)
 
   fun ref property(sample: USize, h: PropertyHelper) ? =>
-    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "libressl" then
+    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl" then
       h.assert_eq[USize](sample,
         Pbkdf2Sha256("p", "s", 1, sample)?.size())
     end
@@ -420,7 +420,7 @@ class \nodoc\ iso _TestPbkdf2Sha256Deterministic is Property1[USize]
     Generators.usize(1, 64)
 
   fun ref property(sample: USize, h: PropertyHelper) ? =>
-    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "libressl" then
+    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl" then
       h.assert_array_eq[U8](
         Pbkdf2Sha256("p", "s", 1, sample)?,
         Pbkdf2Sha256("p", "s", 1, sample)?)
@@ -453,7 +453,7 @@ class \nodoc\ iso _TestShake128OutputLength is Property1[USize]
     Generators.usize(1, 256)
 
   fun ref property(sample: USize, h: PropertyHelper) ? =>
-    ifdef "openssl_3.0.x" then
+    ifdef "openssl_3.0.x" or "openssl_4.0.x" then
       let d = Digest.shake128(sample)
       d.append("test")?
       h.assert_eq[USize](sample, d.final().size())
@@ -466,7 +466,7 @@ class \nodoc\ iso _TestShake256OutputLength is Property1[USize]
     Generators.usize(1, 256)
 
   fun ref property(sample: USize, h: PropertyHelper) ? =>
-    ifdef "openssl_3.0.x" then
+    ifdef "openssl_3.0.x" or "openssl_4.0.x" then
       let d = Digest.shake256(sample)
       d.append("test")?
       h.assert_eq[USize](sample, d.final().size())
@@ -479,7 +479,7 @@ class \nodoc\ iso _TestShake128XofPrefix is Property1[USize]
     Generators.usize(2, 256)
 
   fun ref property(sample: USize, h: PropertyHelper) ? =>
-    ifdef "openssl_3.0.x" then
+    ifdef "openssl_3.0.x" or "openssl_4.0.x" then
       let small_size = sample / 2
       let large_size = sample
 
@@ -502,7 +502,7 @@ class \nodoc\ iso _TestShake256XofPrefix is Property1[USize]
     Generators.usize(2, 256)
 
   fun ref property(sample: USize, h: PropertyHelper) ? =>
-    ifdef "openssl_3.0.x" then
+    ifdef "openssl_3.0.x" or "openssl_4.0.x" then
       let small_size = sample / 2
       let large_size = sample
 

ssl/crypto/crypto.pony

@@ -4,7 +4,7 @@ The crypto package provides cryptographic primitives built on OpenSSL:
 * One-shot hash functions (`MD5`, `SHA256`, etc.) and streaming digests
   (`Digest`)
 * HMAC message authentication (`HmacSha256`)
-* PBKDF2 key derivation (`Pbkdf2Sha256`, requires OpenSSL 1.1.x or 3.0.x)
+* PBKDF2 key derivation (`Pbkdf2Sha256`)
 * Cryptographically secure random bytes (`RandBytes`)
 * Constant-time comparison (`ConstantTimeCompare`)
 """

ssl/crypto/digest.pony

@@ -3,12 +3,12 @@ use "path:/opt/homebrew/opt/libressl/lib" if osx and arm
 use "lib:crypto"
 use "lib:bcrypt" if windows
 
-use @EVP_MD_CTX_new[Pointer[_EVPCTX]]() if "openssl_1.1.x" or "openssl_3.0.x" or "libressl"
+use @EVP_MD_CTX_new[Pointer[_EVPCTX]]() if "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl"
 use @EVP_DigestInit_ex[I32](ctx: Pointer[_EVPCTX] tag, t: Pointer[_EVPMD], impl: USize)
 use @EVP_DigestUpdate[I32](ctx: Pointer[_EVPCTX] tag, d: Pointer[U8] tag, cnt: USize)
 use @EVP_DigestFinal_ex[I32](ctx: Pointer[_EVPCTX] tag, md: Pointer[U8] tag, s: Pointer[USize])
-use @EVP_DigestFinalXOF[I32](ctx: Pointer[_EVPCTX] tag, md: Pointer[U8] tag, len: USize) if "openssl_3.0.x"
-use @EVP_MD_CTX_free[None](ctx: Pointer[_EVPCTX]) if "openssl_1.1.x" or "openssl_3.0.x" or "libressl"
+use @EVP_DigestFinalXOF[I32](ctx: Pointer[_EVPCTX] tag, md: Pointer[U8] tag, len: USize) if "openssl_3.0.x" or "openssl_4.0.x"
+use @EVP_MD_CTX_free[None](ctx: Pointer[_EVPCTX]) if "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl"
 
 use @EVP_md5[Pointer[_EVPMD]]()
 use @EVP_ripemd160[Pointer[_EVPMD]]()
@@ -39,7 +39,7 @@ class Digest
     """
     _variable_length = false
     _digest_size = 16
-    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "libressl" then
+    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl" then
       _ctx = @EVP_MD_CTX_new()
     else
       compile_error "You must select an SSL version to use."
@@ -52,7 +52,7 @@ class Digest
     """
     _variable_length = false
     _digest_size = 20
-    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "libressl" then
+    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl" then
       _ctx = @EVP_MD_CTX_new()
     else
       compile_error "You must select an SSL version to use."
@@ -65,7 +65,7 @@ class Digest
     """
     _variable_length = false
     _digest_size = 20
-    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "libressl" then
+    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl" then
       _ctx = @EVP_MD_CTX_new()
     else
       compile_error "You must select an SSL version to use."
@@ -78,7 +78,7 @@ class Digest
     """
     _variable_length = false
     _digest_size = 28
-    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "libressl" then
+    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl" then
       _ctx = @EVP_MD_CTX_new()
     else
       compile_error "You must select an SSL version to use."
@@ -91,7 +91,7 @@ class Digest
     """
     _variable_length = false
     _digest_size = 32
-    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "libressl" then
+    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl" then
       _ctx = @EVP_MD_CTX_new()
     else
       compile_error "You must select an SSL version to use."
@@ -104,7 +104,7 @@ class Digest
     """
     _variable_length = false
     _digest_size = 48
-    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "libressl" then
+    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl" then
       _ctx = @EVP_MD_CTX_new()
     else
       compile_error "You must select an SSL version to use."
@@ -117,7 +117,7 @@ class Digest
     """
     _variable_length = false
     _digest_size = 64
-    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "libressl" then
+    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl" then
       _ctx = @EVP_MD_CTX_new()
     else
       compile_error "You must select an SSL version to use."
@@ -130,11 +130,11 @@ class Digest
 
     SHAKE128 is an extendable output function (XOF) that can produce
     variable-length output. The `size'` parameter controls the output length
-    in bytes (default: 16). Variable-length output requires OpenSSL 3.0.x;
-    on OpenSSL 1.1.x, the default size is always used.
+    in bytes (default: 16). Variable-length output requires OpenSSL 3.0.x or
+    OpenSSL 4.0.x; on OpenSSL 1.1.x, the default size is always used.
     """
-    ifdef "openssl_1.1.x" or "openssl_3.0.x" then
-      ifdef "openssl_3.0.x" then
+    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" then
+      ifdef "openssl_3.0.x" or "openssl_4.0.x" then
         _variable_length = true
         _digest_size = size'
       else
@@ -144,7 +144,7 @@ class Digest
       _ctx = @EVP_MD_CTX_new()
       @EVP_DigestInit_ex(_ctx, @EVP_shake128(), USize(0))
     else
-      compile_error "shake128 is only supported with OpenSSL 1.1.x or 3.0.x"
+      compile_error "shake128 is only supported with OpenSSL 1.1.x, 3.0.x, or 4.0.x"
     end
 
   new shake256(size': USize = 32) =>
@@ -153,11 +153,11 @@ class Digest
 
     SHAKE256 is an extendable output function (XOF) that can produce
     variable-length output. The `size'` parameter controls the output length
-    in bytes (default: 32). Variable-length output requires OpenSSL 3.0.x;
-    on OpenSSL 1.1.x, the default size is always used.
+    in bytes (default: 32). Variable-length output requires OpenSSL 3.0.x or
+    OpenSSL 4.0.x; on OpenSSL 1.1.x, the default size is always used.
     """
-    ifdef "openssl_1.1.x" or "openssl_3.0.x" then
-      ifdef "openssl_3.0.x" then
+    ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" then
+      ifdef "openssl_3.0.x" or "openssl_4.0.x" then
         _variable_length = true
         _digest_size = size'
       else
@@ -167,7 +167,7 @@ class Digest
       _ctx = @EVP_MD_CTX_new()
       @EVP_DigestInit_ex(_ctx, @EVP_shake256(), USize(0))
     else
-      compile_error "shake256 is only supported with OpenSSL 1.1.x or 3.0.x"
+      compile_error "shake256 is only supported with OpenSSL 1.1.x, 3.0.x, or 4.0.x"
     end
 
   fun ref append(input: ByteSeq) ? =>
@@ -193,13 +193,13 @@ class Digest
       if not _variable_length then
         @EVP_DigestFinal_ex(_ctx, digest.cpointer(), Pointer[USize])
       else
-        ifdef "openssl_3.0.x" then
+        ifdef "openssl_3.0.x" or "openssl_4.0.x" then
           @EVP_DigestFinalXOF(_ctx, digest.cpointer(), size)
         else
           @EVP_DigestFinal_ex(_ctx, digest.cpointer(), Pointer[USize])
         end
       end
-      ifdef "openssl_1.1.x" or "openssl_3.0.x" or "libressl" then
+      ifdef "openssl_1.1.x" or "openssl_3.0.x" or "openssl_4.0.x" or "libressl" then
         @EVP_MD_CTX_free(_ctx)
       else
         compile_error "You must select an SSL version to use."