Add support for ed25519 keys

.github/workflows/ci.yml

@@ -68,7 +68,7 @@ jobs:
         if: ${{ matrix.conf.os == 'ubuntu-latest' }}
         run: |
           # Fetch the latest sigstore/timestamp-authority build
-          SIGSTORE_TIMESTAMP_VERSION=$(gh api /repos/sigstore/timestamp-authority/tags --jq '.[0].name')
+          SIGSTORE_TIMESTAMP_VERSION=$(gh api /repos/sigstore/timestamp-authority/releases --jq '.[0].tag_name')
           wget https://github.com/sigstore/timestamp-authority/releases/download/${SIGSTORE_TIMESTAMP_VERSION}/timestamp-server-linux-amd64 -O /tmp/timestamp-server
           chmod +x /tmp/timestamp-server
 

CHANGELOG.md

@@ -8,6 +8,11 @@ All versions prior to 0.9.0 are untracked.
 
 ## [Unreleased]
 
+### Added
+
+* Added support for ed25519 keys.
+  [#1377](https://github.com/sigstore/sigstore-python/pull/1377)
+
 ### Fixed
 
 * TSA: Changed the Timestamp Authority requests to explicitly use sha256 for message digests.
@@ -20,6 +25,10 @@ All versions prior to 0.9.0 are untracked.
 * API: Make Rekor APIs compatible with Rekor v2 by removing trailing slashes
   from endpoints ([#1366](https://github.com/sigstore/sigstore-python/pull/1366))
 
+* CI: Timestamp Authority tests use latest release, not latest tag, of
+  [sigstore/timestamp-authority](https://github.com/sigstore/timestamp-authority)
+  [#1377](https://github.com/sigstore/sigstore-python/pull/1377)
+
 ### Changed
 
 * `--trust-config` now requires a file with SigningConfig v0.2, and is able to fully

sigstore/_internal/trust.py

@@ -23,12 +23,12 @@
 from datetime import datetime, timezone
 from enum import Enum
 from pathlib import Path
-from typing import ClassVar, NewType
+from typing import ClassVar, NewType, Optional
 
 import cryptography.hazmat.primitives.asymmetric.padding as padding
 from cryptography.exceptions import InvalidSignature
 from cryptography.hazmat.primitives import hashes
-from cryptography.hazmat.primitives.asymmetric import ec, rsa
+from cryptography.hazmat.primitives.asymmetric import ec, ed25519, rsa
 from cryptography.x509 import (
     Certificate,
     load_der_x509_certificate,
@@ -94,7 +94,7 @@ class Key:
     Represents a key in a `Keyring`.
     """
 
-    hash_algorithm: hashes.HashAlgorithm
+    hash_algorithm: Optional[hashes.HashAlgorithm]
     key: PublicKey
     key_id: KeyID
 
@@ -121,7 +121,7 @@ def __init__(self, public_key: _PublicKey) -> None:
         if not public_key.raw_bytes:
             raise VerificationError("public key is empty")
 
-        hash_algorithm: hashes.HashAlgorithm
+        hash_algorithm: Optional[hashes.HashAlgorithm]
         if public_key.key_details in self._RSA_SHA_256_DETAILS:
             hash_algorithm = hashes.SHA256()
             key = load_der_public_key(public_key.raw_bytes, types=(rsa.RSAPublicKey,))
@@ -130,6 +130,11 @@ def __init__(self, public_key: _PublicKey) -> None:
             key = load_der_public_key(
                 public_key.raw_bytes, types=(ec.EllipticCurvePublicKey,)
             )
+        elif public_key.key_details == _PublicKeyDetails.PKIX_ED25519:
+            hash_algorithm = None
+            key = load_der_public_key(
+                public_key.raw_bytes, types=(ed25519.Ed25519PublicKey,)
+            )
         else:
             raise VerificationError(f"unsupported key type: {public_key.key_details}")
 
@@ -141,20 +146,31 @@ def verify(self, signature: bytes, data: bytes) -> None:
         """
         Verifies the given `data` against `signature` using the current key.
         """
-        if isinstance(self.key, rsa.RSAPublicKey):
+        if isinstance(self.key, rsa.RSAPublicKey) and self.hash_algorithm is not None:
             self.key.verify(
                 signature=signature,
                 data=data,
                 # TODO: Parametrize this as well, for PSS.
                 padding=padding.PKCS1v15(),
                 algorithm=self.hash_algorithm,
             )
-        elif isinstance(self.key, ec.EllipticCurvePublicKey):
+        elif (
+            isinstance(self.key, ec.EllipticCurvePublicKey)
+            and self.hash_algorithm is not None
+        ):
             self.key.verify(
                 signature=signature,
                 data=data,
                 signature_algorithm=ec.ECDSA(self.hash_algorithm),
             )
+        elif (
+            isinstance(self.key, ed25519.Ed25519PublicKey)
+            and self.hash_algorithm is None
+        ):
+            self.key.verify(
+                signature=signature,
+                data=data,
+            )
         else:
             # Unreachable without API misuse.
             raise VerificationError(f"keyring: unsupported key: {self.key}")

sigstore/_utils.py

@@ -24,7 +24,7 @@
 from typing import IO, NewType, Union
 
 from cryptography.hazmat.primitives import serialization
-from cryptography.hazmat.primitives.asymmetric import ec, rsa
+from cryptography.hazmat.primitives.asymmetric import ec, ed25519, rsa
 from cryptography.x509 import (
     Certificate,
     ExtensionNotFound,
@@ -43,9 +43,13 @@
     from importlib import resources
 
 
-PublicKey = Union[rsa.RSAPublicKey, ec.EllipticCurvePublicKey]
+PublicKey = Union[rsa.RSAPublicKey, ec.EllipticCurvePublicKey, ed25519.Ed25519PublicKey]
 
-PublicKeyTypes = Union[type[rsa.RSAPublicKey], type[ec.EllipticCurvePublicKey]]
+PublicKeyTypes = Union[
+    type[rsa.RSAPublicKey],
+    type[ec.EllipticCurvePublicKey],
+    type[ed25519.Ed25519PublicKey],
+]
 
 HexStr = NewType("HexStr", str)
 """
@@ -64,7 +68,11 @@
 def load_pem_public_key(
     key_pem: bytes,
     *,
-    types: tuple[PublicKeyTypes, ...] = (rsa.RSAPublicKey, ec.EllipticCurvePublicKey),
+    types: tuple[PublicKeyTypes, ...] = (
+        rsa.RSAPublicKey,
+        ec.EllipticCurvePublicKey,
+        ed25519.Ed25519PublicKey,
+    ),
 ) -> PublicKey:
     """
     A specialization of `cryptography`'s `serialization.load_pem_public_key`
@@ -86,7 +94,11 @@ def load_pem_public_key(
 def load_der_public_key(
     key_der: bytes,
     *,
-    types: tuple[PublicKeyTypes, ...] = (rsa.RSAPublicKey, ec.EllipticCurvePublicKey),
+    types: tuple[PublicKeyTypes, ...] = (
+        rsa.RSAPublicKey,
+        ec.EllipticCurvePublicKey,
+        ed25519.Ed25519PublicKey,
+    ),
 ) -> PublicKey:
     """
     The `load_pem_public_key` specialization, but DER.