limbo: add an explicit EC curve test

Signed-off-by: William Woodruff <[email protected]>

limbo/_assets/explicit_curve_ca.csr

@@ -0,0 +1,13 @@
+-----BEGIN CERTIFICATE REQUEST-----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=
+-----END CERTIFICATE REQUEST-----

limbo/_assets/explicit_curve.key → limbo/_assets/explicit_curve_ca.key

@@ -1,10 +1,10 @@
 -----BEGIN EC PRIVATE KEY-----
-MIIBaAIBAQQgayvHKYGhnU2CmjSWR7YLQl3E3y2x+bmUvgjQc/LvsO6ggfowgfcC
+MIIBaAIBAQQgi3OjXw6++HS38iR1SFAo7lu29McivxVaUW/rYljBmm6ggfowgfcC
 AQEwLAYHKoZIzj0BAQIhAP////8AAAABAAAAAAAAAAAAAAAA////////////////
 MFsEIP////8AAAABAAAAAAAAAAAAAAAA///////////////8BCBaxjXYqjqT57Pr
 vVV2mIa8ZR0GsMxTsPY7zjw+J9JgSwMVAMSdNgiG5wSTamZ44ROdJreBn36QBEEE
 axfR8uEsQkf4vOblY6RA8ncDfYEt6zOg9KE5RdiYwpZP40Li/hp/m47n60p8D54W
 K84zV2sxXs7LtkBoN79R9QIhAP////8AAAAA//////////+85vqtpxeehPO5ysL8
-YyVRAgEBoUQDQgAEPLZcsLO78T1yM5EeELK1cm66GgAe+/+ebMzhkNZxC7/yrxXC
-PfAhs4xAAueYE60iLqibwNYnFcy6NYoaDPHa5g==
+YyVRAgEBoUQDQgAELYTfCK4aFndEXkrD/cBRpEc7nJshNGquXzFZkkXyTUf1Wr7w
+8jsIgb8xgwmmlg0f+yWcrezVGuSl98flwkCoHg==
 -----END EC PRIVATE KEY-----

limbo/_assets/explicit_curve_ca.pem

@@ -0,0 +1,15 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----

limbo/_assets/explicit_curve_leaf.csr

@@ -0,0 +1,14 @@
+-----BEGIN CERTIFICATE REQUEST-----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+-----END CERTIFICATE REQUEST-----

limbo/_assets/explicit_curve_leaf.key

@@ -0,0 +1,10 @@
+-----BEGIN EC PRIVATE KEY-----
+MIIBaAIBAQQgIFOtVZ+XT8l0+e9Yv7XjpWUqqO9XpwApMg1njojbvvmggfowgfcC
+AQEwLAYHKoZIzj0BAQIhAP////8AAAABAAAAAAAAAAAAAAAA////////////////
+MFsEIP////8AAAABAAAAAAAAAAAAAAAA///////////////8BCBaxjXYqjqT57Pr
+vVV2mIa8ZR0GsMxTsPY7zjw+J9JgSwMVAMSdNgiG5wSTamZ44ROdJreBn36QBEEE
+axfR8uEsQkf4vOblY6RA8ncDfYEt6zOg9KE5RdiYwpZP40Li/hp/m47n60p8D54W
+K84zV2sxXs7LtkBoN79R9QIhAP////8AAAAA//////////+85vqtpxeehPO5ysL8
+YyVRAgEBoUQDQgAEfMmSp9aLYgFQMT8Hz9zOjqNTB58DBs9wrVoNstn4Msduype5
+/8OGxHeUIS6tTgkh0Eh48R4ucFGUW/yAxadlNA==
+-----END EC PRIVATE KEY-----

limbo/_assets/explicit_curve_leaf.pem

@@ -0,0 +1,16 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----

limbo/_assets/scripts/generate_explicit_curve_cert.sh

@@ -0,0 +1,68 @@
+#!/usr/bin/env bash
+
+set -e
+
+ca_csr_conf='
+[ req ]
+default_md = sha256
+prompt = no
+req_extensions = req_ext
+distinguished_name = req_distinguished_name
+[ req_distinguished_name ]
+commonName = x509-limbo-explicit-ec-root
+[ req_ext ]
+keyUsage=critical,keyCertSign,cRLSign
+basicConstraints=critical,CA:true
+'
+
+leaf_csr_conf='
+[ req ]
+default_md = sha256
+prompt = no
+req_extensions = req_ext
+distinguished_name = req_distinguished_name
+[ req_distinguished_name ]
+commonName = example.com
+[ req_ext ]
+keyUsage=critical,digitalSignature,keyEncipherment
+extendedKeyUsage=serverAuth,clientAuth
+basicConstraints=critical,CA:false
+subjectAltName = @alt_names
+[ alt_names ]
+DNS.0 = example.com
+'
+
+# CA CSR
+openssl req \
+    -new \
+    -noenc \
+    -key ../explicit_curve_ca.key \
+    -config <(echo "${ca_csr_conf}") \
+    -nameopt utf8 \
+    -utf8 \
+    -out ../explicit_curve_ca.csr
+
+# Self-signed CA (with explicit EC encoding)
+openssl x509 \
+    -signkey ../explicit_curve_ca.key \
+    -days 365 \
+    -req -in ../explicit_curve_ca.csr \
+    -out ../explicit_curve_ca.pem
+
+# Leaf CSR
+openssl req \
+    -new \
+    -noenc \
+    -key ../explicit_curve_leaf.key \
+    -config <(echo "${leaf_csr_conf}") \
+    -nameopt utf8 \
+    -utf8 \
+    -out ../explicit_curve_leaf.csr
+
+# Leaf certificate (with explicit EC encoding)
+openssl x509 \
+    -days 365 \
+    -req -in ../explicit_curve_leaf.csr \
+    -CA ../explicit_curve_ca.pem \
+    -CAkey ../explicit_curve_ca.key \
+    -out ../explicit_curve_leaf.pem

limbo/_assets/scripts/generate_explicit_curve_key.sh

@@ -9,4 +9,12 @@ openssl ecparam \
     -param_enc explicit \
     -noout \
     -outform PEM \
-    -out ../explicit_curve.key
+    -out ../explicit_curve_ca.key
+
+openssl ecparam \
+    -name prime256v1 \
+    -genkey \
+    -param_enc explicit \
+    -noout \
+    -outform PEM \
+    -out ../explicit_curve_leaf.key

limbo/testcases/webpki/__init__.py

@@ -17,6 +17,39 @@
 from .san import *  # noqa: F403
 
 
+@testcase
+def explicit_curve(builder: Builder) -> None:
+    """
+    Produces the following **invalid** chain:
+
+    ```
+    root -> EE
+    ```
+
+    Both root and EE convey EC keys using the "explicit" curve encoding,
+    which is forbidden under CABF 7.1.3.1.2:
+
+    > The CA SHALL indicate an ECDSA key using the id‐ecPublicKey
+    > (OID: 1.2.840.10045.2.1) algorithm identifier. The parameters MUST use
+    > the namedCurve encoding.
+    """
+
+    root_pem = ASSETS_PATH / "explicit_curve_ca.pem"
+    leaf_pem = ASSETS_PATH / "explicit_curve_leaf.pem"
+
+    root = Certificate(x509.load_pem_x509_certificate(root_pem.read_bytes()))
+    leaf = Certificate(x509.load_pem_x509_certificate(leaf_pem.read_bytes()))
+
+    builder = (
+        builder.server_validation()
+        .validation_time(datetime.fromisoformat("2024-03-13T00:00:00Z"))
+        .trusted_certs(root)
+        .peer_certificate(leaf)
+        .expected_peer_name(PeerName(kind="DNS", value="example.com"))
+        .fails()
+    )
+
+
 @testcase
 def cryptographydotio_chain(builder: Builder) -> None:
     """