Java JCA (SunEC, JDK 25)

Facts and the checks behind them

Nothing below is copied from documentation. The check content/libraries/verify/java-jca/run.sh ran Java JCA (SunEC, JDK 25) 25.0.4.1 on Eclipse Adoptium 25.0.4.1+1-LTS in the container image maven:3.9.16-eclipse-temurin-25 on October 20, 2026; the page must match what it printed, and each fact lists those lines.

• ECDSA signature encoding

  der

  SHA256withECDSA returns ASN.1 DER; SHA256withECDSAinP1363Format returns 64 bytes of raw r‖s.

  Recorded by the check

  fact ecdsa-signature-encoding = der
  evidence ecdsa-signature-encoding: SHA256withECDSAinP1363Format output is 64 bytes

• ECDSA nonce

  random

  Random nonce: the RFC 6979 test key signed the same message twice with different results.

  Recorded by the check

  fact ecdsa-nonce = random

• Low-S when signing

  either

  s is not normalized: high-S values appeared among 64 signatures.

  Recorded by the check

  fact ecdsa-low-s-sign = either

• High-S when verifying

  accepts-high-s

  A DER signature with s replaced by n − s verified.

  Recorded by the check

  fact ecdsa-low-s-verify = accepts-high-s

• What the signing call hashes

  hashes-message-or-digest

  SHA256withECDSA hashes the data; NONEwithECDSA signs a precomputed digest, and that signature verified with SHA256withECDSA against the message.

  Recorded by the check

  fact ecdsa-prehash = hashes-message-or-digest

• Hash bound to the curve

  none

  The hash in the algorithm name is not tied to the curve: SHA256withECDSA signed and verified with a P-384 key.

  Recorded by the check

  fact ecdsa-hash-curve-binding = none

• Malformed ECDSA signature

  throws

  A raw signature passed to SHA256withECDSA and a 3-byte blob throw SignatureException; a DER signature passed to the P1363 variant returns false.

  Recorded by the check

  fact ecdsa-malformed-signature = throws
  evidence ecdsa-malformed-signature: raw r||s to SHA256withECDSA: throws SignatureException; DER to the P1363 algorithm: false; 3 bytes: throws SignatureException

• ECDSA curves

  P-256P-384P-521

  secp256r1, secp384r1 and secp521r1; secp224r1, secp256k1 and brainpoolP256r1 were not available.

  Recorded by the check

  fact ecdsa-curves = P-256, P-384, P-521
  evidence ecdsa-curves: P-224 (secp224r1) not available
  evidence ecdsa-curves: secp256k1 (secp256k1) not available
  evidence ecdsa-curves: brainpoolP256r1 (brainpoolP256r1) not available

• EdDSA

  Ed25519Ed448

  Ed25519 and Ed448 through KeyPairGenerator and Signature with those names.

  Recorded by the check

  fact eddsa = Ed25519, Ed448

• Post-quantum algorithms

  ML-KEMML-DSA

  ML-KEM-512/768/1024 through javax.crypto.KEM and ML-DSA-44/65/87 through Signature worked; there is no SLH-DSA KeyPairGenerator.

  Recorded by the check

  fact pqc = ML-KEM, ML-DSA
  evidence pqc: SLH-DSA KeyPairGenerator available: false

• Public key formats

  spki-der

  Public keys load from X.509 SPKI DER; getEncoded() returns the same form.

  Recorded by the check

  fact public-key-formats = spki-der
  evidence public-key-formats: getEncoded() of 256-bit key returns X.509 SPKI DER; format X.509

• Private key formats

  pkcs8-derraw-scalar

  Private keys load from PKCS#8 DER and from the raw scalar with ECPrivateKeySpec.

  Recorded by the check

  fact private-key-formats = pkcs8-der, raw-scalar

• PEM API

  preview

  java.security.PEMDecoder exists as a preview API (JEP 470) and decoded a PEM public key only with --enable-preview.

  Recorded by the check

  fact pem-api = preview
  evidence pem-api: java.security.PEMDecoder present: true (JEP 470, preview in JDK 25; needs --enable-preview)
  evidence pem-api: PEMDecoder.of().decode(PEM text) with --enable-preview: true

Usage

import java.nio.charset.StandardCharsets;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.Signature;
import java.security.spec.ECGenParameterSpec;

public class Usage {
    public static void main(String[] args) throws Exception {
        KeyPairGenerator generator = KeyPairGenerator.getInstance("EC");
        generator.initialize(new ECGenParameterSpec("secp256r1"));
        KeyPair pair = generator.generateKeyPair();
        byte[] message = "order #1042 approved".getBytes(StandardCharsets.UTF_8);

        // The algorithm name picks the hash AND the encoding:
        // SHA256withECDSA = DER, SHA256withECDSAinP1363Format = raw r||s (JWS, WebCrypto).
        Signature signer = Signature.getInstance("SHA256withECDSAinP1363Format");
        signer.initSign(pair.getPrivate());
        signer.update(message);
        byte[] raw = signer.sign();

        Signature verifier = Signature.getInstance("SHA256withECDSAinP1363Format");
        verifier.initVerify(pair.getPublic());
        verifier.update(message);
        System.out.println("raw bytes: " + raw.length + ", verified: " + verifier.verify(raw));
    }
}