Bouncy Castle (Java)

Facts and the checks behind them

Nothing below is copied from documentation. The check content/libraries/verify/bouncy-castle-java/run.sh ran Bouncy Castle (Java) 1.86 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 DER; SHA256withPLAIN-ECDSA returns 64 bytes of raw r‖s.

  Recorded by the check

  fact ecdsa-signature-encoding = der
  evidence ecdsa-signature-encoding: SHA256withPLAIN-ECDSA output is 64 bytes, parses as DER: false

• ECDSA nonce

  rfc6979-opt-in

  Random by default; SHA256withECDDSA gave identical signatures for the same input, and ECDSASigner with HMacDSAKCalculator reproduced RFC 6979 appendix A.2.5.

  Recorded by the check

  fact ecdsa-nonce = rfc6979-opt-in
  evidence ecdsa-nonce: SHA256withECDSA repeats: false; ECDSASigner with HMacDSAKCalculator reproduces RFC 6979 A.2.5: true; SHA256withECDDSA repeats: true

• 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; NONEwithECDSA signs a digest, and that signature verified against the message.

  Recorded by the check

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

• Malformed ECDSA signature

  throws

  A raw r‖s signature and a 3-byte blob passed to SHA256withECDSA throw SignatureException.

  Recorded by the check

  fact ecdsa-malformed-signature = throws
  evidence ecdsa-malformed-signature: raw r||s to SHA256withECDSA: throws SignatureException; 3 bytes: throws SignatureException

• ECDSA curves

  P-224P-256P-384P-521secp256k1brainpoolP256r1brainpoolP384r1brainpoolP512r1

  P-224, P-256, P-384, P-521, secp256k1 and brainpoolP256r1/P384r1/P512r1 signed and verified.

  Recorded by the check

  fact ecdsa-curves = P-224, P-256, P-384, P-521, secp256k1, brainpoolP256r1, brainpoolP384r1, brainpoolP512r1

• EdDSA

  Ed25519Ed448

  Ed25519 and Ed448.

  Recorded by the check

  fact eddsa = Ed25519, Ed448

• Post-quantum algorithms

  ML-KEMML-DSASLH-DSAFalconLMSXMSS

  ML-KEM (through javax.crypto.KEM), ML-DSA, SLH-DSA and LMS in the BC provider, Falcon and XMSS in BCPQC, all round-tripped in the check.

  Recorded by the check

  fact pqc = ML-KEM, ML-DSA, SLH-DSA, Falcon, LMS, XMSS

• Public key formats

  spki-pemspki-der

  Public keys read from SPKI PEM through PEMParser and from SPKI DER.

  Recorded by the check

  fact public-key-formats = spki-pem, spki-der

• Private key formats

  pkcs8-dersec1-pem

  JcaPEMWriter writes EC private keys as SEC1 PEM (EC PRIVATE KEY), which PEMParser reads as a PEMKeyPair; PKCS#8 DER loads through the JCA.

  Recorded by the check

  fact private-key-formats = pkcs8-der, sec1-pem
  evidence private-key-formats: JcaPEMWriter writes an EC private key as -----BEGIN EC PRIVATE KEY-----; PEMParser returns PEMKeyPair

Usage

import java.nio.charset.StandardCharsets;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.Security;
import java.security.Signature;
import java.security.spec.ECGenParameterSpec;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

public class Usage {
    public static void main(String[] args) throws Exception {
        Security.addProvider(new BouncyCastleProvider());
        // secp256k1 is not in the JDK's SunEC; it is in BC.
        KeyPairGenerator generator = KeyPairGenerator.getInstance("EC", "BC");
        generator.initialize(new ECGenParameterSpec("secp256k1"));
        KeyPair pair = generator.generateKeyPair();
        byte[] message = "order #1042 approved".getBytes(StandardCharsets.UTF_8);

        // ECDDSA = deterministic ECDSA (RFC 6979); PLAIN-ECDSA = raw r||s instead of DER.
        Signature signer = Signature.getInstance("SHA256withECDDSA", "BC");
        signer.initSign(pair.getPrivate());
        signer.update(message);
        byte[] der = signer.sign();

        Signature verifier = Signature.getInstance("SHA256withECDSA", "BC");
        verifier.initVerify(pair.getPublic());
        verifier.update(message);
        System.out.println("verified: " + verifier.verify(der) + ", DER starts with 0x" + Integer.toHexString(der[0] & 0xff));
    }
}