Composite Provider 1.0

The IETF is working on the specification of key formats and algorithm identifiers for using PQ algorithms in X.509 certificates and IETF based protocols like TLS, CMS or S/MIME. Although drafts of key and algorithm identifier specifications already exist they are also subject to change.

Online Javadoc for IAIK-COMPOSITE PROVIDER

Since implemented as JCA Provider, the JCA Signature API can be used for calculating/verfiying composite signatures:

1. Use a JCA KeyPairGenerator to generate a composite key pair
2. Use a JCA Signature enngine to calculate a composite signature value for a message with the composite private key
3. Use a JCA Signature enngine to verify the composite signature value with the composite public key

The following example demonsrates key pair generation, signature calculation and signature verification for the MLDSA65-ECDSA-P256-SHA512 signature algorithm:

 // generate key pair
 KeyPairGenerator kpq = KeyPairGenerator.getInstance("MLDSA65-ECDSA-P256-SHA512", IaikComposite.getInstance());
 KeyPair kp = kpq.generateKeyPair();
 PublicKey publicKey = kp.getPublic();
 PrivateKey privateKey = kp.getPrivate();
 
 // the data to be signed
 byte[] data = ...;
 
 // create a Signature engine and initialize it with the private key for signing
 Signature signature = Signature.getInstance("MLDSA65-ECDSA-P256-SHA512", IaikComposite.getInstance());
 signature.initSign(privateKey);

 // update the Signature engine with the data
 signature.update(data);
 
 // calculate the signature value
 byte[] sigVal = signature.sign();

 // create a Signature engine and initialize it with the public key for verification
 Signature sigVer = Signature.getInstance("MLDSA65-ECDSA-P256-SHA512", IaikComposite.getInstance());
 // initialize the Signature engine for verification
 sigVer.initVerify(publicKey);

 // update the Signature engine with the data
 signVer.update(data);

 // verify the signature value 
 boolean valid = sigVer.verify(sigVal);

In some environments it might be appropriate to calcualte the message digest from the message outside the Signature engine and then let the Signature engine calculate the signature value from the calculated hash value. For that purpose you can use a “raw” (e.g. NONEwithMLDSA65-ECDSA-P256-SHA512) Signature engine:

 // generate key pair
 KeyPairGenerator kpq = KeyPairGenerator.getInstance("MLDSA65-ECDSA-P256-SHA512", IaikComposite.getInstance());
 KeyPair kp = kpq.generateKeyPair();
 PublicKey publicKey = kp.getPublic();
 PrivateKey privateKey = kp.getPrivate();
 
 // the data to be signed
 byte[] data = ...;
  
 // calculate the hash value outside the Signature engine
 MessageDigest md = MessageDigest.getInstance("SHA-512");
 md.update(data);
 byte[] digest = md.digest();
 
 // create a raw Signature engine and initialize it for signing
 Signature signature = Signature.getInstance("NONEwithMLDSA65-ECDSA-P256-SHA512", IaikComposite.getInstance());
 signature.initSign(privateKey);

 // update the Signature engine with the externally calculated digest value 
 signature.update(digest);
 
 // calculate the signature value
 byte[] sigVal = signature.sign();

 // create a raw Signature engine and initialize it with the public key for verification
 Signature sigVer = Signature.getInstance("NONEwithMLDSA65-ECDSA-P256-SHA512", IaikComposite.getInstance());
 // initialize the Signature engine for verification
 sigVer.initVerify(publicKey);

 // update the Signature engine with the externally calculated digest value 
 sigVer.update(digest);

 // verify the signature value 
 boolean valid = sigVer.verify(sigVal);