Java tutorial
package org.bouncycastle.crypto.params; import java.io.EOFException; import java.io.IOException; import java.io.InputStream; import java.security.SecureRandom; import org.bouncycastle.math.ec.rfc8032.Ed448; import org.bouncycastle.util.Arrays; import org.bouncycastle.util.io.Streams; public final class Ed448PrivateKeyParameters extends AsymmetricKeyParameter { public static final int KEY_SIZE = Ed448.SECRET_KEY_SIZE; public static final int SIGNATURE_SIZE = Ed448.SIGNATURE_SIZE; private final byte[] data = new byte[KEY_SIZE]; public Ed448PrivateKeyParameters(SecureRandom random) { super(true); Ed448.generatePrivateKey(random, data); } public Ed448PrivateKeyParameters(byte[] buf, int off) { super(true); System.arraycopy(buf, off, data, 0, KEY_SIZE); } public Ed448PrivateKeyParameters(InputStream input) throws IOException { super(true); if (KEY_SIZE != Streams.readFully(input, data)) { throw new EOFException("EOF encountered in middle of Ed448 private key"); } } public void encode(byte[] buf, int off) { System.arraycopy(data, 0, buf, off, KEY_SIZE); } public byte[] getEncoded() { return Arrays.clone(data); } public Ed448PublicKeyParameters generatePublicKey() { byte[] publicKey = new byte[Ed448.PUBLIC_KEY_SIZE]; Ed448.generatePublicKey(data, 0, publicKey, 0); return new Ed448PublicKeyParameters(publicKey, 0); } public void sign(int algorithm, Ed448PublicKeyParameters publicKey, byte[] ctx, byte[] msg, int msgOff, int msgLen, byte[] sig, int sigOff) { byte[] pk = new byte[Ed448.PUBLIC_KEY_SIZE]; if (null == publicKey) { Ed448.generatePublicKey(data, 0, pk, 0); } else { publicKey.encode(pk, 0); } switch (algorithm) { case Ed448.Algorithm.Ed448: { Ed448.sign(data, 0, pk, 0, ctx, msg, msgOff, msgLen, sig, sigOff); break; } case Ed448.Algorithm.Ed448ph: { if (Ed448.PREHASH_SIZE != msgLen) { throw new IllegalArgumentException("msgLen"); } Ed448.signPrehash(data, 0, pk, 0, ctx, msg, msgOff, sig, sigOff); break; } default: { throw new IllegalArgumentException("algorithm"); } } } }