数字签名算法ECDSA

package signature;

import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.SignatureException;
import java.security.interfaces.ECPrivateKey;
import java.security.interfaces.ECPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

public class ECDSA {

private static String src = "何芳";
public static void main(String[] args) {
ecdsaj();
}

public static void ecdsaj(){

try {
//初始化秘钥
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("EC");
keyPairGenerator.initialize(256);
KeyPair keyPair = keyPairGenerator.generateKeyPair();
ECPublicKey ecPublicKey = (ECPublicKey) keyPair.getPublic();
ECPrivateKey ecPrivateKey = (ECPrivateKey) keyPair.getPrivate();

//执行签名
PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(ecPrivateKey.getEncoded());
KeyFactory keyFactory = KeyFactory.getInstance("EC");
PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
Signature signature = Signature.getInstance("SHA1withECDSA");
signature.initSign(privateKey);
signature.update(src.getBytes());
byte[] result = signature.sign();
System.out.println("jdk ECDSA 签名：" + result);

//验证签名
X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(ecPublicKey.getEncoded());
keyFactory = KeyFactory.getInstance("EC");
PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
signature = Signature.getInstance("SHA1withECDSA");
signature.initVerify(publicKey);
signature.update(src.getBytes());
boolean bool = signature.verify(result);
System.out.println("jdk ECDSA 签名：" + bool);

} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (InvalidKeySpecException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (SignatureException e) {
e.printStackTrace();
}

}
}

//很无奈，我这里报错，我用的是jdk6的版本，据说要7的第四个版本上才能使用

有人知道是这样的吗？如果你用7版本以上的成功了，请留下你的足迹，谢谢！

java.security.NoSuchAlgorithmException: EC KeyPairGenerator not available

at java.security.KeyPairGenerator.getInstance(Unknown Source)

at signature.ECDSA.ecdsaj(ECDSA.java:31)

at signature.ECDSA.main(ECDSA.java:23)