1.1
keytool -genkey -keystore chinaJavaworld.keystore -alias chinajavaworld
这个命令用来产生一个密匙库，执行完毕后会在当前操作目录中产生一个chinajavaworld.keystore的文件，在执行命令的时候还有提示你输入密匙库的密码，要记住，后面还要用到。
2. 1
keytool -export -keystore chinajavaworld.keystore
-alias chinajavaworld -file chinajavaworld.cer
这个命令用来产生签名时所要用的证书。
3.在JAVA里操作，将Cer内容改为BASE64编码
123456789
//从密钥库中读取CA证书
String storepass = "123456";
//前面设置的密码
FileInputStream in = new FileInputStream("e:\\license\\a\\chinajavaworld.keystore"); KeyStore ks = KeyStore.getInstance("JKS"); ks.load(in, storepass.toCharArray());
//获取证书 java.security.cert.Certificate c1 = ks.getCertificate("chinajavaworld");
//BASE64编码 System.out.println(StringUtils.encodeBase64(c1.getEncoded()));
//将chinajavaworld.cer内容改为这里输出的内容
4.开始产生（测试）签名
123456789101112131415161718192021222324252627282930313233343536373839
Signature signature;
try {
InputStream streamCert = new java.io.FileInputStream( "e:\\license\\a\\test.cer");
CertificateFactory factory = CertificateFactory.getInstance("X.509");
Certificate cert = factory.generateCertificate(streamCert);
System.out.println(StringUtils.encodeBase64(cert.getEncoded()));
signature = Signature.getInstance("SHA1withDSA");
signature.initVerify(cert.getPublicKey());
//要签名的指纹内容
String sss = "Welcome to ,The java world for you forever.";
//获取CA证书私钥
PrivateKey priKey=(PrivateKey)ks.getKey("test",storepass.toCharArray());
System.out.println("priKey:"+StringUtils.encodeHex(priKey.getEncoded()));
//用私钥签名
sig = Signature.getInstance("SHA1withDSA");
sig.initSign(priKey);
ByteArrayOutputStream streamRaw0 = new ByteArrayOutputStream();
DataOutputStream streamSig0 = new DataOutputStream(streamRaw0);
streamSig0.writeUTF(sss); sig.update(streamRaw0.toByteArray());
String signatureS = StringUtils.encodeHex(sig.sign());
System.out.println("signature: "+signatureS);
//用公钥做验证测试
System.out.println("pubKey:"+StringUtils.encodeHex(cert.getPublicKey().getEncoded()));
ByteArrayOutputStream streamRaw = new ByteArrayOutputStream();
DataOutputStream streamSig = new DataOutputStream(streamRaw);
streamSig.writeUTF(sss); signature.update(streamRaw.toByteArray());
System.out.println("verify: "+signature.verify(StringUtils.decodeHex(signatureS)));
} catch(Exception e)
{
System.out.println(e);
}
接下来，你就可以把chinajavaworld.cer和签名放在你的产品目录里了。认证的时候读取cer证书中的公钥，对签名内容进行认证就可以了。
附
public static String encodeBase64(byte data[]) {
boolean lineSep = false;
int sLen = data == null ? 0 : data.length;
(sLen == 0) return new String("");
int eLen = (sLen / 3) * 3;
int cCnt = (sLen - 1) / 3 + 1 << 2;
int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0);
char dArr[] = new char[dLen];
int s = 0;
int d = 0;
int cc = 0;
do {
if(s >= eLen)
break;
int i = (data[s++] & 0xff) << 16 | (data[s++] & 0xff) << 8 | data[s++] & 0xff;
dArr[d++] = CA[i >>> 18 & 0x3f];
dArr[d++] = CA[i >>> 12 & 0x3f];
dArr[d++] = CA[i >>> 6 & 0x3f];
dArr[d++] = CA[i & 0x3f];
if(lineSep && ++cc == 19 && d < dLen - 2)
{ dArr[d++] = '\r';
dArr[d++] = '\n';
cc = 0;
}
} while(true);
int left = sLen - eLen;
if(left > 0)
{ int i = (data[eLen] & 0xff) << 10 | (left != 2 ? 0 : (data[sLen - 1] & 0xff) << 2);
dArr[dLen - 4] = CA[i >> 12]; dArr[dLen - 3] = CA[i >>> 6 & 0x3f];
dArr[dLen - 2] = left != 2 ? '=' : CA[i & 0x3f]; dArr[dLen - 1] = '=';
} return new String(dArr);
}
public static final String encodeHex(byte bytes[])
{ StringBuffer buf = new StringBuffer(bytes.length * 2);
for(int i = 0; i < bytes.length; i++) {
if((bytes[i] & 0xff) < 16) buf.append("0");
buf.append(Long.toString(bytes[i] & 0xff, 16));
} return buf.toString();
}
public static final byte[] decodeHex(String hex) {
char chars[] = hex.toCharArray();
byte bytes[] = new byte[chars.length / 2];
int byteCount = 0;
for(int i = 0; i < chars.length; i += 2) {
int newByte = 0;
newByte |= hexCharToByte(chars[i]);
newByte <<= 4;
newByte |= hexCharToByte(chars[i + 1]);
bytes[byteCount] = (byte)newByte; byteCount++; } return bytes; }