原文地址：https://www.cnblogs.com/hvaning/p/3636288.html
RSA算法在C#与JAVA之前的交互
在JAVA生成一对RSA私钥和公钥的时候，是以下的形式给到C#去调用：
string publickey = @"MIGfMA0GCSqGSIb4DQEBAQUAA4GNADCBiQKBgQC/M9kJVwi+sO672NBm5fAEbUEl2PqRFuYZVB5ZrKah7eJPP0pKBe/eoA6pOMsjnKFoZGVizz7oCt+TJ+1fpuScn7vAtIFSjn1jgPANE+IcVdk4QKDFKu0LQdiurPQKLpq8Q3wJDAW7FxB2MHw/4ca/9w0N5VL0hQegZ4YhxDss6QIDAQABprivateKey";
string privatekey = @"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";
但是，在C#的，私钥和公钥的格式不是这样的，那应该怎么把JAVA转换成C#需要的格式呢？
C#中需要的密钥是如下格式：
string privatekey = @"<RSAKeyValue><Modulus>vzPZCVcIvrDuu0jQZuXwBG1BJdj6kRbmGVQeWaymoe3iTz9KSgXv3qAOqTjLI5yhaGRlYs8+6ArfkyftX6bknJ+7wLSBUo59Y4DwDRPiHFXZOECgxSrtC0HYrqz0Ci6avEN8CQwFuxcQdjB8P+HGv/cNDeVS9IUHoGeGIcQ7LOk=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>";
string privatekey = @"<RSAKeyValue><Modulus>vzPZCVcIvrDuu1jQZuXwBG1BJdj6kRbmGVQeWaymoe3iTz9KSgXv3qAOqTjLI5yhaGRlYs8+6ArfkyftX6bknJ+7wLSBUo59Y4DwDRPiHFXZOECgxSrtC0HYrqz0Ci6avEN8CQwFuxcQdjB8P+HGv/cNDeVS9IUHoGeGIcQ7LOk=</Modulus><Exponent>AQAB</Exponent><P>81Hqu5RXCBOLloURr3lRYzQBrkrFvqvRjsDu7UuWMLgCENjPl4GBkRaPMTAulf/Un6ibZklNc5O9qTJWLnyKhw==</P><Q>ySqkcKbWuobq5I9KSQISq2qCuGKtj/iUFho4PCD1YxhnQ7gcHA4OpS1dRFjtXJYQPTX9be+mmypsCFIyofE5Dw==</Q><DP>8ZnbTBqFOH2/0tuarfP2flx7dsbEBwmwcODd3T16ijGLy5KcvkFXl+sgj6TZ/RMj2syeUThj8Wk3n7Ndo5cCLQ==</DP><DQ>rNwKn46Nt4yVrT7/y0qPtmJ4325TzAIDZhazud9sXPGsUoGTDfx6Uy9vFHsBw+xjGeYZ1mz3EiBa4q+XOJbquw==</DQ><InverseQ>i90WdnZVPxtSTqkkLYbnh4Ro2WhdwRjkfyBxBZZx8hfaM6MfLPi3A0rw9DPOSB4M/BMchtEh3bXuI7bue2tG+A==</InverseQ><D>ol/9qRjorEjF9XEjSr9rHddKxEGIST8RGeF+BNnCiTHkRziQdlykYIO876jzmsKhsG3STB+EZLsXM3ls9RZefcsPF5mLOCSOCow3DikfCtAy4hntsU9JwpuYE0V4A+Sgfd24fatqbu+JxE2nvpSbAPczDOgBFPNfYBkhMiuZ/iE=</D></RSAKeyValue>";
由于密钥是用在正式使用中，所以以上给的只是一个形式。
既然这对密钥是从JAVA来的，那么，就必须到JAVA中去处理成C#的格式。
就算不会JAVA的新手都可以转换的，只需要把以下的代码添加进eclipse中就可以了，具体的怎么建java工程就自己去查一下。
把上面一对密钥转成C#中格式的密钥在JAVA中的转换代码如下：
package com;
import java.security.KeyFactory;
import java.security.PublicKey;
import java.security.interfaces.RSAPrivateCrtKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
//import org.castor.util.Base64Decoder;
//import org.castor.util.Base64Encoder;
public class test {
public static void main(String[] args)
{
String tes="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";
byte[] temp=b64decode(tes);
String ver=getRSAPrivateKeyAsNetFormat(temp);//转换私钥
String tes1="MIGfMA0GCSqGSIb4DQEBAQUAA4GNADCBiQKBgQC/M9kJVwi+sO672NBm5fAEbUEl2PqRFuYZVB5ZrKah7eJPP0pKBe/eoA6pOMsjnKFoZGVizz7oCt+TJ+1fpuScn7vAtIFSjn1jgPANE+IcVdk4QKDFKu0LQdiurPQKLpq8Q3wJDAW7FxB2MHw/4ca/9w0N5VL0hQegZ4YhxDss6QIDAQAB";
byte[] temp1=b64decode(tes1);
String ver1=getRSAPublicKeyAsNetFormat(temp1);//转换公钥
//String temp2= encodePublicKeyToXml(temp1);
}
private static String getRSAPrivateKeyAsNetFormat(byte[] encodedPrivkey) {
try {
StringBuffer buff = new StringBuffer(1024);
PKCS8EncodedKeySpec pvkKeySpec = new PKCS8EncodedKeySpec(
encodedPrivkey);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPrivateCrtKey pvkKey = (RSAPrivateCrtKey) keyFactory
.generatePrivate(pvkKeySpec);
buff.append("<RSAKeyValue>");
buff.append("<Modulus>"
+ b64encode(removeMSZero(pvkKey.getModulus().toByteArray()))
+ "</Modulus>");
buff.append("<Exponent>"
+ b64encode(removeMSZero(pvkKey.getPublicExponent()
.toByteArray())) + "</Exponent>");
buff.append("<P>"
+ b64encode(removeMSZero(pvkKey.getPrimeP().toByteArray()))
+ "</P>");
buff.append("<Q>"
+ b64encode(removeMSZero(pvkKey.getPrimeQ().toByteArray()))
+ "</Q>");
buff.append("<DP>"
+ b64encode(removeMSZero(pvkKey.getPrimeExponentP()
.toByteArray())) + "</DP>");
buff.append("<DQ>"
+ b64encode(removeMSZero(pvkKey.getPrimeExponentQ()
.toByteArray())) + "</DQ>");
buff.append("<InverseQ>"
+ b64encode(removeMSZero(pvkKey.getCrtCoefficient()
.toByteArray())) + "</InverseQ>");
buff.append("<D>"
+ b64encode(removeMSZero(pvkKey.getPrivateExponent()
.toByteArray())) + "</D>");
buff.append("</RSAKeyValue>");
return buff.toString().replaceAll("[ \t\n\r]", "");
} catch (Exception e) {
System.err.println(e);
return null;
}
}
private static String getRSAPublicKeyAsNetFormat(byte[] encodedPrivkey) {
try {
StringBuffer buff = new StringBuffer(1024);
PKCS8EncodedKeySpec pvkKeySpec = new PKCS8EncodedKeySpec(encodedPrivkey);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPublicKey pukKey=(RSAPublicKey) keyFactory.generatePublic(new X509EncodedKeySpec(encodedPrivkey));
// RSAPrivateCrtKey pvkKey = (RSAPrivateCrtKey) keyFactory.generatePrivate(pvkKeySpec);
//PublicKey publicKey =KeyFactory.getInstance("RSA").generatePublic(pvkKeySpec);
buff.append("<RSAKeyValue>");
buff.append("<Modulus>"
+ b64encode(removeMSZero(pukKey.getModulus().toByteArray()))
+ "</Modulus>");
buff.append("<Exponent>"
+ b64encode(removeMSZero(pukKey.getPublicExponent()
.toByteArray())) + "</Exponent>");
buff.append("</RSAKeyValue>");
return buff.toString().replaceAll("[ \t\n\r]", "");
} catch (Exception e) {
System.err.println(e);
return null;
}
}
public static String encodePublicKeyToXml(PublicKey key) {
if (!RSAPublicKey.class.isInstance(key)) {
return null;
}
RSAPublicKey pubKey = (RSAPublicKey) key;
StringBuilder sb = new StringBuilder();
sb.append("<RSAKeyValue>");
sb.append("<Modulus>")
.append(Base64.encode(pubKey.getModulus().toByteArray()))
.append("</Modulus>");
sb.append("<Exponent>")
.append(Base64.encode(pubKey.getPublicExponent()
.toByteArray())).append("</Exponent>");
sb.append("</RSAKeyValue>");
return sb.toString();
}
private static byte[] removeMSZero(byte[] data) {
byte[] data1;
int len = data.length;
if (data[0] == 0) {
data1 = new byte[data.length - 1];
System.arraycopy(data, 1, data1, 0, len - 1);
} else
data1 = data;
return data1;
}
private static String b64encode(byte[] data) {
String b64str = new String(Base64.encode(data));
return b64str;
}
private static byte[] b64decode(String data) {
byte[] decodeData = Base64.decode(data);
return decodeData;
}
}
到此，JAVA的密钥对，就可以转换成C#中的格式的密钥对了！
