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C# RSA加密

news 来源：原创 2025/5/17 6:43:53

项目需要对接Java的接口，一些参数需要用到Rsa加密，经过多次尝试，该工具类可以跟Java的接口正确解析，在此记录一下，后面会附上Java的代码。

C# RSA工具类代码：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
using static System.Runtime.InteropServices.JavaScript.JSType;namespace Tools
{public class RSAHelper{public static string PubEncrypt1(string pubKey, string src){try{using (RSA rsa = RSA.Create()){// 导入公钥（PEM 格式或 XML 格式）//ImportPublicKey(rsa, pubKey);var pub = pubKey.Replace("-----BEGIN PUBLIC KEY-----", "").Replace("-----END PUBLIC KEY-----", "");rsa.ImportSubjectPublicKeyInfo(Convert.FromBase64String(pub), out _); byte[] dataToEncrypt = Encoding.UTF8.GetBytes(src);//int keySize = rsa.KeySize / 8; // in bytes//int blockSize = keySize - 42; // 最大明文长度（OAEP SHA256）= keySize - 2 * hashLength = 256 - 2*32 = 192int chunkSize = 117; // Java 示例中使用的是 117 字节，对应 1024 bit 密钥 + SHA-256 OAEPbyte[] encryptedData;using (var memoryStream = new MemoryStream()){int offset = 0;while (offset < dataToEncrypt.Length){int remaining = dataToEncrypt.Length - offset;int blockLen = Math.Min(chunkSize, remaining);byte[] block = new byte[blockLen];Array.Copy(dataToEncrypt, offset, block, 0, blockLen);byte[] encryptedBlock = rsa.Encrypt(block, RSAEncryptionPadding.OaepSHA256);memoryStream.Write(encryptedBlock, 0, encryptedBlock.Length);offset += blockLen;}encryptedData = memoryStream.ToArray();}return Convert.ToBase64String(encryptedData);}}catch (Exception ex){Console.WriteLine("加密失败：" + ex.Message);throw;}}}
}

Java那边的部分代码：

public class Encryption {private static final int MAX_ENCRYPT_BLOCK = 117;public static String symEncrypt(String strkey, String src) throws Exception {String target = null;try {Key key = KeysFactory.getSymKey(strkey);Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");IvParameterSpec iv = new IvParameterSpec(strkey.substring(0, 16).getBytes());cipher.init(1, key, iv);byte[] encodeResult = cipher.doFinal(src.getBytes(StandardCharsets.UTF_8));target = Base64Util.encryptBASE64(encodeResult);return target;} catch (NoSuchPaddingException | UnsupportedEncodingException | InvalidKeyException | IllegalBlockSizeException| BadPaddingException | NoSuchAlgorithmException var7) {Logger.error(var7);throw new Exception("加密失败" + var7.getMessage());}}public static String pubEncrypt(String pubKey, String src) throws Exception {String target = null;ByteArrayOutputStream out = null;try {Key key = KeysFactory.getPublicKey(pubKey);Cipher cipher = Cipher.getInstance("RSA/ECB/OAEPWithSHA-256AndMGF1Padding");cipher.init(1, key,new OAEPParameterSpec("SHA-256", "MGF1", new MGF1ParameterSpec("SHA-256"), PSpecified.DEFAULT));byte[] data = src.getBytes();int inputLen = data.length;out = new ByteArrayOutputStream();int offSet = 0;for (int i = 0; inputLen - offSet > 0; offSet = i * 117) {byte[] cache;if (inputLen - offSet > 117) {cache = cipher.doFinal(data, offSet, 117);} else {cache = cipher.doFinal(data, offSet, inputLen - offSet);}out.write(cache, 0, cache.length);++i;}target = Base64Util.encryptBASE64(out.toByteArray());} catch (NoSuchPaddingException | InvalidKeyException | IllegalBlockSizeException | BadPaddingException| NoSuchAlgorithmException var14) {Logger.error(var14);throw new Exception("加密失败" + var14.getMessage());} finally {if (out != null) {out.close();}}return target;}
}