327 lines
10 KiB
C#
327 lines
10 KiB
C#
using System;
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using System.Collections.Generic;
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using System.IO;
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using System.Linq;
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using System.Security.Cryptography;
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using System.Text;
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using System.Text.RegularExpressions;
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using System.Threading.Tasks;
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namespace System
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{
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public class RSA_PEM
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{
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/// <summary>
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/// 用PEM格式密钥对创建RSA，支持PKCS#1、PKCS#8格式的PEM
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/// </summary>
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public static RSACryptoServiceProvider FromPEM(string pem)
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{
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var rsaParams = new CspParameters();
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rsaParams.Flags = CspProviderFlags.UseMachineKeyStore;
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var rsa = new RSACryptoServiceProvider(rsaParams);
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var param = new RSAParameters();
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var base64 = _PEMCode.Replace(pem, "");
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var data = RSA_Unit.Base64DecodeBytes(base64);
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if (data == null)
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{
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throw new Exception("PEM内容无效");
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}
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var idx = 0;
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//读取长度
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Func<byte, int> readLen = (first) => {
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if (data[idx] == first)
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{
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idx++;
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if (data[idx] == 0x81)
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{
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idx++;
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return data[idx++];
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}
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else if (data[idx] == 0x82)
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{
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idx++;
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return (((int)data[idx++]) << 8) + data[idx++];
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}
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else if (data[idx] < 0x80)
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{
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return data[idx++];
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}
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}
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throw new Exception("PEM未能提取到数据");
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};
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//读取块数据
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Func<byte[]> readBlock = () => {
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var len = readLen(0x02);
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if (data[idx] == 0x00)
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{
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idx++;
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len--;
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}
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var val = data.sub(idx, len);
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idx += len;
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return val;
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};
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//比较data从idx位置开始是否是byts内容
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Func<byte[], bool> eq = (byts) => {
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for (var i = 0; i < byts.Length; i++, idx++)
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{
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if (idx >= data.Length)
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{
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return false;
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}
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if (byts[i] != data[idx])
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{
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return false;
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}
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}
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return true;
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};
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if (pem.Contains("PUBLIC KEY"))
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{
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/****使用公钥****/
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//读取数据总长度
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readLen(0x30);
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if (!eq(_SeqOID))
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{
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throw new Exception("PEM未知格式");
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}
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//读取1长度
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readLen(0x03);
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idx++;//跳过0x00
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//读取2长度
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readLen(0x30);
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//Modulus
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param.Modulus = readBlock();
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//Exponent
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param.Exponent = readBlock();
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}
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else if (pem.Contains("PRIVATE KEY"))
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{
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/****使用私钥****/
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//读取数据总长度
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readLen(0x30);
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//读取版本号
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if (!eq(_Ver))
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{
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throw new Exception("PEM未知版本");
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}
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//检测PKCS8
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var idx2 = idx;
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if (eq(_SeqOID))
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{
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//读取1长度
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readLen(0x04);
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//读取2长度
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readLen(0x30);
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//读取版本号
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if (!eq(_Ver))
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{
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throw new Exception("PEM版本无效");
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}
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}
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else
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{
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idx = idx2;
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}
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//读取数据
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param.Modulus = readBlock();
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param.Exponent = readBlock();
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param.D = readBlock();
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param.P = readBlock();
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param.Q = readBlock();
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param.DP = readBlock();
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param.DQ = readBlock();
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param.InverseQ = readBlock();
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}
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else
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{
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throw new Exception("pem需要BEGIN END标头");
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}
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rsa.ImportParameters(param);
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return rsa;
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}
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static private Regex _PEMCode = new Regex(@"--+.+?--+|\s+");
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static private byte[] _SeqOID = new byte[] { 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00 };
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static private byte[] _Ver = new byte[] { 0x02, 0x01, 0x00 };
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/// <summary>
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/// 将RSA中的密钥对转换成PEM格式，usePKCS8=false时返回PKCS#1格式，否则返回PKCS#8格式，如果convertToPublic含私钥的RSA将只返回公钥，仅含公钥的RSA不受影响
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/// </summary>
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public static string ToPEM(RSACryptoServiceProvider rsa, bool convertToPublic, bool usePKCS8)
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{
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//https://www.jianshu.com/p/25803dd9527d
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//https://www.cnblogs.com/ylz8401/p/8443819.html
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//https://blog.csdn.net/jiayanhui2877/article/details/47187077
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//https://blog.csdn.net/xuanshao_/article/details/51679824
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//https://blog.csdn.net/xuanshao_/article/details/51672547
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var ms = new MemoryStream();
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//写入一个长度字节码
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Action<int> writeLenByte = (len) => {
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if (len < 0x80)
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{
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ms.WriteByte((byte)len);
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}
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else if (len <= 0xff)
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{
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ms.WriteByte(0x81);
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ms.WriteByte((byte)len);
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}
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else
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{
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ms.WriteByte(0x82);
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ms.WriteByte((byte)(len >> 8 & 0xff));
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ms.WriteByte((byte)(len & 0xff));
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}
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};
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//写入一块数据
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Action<byte[]> writeBlock = (byts) => {
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var addZero = (byts[0] >> 4) >= 0x8;
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ms.WriteByte(0x02);
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var len = byts.Length + (addZero ? 1 : 0);
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writeLenByte(len);
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if (addZero)
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{
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ms.WriteByte(0x00);
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}
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ms.Write(byts, 0, byts.Length);
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};
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//根据后续内容长度写入长度数据
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Func<int, byte[], byte[]> writeLen = (index, byts) => {
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var len = byts.Length - index;
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ms.SetLength(0);
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ms.Write(byts, 0, index);
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writeLenByte(len);
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ms.Write(byts, index, len);
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return ms.ToArray();
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};
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if (rsa.PublicOnly || convertToPublic)
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{
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/****生成公钥****/
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var param = rsa.ExportParameters(false);
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//写入总字节数，不含本段长度，额外需要24字节的头，后续计算好填入
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ms.WriteByte(0x30);
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var index1 = (int)ms.Length;
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//固定内容
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// encoded OID sequence for PKCS #1 rsaEncryption szOID_RSA_RSA = "1.2.840.113549.1.1.1"
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ms.writeAll(_SeqOID);
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//从0x00开始的后续长度
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ms.WriteByte(0x03);
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var index2 = (int)ms.Length;
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ms.WriteByte(0x00);
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//后续内容长度
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ms.WriteByte(0x30);
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var index3 = (int)ms.Length;
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//写入Modulus
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writeBlock(param.Modulus);
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//写入Exponent
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writeBlock(param.Exponent);
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//计算空缺的长度
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var byts = ms.ToArray();
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byts = writeLen(index3, byts);
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byts = writeLen(index2, byts);
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byts = writeLen(index1, byts);
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return "-----BEGIN PUBLIC KEY-----\n" + RSA_Unit.TextBreak(RSA_Unit.Base64EncodeBytes(byts), 64) + "\n-----END PUBLIC KEY-----";
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}
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else
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{
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/****生成私钥****/
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var param = rsa.ExportParameters(true);
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//写入总字节数，后续写入
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ms.WriteByte(0x30);
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int index1 = (int)ms.Length;
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//写入版本号
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ms.writeAll(_Ver);
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//PKCS8 多一段数据
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int index2 = -1, index3 = -1;
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if (usePKCS8)
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{
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//固定内容
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ms.writeAll(_SeqOID);
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//后续内容长度
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ms.WriteByte(0x04);
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index2 = (int)ms.Length;
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//后续内容长度
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ms.WriteByte(0x30);
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index3 = (int)ms.Length;
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//写入版本号
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ms.writeAll(_Ver);
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}
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//写入数据
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writeBlock(param.Modulus);
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writeBlock(param.Exponent);
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writeBlock(param.D);
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writeBlock(param.P);
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writeBlock(param.Q);
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writeBlock(param.DP);
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writeBlock(param.DQ);
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writeBlock(param.InverseQ);
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//计算空缺的长度
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var byts = ms.ToArray();
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if (index2 != -1)
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{
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byts = writeLen(index3, byts);
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byts = writeLen(index2, byts);
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}
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byts = writeLen(index1, byts);
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var flag = " PRIVATE KEY";
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if (!usePKCS8)
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{
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flag = " RSA" + flag;
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}
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return "-----BEGIN" + flag + "-----\n" + RSA_Unit.TextBreak(RSA_Unit.Base64EncodeBytes(byts), 64) + "\n-----END" + flag + "-----";
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}
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}
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}
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}
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