帮忙分析下这段代码的执行过程。。。

[motol]

帮忙分析下这段代码的执行过程。。。如果用PHP的话怎么实现？

public static RSACryptoServiceProvider DecodeX509PublicKey(byte[] x509key)
    {
        // encoded OID sequence for  PKCS #1 rsaEncryption szOID_RSA_RSA = "1.2.840.113549.1.1.1"
        byte[] SeqOID = { 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00 };
        byte[] seq = new byte[15];
        // ---------  Set up stream to read the asn.1 encoded SubjectPublicKeyInfo blob  ------
        MemoryStream mem = new MemoryStream(x509key);
        BinaryReader binr = new BinaryReader(mem);    //wrap Memory Stream with BinaryReader for easy reading
        byte bt = 0;
        ushort twobytes = 0;

        try
        {

            twobytes = binr.ReadUInt16();
            if (twobytes == 0x8130)	//data read as little endian order (actual data order for Sequence is 30 81)
                binr.ReadByte();	//advance 1 byte
            else if (twobytes == 0x8230)
                binr.ReadInt16();	//advance 2 bytes
            else
                return null;

            seq = binr.ReadBytes(15);		//read the Sequence OID
            if (!CompareBytearrays(seq, SeqOID))	//make sure Sequence for OID is correct
                return null;

            twobytes = binr.ReadUInt16();
            if (twobytes == 0x8103)	//data read as little endian order (actual data order for Bit String is 03 81)
                binr.ReadByte();	//advance 1 byte
            else if (twobytes == 0x8203)
                binr.ReadInt16();	//advance 2 bytes
            else
                return null;

            bt = binr.ReadByte();
            if (bt != 0x00)		//expect null byte next
                return null;

            twobytes = binr.ReadUInt16();
            if (twobytes == 0x8130)	//data read as little endian order (actual data order for Sequence is 30 81)
                binr.ReadByte();	//advance 1 byte
            else if (twobytes == 0x8230)
                binr.ReadInt16();	//advance 2 bytes
            else
                return null;

            twobytes = binr.ReadUInt16();
            byte lowbyte = 0x00;
            byte highbyte = 0x00;

            if (twobytes == 0x8102)	//data read as little endian order (actual data order for Integer is 02 81)
                lowbyte = binr.ReadByte();	// read next bytes which is bytes in modulus
            else if (twobytes == 0x8202)
            {
                highbyte = binr.ReadByte();	//advance 2 bytes
                lowbyte = binr.ReadByte();
            }
            else
                return null;
            byte[] modint = { lowbyte, highbyte, 0x00, 0x00 };   //reverse byte order since asn.1 key uses big endian order
            int modsize = BitConverter.ToInt32(modint, 0);

            byte firstbyte = binr.ReadByte();
            binr.BaseStream.Seek(-1, SeekOrigin.Current);

            if (firstbyte == 0x00)
            {	//if first byte (highest order) of modulus is zero, don't include it
                binr.ReadByte();	//skip this null byte
                modsize -= 1;	//reduce modulus buffer size by 1
            }

            byte[] modulus = binr.ReadBytes(modsize);	//read the modulus bytes

            if (binr.ReadByte() != 0x02)			//expect an Integer for the exponent data
                return null;
            int expbytes = (int)binr.ReadByte();		// should only need one byte for actual exponent data (for all useful values)
            byte[] exponent = binr.ReadBytes(expbytes);


            showBytes("\nExponent", exponent);
            showBytes("\nModulus", modulus);

            // ------- create RSACryptoServiceProvider instance and initialize with public key -----
            RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
            RSAParameters RSAKeyInfo = new RSAParameters();
            RSAKeyInfo.Modulus = modulus;
            RSAKeyInfo.Exponent = exponent;
            RSA.ImportParameters(RSAKeyInfo);
            return RSA;
        }
        catch (Exception)
        {
            return null;
        }

        finally { binr.Close(); }

    }

[码代码的蜗牛]

老长啊，板凳

[motol]

没人说得清楚吗？

[freetd]

路过找人翻译......

[motol]

高手呢？再没人回答只好结帖了。。。。。。

[Baesky]

。。。。你这哪是分析。。。分明找人工翻译器么。。。

[浮游]

做断点执行以下 就明白不是。

这么看很费劲的··

大概意思是 根据传入不同字节的大小 返回不同的对象 或null

另外
MemoryStream mem = new MemoryStream(x509key);
BinaryReader binr = new BinaryReader(mem);

这俩个类内容是什么啊 参数的意义是什么啊？