How get SHA1 RSA signed of bytes in Go?

Question

I'm new in Go and having hard time to figure it out how crypto package works.

Basicly I need to sign a string with pem key and get sha1 of that like the equivalent code in C# in below.

Thanks

RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(); 
rsa.FromXmlString(“<RSAKeyValue><Modulus>oQRshGhLf2Fh...”);
byte[] signMain = rsa.SignData(Encoding.UTF8.GetBytes(data), new SHA1CryptoServiceProvider());

Answer 1

C# code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace RSASHA1
{
    class Program
    {
        static void Main(string[] args)
        {
            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
            rsa.FromXmlString("<RSAKeyValue><Modulus>n9t+R7Zmn4VLaWmixLnUkxfQmwDHqRmtlC3mR0YJ9ntUpqLPIkbZgGbuCM8jzmt3kTs4UIufzxQfim1v8avBYDkijxKRN4/g2juS9IqmWjvdV4CrxfTVGXudiuzeqI3wzoaHY4BmMdhmOA46GV6pifAVeQnJb6Hp6/F9bwi1kFE=</Modulus><Exponent>AQAB</Exponent><P>+ow3plgxHR5BcBApdHu93bLQJHD+DbcUV6qKSHMfQNosjDb6IiPUd6kfHI34DIldot6ooI+AUqZYIqW57J7llw==</P><Q>o1YL/4UkELk5nmU30NA7gLmnZm+bynt9rR2yjkU55SP60tqO5/72aXak/RrSih1BC6WfJxEr2OLMWud6t8wGVw==</Q><DP>U8vXxPPUIVgALNnK86F7RA3NHZMI9U9ZJ2TrcQXH2yndIlw01nxDUG4o8KTu5EqBHbr4jRLRqVLnQVdKUsBmKw==</DP><DQ>XeJJxzeaQVqWOetoJ8hpS1ZrWD/yxnIxDN6zEX/NBV6m/6fM2KD+tiQSNcHDHswt5Snvzx7ZmzLRz7aaHSdSxQ==</DQ><InverseQ>j/DPSjRS09ephgGgiSBFcpxDc+54n6Fo2M2zLhMj/lBoO8klbNPB4YlwFHJjEh9EpbLB1Zwi7XjL2weFX2Ws+g==</InverseQ><D>HRtdMfePVgpyQb5fSczAXQwgCqkosaygQ3PcEyw4ki3AqxrH9mjKH6weOXJmBabhvYr35QqXTaBPYegtUubALda87T7cviK1rCPN18vv+eU4MT9TADQyj9HeYvp7fUfjEfaIaf/QpAXwSRrF/n9CsM1ef4aZX4XFd2uv2SH7yVU=</D></RSAKeyValue>");
            byte[] signMain = rsa.SignData(Encoding.UTF8.GetBytes("hello"), new SHA1CryptoServiceProvider());
            StringBuilder hex = new StringBuilder(signMain.Length * 2);
            foreach (byte b in signMain) hex.AppendFormat("{0:x2}", b);
            Console.Write(hex.ToString());
            Console.ReadLine();
        }
    }
}

Go code for keys generated in OpenSSL < 1.0 and OpenSSL >= 1.0

package main

import (
    "encoding/pem"
    "fmt"
    "crypto/sha1"
    "crypto/rsa"
    "crypto/rand"
    "crypto/x509"
    "crypto"
    "encoding/hex"
)

var openssl_10_key string = `-----BEGIN PRIVATE KEY-----
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
-----END PRIVATE KEY-----`

var openssl_09_key string = `-----BEGIN RSA PRIVATE KEY-----
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
-----END RSA PRIVATE KEY-----`

func main() {
    h := sha1.New()
    h.Write([]byte("hello"))
    sum := h.Sum(nil)

    // For RSA keys generated with OpenSSL < 1.0
    pem09, _ := pem.Decode([]byte(openssl_09_key))
    privateKey09, _ := x509.ParsePKCS1PrivateKey(pem09.Bytes)
    sig, _ := rsa.SignPKCS1v15(rand.Reader, privateKey09, crypto.SHA1, sum)
    fmt.Println("OpenSSL < 1.0", hex.EncodeToString(sig))

    // For RSA keys generated with OpenSSL >= 1.0
    pem10, _ := pem.Decode([]byte(openssl_10_key))
    privateKey10I, _ := x509.ParsePKCS8PrivateKey(pem10.Bytes)
    privateKey10 := privateKey10I.(*rsa.PrivateKey)
    sig, _ = rsa.SignPKCS1v15(rand.Reader, privateKey10, crypto.SHA1, sum)
    fmt.Println("OpenSSL >= 1.0", hex.EncodeToString(sig))
}