rsacryptoserviceprovider.VerifyData always returns false - c#

Below is my C# Program that verifies a response from a php script which is using phpseclib
static void Main(string[] args)
{
var payment =
"VUQxMzE1MTg0OTk0MDM2MzIyMDJ8VDAwMDAxN0kxMFVEMTMxNTE4NDk5NDAzNjMyMjAyfDIwMTctMTAtMDd8MHxwYXltZW50IHN1Y2Nlc3NmdWx8MjAyNTQ=";
var signature =
"V0T9ZedZW8oB9uy4PazRIxWHvJ7rR+FVtnGjUy30mSKqgmEceZWE1aBvkQWeG4ERjAXHjsRge0D0MlHd9zvXjrLog+G5nWBHIu52O0srCd9d71JVztMQy8fV5oSnRPtlUpgdmn8QDnJ27XrbaHzNxnFyybTQhmbfxkT0oJ0MEOk=";
var sigByte = Convert.FromBase64String(signature);
var payBite = Convert.FromBase64String(payment);
Verify(payBite, sigByte);
}
public static bool Verify(byte[] payment, byte[] signature)
{
var key = Resources.PublicKey;
var cipher = Crypto.DecodeX509PublicKey(key);
var res = cipher.VerifyData(payment, "SHA256", signature);
return res;
}
the public key used is below:
-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDSiXzUuH9ePZgSLYrzZ0qhta25
HCb+WG48wIKUl+cQNC/Fl/KZG2cSwRXdo8KZLVWWO5qwzplfTWEylg4IqRA48rYY
f/b+Y7QhORKeAws4pttLZJBbh1mIbZ9HXfQ+zBjP+zfJZ1YjSFs2uZdwSt1itUcJ
/GQFct8GoUevNELG7wIDAQAB
-----END PUBLIC KEY-----
but the verify method seems to be returning false all the time. any idea why this happens.
the same content works in the php code which the vendor gave to me
<?php
//load RSA library
include 'Crypt/RSA.php';
//initialize RSA
$rsa = new Crypt_RSA();
//decode & get POST parameters
$payment = base64_decode("VUQxMzE1MTg0OTk0MDM2MzIyMDJ8VDAwMDAxN0kxMFVEMTMxNTE4NDk5NDAzNjMyMjAyfDIwMTctMTAtMDd8MHxwYXltZW50IHN1Y2Nlc3NmdWx8MjAyNTQ=");
$signature = base64_decode("V0T9ZedZW8oB9uy4PazRIxWHvJ7rR+FVtnGjUy30mSKqgmEceZWE1aBvkQWeG4ERjAXHjsRge0D0MlHd9zvXjrLog+G5nWBHIu52O0srCd9d71JVztMQy8fV5oSnRPtlUpgdmn8QDnJ27XrbaHzNxnFyybTQhmbfxkT0oJ0MEOk=");
//load public key for signature matching
$publickey = "-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDSiXzUuH9ePZgSLYrzZ0qhta25
HCb+WG48wIKUl+cQNC/Fl/KZG2cSwRXdo8KZLVWWO5qwzplfTWEylg4IqRA48rYY
f/b+Y7QhORKeAws4pttLZJBbh1mIbZ9HXfQ+zBjP+zfJZ1YjSFs2uZdwSt1itUcJ
/GQFct8GoUevNELG7wIDAQAB
-----END PUBLIC KEY-----";
$rsa->loadKey($publickey);
//verify signature
$signature_status = $rsa->verify($payment, $signature);
//get payment response in segments
//payment format: order_id|order_refference_number|date_time_transaction|payment_gateway_used|status_code|comment;
$responseVariables = explode('|', $payment);
//display values
echo $signature_status;
echo '<br/>';
var_dump($responseVariables);
?>
Any idea what i'm doing wrong here. i tried passing "SHA512", "MD5" all in the C# code and still returns false.

PSS is supported in-the-box with .NET 4.6+, but requires using the RSACng class (CAPI, which RSACryptoServiceProvider is based on, doesn't offer it).
public static bool Verify(byte[] payment, byte[] signature)
{
var key = Resources.PublicKey;
// Change the function this calls to return RSACng instead of RSACryptoServiceProvider.
RSA cipher = Crypto.DecodeX509PublicKey(key);
// or, failing being able to change it:
RSA tmp = new RSACng();
tmp.ImportParameters(cipher.ExportParameters(false));
cipher = tmp;
return cipher.VerifyData(
payment,
signature,
HashAlgorithmName.SHA256,
RSASignaturePadding.Pss);
}

Well, seems like the vendor is NOT using PKCS1, he's using PSS. Verify it this way (requires Bouncy Castle!):
public static bool Verify(byte[] payment, byte[] signature)
{
var pub = #"MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDSiXzUuH9ePZgSLYrzZ0qhta25HCb+WG48wIKUl+cQNC/Fl/KZG2cSwRXdo8KZLVWWO5qwzplfTWEylg4IqRA48rYYf/b+Y7QhORKeAws4pttLZJBbh1mIbZ9HXfQ+zBjP+zfJZ1YjSFs2uZdwSt1itUcJ/GQFct8GoUevNELG7wIDAQAB";
byte[] raw = Convert.FromBase64String(pub);
AsymmetricKeyParameter aKey = PublicKeyFactory.CreateKey(raw);
RsaKeyParameters rKey = (RsaKeyParameters)aKey;
PssSigner pss = new PssSigner(new RsaEngine(), new Sha1Digest(), 20);
pss.Init(false, rKey);
pss.BlockUpdate(payment, 0, payment.Length);
var res = pss.VerifySignature(signature);
return res;
}

Related

Pasargad payment gateway sign method in nodejs

Iran Pasargad bank requires to sign payment gateway request to be signed using RSA private key, following C# code snippet is provided by the bank and it's working, but I cant get it work using NodeJS.
public string GetSign(string data)
{
var cs = new CspParameters { KeyContainerName = "PaymentTest" };
var rsa = new RSACryptoServiceProvider(cs) { PersistKeyInCsp = false };
rsa.Clear();
rsa = new RSACryptoServiceProvider();
rsa.FromXmlString("<RSAKeyValue>Modulus>...</RSAKeyValue>");
byte[] signMain = rsa.SignData(Encoding.UTF8.GetBytes(data), new
SHA1CryptoServiceProvider());
string sign = Convert.ToBase64String(signMain);
return sign;
}
Finally I solved my problem using following code, Hope it could help others:
function getSign(data) {
const pemKey = `-----BEGIN PRIVATE KEY-----
...
-----END PRIVATE KEY-----
`;
const crypto = require("crypto");
const signature = crypto.sign("sha1", Buffer.from(JSON.stringify(data)), { key: pemKey });
return signature.toString("base64");
}

Trying to decrypt a string with public key(not private) using bouncycastle in .net

As a sample app, I encrypted a string using an rsa public key(supplied by a 3rd party api) using BouncyCastle library in .NET. When I send this encrypted string to the said 3rd party api endpoint, it is able to decrypt it(using its private key). I don't have their private key, but, is it possible to decrypt the string on my end using just the public key that I have?
From my understanding of RSA public/private key pair, when decrypting, you use the private key stored with you to decrypt a string and use the public key to confirm that you are receiving data from a said source.
public string RsaEncryptWithPublic(string clearText
, string publicKey)
{
var bytesToEncrypt = Encoding.UTF8.GetBytes(clearText);
var encryptEngine = new Pkcs1Encoding(new RsaEngine());
using (var txtreader = new StringReader(publicKey))
{
var keyParameter = (AsymmetricKeyParameter)new PemReader(txtreader).ReadObject();
encryptEngine.Init(true, keyParameter);
}
var encrypted = Convert.ToBase64String(encryptEngine.ProcessBlock(bytesToEncrypt, 0, bytesToEncrypt.Length));
return encrypted;
}
public string RsaDecrypt(string base64Input
, string privateKey)
{
var bytesToDecrypt = Convert.FromBase64String(base64Input);
//get a stream from the string
AsymmetricCipherKeyPair keyPair;
var decryptEngine = new Pkcs1Encoding(new RsaEngine());
using (var txtreader = new StringReader(privateKey))
{
keyPair = (AsymmetricCipherKeyPair)new PemReader(txtreader).ReadObject();
//decryptEngine.Init(false, keyPair.Private);
decryptEngine.Init(false, keyPair.Public);
}
var decrypted = Encoding.UTF8.GetString(decryptEngine.ProcessBlock(bytesToDecrypt, 0, bytesToDecrypt.Length));
return decrypted;
}
static void Main(string[] args)
{
string _creditCardNumber = "5454545454545454";
string publicKey = System.IO.File.ReadAllText(#"C:\ThirdPartyKeys\RSAPublicKey_01.txt");
var enc = new EncryptionClass();
var encryptedWithPublic = enc.RsaEncryptWithPublic(_creditCardNumber, publicKey);
Console.WriteLine("String: " + _creditCardNumber);
Console.WriteLine("Encrypted String: " + encryptedWithPublic);
// Decrypt
var outputWithPublic = enc.RsaDecrypt(encryptedWithPublic, publicKey);
//var outputWithPrivate = enc.RsaDecrypt(encryptedWithPrivate, _privateKey);
Console.WriteLine("Decrypted String: " + outputWithPublic);
}
The encryption works, but when I try to decrypt with the same public key, it complains of
Invalid Cast Exception:
Unable to cast object of type 'Org.BouncyCastle.Crypto.Parameters.RsaKeyParameters' to type 'Org.BouncyCastle.Crypto.AsymmetricCipherKeyPair'.
at line in RsaDecrypt function:
keyPair = (AsymmetricCipherKeyPair)new PemReader(txtreader).ReadObject();
No. It's Asymmetric Encryption which means you can't decrypt it with the public key. If you could, it would defeat the purpose and anyone with the public key would be able to decrypt your secret message

How to unwrap a key using RSA in Bouncy castle c#?

How do I unwrap a key using RSA private key in Bouncy castle? I receive the already wrapped key which was wrapped using the RSA public key. I have the RSA key pair. I just cannot find the api in the C# Bouncy Castle that I can use to unwrap it.
This code in the C# source code (https://github.com/bcgit/bc-csharp) is currently commented out. The commented out lines for the RSA is exactly what I need, but when I try to use them it seems that its been removed or never implemented
Key key = cipher.unwrap(wrappedKey, "RSA", IBufferedCipher.PRIVATE_KEY);
The line above is exactly what I need. Why has it been commented out? The full function in WrapTest.cs is given below:
public ITestResult Perform()
{
try
{
// IBufferedCipher cipher = CipherUtilities.GetCipher("DES/ECB/PKCS5Padding");
IWrapper cipher = WrapperUtilities.GetWrapper("DES/ECB/PKCS5Padding");
IAsymmetricCipherKeyPairGenerator fact = GeneratorUtilities.GetKeyPairGenerator("RSA");
fact.Init(
new RsaKeyGenerationParameters(
BigInteger.ValueOf(0x10001),
new SecureRandom(),
512,
25));
AsymmetricCipherKeyPair keyPair = fact.GenerateKeyPair();
AsymmetricKeyParameter priKey = keyPair.Private;
AsymmetricKeyParameter pubKey = keyPair.Public;
byte[] priKeyBytes = PrivateKeyInfoFactory.CreatePrivateKeyInfo(priKey).GetDerEncoded();
CipherKeyGenerator keyGen = GeneratorUtilities.GetKeyGenerator("DES");
// Key wrapKey = keyGen.generateKey();
byte[] wrapKeyBytes = keyGen.GenerateKey();
KeyParameter wrapKey = new DesParameters(wrapKeyBytes);
// cipher.Init(IBufferedCipher.WRAP_MODE, wrapKey);
cipher.Init(true, wrapKey);
// byte[] wrappedKey = cipher.Wrap(priKey);
byte[] wrappedKey = cipher.Wrap(priKeyBytes, 0, priKeyBytes.Length);
// cipher.Init(IBufferedCipher.UNWRAP_MODE, wrapKey);
cipher.Init(false, wrapKey);
// Key key = cipher.unwrap(wrappedKey, "RSA", IBufferedCipher.PRIVATE_KEY);
byte[] unwrapped = cipher.Unwrap(wrappedKey, 0, wrappedKey.Length);
//if (!Arrays.AreEqual(priKey.getEncoded(), key.getEncoded()))
if (!Arrays.AreEqual(priKeyBytes, unwrapped))
{
return new SimpleTestResult(false, "Unwrapped key does not match");
}
return new SimpleTestResult(true, Name + ": Okay");
}
catch (Exception e)
{
return new SimpleTestResult(false, Name + ": exception - " + e.ToString());
}
}
I'm not entirely clear on what you need, but you can use RSA keys to wrap and unwrap AES keys in Bouncycastle. Here is a Java example that creates an RSA keypair, saves the private key to a file, and then saves an AES key that has been wrapped in the public key.
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.SecureRandom;
public class Main {
private static final SecureRandom rand = new SecureRandom();
public static void main(String[] args) throws Exception {
KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
kpg.initialize(1024, rand);
KeyPair kp = kpg.generateKeyPair();
// Write out private key to file, PKCS8-encoded DER
Files.write(Paths.get("privkey.der"), kp.getPrivate().getEncoded());
KeyGenerator kg = KeyGenerator.getInstance("AES");
kg.init(256, rand);
SecretKey aesKey = kg.generateKey();
Cipher c = Cipher.getInstance("RSA/ECB/PKCS1PADDING");
c.init(Cipher.WRAP_MODE, kp.getPublic(), rand);
byte[] wrappedKey = c.wrap(aesKey);
// Write out wrapped key
Files.write(Paths.get("wrappedkey"), wrappedKey);
}
}
And here is a C# example that consumes the output from the Java example and unwraps the AES key.
using System.IO;
using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.Pkcs;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Security;
namespace RSADecryptWithBouncy
{
class MainClass
{
private static KeyParameter Unwrap(byte [] key, AsymmetricKeyParameter privKeyParam) {
var wrapper = WrapperUtilities.GetWrapper("RSA/NONE/PKCS1PADDING");
wrapper.Init(false, privKeyParam);
var aesKeyBytes = wrapper.Unwrap(key, 0, key.Length);
return new KeyParameter(aesKeyBytes);
}
public static void Main(string[] args)
{
var privKeyBytes = File.ReadAllBytes("../../privkey.der");
var seq = Asn1Sequence.GetInstance(privKeyBytes);
var rsaKeyParams = PrivateKeyFactory.CreateKey(PrivateKeyInfo.GetInstance(seq));
var wrappedKey = File.ReadAllBytes("../../wrappedKey");
var aesKey2 = Unwrap(wrappedKey, rsaKeyParams);
}
}
}
You will have to adapt this to your needs.

C# RSA Decrypt Using Private Key

I've been searching but I can't seem to find a simple way of decrypting using RSA.
I have generated a public and private key, they are stored in two separate files and are in the XML format. I have no problem associating the public key to the RSACryptoServiceProvider object using FromXmlString, and then encrypting a string. My confusion comes when trying to decrypt an encrypted string. I'm not sure how I associate the private key data with the RSACryptoServiceProvider so that I can use the Decrypt function.
Any help would be appreciated.
EDIT:
The format of the public and private key is XML generated by the RSACryptoServiceProvider object, which I just put into a file:
<RSAKeyValue><Modulus>vS7Y5up+6kHMx7hQjKA6sKlIVASaw ... etc ...
I load the public key using this code:
StreamReader sr = new StreamReader(HttpContext.Current.Server.MapPath("public.key"));
RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
rsa.FromXmlString(sr.ReadToEnd().ToString());
I currently haven't tried anything with the private key yet, since I'm not sure where to start.
I don't know your situation but I would suggest that you store you key information in a KeyContainer. If you do this you can access the keyContainer by name and can do something like this.
// retrieves the maximum number of characters that can be decrypted at once
private int getMaxBlockSize(int keySize){
int max = ((int)(keysize/8/3) )* 4
if (keySize / 8 mod 3 != 0){
max += 4
}
return max;
}
public string decrypt(string msg, string containerName){
CspParameters params = new CspParameters();
params.KeyContainerName = containerName;
RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(params);
StringBuilder decryptedMsg = new StringBuilder();
int maxDecryptSize = getMaxBlockSize(rsa.KeySize);
int iterationCount = Math.Floor(msg.length / maxDecryptSize)
for(int i=0; i<iterationCount; i++){
int start = i * maxDecryptSize;
int blkSize = Math.min(start + maxDecryptSize, msg.Length);
Byte[] msgBytes = System.Convert.FromBase64String(msg.Substring(start, blkSize));
decryptedMsg.Append(System.Text.Encoding.Unicode.GetString(RSAProvider.Decrypt(msgBytes, false));
}
return decryptedMsg.ToString();
}
I haven't tested this out so there might be a bug in here but the you get the idea.
if you have private key in text format
like given below
-----BEGIN RSA PRIVATE KEY-----
text....
-----END RSA PRIVATE KEY-----
public string RsaDecryptWithPrivate(string base64Input, string privateKey)
{
var bytesToDecrypt = Convert.FromBase64String(base64Input);
AsymmetricCipherKeyPair keyPair;
var decryptEngine = new Pkcs1Encoding(new RsaEngine());
using (var txtreader = new StringReader(privateKey))
{
keyPair = (AsymmetricCipherKeyPair)new PemReader(txtreader).ReadObject();//fetch key pair from text file
decryptEngine.Init(false, keyPair.Private);
}
var decrypted = Encoding.UTF8.GetString(decryptEngine.ProcessBlock(bytesToDecrypt, 0, bytesToDecrypt.Length));
return decrypted;
}

RSA signing and verification with C#,BouncyCastle and imported RSA key - Working Python example and non-working C# code sample inside

I have been tearing what is left of my hair out trying to get a trivial example of RSA data signing and verification with C# and BouncyCastle working.
RSACryptoServiceProvider.VerifyHash() always returns false on an example that works for me with Python and M2Crypto.
I have verified that the hash signatures are identical between the working example and the C# example and it is there I am stuck. I feel I am missing some vital detail.
The working Python code and non working C# code follow.
The key was generated with
openssl genrsa -out testkey.pem 1024
openssl rsa -in testkey.pem -pubout > testkey.pub
Python code (working):
private = """-----BEGIN RSA PRIVATE KEY-----
MIICXQIBAAKBgQCxSHbp1ID/XHEdzVzgqYR1F/79PeMbqzuKNZChvt1gFObBhKyB
pgaHDHw3UZrO8s/hBEE/Mpe2Lh90ZAFdPIXq+HyVoznXMoJYBv0uLDApvSQbJNOd
f7T5VwmpBbkfj1NAlm39Eun9uBSokEOnB24g+bczPQPGOASrQ2Ly9afOZQIDAQAB
AoGBAIEzQIZ1OnXgVwfTLMcGg+QaUtkYizUU+9Vj6D4YrZliYjHSkS4DY2p0rOpb
7Ki5yMpCoZJ/OpWo03+tilj6zNUU6X3aHrPPSv8jcsE0sDi9zYJr/Ztk3EG23sad
bM28Bb4fV/Z0/E6FZJrmuvI2dZP/57oQSHGOhtkHFO21cW5BAkEA3l/i5Rc34YXc
WHYEsOYe0kAxS4dCmhbLWaWvsghW/TomjdxzePsO70GZZqRMdzkfA1iS1OrK+pP4
4suL2rSLrQJBAMwXFnBp4Jmek0CTSxoYf6q91eFm/IRkGLnzE1fEZ76vQOBTas8T
/mpjNQHSEywo/QB62h9A8hy7XNrfZJAMJJkCQA5TYwybKFBxDTbts3Op/4ZP+F0D
Q7klisglsmHnw6Lgoic1coLyuY2UTkucfgiYN3VBuYPZ9GWcLsZ9km7ufqkCQQCz
NVa70Qyqd+cfXfcla/u2pskHCtKTQf3AUmRavhjHBMa39CemvAy7yG9EMP4q2bcH
U9jydqnidtdbTavVHQSJAkA0zJtLzHGPtQqQaI7K6kBDXYPqloGnQxHxad0HPx2e
Vj2qv1tEsqeG6HC7aL/afXOtxcfjq4oMHbGUjDv+dGfP
-----END RSA PRIVATE KEY-----"""
public = """-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCxSHbp1ID/XHEdzVzgqYR1F/79
PeMbqzuKNZChvt1gFObBhKyBpgaHDHw3UZrO8s/hBEE/Mpe2Lh90ZAFdPIXq+HyV
oznXMoJYBv0uLDApvSQbJNOdf7T5VwmpBbkfj1NAlm39Eun9uBSokEOnB24g+bcz
PQPGOASrQ2Ly9afOZQIDAQAB
-----END PUBLIC KEY-----"""
message = "test input string"
import base64
# Use EVP api to sign message
from M2Crypto import EVP
key = EVP.load_key_string(private)
key.reset_context(md='sha1')
key.sign_init()
key.sign_update(message)
signature = key.sign_final()
encoded = base64.b64encode(signature)
print encoded
with open("python_sig2.txt","w") as f:
f.write(encoded)
# Use EVP api to verify signature
from M2Crypto import BIO, RSA, EVP
bio = BIO.MemoryBuffer(public)
rsa = RSA.load_pub_key_bio(bio)
pubkey = EVP.PKey()
pubkey.assign_rsa(rsa)
pubkey.reset_context(md="sha1")
pubkey.verify_init()
pubkey.verify_update(message)
decoded = base64.b64decode(encoded)
print pubkey.verify_final(decoded) == 1
C# code (verifyhash() returns false):
using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.OpenSsl;
using Org.BouncyCastle.Security;
namespace RsaSignTest
{
class Program
{
private const string privateKey =
#"-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----";
private const string publicKey =
#"-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCxSHbp1ID/XHEdzVzgqYR1F/79
PeMbqzuKNZChvt1gFObBhKyBpgaHDHw3UZrO8s/hBEE/Mpe2Lh90ZAFdPIXq+HyV
oznXMoJYBv0uLDApvSQbJNOdf7T5VwmpBbkfj1NAlm39Eun9uBSokEOnB24g+bcz
PQPGOASrQ2Ly9afOZQIDAQAB
-----END PUBLIC KEY-----";
static void Main(string[] args)
{
var data = "test input string";
var sig = SignWithPrivateKey(data);
var valid = VerifyWithPublicKey(data,sig);
}
private static byte[] SignWithPrivateKey(string data)
{
RSACryptoServiceProvider rsa;
using (var keyreader = new StringReader(privateKey))
{
var pemreader = new PemReader(keyreader);
var y = (AsymmetricCipherKeyPair) pemreader.ReadObject();
var rsaPrivKey = (RsaPrivateCrtKeyParameters)y.Private;
rsa = (RSACryptoServiceProvider)RSACryptoServiceProvider.Create();
var rsaParameters = DotNetUtilities.ToRSAParameters(rsaPrivKey);
rsa.ImportParameters(rsaParameters);
}
// compute sha1 hash of the data
var sha = new SHA1CryptoServiceProvider();
byte[] hash = sha.ComputeHash(Encoding.ASCII.GetBytes(data));
// actually compute the signature of the SHA1 hash of the data
var sig = rsa.SignHash(hash, CryptoConfig.MapNameToOID("SHA1"));
// base64 encode the signature and write to compare to the python version
String b64signature = Convert.ToBase64String(sig);
using (var sigwriter = new StreamWriter(#"C:\scratch\csharp_sig2.txt"))
{
sigwriter.Write(b64signature);
}
return sig;
}
private static bool VerifyWithPublicKey(string data,byte[] sig)
{
RSACryptoServiceProvider rsa;
using (var keyreader = new StringReader(publicKey))
{
var pemReader = new PemReader(keyreader);
var y = (RsaKeyParameters) pemReader.ReadObject();
rsa = (RSACryptoServiceProvider) RSACryptoServiceProvider.Create();
var rsaParameters = new RSAParameters();
rsaParameters.Modulus = y.Modulus.ToByteArray();
rsaParameters.Exponent = y.Exponent.ToByteArray();
rsa.ImportParameters(rsaParameters);
}
// compute sha1 hash of the data
var sha = new SHA1CryptoServiceProvider();
byte[] hash = sha.ComputeHash(Encoding.ASCII.GetBytes(data));
// This always returns false
return rsa.VerifyHash(hash, CryptoConfig.MapNameToOID("SHA1"),sig);
}
}
}
At this point I don't know how to proceed and any help would be greatly appreciated.
Something is wrong with how you're re-constructing the private/public key. Obviously in python you're note required to do that.
I created new keys that verify (in a different format) using this code:
private static void GenerateKeys(out string forPubKey, out string forPrivKey)
{
GenerateKeys(out forPubKey, out forPrivKey, 2048, 65537, 80);
}
/// <summary>
///
/// </summary>
/// <param name="forPubKey"></param>
/// <param name="forPrivKey"></param>
/// <param name="keyStrength">1024, 2048,4096</param>
/// <param name="exponent">Typically a fermat number 3, 5, 17, 257, 65537, 4294967297, 18446744073709551617,</param>
/// <param name="certaninty">Should be 80 or higher depending on Key strength number (exponent)</param>
private static void GenerateKeys(out string forPubKey, out string forPrivKey, int keyStrength, int exponent, int certaninty)
{
// Create key
RsaKeyPairGenerator generator = new RsaKeyPairGenerator();
/*
* This value should be a Fermat number. 0x10001 (F4) is current recommended value. 3 (F1) is known to be safe also.
* 3, 5, 17, 257, 65537, 4294967297, 18446744073709551617,
*
* Practically speaking, Windows does not tolerate public exponents which do not fit in a 32-bit unsigned integer. Using e=3 or e=65537 works "everywhere".
*/
BigInteger exponentBigInt = new BigInteger(exponent.ToString());
var param = new RsaKeyGenerationParameters(
exponentBigInt, // new BigInteger("10001", 16) publicExponent
new SecureRandom(), // SecureRandom.getInstance("SHA1PRNG"),//prng
keyStrength, //strength
certaninty);//certainty
generator.Init(param);
AsymmetricCipherKeyPair keyPair = generator.GenerateKeyPair();
// Save to export format
SubjectPublicKeyInfo info = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(keyPair.Public);
byte[] ret = info.GetEncoded();
forPubKey = Convert.ToBase64String(ret);
// EncryptedPrivateKeyInfo asdf = EncryptedPrivateKeyInfoFactory.CreateEncryptedPrivateKeyInfo(
// DerObjectIdentifier.Ber,,,keyPair.Private);
//// demonstration: how to serialise option 1
//TextWriter textWriter = new StringWriter();
//PemWriter pemWriter = new PemWriter(textWriter);
//pemWriter.WriteObject(keyPair);
//pemWriter.Writer.Flush();
//string ret2 = textWriter.ToString();
//// demonstration: how to serialise option 1
//TextReader tr = new StringReader(ret2);
//PemReader read = new PemReader(tr);
//AsymmetricCipherKeyPair something = (AsymmetricCipherKeyPair)read.ReadObject();
//// demonstration: how to serialise option 2 (don't know how to deserailize)
//PrivateKeyInfo pKinfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(keyPair.Private);
//byte[] privRet = pKinfo.GetEncoded();
//string forPrivKey2Test = Convert.ToBase64String(privRet);
PrivateKeyInfo pKinfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(keyPair.Private);
byte[] privRet = pKinfo.GetEncoded();
string forPrivKey2Test = Convert.ToBase64String(privRet);
forPrivKey = forPrivKey2Test;
}
and then turned them back into RSA objects like this:
// Private key
RsaPrivateCrtKeyParameters kparam = ConvertToRSAPrivateKey(privateKey);
RSAParameters p1 = DotNetUtilities.ToRSAParameters(kparam);
rsa = new RSACryptoServiceProvider();
rsa.ImportParameters(p1);
// Public key
RsaKeyParameters kparam = ConvertToRSAPublicKey(publicKey);
RSAParameters p1 = DotNetUtilities.ToRSAParameters(kparam);
rsa = new RSACryptoServiceProvider();
rsa.ImportParameters(p1);

Categories

Resources