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PO"Bad Data" when decrypting using RSACryptoProvider from string encrypted in PHP
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  1. PO"Bad Data" when decrypting using RSACryptoProvider from string encrypted in PHP
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    copied!<p>I am trying to decrypt a string in C# that was encrypted in PHP using RSA, and for the life of me, I can't get it right. I have condensed the problem to two sample test apps in .NET and PHP: </p> <p>In C#:</p> <pre><code>class Program { static void Main(string[] args) { RSACryptoServiceProvider provider = new RSACryptoServiceProvider(); string fileName = @"C:\privateKey"; if (File.Exists(fileName)) { provider.FromXmlString(File.ReadAllText(fileName)); } else { File.WriteAllText(fileName, provider.ToXmlString(true)); } if(args.Length &gt; 0) { string decrypted = Encoding.UTF8.GetString(provider.Decrypt(Convert.FromBase64String(args[0]), false)); Console.WriteLine("decrypted: {0}", decrypted); } else { Console.WriteLine(provider.ToXmlString(false)); } Console.ReadLine(); } } </code></pre> <p>The first time I run this, it outputs(nicely formatted):</p> <pre><code>&lt;RSAKeyValue&gt; &lt;Modulus&gt; 2P8G+ospDboN87+FIWSzFA9E1QVXCDy4bO9YZPe1MTcxO7VhlBYmLy1J7b rSheaTa8RamrdeXe2Ev0y5O7zyxo/Bxw4W2UfnVAAFK+bgb8f0FicnSosAlGC95m5Goid9wWPf/QtqDa NxSMBBjULA1WKzA7+3HQncAenODYypOiE= &lt;/Modulus&gt; &lt;Exponent&gt;AQAB&lt;/Exponent&gt; &lt;/RSAKeyValue&gt; </code></pre> <p>I have verified that the key gets saved and loaded correctly between runs.</p> <p>Then I do this in PHP using the <a href="http://pear.php.net/package/Crypt_RSA/docs/latest/li_Crypt_RSA.html" rel="nofollow">Crypt_RSA Package</a>:</p> <pre><code>include('Crypt/RSA.php'); $keyXML = &lt;&lt;&lt;EOS &lt;RSAKeyValue&gt; &lt;Modulus&gt;2P8G+ospDboN87+FIWSzFA9E1QVXCDy4bO9YZPe1MTcxO7VhlBYmLy1J7brSheaTa8RamrdeXe2Ev0y5O7zyxo/Bxw4W2UfnVAAFK+bgb8f0FicnSosAlGC95m5Goid9wWPf/QtqDaNxSMBBjULA1WKzA7+3HQncAenODYypOiE=&lt;/Modulus&gt; &lt;Exponent&gt;AQAB&lt;/Exponent&gt; &lt;/RSAKeyValue&gt; EOS; $doc = DOMDocument::loadXML($keyXML); $modulus = $doc-&gt;getElementsByTagName("Modulus")-&gt;item(0)-&gt;nodeValue; $exponent = $doc-&gt;getElementsByTagName("Exponent")-&gt;item(0)-&gt;nodeValue; $key = Crypt_RSA_Key::factory(base64_decode($modulus), base64_decode($exponent), 'public'); $crypt = new Crypt_RSA(); echo $crypt-&gt;encrypt("hello", $key) </code></pre> <p>This outputs my decrypted string:</p> <pre><code>CBGFdK+NXq39ZigXkW6JChHHCCUTzHzjsEPqdoaNJtZgTCRQfIIR6IU4m5LOHGidLaLWN7cIM9ImNdSsAsMH9awkZ7uW0KXdqQjhVGeXzmC6EuSHqrSzYiIZp+1F5Rxhg/JFD/Or3eQ+UIHm/4YtNTyys6S3maClitk5KV68lhs= </code></pre> <p>Finally, when I run my C# app again with this as input, I get the following exception when I call the Decrypt method:</p> <pre><code>System.Security.Cryptography.CryptographicException was unhandled Message=Bad Data. Source=mscorlib StackTrace: at System.Security.Cryptography.CryptographicException.ThrowCryptographicException(Int32 hr) at System.Security.Cryptography.RSACryptoServiceProvider.DecryptKey(SafeKeyHandle pKeyContext, Byte[] pbEncryptedKey, Int32 cbEncryptedKey, Boolean fOAEP, ObjectHandleOnStack ohRetDecryptedKey) at System.Security.Cryptography.RSACryptoServiceProvider.Decrypt(Byte[] rgb, Boolean fOAEP) at ConsoleApplication1.Program.Main(String[] args) in C:\development\FundCentric\src\Utilities\ConsoleApplication1\ConsoleApplication1\Program.cs:line 27 at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args) at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() InnerException: </code></pre> <p>Frankly, I'm at a point where I don't know what else I can try anymore. Any suggestions at what could be possibly going wrong or what else I could try would be very welcome.</p>
 

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