RSA decryption using OpenSSL.NET with an existing key

Question

I have the following code below to create an OpenSSL RSA public and public key using OpenSSL.Net. However, I cannot find a way to decrypt the data using this private key. I know if I call to generate keys, then the appropriate methods for encrypting and decrypting the data, which it works fine. However, if I try to decrypt something from an external source using a public key, how can I decrypt using this key.

Note. Please do not specify examples that do not use OpenSSL.NET. Microsoft Cryptographic vendors are much slower than OpenSSL and do not meet my speed requirements.

Thanks!

public class AsymmetricKeyResult { public string PublicKey { get; set; } public string PrivateKey { get; set; } public AsymmetricKeyResult(string publicKey, string privateKey) { this.PublicKey = publicKey; this.PrivateKey = privateKey; } } public static AsymmetricKeyResult GenerateAsymmetricKeys(int keyLength) { RSA rsa = new RSA(); rsa.GenerateKeys(keyLength, 0x10021, null, null); AsymmetricKeyResult kResult = new AsymmetricKeyResult(rsa.PublicKeyAsPEM, rsa.PrivateKeyAsPEM); return kResult; } 

Answer 1

I ended up figuring this out through the object browser in Managed Wrapper for OpenSSL.NET. It works:

  public static byte[] AsymmetricEncrypt(string publicKeyAsPem, byte[] payload) { CryptoKey d = CryptoKey.FromPublicKey(publicKeyAsPem, null); RSA rsa = d.GetRSA(); byte[] result = rsa.PublicEncrypt(payload, RSA.Padding.PKCS1); rsa.Dispose(); return result; } public static byte[] AsymmetricDecrypt(string privateKeyAsPem, byte[] payload) { CryptoKey d = CryptoKey.FromPrivateKey(privateKeyAsPem, null); RSA rsa = d.GetRSA(); byte[] result = rsa.PrivateDecrypt(payload, RSA.Padding.PKCS1); rsa.Dispose(); return result; } 

Answer 2

I found this and thought it was the answer to my prayers. However, using openssl (1.0.0e Mac os x) to generate pubs / private keys, I cannot get clear text back from ciphertext - is there a GetBytes / Baseencode method that I skip? did you come across this?

EDIT: as soon as I sent the message, I came across another example using UTF8 encoding, not ASCII, which works!

Ben

 namespace testopenssl2 { class Program { public static byte[] AsymmetricEncrypt(string publicKeyAsPem, byte[] payload) { CryptoKey d = CryptoKey.FromPublicKey(publicKeyAsPem, null); RSA rsa = d.GetRSA(); byte[] result = rsa.PublicEncrypt(payload, RSA.Padding.PKCS1); rsa.Dispose(); return result; } public static byte[] AsymmetricDecrypt(string privateKeyAsPem, byte[] payload) { //CryptoKey d = CryptoKey.FromPrivateKey(privateKeyAsPem, null); CryptoKey d = CryptoKey.FromPrivateKey(privateKeyAsPem, "pass"); RSA rsa = d.GetRSA(); byte[] result = rsa.PrivateDecrypt(payload, RSA.Padding.PKCS1); rsa.Dispose(); return result; } static void Main(string[] args) { String t = @"-----BEGIN PUBLIC KEY----- MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCbhcU+fhYmYLESZQAj1hKBXsNY si0kYHNkxpP7ftxZiTFowWUVXHzQgkcYiCNnp3pt1eG6Vt0WDzyFYXqUUqugvX41 gkaIrKQw/sRiWEx49krcz7Vxr3dufL6Mg3eK7NyWDGsqwFrx/qVNqdhsHg12PGNx IMY4UBtxin2A8pd4OwIDAQAB -----END PUBLIC KEY-----"; String p = @"-----BEGIN RSA PRIVATE KEY----- Proc-Type: 4,ENCRYPTED DEK-Info: DES-EDE3-CBC,0A128C2617BD2EB1 pTDtXB+mockO7fvVqn4fwGnSb1Zv3HaMAALtpiB7Rn64eAHL7psKQIIM3qoshDWF XgXDdTnMOGO7wtYkd9R7iJYxgt19EuEdtu2SLLXQuN4ll+JSR2R/34dF19iMXI30 d3pe7obTIwKdyRGuu8GgEm6bGai4pkqptP0HRA6qdMI2+Qfl9+VqUuvIm7tfpIRd /ZLENe756IrGDvI7lGx39Md/H2sgAJsWkSYubhmtxVJ0IEvbPuKDC5V5oLyTOoy+ 6sc6ly57C4XHaTLhAKnYEvZAddnXg/e/VtfmTpqKx3n7D6FAKo1RjAjeZqEvefZd XAhh19YhZq3mdZNYUt7ojUarf/q3zrtTMLUxHdR0Be/VaQC5AE0d6quKyUQgxiti XNRS8xk9IJJqJLFSHO3ET+oTfcs+kLPuUDHqq0hY/OgW/THcDgPY1cDwtOX9yuI3 YDoFTb3SXzRTmk2ui33f96wNPwzIAp9+TJzITxJYbF233Pz4YWuabrFuoNWZnwtT E/o6wcGfvAXTQkAKzwfLbTDmg5SSiGokoEcgm7qpfmQxKdmV1LmbW88DuAgdWggm Qf3ydZ2IrrtD1o+XP7JraeVOql0OK77pJh/bcr3bLiAT8YtsQUZLnOjkbDc3F1zW BGr6eeqUHxY6cqKieokhl9cBBjWuxJQL2h997svBufWdNOjTA4+32lXzDzi7bUxC xzIqZ7nm3YC2zUjla/l3Smz5KitqU5Y3Q9URpXOW+qMiPxmTHYOEcRDy9yh2U4iA CoTD6q0ZNJLEo3EVcDB+26O663/mQLuR69xstUgqHpSzGvXbqrmezA== -----END RSA PRIVATE KEY-----"; System.Text.Encoding enc = System.Text.Encoding.ASCII; String s = "hello"; byte[] payload = enc.GetBytes(s); Console.WriteLine("s: {0}", s); byte[] byte_encData = AsymmetricEncrypt(t,payload); String res; res = Convert.ToBase64String(byte_encData); Console.WriteLine("encypted: {0}", res); byte[] byte_decrypted = AsymmetricDecrypt(p, byte_encData); String res_unenc; res_unenc = Convert.ToBase64String(byte_decrypted); // works! Console.WriteLine("decrypted: {0}", res_unenc); } } }