/// <summary>Converts DER binary format to a CAPI CERT_PUBLIC_KEY_INFO structure containing an RSA key.</summary>
internal static byte[] GetRSAFromDER(byte[] DERData)
{
byte[] data = null;
byte[] publicKey = null;
CERT_PUBLIC_KEY_INFO info;
UInt32 dwCertPublicKeyInfoSize = 0;
IntPtr pCertPublicKeyInfo = IntPtr.Zero;
if (RSACryptoServiceProviderExtension.CryptDecodeObject(CRYPT_ENCODING_FLAGS.X509_ASN_ENCODING | CRYPT_ENCODING_FLAGS.PKCS_7_ASN_ENCODING, new IntPtr((int)CRYPT_OUTPUT_TYPES.X509_PUBLIC_KEY_INFO),
DERData, (UInt32)DERData.Length, CRYPT_DECODE_FLAGS.NONE, data, ref dwCertPublicKeyInfoSize))
{
data = new byte[dwCertPublicKeyInfoSize];
if (RSACryptoServiceProviderExtension.CryptDecodeObject(CRYPT_ENCODING_FLAGS.X509_ASN_ENCODING | CRYPT_ENCODING_FLAGS.PKCS_7_ASN_ENCODING, new IntPtr((int)CRYPT_OUTPUT_TYPES.X509_PUBLIC_KEY_INFO),
DERData, (UInt32)DERData.Length, CRYPT_DECODE_FLAGS.NONE, data, ref dwCertPublicKeyInfoSize))
{
GCHandle handle = GCHandle.Alloc(data, GCHandleType.Pinned);
try
{
info = (CERT_PUBLIC_KEY_INFO)Marshal.PtrToStructure(handle.AddrOfPinnedObject(), typeof(CERT_PUBLIC_KEY_INFO));
publicKey = new byte[info.PublicKey.cbData];
Marshal.Copy(info.PublicKey.pbData, publicKey, 0, publicKey.Length);
}
finally
{
handle.Free();
}
}
else
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
}
else
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
return(publicKey);
}
/// <summary>Returns a public key blob from an RSA public key.</summary>
internal static byte[] GetPublicKeyBlobFromRSA(byte[] RSAData)
{
byte[] data = null;
UInt32 dwCertPublicKeyBlobSize = 0;
if (RSACryptoServiceProviderExtension.CryptDecodeObject(CRYPT_ENCODING_FLAGS.X509_ASN_ENCODING | CRYPT_ENCODING_FLAGS.PKCS_7_ASN_ENCODING,
new IntPtr((int)CRYPT_OUTPUT_TYPES.RSA_CSP_PUBLICKEYBLOB), RSAData, (UInt32)RSAData.Length, CRYPT_DECODE_FLAGS.NONE,
data, ref dwCertPublicKeyBlobSize))
{
data = new byte[dwCertPublicKeyBlobSize];
if (!RSACryptoServiceProviderExtension.CryptDecodeObject(CRYPT_ENCODING_FLAGS.X509_ASN_ENCODING | CRYPT_ENCODING_FLAGS.PKCS_7_ASN_ENCODING,
new IntPtr((int)CRYPT_OUTPUT_TYPES.RSA_CSP_PUBLICKEYBLOB), RSAData, (UInt32)RSAData.Length, CRYPT_DECODE_FLAGS.NONE,
data, ref dwCertPublicKeyBlobSize))
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
}
else
{
throw new Win32Exception(Marshal.GetLastWin32Error());
}
return(data);
}
/// <summary>Extension method which initializes an RSACryptoServiceProvider from a PEM public key string.</summary>
public static void LoadPublicKeyPEM(RSACryptoServiceProvider provider, string sPEM)
{
byte[] DERData = RSACryptoServiceProviderExtension.GetDERFromPEM(sPEM);
RSACryptoServiceProviderExtension.LoadPublicKeyDER(provider, DERData);
}
/// <summary>Extension method which initializes an RSACryptoServiceProvider from a DER public key blob.</summary>
public static void LoadPublicKeyDER(RSACryptoServiceProvider provider, byte[] DERData)
{
byte[] RSAData = RSACryptoServiceProviderExtension.GetRSAFromDER(DERData);
byte[] publicKeyBlob = RSACryptoServiceProviderExtension.GetPublicKeyBlobFromRSA(RSAData);
provider.ImportCspBlob(publicKeyBlob);
}
