public async Task <byte[]> GenerateCKC(byte[] spc, object info = null)
{
var buffer = new ReadOnlyMemory <byte>(spc);
// We try to read SPC message.
SPCMessage request = null;
try { request = new SPCMessage(buffer); }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_0001", "Unable to parse SPC. See 'innerException' for more information.", ex); }
FPProvider provider = null;
try { provider = this.Providers.First(p => Enumerable.SequenceEqual(p.Hash, request.ProviderHash)); }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidProviderException("EXC_0002", "Received SPCMessage contains a unregistered FairPlay provider.", ex); }
CKCMessage response = null;
try { response = await GenerateCKC(provider, request, info); }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_0003", "Unable to process SPC. See 'innerException' for more information.", ex); }
return(response.Binary);
}
public IContentKey FetchKey(byte[] spc, byte[] ckc)
{
var spcBuffer = new ReadOnlyMemory <byte>(spc);
var ckcBuffer = new ReadOnlyMemory <byte>(ckc);
// We try to read SPC message.
SPCMessage request = null;
try { request = new SPCMessage(spcBuffer); }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_2001", "Unable to parse SPC. See 'innerException' for more information.", ex); }
CKCMessage response = null;
try { response = new CKCMessage(ckcBuffer); }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_2002", "Unable to parse CKC. See 'innerException' for more information.", ex); }
FPProvider provider = null;
try { provider = this.Providers.First(p => Enumerable.SequenceEqual(p.Hash, request.ProviderHash)); }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidProviderException("EXC_2003", "Received SPCMessage contains a unregistered FairPlay provider.", ex); }
return(FetchKey(provider, request, response));
}
private byte[] FetchId(FPProvider provider, SPCMessage spc, CKCMessage ckc)
{
IEnumerable <TLLVSlab> spcSlabs = null;
try { spcSlabs = TLLVSlab.FromBuffer(spc.UnscrambledPayload(provider.RSAKey)); }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_2030", "Unable to process inspection. See 'innerException' for more information.", ex); }
AssetPayload AssetPayload = null;
try { AssetPayload = spcSlabs.First(p => p.Tag.Same(TLLVTag.Id.Asset)).Payload <AssetPayload>(); }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_2031", "Unable to process inspection. See 'innerException' for more information.", ex); }
byte[] ID = null;
try { ID = AssetPayload.Identifier; }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_2032", "Unable to process inspection. See 'innerException' for more information.", ex); }
return(ID);
}
public static byte[] UnscrambledPayload(this CKCMessage message, byte[] key)
{
ArgumentThrow.IfNull(message, $"Invalid {typeof(CKCMessage).Name} to unscramble. Message can not be null.", nameof(message));
ArgumentThrow.IfLengthNot(key, 16, "Invalid key to unscramble. Key buffer should be 16 bytes.", nameof(key));
using (var aes = Aes.Create())
{
aes.IV = message.IV;
aes.Key = key;
aes.Mode = CipherMode.CBC;
aes.Padding = PaddingMode.None;
using (var decryptor = aes.CreateDecryptor())
using (var memoryStream = new MemoryStream())
using (var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Write))
{
cryptoStream.Write(message.ContentPayload);
return(memoryStream.ToArray());
}
}
}
private IContentKey FetchKey(FPProvider provider, SPCMessage spc, CKCMessage ckc)
{
IEnumerable <TLLVSlab> spcSlabs = null;
try { spcSlabs = TLLVSlab.FromBuffer(spc.UnscrambledPayload(provider.RSAKey)); }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_2010", "Unable to process inspection. See 'innerException' for more information.", ex); }
byte[] DASk = null;
try { DASk = new DFunction(provider.ASKey).DeriveBytes(spcSlabs.First(p => p.Tag.Same(TLLVTag.Id.R2)).Payload <R2Payload>().R2); }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_2011", "Unable to process inspection. See 'innerException' for more information.", ex); }
SKR1Payload SessionRandom1Payload = null;
try { SessionRandom1Payload = spcSlabs.First(p => p.Tag.Same(TLLVTag.Id.SKR1)).Payload <SKR1Payload>(); }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_2012", "Unable to process inspection. See 'innerException' for more information.", ex); }
SKR1IntegrityPayload SessionRandom1IntegrityPayload = null;
try { SessionRandom1IntegrityPayload = spcSlabs.First(p => p.Tag.Same(TLLVTag.Id.SKR1Integrity)).Payload <SKR1IntegrityPayload>(); }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_2013", "Unable to process inspection. See 'innerException' for more information.", ex); }
SKR1Parcel SessionRandom1Parcel = null;
try { SessionRandom1Parcel = new SKR1Parcel(new ReadOnlyMemory <byte>(SessionRandom1Payload.UnscrambledParcel(DASk))); }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_2014", "Unable to process inspection. See 'innerException' for more information.", ex); }
if (Enumerable.SequenceEqual(SessionRandom1Parcel.Integrity, SessionRandom1IntegrityPayload.Integrity) == false)
{
throw new FPContextIntegrityViolatedException("EXC_0034", "Unable to process SPC. SPC integrity violated.");
}
byte[] seed = null;
try { seed = spcSlabs.First(s => s.Tag.Same(TLLVTag.Id.AR)).Payload <ARPayload>().Seed; }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_2015", "Unable to process inspection. See 'innerException' for more information.", ex); }
byte[] random = null;
try { random = SessionRandom1Parcel.R1; }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_2016", "Unable to process inspection. See 'innerException' for more information.", ex); }
byte[] key = null;
try {
using (var sha = SHA1.Create())
using (var aes = Aes.Create())
{
// aes.IV = new byte[16];
aes.Key = sha.ComputeHash(random).Take(16).ToArray();
aes.Mode = CipherMode.ECB;
aes.Padding = PaddingMode.None;
using (var encryptor = aes.CreateEncryptor())
using (var memoryStream = new MemoryStream())
using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
{
cryptoStream.Write(seed);
key = memoryStream.ToArray();
}
}
}
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_2017", "Unable to process inspection. See 'innerException' for more information.", ex); }
IEnumerable <TLLVSlab> ckcSlabs = null;
try { ckcSlabs = TLLVSlab.FromBuffer(ckc.UnscrambledPayload(key)); }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_2018", "Unable to process inspection. See 'innerException' for more information.", ex); }
byte[] SK = null;
try { SK = SessionRandom1Parcel.SK; }
catch (FPException) { throw; }
catch (Exception ex) { throw new FPInvalidContextException("EXC_2019", "Unable to process inspection. See 'innerException' for more information.", ex); }
return(FetchKey(spcSlabs, ckcSlabs, SK));
}