241 lines
8.2 KiB
C#
241 lines
8.2 KiB
C#
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using System;
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using System.Collections;
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using System.Collections.Generic;
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using LipingShare.LCLib.Asn1Processor;
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using System.Security.Cryptography;
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namespace UnityEngine.Purchasing.Security
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{
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internal class PKCS7
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{
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private Asn1Node root;
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public Asn1Node data { get; private set; }
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public List<SignerInfo> sinfos { get; private set; }
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public List<X509Cert> certChain { get; private set; }
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private bool validStructure;
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public static PKCS7 Load(byte[] data)
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{
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using (var stm = new System.IO.MemoryStream(data))
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{
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Asn1Parser parser = new Asn1Parser();
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parser.LoadData(stm);
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return new PKCS7(parser.RootNode);
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}
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}
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public PKCS7(Asn1Node node)
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{
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this.root = node;
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CheckStructure();
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}
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public bool Verify(X509Cert cert, DateTime certificateCreationTime)
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{
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if (validStructure)
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{
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bool ok = true;
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foreach (var sinfo in sinfos)
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{
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X509Cert signCert = FindSignCert(sinfo);
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if (signCert != null && signCert.PubKey != null)
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{
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ok = ok && signCert.CheckCertTime(certificateCreationTime);
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if (IsStoreKitSimulatorData())
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{
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ok = ok && signCert.PubKey.VerifySha256(data.GetChildNode(0).Data, sinfo.EncryptedDigest);
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ok = ok && ValidateStoreKitSimulatorCertRoot(cert, signCert);
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}
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else
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{
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ok = ok && VerifyPublicKeyWithSha256OrSha1(signCert, sinfo);
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ok = ok && ValidateChain(cert, signCert, certificateCreationTime);
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}
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}
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}
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return ok && sinfos.Count > 0;
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}
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return false;
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}
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X509Cert FindSignCert(SignerInfo sinfo)
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{
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foreach (var cert in certChain)
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{
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if (cert.SerialNumber == sinfo.IssuerSerialNumber)
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{
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return cert;
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}
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}
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return null;
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}
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bool IsStoreKitSimulatorData()
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{
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return data.IsIndefiniteLength && data.ChildNodeCount == 1;
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}
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bool VerifyPublicKeyWithSha256OrSha1(X509Cert signCert, SignerInfo sinfo)
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{
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if (signCert.PubKey.VerifySha256(data.Data, sinfo.EncryptedDigest))
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{
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return true;
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}
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return signCert.PubKey.VerifySha1(data.Data, sinfo.EncryptedDigest);
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}
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static bool ValidateStoreKitSimulatorCertRoot(X509Cert root, X509Cert cert)
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{
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return cert.CheckSignatureSha256(root);
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}
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private bool ValidateChain(X509Cert root, X509Cert cert, DateTime certificateCreationTime)
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{
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if (cert.Issuer.Equals(root.Subject))
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{
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return cert.CheckSignature(root);
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}
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/**
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* TODO: improve this logic
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*/
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foreach (var c in certChain)
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{
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if (c != cert && c.Subject.Equals(cert.Issuer) && c.CheckCertTime(certificateCreationTime))
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{
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if (c.Issuer.Equals(root.Subject) && c.SerialNumber == root.SerialNumber)
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{
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return c.CheckSignature(root);
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}
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else
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{
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// cert was issued by c
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if (cert.CheckSignature(c))
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{
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return ValidateChain(root, c, certificateCreationTime);
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}
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}
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}
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}
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return false;
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}
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private void CheckStructure()
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{
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validStructure = false;
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if ((root.Tag & Asn1Tag.TAG_MASK) == Asn1Tag.SEQUENCE &&
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root.ChildNodeCount == 2)
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{
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Asn1Node tt = root.GetChildNode(0);
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if ((tt.Tag & Asn1Tag.TAG_MASK) != Asn1Tag.OBJECT_IDENTIFIER ||
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tt.GetDataStr(false) != "1.2.840.113549.1.7.2")
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{
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throw new InvalidPKCS7Data();
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}
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tt = root.GetChildNode(1); // [0]
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if (tt.ChildNodeCount != 1)
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throw new InvalidPKCS7Data();
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int curChild = 0;
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tt = tt.GetChildNode(curChild++); // Seq
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if (tt.ChildNodeCount < 4 || (tt.Tag & Asn1Tag.TAG_MASK) != Asn1Tag.SEQUENCE)
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throw new InvalidPKCS7Data();
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Asn1Node tt2 = tt.GetChildNode(0); // version
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if ((tt2.Tag & Asn1Tag.TAG_MASK) != Asn1Tag.INTEGER)
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throw new InvalidPKCS7Data();
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tt2 = tt.GetChildNode(curChild++); // digest algo
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// TODO: check algo
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if ((tt2.Tag & Asn1Tag.TAG_MASK) != Asn1Tag.SET)
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throw new InvalidPKCS7Data();
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tt2 = tt.GetChildNode(curChild++); // pkcs7 data
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if ((tt2.Tag & Asn1Tag.TAG_MASK) != Asn1Tag.SEQUENCE && tt2.ChildNodeCount != 2)
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throw new InvalidPKCS7Data();
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data = tt2.GetChildNode(1).GetChildNode(0);
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if (tt.ChildNodeCount == 5)
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{
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// cert chain, this is optional
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certChain = new List<X509Cert>();
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tt2 = tt.GetChildNode(curChild++);
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if (tt2.ChildNodeCount == 0)
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throw new InvalidPKCS7Data();
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for (int i = 0; i < tt2.ChildNodeCount; i++)
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{
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certChain.Add(new X509Cert(tt2.GetChildNode(i)));
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}
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}
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tt2 = tt.GetChildNode(curChild++); // signer's info
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if ((tt2.Tag & Asn1Tag.TAG_MASK) != Asn1Tag.SET || tt2.ChildNodeCount == 0)
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throw new InvalidPKCS7Data();
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sinfos = new List<SignerInfo>();
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for (int i = 0; i < tt2.ChildNodeCount; i++)
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{
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sinfos.Add(new SignerInfo(tt2.GetChildNode(i)));
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}
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validStructure = true;
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}
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}
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}
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internal class SignerInfo
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{
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public int Version { get; private set; }
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public string IssuerSerialNumber { get; private set; }
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public byte[] EncryptedDigest { get; private set; }
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public SignerInfo(Asn1Node n)
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{
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if (n.ChildNodeCount != 5)
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throw new InvalidPKCS7Data();
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Asn1Node tt;
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// version
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tt = n.GetChildNode(0);
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if ((tt.Tag & Asn1Tag.TAG_MASK) != Asn1Tag.INTEGER)
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throw new InvalidPKCS7Data();
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Version = tt.Data[0];
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if (Version != 1 || tt.Data.Length != 1)
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throw new UnsupportedSignerInfoVersion();
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// get the issuer SN
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tt = n.GetChildNode(1);
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if ((tt.Tag & Asn1Tag.TAG_MASK) != Asn1Tag.SEQUENCE || tt.ChildNodeCount != 2)
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throw new InvalidPKCS7Data();
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tt = tt.GetChildNode(1);
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if ((tt.Tag & Asn1Tag.TAG_MASK) != Asn1Tag.INTEGER)
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throw new InvalidPKCS7Data();
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IssuerSerialNumber = Asn1Util.ToHexString(tt.Data);
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// get the data
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tt = n.GetChildNode(4);
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if ((tt.Tag & Asn1Tag.TAG_MASK) != Asn1Tag.OCTET_STRING)
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throw new InvalidPKCS7Data();
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EncryptedDigest = tt.Data;
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}
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}
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/// <summary>
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/// An IAP Security exception indicating some invalid data for PKCS7 checks.
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/// </summary>
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public class InvalidPKCS7Data : IAPSecurityException { }
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/// <summary>
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/// An IAP Security exception indicating unsupported signer information.
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/// </summary>
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public class UnsupportedSignerInfoVersion : IAPSecurityException { }
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}
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