Como: alterar o provedor de criptografia de uma chave privada de certificado X.509
Este tópico mostra como alterar o provedor criptográfico usado para fornecer a chave privada de um certificado X.509 e como integrar o provedor à estrutura de segurança do Windows Communication Foundation (WCF). Para obter mais informações sobre o uso de certificados, consulte Trabalhando com certificados.
A estrutura de segurança do WCF fornece uma maneira de introduzir novos tipos de token de segurança, conforme descrito em Como: criar um token personalizado. Também é possível usar um token personalizado para substituir os tipos de token fornecidos pelo sistema existentes.
Neste tópico, o token de segurança X.509 fornecido pelo sistema é substituído por um token X.509 personalizado que fornece uma implementação diferente para a chave privada do certificado. Isso é útil em cenários em que a chave privada real é fornecida por um provedor criptográfico diferente do provedor criptográfico padrão do Windows. Um exemplo de um provedor criptográfico alternativo é um módulo de segurança de hardware que executa todas as operações criptográficas relacionadas à chave privada e não armazena as chaves privadas na memória, melhorando assim a segurança do sistema.
O exemplo a seguir é apenas para fins de demonstração. Ele não substitui o provedor criptográfico padrão do Windows, mas mostra onde esse provedor pode ser integrado.
Procedimentos
Cada token de segurança que tem uma chave ou chaves de segurança associadas deve implementar a propriedade SecurityKeys, que retorna uma coleção de chaves da instância do token de segurança. Se o token for um token de segurança X.509, a coleção conterá uma única instância da classe X509AsymmetricSecurityKey que representa as chaves públicas e privadas associadas ao certificado. Para substituir o provedor criptográfico padrão usado para fornecer as chaves do certificado, crie uma nova implementação dessa classe.
Para criar uma chave assimétrica X.509 personalizada
Defina uma nova classe derivada da classe X509AsymmetricSecurityKey.
Substitua a propriedade somente leitura KeySize. Essa propriedade retorna o tamanho real da chave do par de chaves pública/privada do certificado.
Substitua o método DecryptKey. Esse método é chamado pela estrutura de segurança WCF para descriptografar uma chave simétrica com a chave privada do certificado. (A chave foi previamente criptografada com a chave pública do certificado.)
Substitua o método GetAsymmetricAlgorithm. Esse método é chamado pela estrutura de segurança WCF para obter uma instância da classe AsymmetricAlgorithm que representa o provedor criptográfico para a chave pública ou privada do certificado, dependendo dos parâmetros passados para o método.
Opcional. Substitua o método GetHashAlgorithmForSignature. Substitua este método se for necessária uma implementação diferente da classe HashAlgorithm.
Substitua o método GetSignatureFormatter. Esse método retorna uma instância da classe AsymmetricSignatureFormatter que está associada à chave privada do certificado.
Substitua o método IsSupportedAlgorithm. Esse método é usado para indicar se um algoritmo criptográfico específico é compatível com a implementação da chave de segurança.
class CustomX509AsymmetricSecurityKey : X509AsymmetricSecurityKey { X509Certificate2 certificate; object thisLock = new Object(); bool privateKeyAvailabilityDetermined; AsymmetricAlgorithm privateKey; PublicKey publicKey; public CustomX509AsymmetricSecurityKey(X509Certificate2 certificate) : base(certificate) { this.certificate = certificate; } public override int KeySize { get { return this.PublicKey.Key.KeySize; } } AsymmetricAlgorithm PrivateKey { // You need to modify this to obtain the private key using a different cryptographic // provider if you do not want to use the default provider. get { if (!this.privateKeyAvailabilityDetermined) { lock (ThisLock) { if (!this.privateKeyAvailabilityDetermined) { this.privateKey = this.certificate.PrivateKey; this.privateKeyAvailabilityDetermined = true; } } } return this.privateKey; } } PublicKey PublicKey { get { if (this.publicKey == null) { lock (ThisLock) { this.publicKey ??= this.certificate.PublicKey; } } return this.publicKey; } } Object ThisLock { get { return thisLock; } } public override byte[] DecryptKey(string algorithm, byte[] keyData) { // You can decrypt the key only if you have the private key in the certificate. if (this.PrivateKey == null) { throw new NotSupportedException("Missing private key"); } RSA rsa = this.PrivateKey as RSA; if (rsa == null) { throw new NotSupportedException("Private key cannot be used with RSA algorithm"); } // Support exchange keySpec, AT_EXCHANGE ? if (rsa.KeyExchangeAlgorithm == null) { throw new NotSupportedException("Private key does not support key exchange"); } switch (algorithm) { case EncryptedXml.XmlEncRSA15Url: return EncryptedXml.DecryptKey(keyData, rsa, false); case EncryptedXml.XmlEncRSAOAEPUrl: return EncryptedXml.DecryptKey(keyData, rsa, true); default: throw new NotSupportedException(String.Format("Algorithm {0} is not supported", algorithm)); } } public override AsymmetricAlgorithm GetAsymmetricAlgorithm(string algorithm, bool privateKey) { if (privateKey) { if (this.PrivateKey == null) { throw new NotSupportedException("Missing private key"); } switch (algorithm) { case SignedXml.XmlDsigDSAUrl: if ((this.PrivateKey as DSA) != null) { return (this.PrivateKey as DSA); } throw new NotSupportedException("Private key cannot be used with DSA"); case SignedXml.XmlDsigRSASHA1Url: case EncryptedXml.XmlEncRSA15Url: case EncryptedXml.XmlEncRSAOAEPUrl: if ((this.PrivateKey as RSA) != null) { return (this.PrivateKey as RSA); } throw new NotSupportedException("Private key cannot be used with RSA"); default: throw new NotSupportedException(String.Format("Algorithm {0} is not supported", algorithm)); } } else { switch (algorithm) { case SignedXml.XmlDsigDSAUrl: if ((this.PublicKey.Key as DSA) != null) { return (this.PublicKey.Key as DSA); } throw new NotSupportedException("Public key cannot be used with DSA"); case SignedXml.XmlDsigRSASHA1Url: case EncryptedXml.XmlEncRSA15Url: case EncryptedXml.XmlEncRSAOAEPUrl: if ((this.PublicKey.Key as RSA) != null) { return (this.PublicKey.Key as RSA); } throw new NotSupportedException("Public key cannot be used with RSA"); default: throw new NotSupportedException(String.Format("Algorithm {0} is not supported", algorithm)); } } } public override HashAlgorithm GetHashAlgorithmForSignature(string algorithm) { if (!this.IsSupportedAlgorithm(algorithm)) { throw new NotSupportedException(String.Format("Algorithm {0} is not supported", algorithm)); } switch (algorithm) { case SignedXml.XmlDsigDSAUrl: case SignedXml.XmlDsigRSASHA1Url: return new SHA1Managed(); default: throw new NotSupportedException(String.Format("Algorithm {0} is not supported", algorithm)); } } public override AsymmetricSignatureFormatter GetSignatureFormatter(string algorithm) { // The signature can be created only if the private key is present. if (this.PrivateKey == null) { throw new NotSupportedException("Private key is missing"); } // Only one of the two algorithms is supported, not both. // XmlDsigDSAUrl = "http://www.w3.org/2000/09/xmldsig#dsa-sha1"; // XmlDsigRSASHA1Url = "http://www.w3.org/2000/09/xmldsig#rsa-sha1"; switch (algorithm) { case SignedXml.XmlDsigDSAUrl: // Ensure that this is a DSA algorithm object. DSA dsa = (this.PrivateKey as DSA); if (dsa == null) { throw new NotSupportedException("Private key cannot be used DSA"); } return new DSASignatureFormatter(dsa); case SignedXml.XmlDsigRSASHA1Url: // Ensure that this is an RSA algorithm object. RSA rsa = (this.PrivateKey as RSA); if (rsa == null) { throw new NotSupportedException("Private key cannot be used RSA"); } return new RSAPKCS1SignatureFormatter(rsa); default: throw new NotSupportedException(String.Format("Algorithm {0} is not supported", algorithm)); } } public override bool IsSupportedAlgorithm(string algorithm) { switch (algorithm) { case SignedXml.XmlDsigDSAUrl: return (this.PublicKey.Key is DSA); case SignedXml.XmlDsigRSASHA1Url: case EncryptedXml.XmlEncRSA15Url: case EncryptedXml.XmlEncRSAOAEPUrl: return (this.PublicKey.Key is RSA); default: return false; } } }
Friend Class CustomX509AsymmetricSecurityKey Inherits X509AsymmetricSecurityKey Private _certificate As X509Certificate2 Private _thisLock As New Object() Private _privateKeyAvailabilityDetermined As Boolean Private _privateKey As AsymmetricAlgorithm Private _publicKey As PublicKey Public Sub New(ByVal certificate As X509Certificate2) MyBase.New(certificate) Me._certificate = certificate End Sub Public Overrides ReadOnly Property KeySize() As Integer Get Return Me.PublicKey.Key.KeySize End Get End Property Private Overloads ReadOnly Property PrivateKey() As AsymmetricAlgorithm ' You need to modify this to obtain the private key using a different cryptographic ' provider if you do not want to use the default provider. Get If Not Me._privateKeyAvailabilityDetermined Then SyncLock ThisLock If Not Me._privateKeyAvailabilityDetermined Then Me._privateKey = Me._certificate.PrivateKey Me._privateKeyAvailabilityDetermined = True End If End SyncLock End If Return Me._privateKey End Get End Property Private Overloads ReadOnly Property PublicKey() As PublicKey Get If Me._publicKey Is Nothing Then SyncLock ThisLock If Me._publicKey Is Nothing Then Me._publicKey = Me._certificate.PublicKey End If End SyncLock End If Return Me._publicKey End Get End Property Private Overloads ReadOnly Property ThisLock() As Object Get Return _thisLock End Get End Property Public Overrides Function DecryptKey(ByVal algorithm As String, _ ByVal keyData() As Byte) As Byte() ' You can decrypt the key only if you have the private key in the certificate. If Me.PrivateKey Is Nothing Then Throw New NotSupportedException("Missing private key") End If Dim rsa = TryCast(Me.PrivateKey, RSA) If rsa Is Nothing Then Throw New NotSupportedException("Private key cannot be used with RSA algorithm") End If ' Support exchange keySpec, AT_EXCHANGE ? If rsa.KeyExchangeAlgorithm Is Nothing Then Throw New NotSupportedException("Private key does not support key exchange") End If Select Case algorithm Case EncryptedXml.XmlEncRSA15Url Return EncryptedXml.DecryptKey(keyData, rsa, False) Case EncryptedXml.XmlEncRSAOAEPUrl Return EncryptedXml.DecryptKey(keyData, rsa, True) Case Else Throw New NotSupportedException(String.Format("Algorithm {0} is not supported", algorithm)) End Select End Function Public Overrides Function GetAsymmetricAlgorithm(ByVal algorithm As String, _ ByVal privateKey As Boolean) As AsymmetricAlgorithm If privateKey Then If Me.PrivateKey Is Nothing Then Throw New NotSupportedException("Missing private key") End If Select Case algorithm Case SignedXml.XmlDsigDSAUrl If TryCast(Me.PrivateKey, DSA) IsNot Nothing Then Return (TryCast(Me.PrivateKey, DSA)) End If Throw New NotSupportedException("Private key cannot be used with DSA") Case SignedXml.XmlDsigRSASHA1Url, EncryptedXml.XmlEncRSA15Url, EncryptedXml.XmlEncRSAOAEPUrl If TryCast(Me.PrivateKey, RSA) IsNot Nothing Then Return (TryCast(Me.PrivateKey, RSA)) End If Throw New NotSupportedException("Private key cannot be used with RSA") Case Else Throw New NotSupportedException(String.Format("Algorithm {0} is not supported", algorithm)) End Select Else Select Case algorithm Case SignedXml.XmlDsigDSAUrl If TryCast(Me.PublicKey.Key, DSA) IsNot Nothing Then Return (TryCast(Me.PublicKey.Key, DSA)) End If Throw New NotSupportedException("Public key cannot be used with DSA") Case SignedXml.XmlDsigRSASHA1Url, EncryptedXml.XmlEncRSA15Url, EncryptedXml.XmlEncRSAOAEPUrl If TryCast(Me.PublicKey.Key, RSA) IsNot Nothing Then Return (TryCast(Me.PublicKey.Key, RSA)) End If Throw New NotSupportedException("Public key cannot be used with RSA") Case Else Throw New NotSupportedException(String.Format("Algorithm {0} is not supported", algorithm)) End Select End If End Function Public Overrides Function GetHashAlgorithmForSignature(ByVal algorithm As String) As HashAlgorithm If Not Me.IsSupportedAlgorithm(algorithm) Then Throw New NotSupportedException(String.Format("Algorithm {0} is not supported", algorithm)) End If Select Case algorithm Case SignedXml.XmlDsigDSAUrl, SignedXml.XmlDsigRSASHA1Url Return New SHA1Managed() Case Else Throw New NotSupportedException(String.Format("Algorithm {0} is not supported", algorithm)) End Select End Function Public Overrides Function GetSignatureFormatter(ByVal algorithm As String) As AsymmetricSignatureFormatter ' The signature can be created only if the private key is present. If Me.PrivateKey Is Nothing Then Throw New NotSupportedException("Private key is missing") End If ' Only one of the two algorithms is supported, not both. ' XmlDsigDSAUrl = "http://www.w3.org/2000/09/xmldsig#dsa-sha1"; ' XmlDsigRSASHA1Url = "http://www.w3.org/2000/09/xmldsig#rsa-sha1"; Select Case algorithm Case SignedXml.XmlDsigDSAUrl ' Ensure that this is a DSA algorithm object. Dim dsa = (TryCast(Me.PrivateKey, DSA)) If dsa Is Nothing Then Throw New NotSupportedException("Private key cannot be used DSA") End If Return New DSASignatureFormatter(dsa) Case SignedXml.XmlDsigRSASHA1Url ' Ensure that this is an RSA algorithm object. Dim rsa = (TryCast(Me.PrivateKey, RSA)) If rsa Is Nothing Then Throw New NotSupportedException("Private key cannot be used RSA") End If Return New RSAPKCS1SignatureFormatter(rsa) Case Else Throw New NotSupportedException(String.Format("Algorithm {0} is not supported", algorithm)) End Select End Function Public Overrides Function IsSupportedAlgorithm(ByVal algorithm As String) As Boolean Select Case algorithm Case SignedXml.XmlDsigDSAUrl Return (TypeOf Me.PublicKey.Key Is DSA) Case SignedXml.XmlDsigRSASHA1Url, EncryptedXml.XmlEncRSA15Url, EncryptedXml.XmlEncRSAOAEPUrl Return (TypeOf Me.PublicKey.Key Is RSA) Case Else Return False End Select End Function End Class
O procedimento a seguir mostra como integrar a implementação de chave de segurança assimétrica X.509 personalizada criada no procedimento anterior com a estrutura de segurança WCF para substituir o token de segurança X.509 fornecido pelo sistema.
Para substituir o token de segurança X.509 fornecido pelo sistema por um token de chave de segurança assimétrica X.509 personalizado
Crie um token de segurança X.509 personalizado que retorne a chave de segurança assimétrica X.509 personalizada em vez da chave de segurança fornecida pelo sistema, conforme mostrado no exemplo a seguir. Para obter mais informações sobre tokens de segurança personalizados, consulte Como: criar um token personalizado.
class CustomX509SecurityToken : X509SecurityToken { ReadOnlyCollection<SecurityKey> securityKeys; public CustomX509SecurityToken(X509Certificate2 certificate) : base(certificate) { } public override ReadOnlyCollection<SecurityKey> SecurityKeys { get { if (this.securityKeys == null) { List<SecurityKey> temp = new List<SecurityKey>(1); temp.Add(new CustomX509AsymmetricSecurityKey(this.Certificate)); this.securityKeys = temp.AsReadOnly(); } return this.securityKeys; } } }
Friend Class CustomX509SecurityToken Inherits X509SecurityToken Private _securityKeys As ReadOnlyCollection(Of SecurityKey) Public Sub New(ByVal certificate As X509Certificate2) MyBase.New(certificate) End Sub Public Overrides ReadOnly Property SecurityKeys() As ReadOnlyCollection(Of SecurityKey) Get If Me._securityKeys Is Nothing Then Dim temp As New List(Of SecurityKey)(1) temp.Add(New CustomX509AsymmetricSecurityKey(Me.Certificate)) Me._securityKeys = temp.AsReadOnly() End If Return Me._securityKeys End Get End Property End Class
Crie um provedor de token de segurança personalizado que retorne um token de segurança X.509 personalizado, conforme mostrado no exemplo. Para obter mais informações sobre provedores de token de segurança personalizados, consulte Como criar um provedor de token de segurança personalizado.
class CustomX509SecurityTokenProvider : SecurityTokenProvider { X509Certificate2 certificate; public CustomX509SecurityTokenProvider(X509Certificate2 certificate) { this.certificate = certificate; } protected override SecurityToken GetTokenCore(TimeSpan timeout) { return new CustomX509SecurityToken(certificate); } }
Friend Class CustomX509SecurityTokenProvider Inherits SecurityTokenProvider Private _certificate As X509Certificate2 Public Sub New(ByVal certificate As X509Certificate2) Me._certificate = certificate End Sub Protected Overrides Function GetTokenCore(ByVal timeout As TimeSpan) As SecurityToken Return New CustomX509SecurityToken(_certificate) End Function End Class
Se a chave de segurança personalizada precisar ser usada no lado do iniciador, crie um gerenciador de token de segurança de cliente personalizado e classes de credenciais de cliente personalizadas, conforme mostrado no exemplo a seguir. Para obter mais informações sobre credenciais de cliente personalizadas e gerenciadores de token de segurança de cliente, consulte Passo a passo: Criando credenciais personalizadas de cliente e serviço.
class CustomClientSecurityTokenManager : ClientCredentialsSecurityTokenManager { CustomClientCredentials credentials; public CustomClientSecurityTokenManager(CustomClientCredentials credentials) : base(credentials) { this.credentials = credentials; } public override SecurityTokenProvider CreateSecurityTokenProvider(SecurityTokenRequirement tokenRequirement) { SecurityTokenProvider result = null; if (tokenRequirement.TokenType == SecurityTokenTypes.X509Certificate) { MessageDirection direction = tokenRequirement.GetProperty<MessageDirection>(ServiceModelSecurityTokenRequirement.MessageDirectionProperty); if (direction == MessageDirection.Output) { if (tokenRequirement.KeyUsage == SecurityKeyUsage.Signature) { result = new CustomX509SecurityTokenProvider(credentials.ClientCertificate.Certificate); } } else { if (tokenRequirement.KeyUsage == SecurityKeyUsage.Exchange) { result = new CustomX509SecurityTokenProvider(credentials.ClientCertificate.Certificate); } } } result ??= base.CreateSecurityTokenProvider(tokenRequirement); return result; } }
Friend Class CustomClientSecurityTokenManager Inherits ClientCredentialsSecurityTokenManager Private credentials As CustomClientCredentials Public Sub New(ByVal credentials As CustomClientCredentials) MyBase.New(credentials) Me.credentials = credentials End Sub Public Overrides Function CreateSecurityTokenProvider(ByVal tokenRequirement As SecurityTokenRequirement) _ As SecurityTokenProvider Dim result As SecurityTokenProvider = Nothing If tokenRequirement.TokenType = SecurityTokenTypes.X509Certificate Then Dim direction = tokenRequirement.GetProperty(Of MessageDirection) _ (ServiceModelSecurityTokenRequirement.MessageDirectionProperty) If direction = MessageDirection.Output Then If tokenRequirement.KeyUsage = SecurityKeyUsage.Signature Then result = New CustomX509SecurityTokenProvider(credentials.ClientCertificate.Certificate) End If Else If tokenRequirement.KeyUsage = SecurityKeyUsage.Exchange Then result = New CustomX509SecurityTokenProvider(credentials.ClientCertificate.Certificate) End If End If End If If result Is Nothing Then result = MyBase.CreateSecurityTokenProvider(tokenRequirement) End If Return result End Function End Class
public class CustomClientCredentials : ClientCredentials { public CustomClientCredentials() { } protected CustomClientCredentials(CustomClientCredentials other) : base(other) { } protected override ClientCredentials CloneCore() { return new CustomClientCredentials(this); } public override SecurityTokenManager CreateSecurityTokenManager() { return new CustomClientSecurityTokenManager(this); } }
Public Class CustomClientCredentials Inherits ClientCredentials Public Sub New() End Sub Protected Sub New(ByVal other As CustomClientCredentials) MyBase.New(other) End Sub Protected Overrides Function CloneCore() As ClientCredentials Return New CustomClientCredentials(Me) End Function Public Overrides Function CreateSecurityTokenManager() As SecurityTokenManager Return New CustomClientSecurityTokenManager(Me) End Function End Class
Se a chave de segurança personalizada precisar ser usada no lado do destinatário, crie um gerenciador de token de segurança de serviço personalizado e credenciais de serviço personalizadas, conforme mostrado no exemplo a seguir. Para obter mais informações sobre credenciais de serviço personalizadas e gerenciadores de token de segurança de serviço, consulte Passo a passo: Criando credenciais personalizadas de cliente e serviço.
class CustomServiceSecurityTokenManager : ServiceCredentialsSecurityTokenManager { CustomServiceCredentials credentials; public CustomServiceSecurityTokenManager(CustomServiceCredentials credentials) : base(credentials) { this.credentials = credentials; } public override SecurityTokenProvider CreateSecurityTokenProvider(SecurityTokenRequirement tokenRequirement) { SecurityTokenProvider result = null; if (tokenRequirement.TokenType == SecurityTokenTypes.X509Certificate) { MessageDirection direction = tokenRequirement.GetProperty<MessageDirection>(ServiceModelSecurityTokenRequirement.MessageDirectionProperty); if (direction == MessageDirection.Input) { if (tokenRequirement.KeyUsage == SecurityKeyUsage.Exchange) { result = new CustomX509SecurityTokenProvider(credentials.ServiceCertificate.Certificate); } } else { if (tokenRequirement.KeyUsage == SecurityKeyUsage.Signature) { result = new CustomX509SecurityTokenProvider(credentials.ServiceCertificate.Certificate); } } } result ??= base.CreateSecurityTokenProvider(tokenRequirement); return result; } }
Friend Class CustomServiceSecurityTokenManager Inherits ServiceCredentialsSecurityTokenManager Private credentials As CustomServiceCredentials Public Sub New(ByVal credentials As CustomServiceCredentials) MyBase.New(credentials) Me.credentials = credentials End Sub Public Overrides Function CreateSecurityTokenProvider(ByVal tokenRequirement As SecurityTokenRequirement) As SecurityTokenProvider Dim result As SecurityTokenProvider = Nothing If tokenRequirement.TokenType = SecurityTokenTypes.X509Certificate Then Dim direction = tokenRequirement.GetProperty(Of MessageDirection) _ (ServiceModelSecurityTokenRequirement.MessageDirectionProperty) If direction = MessageDirection.Input Then If tokenRequirement.KeyUsage = SecurityKeyUsage.Exchange Then result = New CustomX509SecurityTokenProvider(credentials.ServiceCertificate.Certificate) End If Else If tokenRequirement.KeyUsage = SecurityKeyUsage.Signature Then result = New CustomX509SecurityTokenProvider(credentials.ServiceCertificate.Certificate) End If End If End If If result Is Nothing Then result = MyBase.CreateSecurityTokenProvider(tokenRequirement) End If Return result End Function End Class
public class CustomServiceCredentials : ServiceCredentials { public CustomServiceCredentials() { } protected CustomServiceCredentials(CustomServiceCredentials other) : base(other) { } protected override ServiceCredentials CloneCore() { return new CustomServiceCredentials(this); } public override SecurityTokenManager CreateSecurityTokenManager() { return new CustomServiceSecurityTokenManager(this); } }
Public Class CustomServiceCredentials Inherits ServiceCredentials Public Sub New() End Sub Protected Sub New(ByVal other As CustomServiceCredentials) MyBase.New(other) End Sub Protected Overrides Function CloneCore() As ServiceCredentials Return New CustomServiceCredentials(Me) End Function Public Overrides Function CreateSecurityTokenManager() As SecurityTokenManager Return New CustomServiceSecurityTokenManager(Me) End Function End Class
Confira também
- X509AsymmetricSecurityKey
- AsymmetricSecurityKey
- SecurityKey
- AsymmetricAlgorithm
- HashAlgorithm
- AsymmetricSignatureFormatter
- Passo a passo: criar credenciais de serviço e cliente personalizados
- Como: criar um autenticador de token de segurança personalizado
- Como: criar um provedor de token de segurança personalizado
- Como: criar um token personalizado