// x509cert.h - X.509 certificate read and write routines for Crypto++.
//              Written and placed in the public domain by Jeffrey Walton
//              and Geoff Beier

/// \file x509cert.h
/// \brief Classes and functions to read X.509 certificates
/// \details X509Certificate is a partial implementation of X.509 certificate
///  parsing. The class loads a DER encoded certificate and presents many of
///  the more important attributes and values through accessor functions. The
///  attributes and values include signature, signature algorithm, toBeSigned,
///  and subjectPublicKeyInfo exposed as a X509PubliKey ready for use in
///  Crypto++ library algorithms.
/// \details This is a library add-on. You must download and compile it
///  yourself as part of the library.
/// \since Crypto++ 8.3
/// \sa <A HREF="http://www.cryptopp.com/wiki/X509Certificate">X509Certificate</A>
///  and <A HREF="http://www.cryptopp.com/wiki/PEM_Pack">PEM Pack</A> on the
///  Crypto++ wiki.

/////////////////////////////////////////////////////////////////////////////

#ifndef CRYPTOPP_X509_CERTIFICATE_H
#define CRYPTOPP_X509_CERTIFICATE_H

#include "cryptlib.h"
#include "secblock.h"
#include "stdcpp.h"
#include "asn.h"

#include <iosfwd>
#include <string>
#include <vector>
#include <sstream>

NAMESPACE_BEGIN(CryptoPP)

// Forward declaration
class Integer;

/// \brief Convert OID to a LDAP name
/// \param oid the object identifier
/// \param defaultName the name to use if lookup fails
/// \returns the LDAP name for display
/// \details LDAP names are specified in ITU X.520 and other places, like the RFCs.
///  If defaultName is NULL, then the OID is used.
std::string OidToNameLookup(const OID& oid, const char *defaultName=NULLPTR);

/// \brief ASNTag initializer
/// \details 0 is an invalid tag value
const ASNTag InvalidTag = static_cast<ASNTag>(0);

//////////////////////////////////////////////////

/// \brief X.500 Relative Distinguished Name value
struct RdnValue : public ASN1Object
{
    virtual ~RdnValue() {}
    RdnValue() : m_tag(InvalidTag) {}

    void BERDecode(BufferedTransformation &bt);
    void DEREncode(BufferedTransformation &bt) const;

    bool ValidateTag(byte tag) const;

    /// \brief Print an RDN value
    /// \returns ostream reference
    std::ostream& Print(std::ostream& out) const;

    /// \brief Textual representation
    /// \returns string representing the value
    std::string EncodeValue() const;

    OID m_oid;
    SecByteBlock m_value;
    ASNTag m_tag;
};

/// \brief Array of Relative Distinguished Name values
/// \details Vector or RdnValue
/// \sa RdnValue
typedef std::vector<RdnValue> RdnValueArray;

//////////////////////////////////////////////////

/// \brief X.690 Date value
struct DateValue : public ASN1Object
{
    DateValue() : m_tag(InvalidTag) {}
    virtual ~DateValue() {}

    void BERDecode(BufferedTransformation &bt);
    void DEREncode(BufferedTransformation &bt) const;

    bool ValidateTag(byte tag) const;

    /// \brief Print a Date value
    /// \returns ostream reference
    std::ostream& Print(std::ostream& out) const;

    /// \brief Textual representation
    /// \returns string representing the value
    std::string EncodeValue() const;

    SecByteBlock m_value;
    ASNTag m_tag;
};

//////////////////////////////////////////////////

/// \brief X.509 Extension value
struct ExtensionValue : public ASN1Object
{
    virtual ~ExtensionValue() {}
    ExtensionValue() : m_tag(InvalidTag), m_critical(false) {}

    void BERDecode(BufferedTransformation &bt);
    void DEREncode(BufferedTransformation &bt) const;

    bool ValidateTag(byte tag) const;

    /// \brief Print an Extension value
    /// \returns ostream reference
    std::ostream& Print(std::ostream& out) const;

    /// \brief Textual representation
    /// \returns string representing the value
    std::string EncodeValue() const;

    OID m_oid;
    SecByteBlock m_value;
    ASNTag m_tag;
    bool m_critical;
};

/// \brief Array of X.509 Extension values
/// \details Vector or ExtensionValue
/// \sa ExtensionValue
typedef std::vector<ExtensionValue> ExtensionValueArray;

//////////////////////////////////////////////////

/// \brief X.509 KeyIdentifier value
struct KeyIdentifierValue : public ASN1Object
{
    enum KeyIdentifierEnum {
        /// \brief Hash of the public key
        Hash=1,
        /// \brief Distinguised name and serial number
        DnAndSn
    };
    /// \brief Invalid identifier
    static const KeyIdentifierEnum InvalidKeyIdentifier = static_cast<KeyIdentifierEnum>(0);

    virtual ~KeyIdentifierValue() {}
    KeyIdentifierValue() : m_type(InvalidKeyIdentifier) {}

    void BERDecode(BufferedTransformation &bt);
    void DEREncode(BufferedTransformation &bt) const;

    bool ValidateTag(byte tag) const;

    /// \brief Print an Extension value
    /// \returns ostream reference
    std::ostream& Print(std::ostream& out) const;

    /// \brief Textual representation
    /// \returns string representing the value
    std::string EncodeValue() const;

    // The hash of the key is placed in m_value.
    // The remaining bits, like DN and Serno, are placed in m_other.
    OID m_oid;
    SecByteBlock m_value;
    SecByteBlock m_other;  // raw
    KeyIdentifierEnum m_type;
};

//////////////////////////////////////////////////

/// \brief X.509 KU and EKU value
/// \details KeyUsageValue represents Key Usage and Extended Key Usage values
/// \sa KeyUsageValueArray
struct KeyUsageValue : public ASN1Object
{
    // https://www.iana.org/assignments/smi-numbers/smi-numbers.xhtml#smi-numbers-1.3.6.1.5.5.7.3
    enum KeyUsageEnum {
        /// \brief Digital signature
        digitalSignature=0,
        /// \brief Signature verification
        /// \details nonRepudiation applies to non-certificate data
        nonRepudiation=1,
        /// \brief Signature verification
        /// \details contentCommitment is nonRepudiation and applies to non-certificate data
        contentCommitment=nonRepudiation,
        /// \brief Key transport
        keyEncipherment,
        /// \brief Data encryption
        /// \details Encryption occurs with the public key, and not a symmetric key
        dataEncipherment,
        /// \brief Key agreement
        keyAgreement,
        /// \brief Certificate signature verification
        keyCertSign,
        /// \brief Certificate revocation list signature verification
        cRLSign,
        /// \brief Data encryption
        /// \details Data encryption occurs with a key agreement key
        encipherOnly,
        /// \brief Data decryption
        /// \details Data decryption occurs with a key agreement key
        decipherOnly,
        /// \brief TLS server authentication
        serverAuth,
        /// \brief TLS client authentication
        clientAuth,
        /// \brief Code signing
        codeSigning,
        /// \brief Email protection
        emailProtection,
        /// \brief IPsec end system
        ipsecEndSystem,
        /// \brief IPsec tunnel
        ipsecTunnel,
        /// \brief IPsec user
        ipsecUser,
        /// \brief Time stamping
        timeStamping,
        /// \brief OCSP signing
        OCSPSigning,
        /// \brief Data Validation and Certification Server
        dvcs,
        /// \brief Border gateway CA server
        sbgpCertAAServerAuth,
        /// \brief SCVP responder
        scvpResponder,
        /// \brief Extensible Authentication Protocol (EAP) over PPP
        eapOverPPP,
        /// \brief Extensible Authentication Protocol (EAP) over LAN
        eapOverLAN,
        /// \brief Server-Based Certificate Validation Protocol
        scvpServer,
        /// \brief Server-Based Certificate Validation Protocol
        scvpClient,
        /// \brief IPsec Internet Key Exchange
        ipsecIKE,
        /// \brief Control And Provisioning of Wireless Access Points (CAPWAP) Protocol
        capwapAC,
        /// \brief Control And Provisioning of Wireless Access Points (CAPWAP) Protocol
        capwapWTP,
        /// \brief Session Initiation Protocol (SIP) X.509 Certificates
        sipDomain,
        /// \brief X.509v3 Certificates for Secure Shell Authentication
        secureShellClient,
        /// \brief X.509v3 Certificates for Secure Shell Authentication
        secureShellServer,
        /// \brief Certificate Profile and Certificate Management for SEcure Neighbor Discovery (SEND)
        sendRouter,
        /// \brief Certificate Profile and Certificate Management for SEcure Neighbor Discovery (SEND)
        sendProxiedRouter,
        /// \brief Certificate Profile and Certificate Management for SEcure Neighbor Discovery (SEND)
        sendOwner,
        /// \brief Certificate Profile and Certificate Management for SEcure Neighbor Discovery (SEND)
        sendProxiedOwner,
        /// \brief Certificate Management over CMS
        cmcCA,
        /// \brief Certificate Management over CMS
        cmcRA,
        /// \brief Certificate Management over CMS
        cmcArchive,
        /// \brief BGPsec Router Certificates, Certificate Revocation Lists, and Certification Requests
        bgpsecRouter,
        /// \brief Certificate profile for carrying logotypes
        brandIndicatorforMessageIdentification
    };
    /// \brief Invalid key usage
    static const KeyUsageEnum InvalidKeyUsage = static_cast<KeyUsageEnum>(128);

    virtual ~KeyUsageValue() {}

    /// \brief Construct a KeyUsageValue
    /// \details Use this ctor for Extended Key Usage (EKU).
    ///  KeyUsageEnum can be looked up based on a unique OID.
    KeyUsageValue(const OID& oid);

    /// \brief Construct a KeyUsageValue
    /// \details Use this ctor for Key Usage (KU). KeyUsageEnum
    ///  bitmask is a value of a common OID.
    KeyUsageValue(const OID& oid, KeyUsageEnum usage);

    void BERDecode(BufferedTransformation &bt);
    void DEREncode(BufferedTransformation &bt) const;

    /// \brief Print an Extension value
    /// \returns ostream reference
    std::ostream& Print(std::ostream& out) const;

    /// \brief Textual representation
    /// \returns string representing the value
    std::string EncodeValue() const;

    OID m_oid;
    // SecByteBlock m_value;
    KeyUsageEnum m_usage;
};

/// \brief Array of X.509 Key usage values
/// \details Vector or KeyUsageValue
/// \sa KeyUsageValue
typedef std::vector<KeyUsageValue> KeyUsageValueArray;

//////////////////////////////////////////////////

/// \brief X.509 Basic Constraint
struct BasicConstraintValue : public ASN1Object
{
    virtual ~BasicConstraintValue() {}
    BasicConstraintValue(bool critical=true) : m_pathLen(0), m_critical(critical), m_ca(false) {}

    void BERDecode(BufferedTransformation &bt);
    void DEREncode(BufferedTransformation &bt) const;

    /// \brief Print an Extension value
    /// \returns ostream reference
    std::ostream& Print(std::ostream& out) const;

    /// \brief Textual representation
    /// \returns string representing the value
    std::string EncodeValue() const;

    word32 m_pathLen;
    bool m_critical, m_ca;
};

//////////////////////////////////////////////////

/// \brief Identity value
/// \details IdentityValue holds an identity and provides a textual representation of it.
struct IdentityValue
{
    /// \brief Identity source
    enum IdentityEnum {
        /// \brief Subject Unique Identifier
        /// \details Optional part of X.509 v2 specification
        UniqueId=1,
        /// \brief Subject Distinguished Name
        /// \details Subject Distinguished Name (DN), which is a mashup of the RDNs
        SubjectDN,
        /// \brief Subject Common Name
        /// \details Common Name RDN, optional part of Subject Distinguished Name (DN)
        SubjectCN,
        /// \brief Subject Unique Identifier
        /// \details Subject Unique Identifier RDN, optional part of Subject Distinguished Name (DN)
        SubjectUID,
        /// \brief PKCS #9 email address
        /// \details PKCS #9 Email RDN, optional part of Subject Distinguished Name (DN)
        SubjectEmail,
        /// \brief Subject Public Key Identifier (SPKI)
        /// \details Optional part of X.509 v3 specification
        SubjectPKI,
        /// \brief SAN otherName
        /// \details Optional Subject Alternate Name (SAN)
        otherName,
        /// \brief SAN rfc822Name
        /// \details Optional Subject Alternate Name (SAN)
        rfc822Name,
        /// \brief SAN dNSName
        /// \details Optional Subject Alternate Name (SAN)
        dNSName,
        /// \brief SAN x400Address
        /// \details Optional Subject Alternate Name (SAN)
        x400Address,
        /// \brief SAN directoryName
        /// \details Optional Subject Alternate Name (SAN)
        directoryName,
        /// \brief SAN ediPartyName
        /// \details Optional Subject Alternate Name (SAN)
        ediPartyName,
        /// \brief SAN uniformResourceIdentifier
        /// \details Optional Subject Alternate Name (SAN)
        uniformResourceIdentifier,
        /// \brief SAN iPAddress
        /// \details Optional Subject Alternate Name (SAN)
        iPAddress,
        /// \brief SAN registeredID
        /// \details Optional Subject Alternate Name (SAN)
        registeredID,
        /// \brief nsServer
        /// \details Optional part of original Netscape specification
        nsServer,
        /// \brief msOtherNameUPN
        /// \details Microsoft Kerberos UserPrincipalName extracted from SAN otherName
        msOtherNameUPN
    };
    static const IdentityEnum InvalidIdentityEnum = static_cast<IdentityEnum>(0);

    virtual ~IdentityValue() {}

    IdentityValue(const SecByteBlock &value, IdentityEnum src);
    IdentityValue(const std::string &value, IdentityEnum src);
    IdentityValue(const OID &oid, const SecByteBlock &value, IdentityEnum src);
    IdentityValue(const OID &oid, const std::string &value, IdentityEnum src);

    /// \brief Print an Identity value
    /// \returns ostream reference
    std::ostream& Print(std::ostream& out) const;

    /// \brief Textual representation
    /// \returns string representing the value
    std::string EncodeValue() const;

    /// \brief Convert otherName into a different IdentityValue
    /// \details ConvertOtherName() operates on this object.
    ///  m_value and m_src can be changed to a new identity
    ///  type, like a UPN string and msOtherNameUPN type.
    void ConvertOtherName();

    OID m_oid;
    SecByteBlock m_value;  // Raw value from source
    IdentityEnum m_src;
};

/// \brief Array of Identity values
/// \details Vector or IdentityValue
/// \sa IdentityValue
typedef std::vector<IdentityValue> IdentityValueArray;

//////////////////////////////////////////////////

/// \brief X.509 Certificate
/// \details X509Certificate is a partial implementation of X.509 certificate
///  support. The class loads a DER encoded certificate and presents many of
///  the important attributes and values through accessor functions. The
///  attributes and values include signature, signature algorithm, toBeSigned,
///  serialNumber, issuerDistinguishedName, subjectDistinguishedName, and
///  subjectPublicKeyInfo exposed as a X509PubliKey ready for use in Crypto++
///  library algorithms.
/// \details Most member functions related to saving or encoding a certificate
///  have not been cut-in. Calling member functions that have not been cut-in will
///  result in NotImplemented exception. Future versions of the X509Certificate
///  can provide them.
/// \throws NotImplemented if a particular function has not been cut-in. Member
///  functions that throw NotImplemented include <tt>DEREncode*</tt>.
/// \details This is a library add-on. You must download and compile it
///  yourself as part of the library.
/// \since Crypto++ 8.3
/// \sa <A HREF="http://www.cryptopp.com/wiki/X509Certificate">X509Certificate</A>
///  and <A HREF="http://www.cryptopp.com/wiki/PEM_Pack">PEM Pack</A> on the
///  Crypto++ wiki.
class X509Certificate : public ASN1CryptoMaterial<Certificate>
{
public:

    /// \brief Certificate version
    enum Version {
        /// \brief Version 1
        v1=0,
        /// \brief Version 2
        v2,
        /// \brief Version 3
        v3
    };

public:
    virtual ~X509Certificate() {}
    X509Certificate() {}

    // NameValuePairs
    virtual void AssignFrom (const NameValuePairs &source);
    virtual bool GetVoidValue (const char *name, const std::type_info &valueType, void *pValue) const;

    /// \name VALIDATION
    //@{

    // CryptoMaterial
    virtual bool Validate (RandomNumberGenerator &rng, unsigned int level) const;

    /// \brief Validate signature on this certificate
    /// \param rng a RandomNumberGenerator for objects which use randomized
    ///  testing
    /// \param key the public key of the keypair used to sign this certificate
    /// \returns true if the test succeeds, false otherwise
    /// \details If this certificate is self-signed then the signature can be
    ///  verified using the public key in this certificate. In this case call
    ///  ValidateSignature() with GetSubjectPublicKey().
    /// \details If this certificate is signed by a CA certificate, then call
    ///  ValidateSignature() using signing CA's public key. The CA's public
    ///  key is found in the CA certificate using GetSubjectPublicKey().
    /// \sa GetSubjectPublicKey
    bool ValidateSignature (RandomNumberGenerator &rng, const X509PublicKey &key) const;

    //@}

    /// \name ENCODE/DECODE
    //@{

    // ASN1CryptoMaterial
    virtual void Save (BufferedTransformation &bt) const;
    virtual void Load (BufferedTransformation &bt);

    // ASN1Object
    virtual void BERDecode (BufferedTransformation &bt);
    virtual void DEREncode (BufferedTransformation &bt) const;

    //@}

    /// \name ASN.1 OPTIONAL
    //@{

    /// \brief Determine if Issuer UniqueId is present
    /// \returns true if Issuer UniqueId is present, false otherwise
    /// \details Issuer UniqueId is optional and available with X.509 v2.
    /// \sa HasSubjectUniqueId, GetIssuerUniqueId
    bool HasIssuerUniqueId() const;

    /// \brief Determine if Subject UniqueId is present
    /// \returns true if Subject UniqueId is present, false otherwise
    /// \details Subject UniqueId is optional and available with X.509 v2.
    /// \sa HasIssuerUniqueId, GetSubjectUniqueId
    bool HasSubjectUniqueId() const;

    /// \brief Determine if Extensions are present
    /// \returns true if Extensions are present, false otherwise
    /// \details Extensions are optional and available with X.509 v3.
    /// \sa GetExtensions
    bool HasExtensions() const;

    /// \brief Determine if AKI is present
    /// \returns true if Authority Key Identifier is present, false otherwise
    /// \details AKI is an optional extension and available with X.509 v3.
    /// \sa HasSubjectKeyIdentifier, GetAuthorityKeyIdentifier
    bool HasAuthorityKeyIdentifier() const;

    /// \brief Determine if SPKI is present
    /// \returns true if Subject Public Key Identifier is present, false otherwise
    /// \details SPKI is an optional extension and available with X.509 v3.
    /// \sa HasAuthorityKeyIdentifier, GetSubjectKeyIdentifier
    bool HasSubjectKeyIdentifier() const;

    //@}

    /// \name ACCESSORS
    //@{

    /// \brief Retrieve complete DER encoded certicate
    /// \returns the certificate data
    /// \sa GetToBeSigned, GetCertificateSignature
    const SecByteBlock& GetCertificate () const
        { return m_origCertificate; }

    /// \brief Retrieve DER encoded ToBeSigned
    /// \returns the toBeSigned data
    /// \sa GetCertificate, GetCertificateSignature
    const SecByteBlock& GetToBeSigned () const;

    /// \brief Version number
    /// \returns Certificate version number
    /// \note Version number is 0 based, so X.509 v3 value is 2.
    Version GetVersion() const
        { return m_version; }

    /// \brief Serial number
    /// \returns Certificate serial number
    const Integer& GetSerialNumber() const
        { return m_serialNumber; }

    /// \brief Certificate signature algorithm
    /// \returns Certificate signature algorithm
    /// \sa GetCertificate, GetToBeSigned, GetCertificateSignature
    const OID& GetCertificateSignatureAlgorithm() const
        { return m_certSignatureAlgortihm; }

    /// \brief Certificate signature
    /// \returns Certificate signature
    /// \sa GetCertificate, GetToBeSigned, GetCertificateSignatureAlgorithm
    const SecByteBlock& GetCertificateSignature() const
        { return m_certSignature; }

    /// \brief Validity not before
    /// \returns Validity not before
    /// \sa GetNotAfter
    const DateValue& GetNotBefore() const
        { return m_notBefore; }

    /// \brief Validity not after
    /// \returns Validity not after
    /// \sa GetNotBefore
    const DateValue& GetNotAfter() const
        { return m_notAfter; }

    /// \brief Issuer distinguished name
    /// \returns Issuer distinguished name
    const RdnValueArray& GetIssuerDistinguishedName() const
        { return m_issuerName; }

    /// \brief Subject distinguished name
    /// \returns Subject distinguished name
    const RdnValueArray& GetSubjectDistinguishedName() const
        { return m_subjectName; }

    /// \brief Issuer UniqueId
    /// \returns Issuer UniqueId
    /// \details Issuer UniqueId is optional and available with X.509 v2.
    /// \sa HasIssuerUniqueId
    const SecByteBlock& GetIssuerUniqueId() const
        { return m_issuerUid.get() ? *m_issuerUid.get() : g_nullByteBlock; }

    /// \brief Subject UniqueId
    /// \returns Subject UniqueId
    /// \details Subject UniqueId is optional and available with X.509 v2.
    /// \sa HasSubjectUniqueId
    const SecByteBlock& GetSubjectUniqueId() const
        { return m_subjectUid.get() ? *m_subjectUid.get() : g_nullByteBlock; }

    /// \brief Certificate extensions
    /// \returns Certificate extensions array
    /// \details Certificate extensions are available with X.509 v3.
    /// \sa HasExtensions
    const ExtensionValueArray& GetExtensions() const
        { return m_extensions.get() ? *m_extensions.get() : g_nullExtensions; }

    /// \brief Subject public key algorithm
    /// \returns Subject public key algorithm
    /// \sa GetSubjectPublicKey
    const OID& GetSubjectPublicKeyAlgorithm() const
        { return m_subjectSignatureAlgortihm; }

    /// \brief Subject public key
    /// \returns Subject public key
    /// \sa GetSubjectPublicKeyAlgorithm
    const X509PublicKey& GetSubjectPublicKey() const
        { return *m_subjectPublicKey.get(); }

    /// \brief Authority key identifier
    /// \returns Authority key identifier
    /// \details Authority key identifier is optional and available with X.509 v3.
    /// \sa HasAuthorityKeyIdentifier, GetSubjectKeyIdentifier
    const KeyIdentifierValue& GetAuthorityKeyIdentifier() const;

    /// \brief Subject key identifier
    /// \returns Subject key identifier
    /// \details Subject key identifier is optional and available with X.509 v3.
    /// \sa HasSubjectKeyIdentifier, GetAuthorityKeyIdentifier
    const KeyIdentifierValue& GetSubjectKeyIdentifier() const;

    /// \brief Identities
    /// \returns Identities
    /// \details GetSubjectIdentities() collects the identities in the certificate.
    const IdentityValueArray& GetSubjectIdentities() const;

    /// \brief Identities
    /// \returns Identities
    /// \details GetSubjectIdentities() collects the identities in the certificate.
    const KeyUsageValueArray& GetSubjectKeyUsage() const;

    //@}

    /// \name CERTIFICATE
    //@{

    /// \brief Determine if certificate is a CA
    /// \returns true if the certificate is a CA, false otherwise
    /// \details There are two types of certificates. The first is a CA certificate and
    ///  signaled with <tt>basicConstraint, CA:TRUE</tt>. The second is an end entity
    ///  certificate and signaled with <tt>basicConstraint, CA:FALSE</tt>.
    ///  CA certificates can certify other certificates, while end entity certificates
    ///  cannot. End entity certificates are leaf certificates.
    /// \sa IsSelfSigned
    bool IsCertificateAuthority() const;

    /// \brief Determine if certificate is self-signed
    /// \returns true if the certificate is self-signed, false otherwise
    /// \sa IsCertificateAuthority
    bool IsSelfSigned() const;

    //@}

    /// \name DEBUG
    //@{

    /// \brief Print a certificate
    /// \param out ostream object
    /// \returns ostream reference
    /// \details Print() displays some of the fields of a certificate for
    ///  debug purposes. Users should modify the class or override this
    ///  class in a derived class to suit their taste.
    virtual std::ostream& Print(std::ostream& out) const;

    /// \brief Write certificate data
    /// \param bt BufferedTransformation object
    /// \details WriteCertificateBytes() is a debug function. It dumps
    ///  the bytes stored in m_origCertificate. WriteCertificateBytes()
    ///  also sets up a try/catch and silently swallows exceptions.
    void WriteCertificateBytes(BufferedTransformation &bt) const;

    //@}

protected:
    // Crib away the original certificate
    void SaveCertificateBytes(BufferedTransformation &bt);
    // Clear old certificate data
    void Reset();

    // RFC 2459, section 7.3.1, http://www.ietf.org/rfc/rfc2459.txt
    virtual bool BERDecodeAlgorithmParameters (BufferedTransformation &bt)
        {BERDecodeNull(bt); return false;}
    virtual bool DEREncodeAlgorithmParameters (BufferedTransformation &bt) const
        {DEREncodeNull(bt); return false;}

    // X509Certificate
    void BERDecodeVersion(BufferedTransformation &bt, Version &version);
    void BERDecodeSerialNumber(BufferedTransformation &bt, Integer &serno);
    void BERDecodeSignature(BufferedTransformation &bt, SecByteBlock &signature);
    void BERDecodeSignatureAlgorithm(BufferedTransformation &bt, OID &algorithm);
    void BERDecodeDistinguishedName(BufferedTransformation &bt, RdnValueArray &rdnArray);
    void BERDecodeValidity(BufferedTransformation &bt, DateValue &notBefore, DateValue &notAfter);
    void BERDecodeSubjectPublicKeyInfo(BufferedTransformation &bt, member_ptr<X509PublicKey>& publicKey);

    // Optional attributes
    bool HasOptionalAttribute(const BufferedTransformation &bt, byte tag) const;
    void BERDecodeIssuerUniqueId(BufferedTransformation &bt);
    void BERDecodeSubjectUniqueId(BufferedTransformation &bt);
    void BERDecodeExtensions(BufferedTransformation &bt);

    // BERDecodeSubjectPublicKeyInfo peeks at the subjectPublicKeyInfo because the
    // information is less ambiguous. If we used subjectPublicKeyAlgorithm we would
    // still need to peek because subjectPublicKeyAlgorithm lacks field information
    // (prime vs. binary). We need a field to instantiate a key. For example,
    // subjectPublicKeyAlgorithm==ecdsa_with_sha384() does not contain enough
    // information to determine PublicKey_EC<ECP> or PublicKey_EC<EC2N>.
    void GetSubjectPublicKeyInfoOids(const BufferedTransformation &bt, OID& algorithm, OID& field) const;

    // Identity helper functions. Find them wherever we can.
    void GetIdentitiesFromSubjectDistName(IdentityValueArray& identityArray) const;
    void GetIdentitiesFromSubjectAltName(IdentityValueArray& identityArray) const;
    void GetIdentitiesFromSubjectUniqueId(IdentityValueArray& identityArray) const;
    void GetIdentitiesFromSubjectPublicKeyId(IdentityValueArray& identityArray) const;
    void GetIdentitiesFromNetscapeServer(IdentityValueArray& identityArray) const;

    // Find an extension with the OID. Returns false and end() if not found.
    bool FindExtension(const OID& oid, ExtensionValueArray::const_iterator& loc) const;

    // Get the verifier object for an algorithm and key
    PK_Verifier* GetPK_VerifierObject(const OID &algorithm, const X509PublicKey &key) const;

private:
    // Version and serial number, required v1
    Version m_version;
    Integer m_serialNumber;

    // Certificate algorithm and signature, required v1
    OID m_certSignatureAlgortihm;
    SecByteBlock m_certSignature;

    // Issuer and subject DNs, required v1
    RdnValueArray m_issuerName;
    RdnValueArray m_subjectName;

    // Validity dates, required v1
    DateValue m_notBefore, m_notAfter;

    // The subject's key and algorithm, required v1
    OID m_subjectSignatureAlgortihm;
    member_ptr<X509PublicKey> m_subjectPublicKey;

    // Issue and Subject UniqueId, optional v2
    ASNOptional<SecByteBlock> m_issuerUid;
    ASNOptional<SecByteBlock> m_subjectUid;

    // Extensions, optional v3
    ASNOptional<ExtensionValueArray> m_extensions;

    // AKI and SPKI extensions, optional v3
    mutable member_ptr<KeyIdentifierValue> m_authorityKeyIdentifier;  // lazy
    mutable member_ptr<KeyIdentifierValue> m_subjectKeyIdentifier;    // lazy

    // KU and EKU, optional v3
    mutable member_ptr<KeyUsageValueArray> m_keyUsage;  // lazy

    // Identities
    mutable member_ptr<IdentityValueArray> m_identities;  // lazy

    // To be signed, required v1
    mutable member_ptr<SecByteBlock> m_toBeSigned;  // lazy

    // Hack so we can examine the octets. Also see WriteCertificateBytes.
    SecByteBlock m_origCertificate;

    // Null values so we can return something
    static const SecByteBlock  g_nullByteBlock;
    static const ExtensionValueArray g_nullExtensions;
};

//////////////////////////////////////////////////

inline std::ostream& operator<<(std::ostream& out, const X509Certificate &cert)
    { return cert.Print(out); }
inline std::ostream& operator<<(std::ostream& out, const RdnValue &value)
    { return value.Print(out); }
inline std::ostream& operator<<(std::ostream& out, const DateValue &value)
    { return value.Print(out); }
inline std::ostream& operator<<(std::ostream& out, const KeyIdentifierValue &value)
    { return value.Print(out); }
inline std::ostream& operator<<(std::ostream& out, const KeyUsageValue &value)
    { return value.Print(out); }
inline std::ostream& operator<<(std::ostream& out, const IdentityValue &value)
    { return value.Print(out); }

inline bool operator==(const RdnValue &first, const RdnValue &second)
    { return first.m_value == second.m_value; }
inline bool operator==(const KeyIdentifierValue &first, const KeyIdentifierValue &second)
    { return first.m_value == second.m_value; }

inline std::ostream& operator<<(std::ostream& out, const RdnValueArray &values)
{
    RdnValueArray::const_iterator first = values.begin();
    RdnValueArray::const_iterator last = values.end();
    std::ostringstream oss;

    while (first != last)
    {
        oss << *first;
        if (++first != last)
            { oss << "; "; }
    }
    return out << oss.str();
}

inline std::ostream& operator<<(std::ostream& out, const IdentityValueArray &values)
{
    IdentityValueArray::const_iterator first = values.begin();
    IdentityValueArray::const_iterator last = values.end();
    std::ostringstream oss;

    while (first != last)
    {
        oss << *first;
        if (++first != last)
            { oss << "\n"; }
    }
    return out << oss.str();
}

inline std::ostream& operator<<(std::ostream& out, const KeyUsageValueArray &values)
{
    KeyUsageValueArray::const_iterator first = values.begin();
    KeyUsageValueArray::const_iterator last = values.end();
    std::ostringstream oss;

    while (first != last)
    {
        oss << *first;
        if (++first != last)
            { oss << ", "; }
    }
    return out << oss.str();
}

//////////////////////////////////////////////////

// Make these defines to avoid global objects
#define id_sha1WithRSASignature     (OID(1)+2+840+113549+1+1+5)
#define id_sha256WithRSAEncryption  (OID(1)+2+840+113549+1+1+11)
#define id_sha384WithRSAEncryption  (OID(1)+2+840+113549+1+1+12)
#define id_sha512WithRSAEncryption  (OID(1)+2+840+113549+1+1+13)

#define id_secp256v1        (OID(1)+2+840+10045+3+1+7)
#define id_ecdsaWithSHA1    (OID(1)+2+840+10045+4+1)
#define id_ecdsaWithSHA256  (OID(1)+2+840+10045+4+3+2)
#define id_ecdsaWithSHA384  (OID(1)+2+840+10045+4+3+3)
#define id_ecdsaWithSHA512  (OID(1)+2+840+10045+4+3+4)

NAMESPACE_END

#endif  // CRYPTOPP_X509_CERTIFICATE_H