i2pd/Identity.cpp

#include <time.h>
#include <stdio.h>
#include <cryptopp/sha.h>
#include <cryptopp/osrng.h>
#include <cryptopp/dsa.h>
#include "base64.h"
#include "CryptoConst.h"
#include "ElGamal.h"
#include "RouterContext.h"
#include "Identity.h"
#include "I2PEndian.h"

namespace i2p
{
namespace data
{
    Identity& Identity::operator=(const Keys& keys)
    {
        // copy public and signing keys together
        memcpy (publicKey, keys.publicKey, sizeof (publicKey) + sizeof (signingKey));
        memset (&certificate, 0, sizeof (certificate));     
        return *this;
    }

    size_t Identity::FromBuffer (const uint8_t * buf, size_t len)
    {
        memcpy (publicKey, buf, DEFAULT_IDENTITY_SIZE);
        return DEFAULT_IDENTITY_SIZE;
    }

    IdentHash Identity::Hash () const
    {
        IdentHash hash;
        CryptoPP::SHA256().CalculateDigest(hash, publicKey, DEFAULT_IDENTITY_SIZE);
        return hash;
    }   
    
    IdentityEx::IdentityEx ():
        m_Verifier (nullptr), m_ExtendedLen (0), m_ExtendedBuffer (nullptr)
    {
    }

    IdentityEx::IdentityEx(const uint8_t * publicKey, const uint8_t * signingKey, SigningKeyType type)
    {   
        memcpy (m_StandardIdentity.publicKey, publicKey, sizeof (m_StandardIdentity.publicKey));
        if (type != SIGNING_KEY_TYPE_DSA_SHA1)
        {
            size_t excessLen = 0;
            uint8_t * excessBuf = nullptr;
            switch (type)
            {
                case SIGNING_KEY_TYPE_ECDSA_SHA256_P256:
                {   
                    size_t padding =  128 - i2p::crypto::ECDSAP256_KEY_LENGTH; // 64 = 128 - 64
                    i2p::context.GetRandomNumberGenerator ().GenerateBlock (m_StandardIdentity.signingKey, padding);
                    memcpy (m_StandardIdentity.signingKey + padding, signingKey, i2p::crypto::ECDSAP256_KEY_LENGTH);
                    break;
                }
                case SIGNING_KEY_TYPE_ECDSA_SHA384_P384:
                {   
                    size_t padding = 128 - i2p::crypto::ECDSAP384_KEY_LENGTH; // 32 = 128 - 96
                    i2p::context.GetRandomNumberGenerator ().GenerateBlock (m_StandardIdentity.signingKey, padding);
                    memcpy (m_StandardIdentity.signingKey + padding, signingKey, i2p::crypto::ECDSAP384_KEY_LENGTH);
                    break;
                }   
                case SIGNING_KEY_TYPE_ECDSA_SHA512_P521:
                {
                    memcpy (m_StandardIdentity.signingKey, signingKey, 128);
                    excessLen = i2p::crypto::ECDSAP521_KEY_LENGTH - 128; // 4 = 132 - 128
                    excessBuf = new uint8_t[excessLen];
                    memcpy (excessBuf, signingKey + 128, excessLen);
                    break;
                }   
                case SIGNING_KEY_TYPE_RSA_SHA256_2048:
                {
                    memcpy (m_StandardIdentity.signingKey, signingKey, 128);
                    excessLen = i2p::crypto::RSASHA2562048_KEY_LENGTH - 128; // 128 = 256 - 128
                    excessBuf = new uint8_t[excessLen];
                    memcpy (excessBuf, signingKey + 128, excessLen);
                    break;
                }   
                case SIGNING_KEY_TYPE_RSA_SHA384_3072:
                {
                    memcpy (m_StandardIdentity.signingKey, signingKey, 128);
                    excessLen = i2p::crypto::RSASHA3843072_KEY_LENGTH - 128; // 256 = 384 - 128
                    excessBuf = new uint8_t[excessLen];
                    memcpy (excessBuf, signingKey + 128, excessLen);
                    break;
                }   
                case SIGNING_KEY_TYPE_RSA_SHA512_4096:
                {
                    memcpy (m_StandardIdentity.signingKey, signingKey, 128);
                    excessLen = i2p::crypto::RSASHA5124096_KEY_LENGTH - 128; // 384 = 512 - 128
                    excessBuf = new uint8_t[excessLen];
                    memcpy (excessBuf, signingKey + 128, excessLen);
                    break;
                }   
                case SIGNING_KEY_TYPE_EDDSA_SHA512_ED25519:
                {
                    size_t padding =  128 - i2p::crypto::EDDSA25519_PUBLIC_KEY_LENGTH; // 96 = 128 - 32
                    i2p::context.GetRandomNumberGenerator ().GenerateBlock (m_StandardIdentity.signingKey, padding);
                    memcpy (m_StandardIdentity.signingKey + padding, signingKey, i2p::crypto::EDDSA25519_PUBLIC_KEY_LENGTH);
                    break;
                }   
                default:
                    LogPrint ("Signing key type ", (int)type, " is not supported");
            }   
            m_ExtendedLen = 4 + excessLen; // 4 bytes extra + excess length
            // fill certificate
            m_StandardIdentity.certificate.type = CERTIFICATE_TYPE_KEY;
            m_StandardIdentity.certificate.length = htobe16 (m_ExtendedLen); 
            // fill extended buffer
            m_ExtendedBuffer = new uint8_t[m_ExtendedLen];
            htobe16buf (m_ExtendedBuffer, type);
            htobe16buf (m_ExtendedBuffer + 2, CRYPTO_KEY_TYPE_ELGAMAL);
            if (excessLen && excessBuf)
            {
                memcpy (m_ExtendedBuffer + 4, excessBuf, excessLen);
                delete[] excessBuf;
            }   
            // calculate ident hash
            uint8_t * buf = new uint8_t[GetFullLen ()];
            ToBuffer (buf, GetFullLen ());
            CryptoPP::SHA256().CalculateDigest(m_IdentHash, buf, GetFullLen ());
            delete[] buf;
        }
        else // DSA-SHA1
        {
            memcpy (m_StandardIdentity.signingKey, signingKey, sizeof (m_StandardIdentity.signingKey));
            memset (&m_StandardIdentity.certificate, 0, sizeof (m_StandardIdentity.certificate));
            m_IdentHash = m_StandardIdentity.Hash ();
            m_ExtendedLen = 0;
            m_ExtendedBuffer = nullptr;
        }   
        CreateVerifier ();
    }   
        
    IdentityEx::IdentityEx (const uint8_t * buf, size_t len):
        m_Verifier (nullptr), m_ExtendedLen (0), m_ExtendedBuffer (nullptr)
    {
        FromBuffer (buf, len);
    }

    IdentityEx::IdentityEx (const IdentityEx& other):
        m_Verifier (nullptr), m_ExtendedBuffer (nullptr)
    {
        *this = other;
    }   
        
    IdentityEx::~IdentityEx ()
    {
        delete m_Verifier;
        delete[] m_ExtendedBuffer;
    }   

    IdentityEx& IdentityEx::operator=(const IdentityEx& other)
    {
        memcpy (&m_StandardIdentity, &other.m_StandardIdentity, DEFAULT_IDENTITY_SIZE);
        m_IdentHash = other.m_IdentHash;
        
        delete[] m_ExtendedBuffer;
        m_ExtendedLen = other.m_ExtendedLen;
        if (m_ExtendedLen > 0)
        {   
            m_ExtendedBuffer = new uint8_t[m_ExtendedLen];
            memcpy (m_ExtendedBuffer, other.m_ExtendedBuffer, m_ExtendedLen);
        }           
        else
            m_ExtendedBuffer = nullptr;
        
        delete m_Verifier;
        m_Verifier = nullptr;
        
        return *this;
    }   

    IdentityEx& IdentityEx::operator=(const Identity& standard)
    {
        m_StandardIdentity = standard;
        m_IdentHash = m_StandardIdentity.Hash ();
        
        delete[] m_ExtendedBuffer;
        m_ExtendedBuffer = nullptr;
        m_ExtendedLen = 0;

        delete m_Verifier;
        m_Verifier = nullptr;
        
        return *this;
    }   
        
    size_t IdentityEx::FromBuffer (const uint8_t * buf, size_t len)
    {
        if (len < DEFAULT_IDENTITY_SIZE)
        {
            LogPrint (eLogError, "Identity buffer length ", len, " is too small");
            return 0;
        }   
        memcpy (&m_StandardIdentity, buf, DEFAULT_IDENTITY_SIZE);

        delete[] m_ExtendedBuffer;
        if (m_StandardIdentity.certificate.length)
        {
            m_ExtendedLen = be16toh (m_StandardIdentity.certificate.length);
            if (m_ExtendedLen + DEFAULT_IDENTITY_SIZE <= len)
            {   
                m_ExtendedBuffer = new uint8_t[m_ExtendedLen];
                memcpy (m_ExtendedBuffer, buf + DEFAULT_IDENTITY_SIZE, m_ExtendedLen);
            }   
            else
            {
                LogPrint (eLogError, "Certificate length ", m_ExtendedLen, " exceeds buffer length ", len - DEFAULT_IDENTITY_SIZE);
                return 0;
            }   
        }       
        else
        {
            m_ExtendedLen = 0;
            m_ExtendedBuffer = nullptr;
        }   
        CryptoPP::SHA256().CalculateDigest(m_IdentHash, buf, GetFullLen ());
        
        delete m_Verifier;
        m_Verifier = nullptr;
        
        return GetFullLen ();
    }   

    size_t IdentityEx::ToBuffer (uint8_t * buf, size_t len) const
    {       
        memcpy (buf, &m_StandardIdentity, DEFAULT_IDENTITY_SIZE);
        if (m_ExtendedLen > 0 && m_ExtendedBuffer)
            memcpy (buf + DEFAULT_IDENTITY_SIZE, m_ExtendedBuffer, m_ExtendedLen);
        return GetFullLen ();
    }

    size_t IdentityEx::FromBase64(const std::string& s)
    {
        uint8_t buf[1024];
        auto len = Base64ToByteStream (s.c_str(), s.length(), buf, 1024);
        return FromBuffer (buf, len);
    }   
    
    std::string IdentityEx::ToBase64 () const
    {
        uint8_t buf[1024];
        char str[1536];
        size_t l = ToBuffer (buf, 1024);
        size_t l1 = i2p::data::ByteStreamToBase64 (buf, l, str, 1536);
        str[l1] = 0;
        return std::string (str);
    }
    
    size_t IdentityEx::GetSigningPublicKeyLen () const
    {
        if (!m_Verifier) CreateVerifier ();
        if (m_Verifier) 
            return m_Verifier->GetPublicKeyLen ();
        return 128;
    }   

    size_t IdentityEx::GetSigningPrivateKeyLen () const
    {
        if (!m_Verifier) CreateVerifier ();
        if (m_Verifier) 
            return m_Verifier->GetPrivateKeyLen ();
        return GetSignatureLen ()/2;
    }   
        
    size_t IdentityEx::GetSignatureLen () const
    {   
        if (!m_Verifier) CreateVerifier (); 
        if (m_Verifier)
            return m_Verifier->GetSignatureLen ();
        return 40;
    }   
    bool IdentityEx::Verify (const uint8_t * buf, size_t len, const uint8_t * signature) const 
    {
        if (!m_Verifier) CreateVerifier ();
        if (m_Verifier)
            return m_Verifier->Verify (buf, len, signature);
        return false;
    }   

    SigningKeyType IdentityEx::GetSigningKeyType () const
    {
        if (m_StandardIdentity.certificate.type == CERTIFICATE_TYPE_KEY && m_ExtendedBuffer)                
            return bufbe16toh (m_ExtendedBuffer); // signing key
        return SIGNING_KEY_TYPE_DSA_SHA1;
    }   

    CryptoKeyType IdentityEx::GetCryptoKeyType () const
    {
        if (m_StandardIdentity.certificate.type == CERTIFICATE_TYPE_KEY && m_ExtendedBuffer)                
            return bufbe16toh (m_ExtendedBuffer + 2); // crypto key
        return CRYPTO_KEY_TYPE_ELGAMAL;
    }   
        
    void IdentityEx::CreateVerifier () const 
    {
        auto keyType = GetSigningKeyType ();
        switch (keyType)
        {
            case SIGNING_KEY_TYPE_DSA_SHA1:
                m_Verifier = new i2p::crypto::DSAVerifier (m_StandardIdentity.signingKey);
            break;
            case SIGNING_KEY_TYPE_ECDSA_SHA256_P256:
            {   
                size_t padding =  128 - i2p::crypto::ECDSAP256_KEY_LENGTH; // 64 = 128 - 64
                m_Verifier = new i2p::crypto::ECDSAP256Verifier (m_StandardIdentity.signingKey + padding);
                break;
            }   
            case SIGNING_KEY_TYPE_ECDSA_SHA384_P384:
            {   
                size_t padding = 128 - i2p::crypto::ECDSAP384_KEY_LENGTH; // 32 = 128 - 96
                m_Verifier = new i2p::crypto::ECDSAP384Verifier (m_StandardIdentity.signingKey + padding);
                break;
            }   
            case SIGNING_KEY_TYPE_ECDSA_SHA512_P521:
            {   
                uint8_t signingKey[i2p::crypto::ECDSAP521_KEY_LENGTH];
                memcpy (signingKey, m_StandardIdentity.signingKey, 128);
                size_t excessLen = i2p::crypto::ECDSAP521_KEY_LENGTH - 128; // 4 = 132- 128
                memcpy (signingKey + 128, m_ExtendedBuffer + 4, excessLen); // right after signing and crypto key types
                m_Verifier = new i2p::crypto::ECDSAP521Verifier (signingKey);
                break;
            }       
            case SIGNING_KEY_TYPE_RSA_SHA256_2048:
            {   
                uint8_t signingKey[i2p::crypto::RSASHA2562048_KEY_LENGTH];
                memcpy (signingKey, m_StandardIdentity.signingKey, 128);
                size_t excessLen = i2p::crypto::RSASHA2562048_KEY_LENGTH - 128; // 128 = 256- 128
                memcpy (signingKey + 128, m_ExtendedBuffer + 4, excessLen); // right after signing and crypto key types
                m_Verifier = new i2p::crypto:: RSASHA2562048Verifier (signingKey);
                break;
            }   
            case SIGNING_KEY_TYPE_RSA_SHA384_3072:
            {   
                uint8_t signingKey[i2p::crypto::RSASHA3843072_KEY_LENGTH];
                memcpy (signingKey, m_StandardIdentity.signingKey, 128);
                size_t excessLen = i2p::crypto::RSASHA3843072_KEY_LENGTH - 128; // 256 = 384- 128
                memcpy (signingKey + 128, m_ExtendedBuffer + 4, excessLen); // right after signing and crypto key types
                m_Verifier = new i2p::crypto:: RSASHA3843072Verifier (signingKey);
                break;
            }   
            case SIGNING_KEY_TYPE_RSA_SHA512_4096:
            {   
                uint8_t signingKey[i2p::crypto::RSASHA5124096_KEY_LENGTH];
                memcpy (signingKey, m_StandardIdentity.signingKey, 128);
                size_t excessLen = i2p::crypto::RSASHA5124096_KEY_LENGTH - 128; // 384 = 512- 128
                memcpy (signingKey + 128, m_ExtendedBuffer + 4, excessLen); // right after signing and crypto key types
                m_Verifier = new i2p::crypto:: RSASHA5124096Verifier (signingKey);
                break;
            }   
            case SIGNING_KEY_TYPE_EDDSA_SHA512_ED25519:
            {
                size_t padding =  128 - i2p::crypto::EDDSA25519_PUBLIC_KEY_LENGTH; // 96 = 128 - 32
                m_Verifier = new i2p::crypto::EDDSA25519Verifier (m_StandardIdentity.signingKey + padding);
                break;
            }   
            default:
                LogPrint ("Signing key type ", (int)keyType, " is not supported");
        }           
    }   
    
    void IdentityEx::DropVerifier ()
    {
        auto verifier = m_Verifier;
        m_Verifier = nullptr; // TODO: make this atomic
        delete verifier;
    }

    PrivateKeys& PrivateKeys::operator=(const Keys& keys)
    {
        m_Public = Identity (keys);
        memcpy (m_PrivateKey, keys.privateKey, 256); // 256 
        memcpy (m_SigningPrivateKey, keys.signingPrivateKey, m_Public.GetSigningPrivateKeyLen ());
        delete m_Signer;
        m_Signer = nullptr;
        CreateSigner ();
        return *this;
    }

    PrivateKeys& PrivateKeys::operator=(const PrivateKeys& other)
    {       
        m_Public = other.m_Public;
        memcpy (m_PrivateKey, other.m_PrivateKey, 256); // 256 
        memcpy (m_SigningPrivateKey, other.m_SigningPrivateKey, m_Public.GetSigningPrivateKeyLen ()); 
        delete m_Signer;
        m_Signer = nullptr;
        CreateSigner ();
        return *this;
    }   
        
    size_t PrivateKeys::FromBuffer (const uint8_t * buf, size_t len)
    {
        size_t ret = m_Public.FromBuffer (buf, len);
        memcpy (m_PrivateKey, buf + ret, 256); // private key always 256
        ret += 256;
        size_t signingPrivateKeySize = m_Public.GetSigningPrivateKeyLen ();
        memcpy (m_SigningPrivateKey, buf + ret, signingPrivateKeySize); 
        ret += signingPrivateKeySize;
        delete m_Signer;
        m_Signer = nullptr;
        CreateSigner ();
        return ret;
    }
        
    size_t PrivateKeys::ToBuffer (uint8_t * buf, size_t len) const
    {
        size_t ret = m_Public.ToBuffer (buf, len);
        memcpy (buf + ret, m_PrivateKey, 256); // private key always 256
        ret += 256;
        size_t signingPrivateKeySize = m_Public.GetSigningPrivateKeyLen (); 
        memcpy (buf + ret, m_SigningPrivateKey, signingPrivateKeySize); 
        ret += signingPrivateKeySize;
        return ret;
    }   

    size_t PrivateKeys::FromBase64(const std::string& s)
    {
        uint8_t * buf = new uint8_t[s.length ()];
        size_t l = i2p::data::Base64ToByteStream (s.c_str (), s.length (), buf, s.length ());
        size_t ret = FromBuffer (buf, l);
        delete[] buf;
        return ret;
    }   
    
    std::string PrivateKeys::ToBase64 () const
    {
        uint8_t * buf = new uint8_t[GetFullLen ()];
        char * str = new char[GetFullLen ()*2];
        size_t l = ToBuffer (buf, GetFullLen ());
        size_t l1 = i2p::data::ByteStreamToBase64 (buf, l, str, GetFullLen ()*2);
        str[l1] = 0;
        delete[] buf;
        std::string ret(str);
        delete[] str;
        return ret;
    }

    void PrivateKeys::Sign (const uint8_t * buf, int len, uint8_t * signature) const
    {
        if (m_Signer)
            m_Signer->Sign (i2p::context.GetRandomNumberGenerator (), buf, len, signature);
    }           

    void PrivateKeys::CreateSigner ()
    {
        switch (m_Public.GetSigningKeyType ())
        {   
            case SIGNING_KEY_TYPE_DSA_SHA1:
                m_Signer = new i2p::crypto::DSASigner (m_SigningPrivateKey);
            break;  
            case SIGNING_KEY_TYPE_ECDSA_SHA256_P256:
                m_Signer = new i2p::crypto::ECDSAP256Signer (m_SigningPrivateKey);
            break;
            case SIGNING_KEY_TYPE_ECDSA_SHA384_P384:
                m_Signer = new i2p::crypto::ECDSAP384Signer (m_SigningPrivateKey);
            break;  
            case SIGNING_KEY_TYPE_ECDSA_SHA512_P521:
                m_Signer = new i2p::crypto::ECDSAP521Signer (m_SigningPrivateKey);
            break;  
            case SIGNING_KEY_TYPE_RSA_SHA256_2048:
                m_Signer = new i2p::crypto::RSASHA2562048Signer (m_SigningPrivateKey);
            break;
            case SIGNING_KEY_TYPE_RSA_SHA384_3072:
                m_Signer = new i2p::crypto::RSASHA3843072Signer (m_SigningPrivateKey);
            break;
            case SIGNING_KEY_TYPE_RSA_SHA512_4096:
                m_Signer = new i2p::crypto::RSASHA5124096Signer (m_SigningPrivateKey);
            break;  
            case SIGNING_KEY_TYPE_EDDSA_SHA512_ED25519:
                m_Signer = new i2p::crypto::EDDSA25519Signer (m_SigningPrivateKey);
            break;
            default:
                LogPrint ("Signing key type ", (int)m_Public.GetSigningKeyType (), " is not supported");
        }
    }   
        
    PrivateKeys PrivateKeys::CreateRandomKeys (SigningKeyType type)
    {
        if (type != SIGNING_KEY_TYPE_DSA_SHA1)
        {
            PrivateKeys keys;
            auto& rnd = i2p::context.GetRandomNumberGenerator ();
            // signature
            uint8_t signingPublicKey[512]; // signing public key is 512 bytes max 
            switch (type)
            {   
                case SIGNING_KEY_TYPE_ECDSA_SHA256_P256:
                    i2p::crypto::CreateECDSAP256RandomKeys (rnd, keys.m_SigningPrivateKey, signingPublicKey);
                break;  
                case SIGNING_KEY_TYPE_ECDSA_SHA384_P384:
                    i2p::crypto::CreateECDSAP384RandomKeys (rnd, keys.m_SigningPrivateKey, signingPublicKey);   
                break;
                case SIGNING_KEY_TYPE_ECDSA_SHA512_P521:
                    i2p::crypto::CreateECDSAP521RandomKeys (rnd, keys.m_SigningPrivateKey, signingPublicKey);   
                break;  
                case SIGNING_KEY_TYPE_RSA_SHA256_2048:
                    i2p::crypto::CreateRSARandomKeys (rnd, i2p::crypto::RSASHA2562048_KEY_LENGTH, keys.m_SigningPrivateKey, signingPublicKey);  
                break;
                case SIGNING_KEY_TYPE_RSA_SHA384_3072:
                    i2p::crypto::CreateRSARandomKeys (rnd, i2p::crypto::RSASHA3843072_KEY_LENGTH, keys.m_SigningPrivateKey, signingPublicKey);  
                break;
                case SIGNING_KEY_TYPE_RSA_SHA512_4096:
                    i2p::crypto::CreateRSARandomKeys (rnd, i2p::crypto::RSASHA5124096_KEY_LENGTH, keys.m_SigningPrivateKey, signingPublicKey);  
                break;  
                default:
                    LogPrint ("Signing key type ", (int)type, " is not supported. Create DSA-SHA1");
                    return PrivateKeys (i2p::data::CreateRandomKeys ()); // DSA-SHA1
            }   
            // encryption
            uint8_t publicKey[256];
            CryptoPP::DH dh (i2p::crypto::elgp, i2p::crypto::elgg);
            dh.GenerateKeyPair(rnd, keys.m_PrivateKey, publicKey);
            // identity
            keys.m_Public = IdentityEx (publicKey, signingPublicKey, type);

            keys.CreateSigner ();
            return keys;
        }   
        return PrivateKeys (i2p::data::CreateRandomKeys ()); // DSA-SHA1
    }   
        
    Keys CreateRandomKeys ()
    {
        Keys keys;      
        auto& rnd = i2p::context.GetRandomNumberGenerator ();
        // encryption
        i2p::crypto::GenerateElGamalKeyPair(rnd, keys.privateKey, keys.publicKey);
        // signing
        i2p::crypto::CreateDSARandomKeys (rnd, keys.signingPrivateKey, keys.signingKey);    
        return keys;
    }   

    IdentHash CreateRoutingKey (const IdentHash& ident)
    {
        uint8_t buf[41]; // ident + yyyymmdd
        memcpy (buf, (const uint8_t *)ident, 32);
        time_t t = time (nullptr);
        struct tm tm;
#ifdef _WIN32
        gmtime_s(&tm, &t);
        sprintf_s((char *)(buf + 32), 9, "%04i%02i%02i", tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
#else
        gmtime_r(&t, &tm);
        sprintf((char *)(buf + 32), "%04i%02i%02i", tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
#endif      
        IdentHash key;
        CryptoPP::SHA256().CalculateDigest((uint8_t *)key, buf, 40);
        return key;
    }   
    
    XORMetric operator^(const IdentHash& key1, const IdentHash& key2)
    {
        XORMetric m;
        const uint64_t * hash1 = key1.GetLL (), * hash2 = key2.GetLL ();
        m.metric_ll[0] = hash1[0] ^ hash2[0];
        m.metric_ll[1] = hash1[1] ^ hash2[1];
        m.metric_ll[2] = hash1[2] ^ hash2[2];
        m.metric_ll[3] = hash1[3] ^ hash2[3];
        return m;
    }   
}
}