// C implementation of the zxcvbn password strength estimation method.
// SPDX-FileCopyrightText: 2015-2017 Tony Evans
// SPDX-License-Identifier: MIT

#include "zxcvbn.h"
#include <ctype.h>
#include <float.h>
#include <math.h>
#include <stdint.h>
#include <string.h>

/* printf */
#ifdef __cplusplus
#include <cstdio>
#else
#include <stdio.h>
#endif

#ifdef USE_DICT_FILE
#if defined(USE_FILE_IO) || !defined(__cplusplus)
#include <stdio.h>
#else
#include <fstream>
#endif
#endif

/* Minimum number of characters in a incrementing/decrementing sequence match */
#define MIN_SEQUENCE_LEN 3

/* Year range for data matching */
#define MIN_YEAR 1901
#define MAX_YEAR 2050

/* Minimum number of characters in a spatial matching sequence */
#define MIN_SPATIAL_LEN 3

/* Minimum number of characters in a repeat sequence match */
#define MIN_REPEAT_LEN 2

/* Additional entropy to add when password is made of multiple matches. Use different
 * amounts depending on whether the match is at the end of the password, or in the
 * middle. If the match is at the beginning then there is no additional entropy.
 */
#define MULTI_END_ADDITION 1.0
#define MULTI_MID_ADDITION 1.75

/*################################################################################*
 *################################################################################*
 * Begin utility function code
 *################################################################################*
 *################################################################################*/

/**********************************************************************************
 * Binomial coefficient function. Uses method described at
 *      http://blog.plover.com/math/choose.html
 */
static double nCk(int n, int k)
{
    int d;
    double r;
    if (k > n)
        return 0.0;
    if (!k)
        return 1.0;
    r = 1.0;
    for (d = 1; d <= k; ++d) {
        r *= n--;
        r /= d;
    }
    return r;
}

/**********************************************************************************
 * Binary search function to find a character in a string.
 * Parameters:
 *  Ch      The character to find
 *  Ents    The string to search
 *  NumEnts The number character groups in the string Ents
 *  SizeEnt The size of each character group.
 * Returns a pointer to the found character, or null if not found.
 */
static const uint8_t *CharBinSearch(uint8_t Ch, const uint8_t *Ents, unsigned int NumEnts, unsigned int SizeEnt)
{
    while (NumEnts > 0) {
        const uint8_t *Mid = Ents + (NumEnts >> 1) * SizeEnt;
        int Dif = Ch - *Mid;
        if (!Dif) {
            return Mid;
        }
        if (Dif > 0) {
            Ents = Mid + SizeEnt;
            --NumEnts;
        }
        NumEnts /= 2;
    }
    return 0;
}

/**********************************************************************************
 * Calculate potential number of different characters in the passed string.
 * Parameters:
 *  Str     The string of characters
 *  Len     The maximum number of characters to scan
 * Returns the potential number of different characters in the string.
 */
static int Cardinality(const uint8_t *Str, int Len)
{
    int Card = 0, Types = 0;
    int c;
    while (Len > 0) {
        c = *Str++ & 0xFF;
        if (!c)
            break;
        if (islower(c))
            Types |= 1; /* Lowercase letter */
        else if (isupper(c))
            Types |= 2; /* Uppercase letter */
        else if (isdigit(c))
            Types |= 4; /* Numeric digit */
        else if (c <= 0x7F)
            Types |= 8; /* Punctuation character */
        else
            Types |= 16; /* Other (Unicode?) */
        --Len;
    }
    if (Types & 1)
        Card += 26;
    if (Types & 2)
        Card += 26;
    if (Types & 4)
        Card += 10;
    if (Types & 8)
        Card += 33;
    if (Types & 16)
        Card += 100;
    return Card;
}

/**********************************************************************************
 * Allocate a ZxcMatch_t struct, clear it to zero
 */
static ZxcMatch_t *AllocMatch()
{
    ZxcMatch_t *p = MallocFn(ZxcMatch_t, 1);
    memset(p, 0, sizeof *p);
    return p;
}

/**********************************************************************************
 * Add new match struct to linked list of matches. List ordered with shortest at
 * head of list. Note: passed new match struct in parameter Nu may be de allocated.
 */
static void AddResult(ZxcMatch_t **HeadRef, ZxcMatch_t *Nu, int MaxLen)
{
    /* Adjust the entropy to be used for calculations depending on whether the passed match is
     * at the beginning, middle or end of the password
     */
    if (Nu->Begin) {
        if (Nu->Length >= MaxLen)
            Nu->MltEnpy = Nu->Entrpy + MULTI_END_ADDITION * log(2.0);
        else
            Nu->MltEnpy = Nu->Entrpy + MULTI_MID_ADDITION * log(2.0);
    } else
        Nu->MltEnpy = Nu->Entrpy;

    /* Find the correct insert point */
    while (*HeadRef && ((*HeadRef)->Length < Nu->Length))
        HeadRef = &((*HeadRef)->Next);

    /* Add new entry or replace existing */
    if (*HeadRef && ((*HeadRef)->Length == Nu->Length)) {
        /* New entry has same length as existing, so one of them needs discarding */
        if ((*HeadRef)->MltEnpy <= Nu->MltEnpy) {
            /* Existing entry has lower entropy - keep it, discard new entry */
            FreeFn(Nu);
        } else {
            /* New entry has lower entropy - replace existing entry */
            Nu->Next = (*HeadRef)->Next;
            FreeFn(*HeadRef);
            *HeadRef = Nu;
        }
    } else {
        /* New entry has different length, so add it */
        Nu->Next = *HeadRef;
        *HeadRef = Nu;
    }
}

/**********************************************************************************
 * See if the match is repeated. If it is then add a new repeated match to the results.
 */
static void AddMatchRepeats(ZxcMatch_t **Result, ZxcMatch_t *Match, const uint8_t *Passwd, int MaxLen)
{
    int Len = Match->Length;
    const uint8_t *Rpt = Passwd + Len;
    int RepeatCount = 2;

    while (MaxLen >= (Len * RepeatCount)) {
        if (strncmp((const char *)Passwd, (const char *)Rpt, Len) == 0) {
            /* Found a repeat */
            ZxcMatch_t *p = AllocMatch();
            p->Entrpy = Match->Entrpy + log(RepeatCount);
            p->Type = (ZxcTypeMatch_t)(Match->Type + MULTIPLE_MATCH);
            p->Length = Len * RepeatCount;
            p->Begin = Match->Begin;
            AddResult(Result, p, MaxLen);
        } else
            break;
        ++RepeatCount;
        Rpt += Len;
    }
}

/*################################################################################*
 *################################################################################*
 * Begin dictionary matching code
 *################################################################################*
 *################################################################################*/

#ifdef USE_DICT_FILE
/* Use dictionary data from file */

#if defined(USE_FILE_IO) || !defined(__cplusplus)
/* Use the FILE streams from stdio.h */

typedef FILE *FileHandle;

#define MyOpenFile(f, name) (f = fopen(name, "rb"))
#define MyReadFile(f, buf, bytes) (fread(buf, 1, bytes, f) == (bytes))
#define MyCloseFile(f) fclose(f)

#else

/* Use the C++ iostreams */
typedef std::ifstream FileHandle;

static inline void MyOpenFile(FileHandle &f, const char *Name)
{
    f.open(Name, std::ifstream::in | std::ifstream::binary);
}
static inline bool MyReadFile(FileHandle &f, void *Buf, unsigned int Num)
{
    return (bool)f.read((char *)Buf, Num);
}
static inline void MyCloseFile(FileHandle &f)
{
    f.close();
}

#endif

/* Include file contains the CRC of the dictionary data file. Used to detect corruption */
/* of the file. */
#include "dict-crc.h"

#define MAX_DICT_FILE_SIZE (100 + WORD_FILE_SIZE)
#define CHK_INIT 0xffffffffffffffffULL

/* Static table used for the crc implementation. */
static const uint64_t CrcTable[16] = {0x0000000000000000ULL,
                                      0x7d08ff3b88be6f81ULL,
                                      0xfa11fe77117cdf02ULL,
                                      0x8719014c99c2b083ULL,
                                      0xdf7adabd7a6e2d6fULL,
                                      0xa2722586f2d042eeULL,
                                      0x256b24ca6b12f26dULL,
                                      0x5863dbf1e3ac9decULL,
                                      0x95ac9329ac4bc9b5ULL,
                                      0xe8a46c1224f5a634ULL,
                                      0x6fbd6d5ebd3716b7ULL,
                                      0x12b5926535897936ULL,
                                      0x4ad64994d625e4daULL,
                                      0x37deb6af5e9b8b5bULL,
                                      0xb0c7b7e3c7593bd8ULL,
                                      0xcdcf48d84fe75459ULL};

static const unsigned int MAGIC = 'z' + ('x' << 8) + ('c' << 16) + ('v' << 24);

static unsigned int NumNodes, NumChildLocs, NumRanks, NumWordEnd, NumChildMaps;
static unsigned int SizeChildMapEntry, NumLargeCounts, NumSmallCounts, SizeCharSet;

static unsigned int *DictNodes;
static uint8_t *WordEndBits;
static unsigned int *ChildLocs;
static unsigned short *Ranks;
static uint8_t *ChildMap;
static uint8_t *EndCountLge;
static uint8_t *EndCountSml;
static char *CharSet;

/**********************************************************************************
 * Calculate the CRC-64 of passed data.
 * Parameters:
 *  Crc     The initial or previous CRC value
 *  v       Pointer to the data to add to CRC calculation
 *  Len     Length of the passed data
 * Returns the updated CRC value.
 */
static uint64_t CalcCrc64(uint64_t Crc, const void *v, unsigned int Len)
{
    const uint8_t *Data = (const unsigned char *)v;
    while (Len--) {
        Crc = CrcTable[(Crc ^ (*Data >> 0)) & 0x0f] ^ (Crc >> 4);
        Crc = CrcTable[(Crc ^ (*Data >> 4)) & 0x0f] ^ (Crc >> 4);
        ++Data;
    }
    return Crc;
}

/**********************************************************************************
 * Read the dictionary data from file.
 * Parameters:
 *  Filename    Name of the file to read.
 * Returns 1 on success, 0 on error
 */
int ZxcvbnInit(const char *Filename)
{
    FileHandle f;
    uint64_t Crc = CHK_INIT;
    if (DictNodes)
        return 1;
    MyOpenFile(f, Filename);
    if (f) {
        unsigned int i, DictSize;

        /* Get magic number */
        if (!MyReadFile(f, &i, sizeof i))
            i = 0;

        /* Get header data */
        if (!MyReadFile(f, &NumNodes, sizeof NumNodes))
            i = 0;
        if (!MyReadFile(f, &NumChildLocs, sizeof NumChildLocs))
            i = 0;
        if (!MyReadFile(f, &NumRanks, sizeof NumRanks))
            i = 0;
        if (!MyReadFile(f, &NumWordEnd, sizeof NumWordEnd))
            i = 0;
        if (!MyReadFile(f, &NumChildMaps, sizeof NumChildMaps))
            i = 0;
        if (!MyReadFile(f, &SizeChildMapEntry, sizeof SizeChildMapEntry))
            i = 0;
        if (!MyReadFile(f, &NumLargeCounts, sizeof NumLargeCounts))
            i = 0;
        if (!MyReadFile(f, &NumSmallCounts, sizeof NumSmallCounts))
            i = 0;
        if (!MyReadFile(f, &SizeCharSet, sizeof SizeCharSet))
            i = 0;

        /* Validate the header data */
        if (NumNodes >= (1 << 17))
            i = 1;
        if (NumChildLocs >= (1 << BITS_CHILD_MAP_INDEX))
            i = 2;
        if (NumChildMaps >= (1 << BITS_CHILD_PATT_INDEX))
            i = 3;
        if ((SizeChildMapEntry * 8) < SizeCharSet)
            i = 4;
        if (NumLargeCounts >= (1 << 9))
            i = 5;
        if (NumSmallCounts != NumNodes)
            i = 6;

        if (i != MAGIC) {
            MyCloseFile(f);
            return 0;
        }
        Crc = CalcCrc64(Crc, &i, sizeof i);
        Crc = CalcCrc64(Crc, &NumNodes, sizeof NumNodes);
        Crc = CalcCrc64(Crc, &NumChildLocs, sizeof NumChildLocs);
        Crc = CalcCrc64(Crc, &NumRanks, sizeof NumRanks);
        Crc = CalcCrc64(Crc, &NumWordEnd, sizeof NumWordEnd);
        Crc = CalcCrc64(Crc, &NumChildMaps, sizeof NumChildMaps);
        Crc = CalcCrc64(Crc, &SizeChildMapEntry, sizeof SizeChildMapEntry);
        Crc = CalcCrc64(Crc, &NumLargeCounts, sizeof NumLargeCounts);
        Crc = CalcCrc64(Crc, &NumSmallCounts, sizeof NumSmallCounts);
        Crc = CalcCrc64(Crc, &SizeCharSet, sizeof SizeCharSet);

        DictSize = NumNodes * sizeof(*DictNodes) + NumChildLocs * sizeof(*ChildLocs) + NumRanks * sizeof(*Ranks) + NumWordEnd + NumChildMaps * SizeChildMapEntry
            + NumLargeCounts + NumSmallCounts + SizeCharSet;
        if (DictSize < MAX_DICT_FILE_SIZE) {
            DictNodes = MallocFn(unsigned int, DictSize / sizeof(unsigned int) + 1);
            if (!MyReadFile(f, DictNodes, DictSize)) {
                FreeFn(DictNodes);
                DictNodes = 0;
            }
        }
        MyCloseFile(f);

        if (!DictNodes)
            return 0;
        /* Check crc */
        Crc = CalcCrc64(Crc, DictNodes, DictSize);
        if (memcmp(&Crc, WordCheck, sizeof Crc)) {
            /* File corrupted */
            FreeFn(DictNodes);
            DictNodes = 0;
            return 0;
        }
        fflush(stdout);
        /* Set pointers to the data */
        ChildLocs = DictNodes + NumNodes;
        Ranks = (unsigned short *)(ChildLocs + NumChildLocs);
        WordEndBits = (unsigned char *)(Ranks + NumRanks);
        ChildMap = (unsigned char *)(WordEndBits + NumWordEnd);
        EndCountLge = ChildMap + NumChildMaps * SizeChildMapEntry;
        EndCountSml = EndCountLge + NumLargeCounts;
        CharSet = (char *)EndCountSml + NumSmallCounts;
        CharSet[SizeCharSet] = 0;
        return 1;
    }
    return 0;
}
/**********************************************************************************
 * Free the data allocated by ZxcvbnInit().
 */
void ZxcvbnUnInit()
{
    if (DictNodes)
        FreeFn(DictNodes);
    DictNodes = 0;
}

#else

/* Include the source file containing the dictionary data */
#include "dict-src.h"

#endif

/**********************************************************************************
 * Leet conversion strings
 */
/* String of normal chars that could be given as leet chars in the password */
static const uint8_t L33TChr[] = "abcegilostxz";

/* String of leet,normal,normal char triples. Used to convert supplied leet char to normal. */
static const uint8_t L33TCnv[] = "!i $s %x (c +t 0o 1il2z 3e 4a 5s 6g 7lt8b 9g <c @a [c {c |il";
#define LEET_NORM_MAP_SIZE 3

/* Struct holding additional data on the word match */
typedef struct {
    int Rank; /* Rank of word in dictionary */
    int Caps; /* Number of capital letters */
    int Lower; /* Number of lower case letters */
    int NumLeet; /* Total number of leeted characters */
    uint8_t Leeted[sizeof L33TChr]; /* Number of leeted chars for each char found in L33TChr */
    uint8_t UnLeet[sizeof L33TChr]; /* Number of normal chars for each char found in L33TChr */
} DictMatchInfo_t;

/* Struct holding working data for the word match */
typedef struct {
    uint32_t StartLoc;
    int Ordinal;
    int PwdLength;
    int Begin;
    int Caps;
    int Lower;
    int NumPossChrs;
    uint8_t Leeted[sizeof L33TChr];
    uint8_t UnLeet[sizeof L33TChr];
    uint8_t LeetCnv[sizeof L33TCnv / LEET_NORM_MAP_SIZE + 1];
    uint8_t First;
    uint8_t PossChars[CHARSET_SIZE];
} DictWork_t;

/**********************************************************************************
 * Given a map entry create a string of all possible characters for following to
 * a child node
 */
static int ListPossibleChars(uint8_t *List, const uint8_t *Map)
{
    unsigned int i, j, k;
    int Len = 0;
    for (k = i = 0; i < SizeChildMapEntry; ++i, ++Map) {
        if (!*Map) {
            k += 8;
            continue;
        }
        for (j = 0; j < 8; ++j) {
            if (*Map & (1 << j)) {
                *List++ = CharSet[k];
                ++Len;
            }
            ++k;
        }
    }
    *List = 0;
    return Len;
}

/**********************************************************************************
 * Increment count of each char that could be leeted.
 */
static void AddLeetChr(uint8_t c, int IsLeet, uint8_t *Leeted, uint8_t *UnLeet)
{
    const uint8_t *p = CharBinSearch(c, L33TChr, sizeof L33TChr - 1, 1);
    if (p) {
        int i = p - L33TChr;
        if (IsLeet > 0) {
            Leeted[i] += 1;
        } else if (IsLeet < 0) {
            Leeted[i] += 1;
            UnLeet[i] -= 1;
        } else {
            UnLeet[i] += 1;
        }
    }
}

/**********************************************************************************
 * Given details of a word match, update it with the entropy (as natural log of
 * number of possibilities)
 */
static void DictionaryEntropy(ZxcMatch_t *m, DictMatchInfo_t *Extra, const uint8_t *Pwd)
{
    double e = 0.0;
    /* Add allowance for uppercase letters */
    if (Extra->Caps) {
        if (Extra->Caps == m->Length) {
            /* All uppercase, common case so only 1 bit */
            e += log(2.0);
        } else if ((Extra->Caps == 1) && (isupper(*Pwd) || isupper(Pwd[m->Length - 1]))) {
            /* Only first or last uppercase, also common so only 1 bit */
            e += log(2.0);
        } else {
            /* Get number of combinations of lowercase, uppercase letters */
            int Up = Extra->Caps;
            int Lo = Extra->Lower;
            int i = Up;
            if (i > Lo)
                i = Lo;
            for (Lo += Up; i >= 0; --i)
                e += nCk(Lo, i);
            if (e > 0.0)
                e = log(e);
        }
    }
    /* Add allowance for using leet substitution */
    if (Extra->NumLeet) {
        int i;
        double d = 0.0;
        for (i = sizeof Extra->Leeted - 1; i >= 0; --i) {
            int Sb = Extra->Leeted[i];
            if (Sb) {
                int Un = Extra->UnLeet[i];
                int j = m->Length - Extra->NumLeet;
                if ((j >= 0) && (Un > j))
                    Un = j;
                j = Sb;
                if (j > Un)
                    j = Un;
                for (Un += Sb; j >= 0; --j) {
                    double z = nCk(Un, j);
                    d += z;
                }
            }
        }
        if (d > 0.0)
            d = log(d);
        if (d < log(2.0))
            d = log(2.0);
        e += d;
    }
    /* Add entropy due to word's rank */
    e += log((double)Extra->Rank);
    m->Entrpy = e;
}

/**********************************************************************************
 * Function that does the word matching
 */
static void DoDictMatch(const uint8_t *Passwd, int Start, int MaxLen, DictWork_t *Wrk, ZxcMatch_t **Result, DictMatchInfo_t *Extra, int Lev)
{
    int Len;
    uint8_t TempLeet[LEET_NORM_MAP_SIZE];
    int Ord = Wrk->Ordinal;
    int Caps = Wrk->Caps;
    int Lower = Wrk->Lower;
    unsigned int NodeLoc = Wrk->StartLoc;
    uint8_t *PossChars = Wrk->PossChars;
    int NumPossChrs = Wrk->NumPossChrs;
    const uint8_t *Pwd = Passwd;
    uint32_t NodeData = DictNodes[NodeLoc];
    Passwd += Start;
    for (Len = 0; *Passwd && (Len < MaxLen); ++Len, ++Passwd) {
        uint8_t c;
        int w, x, y, z;
        const uint8_t *q;
        z = 0;
        if (!Len && Wrk->First) {
            c = Wrk->First;
        } else {
            /* Get char and set of possible chars at current point in word. */
            const uint8_t *Bmap;
            c = *Passwd;
            Bmap = ChildMap + (NodeData & ((1 << BITS_CHILD_PATT_INDEX) - 1)) * SizeChildMapEntry;
            NumPossChrs = ListPossibleChars(PossChars, Bmap);

            /* Make it lowercase and update lowercase, uppercase counts */
            if (isupper(c)) {
                c = tolower(c);
                ++Caps;
            } else if (islower(c)) {
                ++Lower;
            }
            /* See if current char is a leet and can be converted  */
            q = CharBinSearch(c, L33TCnv, sizeof L33TCnv / LEET_NORM_MAP_SIZE, LEET_NORM_MAP_SIZE);
            if (q) {
                /* Found, see if used before */
                unsigned int j;
                unsigned int i = (q - L33TCnv) / LEET_NORM_MAP_SIZE;
                if (Wrk->LeetCnv[i]) {
                    /* Used before, so limit characters to try */
                    TempLeet[0] = c;
                    TempLeet[1] = Wrk->LeetCnv[i];
                    TempLeet[2] = 0;
                    q = TempLeet;
                }
                for (j = 0; (*q > ' ') && (j < LEET_NORM_MAP_SIZE); ++j, ++q) {
                    const uint8_t *r = CharBinSearch(*q, PossChars, NumPossChrs, 1);
                    if (r) {
                        /* valid conversion from leet */
                        DictWork_t wrk;
                        wrk = *Wrk;
                        wrk.StartLoc = NodeLoc;
                        wrk.Ordinal = Ord;
                        wrk.PwdLength += Len;
                        wrk.Caps = Caps;
                        wrk.Lower = Lower;
                        wrk.First = *r;
                        wrk.NumPossChrs = NumPossChrs;
                        memcpy(wrk.PossChars, PossChars, sizeof wrk.PossChars);
                        if (j) {
                            wrk.LeetCnv[i] = *r;
                            AddLeetChr(*r, -1, wrk.Leeted, wrk.UnLeet);
                        }
                        DoDictMatch(Pwd, Passwd - Pwd, MaxLen - Len, &wrk, Result, Extra, Lev + 1);
                    }
                }
                return;
            }
        }
        q = CharBinSearch(c, PossChars, NumPossChrs, 1);
        if (q) {
            /* Found the char as a normal char */
            if (CharBinSearch(c, L33TChr, sizeof L33TChr - 1, 1)) {
                /* Char matches, but also a normal equivalent to a leet char */
                AddLeetChr(c, 0, Wrk->Leeted, Wrk->UnLeet);
            }
        }
        if (!q) {
            /* No match for char - return */
            return;
        }
        /* Add all the end counts of the child nodes before the one that matches */
        x = (q - Wrk->PossChars);
        y = (NodeData >> BITS_CHILD_PATT_INDEX) & ((1 << BITS_CHILD_MAP_INDEX) - 1);
        NodeLoc = ChildLocs[x + y];
        for (w = 0; w < x; ++w) {
            unsigned int Cloc = ChildLocs[w + y];
            z = EndCountSml[Cloc];
            if (Cloc < NumLargeCounts)
                z += EndCountLge[Cloc] * 256;
            Ord += z;
        }

        /* Move to next node */
        NodeData = DictNodes[NodeLoc];
        if (WordEndBits[NodeLoc >> 3] & (1 << (NodeLoc & 7))) {
            /* Word matches, save result */
            unsigned int v;
            ZxcMatch_t *p;
            v = Ranks[Ord];
            if (v & (1 << 15))
                v = (v & ((1 << 15) - 1)) * 4 + (1 << 15);
            Extra->Caps = Caps;
            Extra->Rank = v;
            Extra->Lower = Lower;
            for (x = 0, y = sizeof Extra->Leeted - 1; y >= 0; --y)
                x += Wrk->Leeted[y];
            Extra->NumLeet = x;

            memcpy(Extra->UnLeet, Wrk->UnLeet, sizeof Extra->UnLeet);
            memcpy(Extra->Leeted, Wrk->Leeted, sizeof Extra->Leeted);

            p = AllocMatch();
            if (x)
                p->Type = DICT_LEET_MATCH;
            else
                p->Type = DICTIONARY_MATCH;
            p->Length = Wrk->PwdLength + Len + 1;
            p->Begin = Wrk->Begin;
            DictionaryEntropy(p, Extra, Pwd);
            AddMatchRepeats(Result, p, Pwd, MaxLen);
            AddResult(Result, p, MaxLen);
            ++Ord;
        }
    }
}

/**********************************************************************************
 * Try to match password part with user supplied dictionary words
 * Parameters:
 *  Result  Pointer head of linked list used to store results
 *  Words   Array of pointers to dictionary words
 *  Passwd  The start of the password
 *  Start   Where in the password to start attempting to match
 *  MaxLen  Maximum number characters to consider
 */
static void UserMatch(ZxcMatch_t **Result, const char *Words[], const uint8_t *Passwd, int Start, int MaxLen)
{
    int Rank;
    if (!Words)
        return;
    Passwd += Start;
    for (Rank = 0; Words[Rank]; ++Rank) {
        DictMatchInfo_t Extra;
        uint8_t LeetChr[sizeof L33TCnv / LEET_NORM_MAP_SIZE + 1];
        uint8_t TempLeet[3];
        int Len = 0;
        int Caps = 0;
        int Lowers = 0;
        int Leets = 0;
        const uint8_t *Wrd = (const uint8_t *)(Words[Rank]);
        const uint8_t *Pwd = Passwd;
        memset(Extra.Leeted, 0, sizeof Extra.Leeted);
        memset(Extra.UnLeet, 0, sizeof Extra.UnLeet);
        memset(LeetChr, 0, sizeof LeetChr);
        while (*Wrd) {
            const uint8_t *q;
            uint8_t d = tolower(*Wrd++);
            uint8_t c = *Pwd++;
            if (isupper(c)) {
                c = tolower(c);
                ++Caps;
            } else if (islower(c)) {
                ++Lowers;
            }
            /* See if current char is a leet and can be converted  */
            q = CharBinSearch(c, L33TCnv, sizeof L33TCnv / LEET_NORM_MAP_SIZE, LEET_NORM_MAP_SIZE);
            if (q) {
                /* Found, see if used before */
                unsigned int j;
                unsigned int i = (q - L33TCnv) / LEET_NORM_MAP_SIZE;
                if (LeetChr[i]) {
                    /* Used before, so limit characters to try */
                    TempLeet[0] = c;
                    TempLeet[1] = LeetChr[i];
                    TempLeet[2] = 0;
                    q = TempLeet;
                }
                c = d + 1;
                for (j = 0; (*q > ' ') && (j < LEET_NORM_MAP_SIZE); ++j, ++q) {
                    if (d == *q) {
                        c = d;
                        if (i) {
                            LeetChr[i] = c;
                            AddLeetChr(c, 1, Extra.Leeted, Extra.UnLeet);
                            ++Leets;
                        }
                        break;
                    }
                }
                if (c != d) {
                    Len = 0;
                    break;
                }
            } else if (c == d) {
                /* Found the char as a normal char */
                if (CharBinSearch(c, L33TChr, sizeof L33TChr - 1, 1)) {
                    /* Char matches, but also a normal equivalent to a leet char */
                    AddLeetChr(c, 0, Extra.Leeted, Extra.UnLeet);
                }
            } else {
                /* No Match */
                Len = 0;
                break;
            }
            if (++Len > MaxLen) {
                Len = 0;
                break;
            }
        }
        if (Len) {
            ZxcMatch_t *p = AllocMatch();
            if (!Leets)
                p->Type = USER_MATCH;
            else
                p->Type = USER_LEET_MATCH;
            p->Length = Len;
            p->Begin = Start;
            /* Add Entrpy */
            Extra.Caps = Caps;
            Extra.Lower = Lowers;
            Extra.NumLeet = Leets;
            Extra.Rank = Rank + 1;
            DictionaryEntropy(p, &Extra, Passwd);
            AddMatchRepeats(Result, p, Passwd, MaxLen);
            AddResult(Result, p, MaxLen);
        }
    }
}

/**********************************************************************************
 * Try to match password part with the dictionary words
 * Parameters:
 *  Result  Pointer head of linked list used to store results
 *  Passwd  The start of the password
 *  Start   Where in the password to start attempting to match
 *  MaxLen  Maximum number characters to consider
 */
static void DictionaryMatch(ZxcMatch_t **Result, const uint8_t *Passwd, int Start, int MaxLen)
{
    DictWork_t Wrk;
    DictMatchInfo_t Extra;

    memset(&Extra, 0, sizeof Extra);
    memset(&Wrk, 0, sizeof Wrk);
    Wrk.Ordinal = 1;
    Wrk.StartLoc = ROOT_NODE_LOC;
    Wrk.Begin = Start;
    DoDictMatch(Passwd + Start, 0, MaxLen, &Wrk, Result, &Extra, 0);
}

/*################################################################################*
 *################################################################################*
 * Begin keyboard spatial sequence matching code
 *################################################################################*
 *################################################################################*/

/* Struct to hold information on a keyboard layout */
typedef struct Keyboard {
    const uint8_t *Keys;
    const uint8_t *Shifts;
    int NumKeys;
    int NumNear;
    int NumShift;
    int NumBlank;
} Keyboard_t;

/* Struct to hold information on the match */
typedef struct {
    int Keyb;
    int Turns;
    int Shifts;
} SpatialMatchInfo_t;

/* Shift mapping, characters in pairs: first is shifted, second un-shifted. */
static const uint8_t UK_Shift[] = "!1\"2$4%5&7(9)0*8:;<,>.?/@'AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz^6_-{[|\\}]~#�4�3�`";
static const uint8_t US_Shift[] = "!1\"'#3$4%5&7(9)0*8:;<,>.?/@2AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz^6_-{[|\\}]~`";

/* Neighbour tables */
static const uint8_t UK_Qwerty[48 * 7] = {
    /* key, left, up-left, up-right, right, down-right, down-left */
    '#', '\'', ']', 0,   0,    0,   0,    '\'', ';', '[', ']',  '#', 0,   '/', ',', 'm', 'k', 'l', '.', 0,    0,    '-',  '0',  0,   0,   '=', '[', 'p',
    '.', ',',  'l', ';', '/',  0,   0,    '/',  '.', ';', '\'', 0,   0,   0,   '0', '9', 0,   0,   '-', 'p',  'o',  '1',  '`',  0,   0,   '2', 'q', 0,
    '2', '1',  0,   0,   '3',  'w', 'q',  '3',  '2', 0,   0,    '4', 'e', 'w', '4', '3', 0,   0,   '5', 'r',  'e',  '5',  '4',  0,   0,   '6', 't', 'r',
    '6', '5',  0,   0,   '7',  'y', 't',  '7',  '6', 0,   0,    '8', 'u', 'y', '8', '7', 0,   0,   '9', 'i',  'u',  '9',  '8',  0,   0,   '0', 'o', 'i',
    ';', 'l',  'p', '[', '\'', '/', '.',  '=',  '-', 0,   0,    0,   ']', '[', '[', 'p', '-', '=', ']', '\'', ';',  '\\', 0,    0,   'a', 'z', 0,   0,
    ']', '[',  '=', 0,   0,    '#', '\'', '`',  0,   0,   0,    '1', 0,   0,   'a', 0,   'q', 'w', 's', 'z',  '\\', 'b',  'v',  'g', 'h', 'n', 0,   0,
    'c', 'x',  'd', 'f', 'v',  0,   0,    'd',  's', 'e', 'r',  'f', 'c', 'x', 'e', 'w', '3', '4', 'r', 'd',  's',  'f',  'd',  'r', 't', 'g', 'v', 'c',
    'g', 'f',  't', 'y', 'h',  'b', 'v',  'h',  'g', 'y', 'u',  'j', 'n', 'b', 'i', 'u', '8', '9', 'o', 'k',  'j',  'j',  'h',  'u', 'i', 'k', 'm', 'n',
    'k', 'j',  'i', 'o', 'l',  ',', 'm',  'l',  'k', 'o', 'p',  ';', '.', ',', 'm', 'n', 'j', 'k', ',', 0,    0,    'n',  'b',  'h', 'j', 'm', 0,   0,
    'o', 'i',  '9', '0', 'p',  'l', 'k',  'p',  'o', '0', '-',  '[', ';', 'l', 'q', 0,   '1', '2', 'w', 'a',  0,    'r',  'e',  '4', '5', 't', 'f', 'd',
    's', 'a',  'w', 'e', 'd',  'x', 'z',  't',  'r', '5', '6',  'y', 'g', 'f', 'u', 'y', '7', '8', 'i', 'j',  'h',  'v',  'c',  'f', 'g', 'b', 0,   0,
    'w', 'q',  '2', '3', 'e',  's', 'a',  'x',  'z', 's', 'd',  'c', 0,   0,   'y', 't', '6', '7', 'u', 'h',  'g',  'z',  '\\', 'a', 's', 'x', 0,   0};

static const uint8_t US_Qwerty[47 * 7] = {
    /* key, left, up-left, up-right, right, down-right, down-left */
    '\'', ';',  '[', ']', 0,    0,   '/',  ',', 'm', 'k', 'l', '.', 0,   0,   '-', '0', 0,   0,    '=', '[',  'p', '.', ',', 'l', ';', '/', 0,   0,   '/', '.',
    ';',  '\'', 0,   0,   0,    '0', '9',  0,   0,   '-', 'p', 'o', '1', '`', 0,   0,   '2', 'q',  0,   '2',  '1', 0,   0,   '3', 'w', 'q', '3', '2', 0,   0,
    '4',  'e',  'w', '4', '3',  0,   0,    '5', 'r', 'e', '5', '4', 0,   0,   '6', 't', 'r', '6',  '5', 0,    0,   '7', 'y', 't', '7', '6', 0,   0,   '8', 'u',
    'y',  '8',  '7', 0,   0,    '9', 'i',  'u', '9', '8', 0,   0,   '0', 'o', 'i', ';', 'l', 'p',  '[', '\'', '/', '.', '=', '-', 0,   0,   0,   ']', '[', '[',
    'p',  '-',  '=', ']', '\'', ';', '\\', ']', 0,   0,   0,   0,   0,   ']', '[', '=', 0,   '\\', 0,   '\'', '`', 0,   0,   0,   '1', 0,   0,   'a', 0,   'q',
    'w',  's',  'z', 0,   'b',  'v', 'g',  'h', 'n', 0,   0,   'c', 'x', 'd', 'f', 'v', 0,   0,    'd', 's',  'e', 'r', 'f', 'c', 'x', 'e', 'w', '3', '4', 'r',
    'd',  's',  'f', 'd', 'r',  't', 'g',  'v', 'c', 'g', 'f', 't', 'y', 'h', 'b', 'v', 'h', 'g',  'y', 'u',  'j', 'n', 'b', 'i', 'u', '8', '9', 'o', 'k', 'j',
    'j',  'h',  'u', 'i', 'k',  'm', 'n',  'k', 'j', 'i', 'o', 'l', ',', 'm', 'l', 'k', 'o', 'p',  ';', '.',  ',', 'm', 'n', 'j', 'k', ',', 0,   0,   'n', 'b',
    'h',  'j',  'm', 0,   0,    'o', 'i',  '9', '0', 'p', 'l', 'k', 'p', 'o', '0', '-', '[', ';',  'l', 'q',  0,   '1', '2', 'w', 'a', 0,   'r', 'e', '4', '5',
    't',  'f',  'd', 's', 'a',  'w', 'e',  'd', 'x', 'z', 't', 'r', '5', '6', 'y', 'g', 'f', 'u',  'y', '7',  '8', 'i', 'j', 'h', 'v', 'c', 'f', 'g', 'b', 0,
    0,    'w',  'q', '2', '3',  'e', 's',  'a', 'x', 'z', 's', 'd', 'c', 0,   0,   'y', 't', '6',  '7', 'u',  'h', 'g', 'z', 0,   'a', 's', 'x', 0,   0,
};
static const uint8_t Dvorak[47 * 7] = {
    '\'', 0,   '1', '2', ',', 'a', 0,    ',', '\'', '2', '3', '.', 'o', 'a', '-', 's', '/', '=',  0,   0,   'z', '.', ',', '3', '4', 'p',  'e',  'o', '/', 'l',
    '[',  ']', '=', '-', 's', '0', '9',  0,   0,    '[', 'l', 'r', '1', '`', 0,   0,   '2', '\'', 0,   '2', '1', 0,   0,   '3', ',', '\'', '3',  '2', 0,   0,
    '4',  '.', ',', '4', '3', 0,   0,    '5', 'p',  '.', '5', '4', 0,   0,   '6', 'y', 'p', '6',  '5', 0,   0,   '7', 'f', 'y', '7', '6',  0,    0,   '8', 'g',
    'f',  '8', '7', 0,   0,   '9', 'c',  'g', '9',  '8', 0,   0,   '0', 'r', 'c', ';', 0,   'a',  'o', 'q', 0,   0,   '=', '/', ']', 0,    '\\', 0,   '-', '[',
    '0',  0,   0,   ']', '/', 'l', '\\', '=', 0,    0,   0,   0,   0,   ']', '[', 0,   0,   0,    '=', '/', '`', 0,   0,   0,   '1', 0,    0,    'a', 0,   '\'',
    ',',  'o', ';', 0,   'b', 'x', 'd',  'h', 'm',  0,   0,   'c', 'g', '8', '9', 'r', 't', 'h',  'd', 'i', 'f', 'g', 'h', 'b', 'x', 'e',  'o',  '.', 'p', 'u',
    'j',  'q', 'f', 'y', '6', '7', 'g',  'd', 'i',  'g', 'f', '7', '8', 'c', 'h', 'd', 'h', 'd',  'g', 'c', 't', 'm', 'b', 'i', 'u', 'y',  'f',  'd', 'x', 'k',
    'j',  'q', 'e', 'u', 'k', 0,   0,    'k', 'j',  'u', 'i', 'x', 0,   0,   'l', 'r', '0', '[',  '/', 's', 'n', 'm', 'b', 'h', 't', 'w',  0,    0,   'n', 't',
    'r',  'l', 's', 'v', 'w', 'o', 'a',  ',', '.',  'e', 'q', ';', 'p', '.', '4', '5', 'y', 'u',  'e', 'q', ';', 'o', 'e', 'j', 0,   0,    'r',  'c', '9', '0',
    'l',  'n', 't', 's', 'n', 'l', '/',  '-', 'z',  'v', 't', 'h', 'c', 'r', 'n', 'w', 'm', 'u',  'e', 'p', 'y', 'i', 'k', 'j', 'v', 'w',  'n',  's', 'z', 0,
    0,    'w', 'm', 't', 'n', 'v', 0,    0,   'x',  'k', 'i', 'd', 'b', 0,   0,   'y', 'p', '5',  '6', 'f', 'i', 'u', 'z', 'v', 's', '-',  0,    0,   0};

static const uint8_t PC_Keypad[15 * 9] = {
    /*Key, left, up-left, up, up-right, right, down-right, down, down-left */
    '*', '/', 0,   0,   0,   '-', '+', '9', '8', '+', '9', '*', '-', 0,   0,   0,   0,   '6', '-', '*', 0,   0,   0,   0,   0, '+', '9',
    '.', '0', '2', '3', 0,   0,   0,   0,   0,   '/', 0,   0,   0,   0,   '*', '9', '8', '7', '0', 0,   '1', '2', '3', '.', 0, 0,   0,
    '1', 0,   0,   '4', '5', '2', '0', 0,   0,   '2', '1', '4', '5', '6', '3', '.', '0', 0,   '3', '2', '5', '6', 0,   0,   0, '.', '0',
    '4', 0,   0,   '7', '8', '5', '2', '1', 0,   '5', '4', '7', '8', '9', '6', '3', '2', '1', '6', '5', '8', '9', '+', 0,   0, '3', '2',
    '7', 0,   0,   0,   '/', '8', '5', '4', 0,   '8', '7', 0,   '/', '*', '9', '6', '5', '4', '9', '8', '/', '*', '-', '+', 0, '6', '5'};

static const uint8_t MacKeypad[16 * 9] = {
    '*', '/', 0,   0,   0,   0,   0,   '-', '9', '+', '6', '9', '-', 0,   0,   0,   0,   '3', '-', '9', '/', '*', 0,   0,   0,   '+', '6', '.', '0',
    '2', '3', 0,   0,   0,   0,   0,   '/', '=', 0,   0,   0,   '*', '-', '9', '8', '0', 0,   '1', '2', '3', '.', 0,   0,   0,   '1', 0,   0,   '4',
    '5', '2', '0', 0,   0,   '2', '1', '4', '5', '6', '3', '.', '0', 0,   '3', '2', '5', '6', '+', 0,   0,   '.', '0', '4', 0,   0,   '7', '8', '5',
    '2', '1', 0,   '5', '4', '7', '8', '9', '6', '3', '2', '1', '6', '5', '8', '9', '-', '+', 0,   '3', '2', '7', 0,   0,   0,   '=', '8', '5', '4',
    0,   '8', '7', 0,   '=', '/', '9', '6', '5', '4', '9', '8', '=', '/', '*', '-', '+', '6', '5', '=', 0,   0,   0,   0,   '/', '9', '8', '7'};

static const Keyboard_t Keyboards[] = {{US_Qwerty, US_Shift, sizeof US_Qwerty / 7, 7, sizeof US_Shift / 2, 66},
                                       {Dvorak, US_Shift, sizeof Dvorak / 7, 7, sizeof US_Shift / 2, 66},
                                       {UK_Qwerty, UK_Shift, sizeof UK_Qwerty / 7, 7, sizeof UK_Shift / 2, 66},
                                       {MacKeypad, 0, sizeof MacKeypad / 9, 9, 0, 44},
                                       {PC_Keypad, 0, sizeof PC_Keypad / 9, 9, 0, 44}};

/**********************************************************************************
 * Match password for the given keyboard layout
 */
static int DoSptlMatch(const uint8_t *Passwd, int MaxLen, const Keyboard_t *Keyb, SpatialMatchInfo_t *Extra)
{
    int i;
    int ShiftCount = 0;
    int Turns = 0;
    int Dir = -1;
    int Len = 0;
    uint8_t PrevChar = 0;
    for (; *Passwd && (Len < MaxLen); ++Passwd, ++Len) {
        const uint8_t *Key;
        int s = 0;
        uint8_t CurChar = *Passwd;
        /* Try to unshift the character */
        if (Keyb->Shifts) {
            Key = CharBinSearch(CurChar, Keyb->Shifts, Keyb->NumShift, 2);
            if (Key) {
                /* Shifted char */
                CurChar = Key[1];
                s = 1;
            }
        }
        if (PrevChar) {
            /* See if the pattern can be extended */
            i = 0;
            Key = CharBinSearch(PrevChar, Keyb->Keys, Keyb->NumKeys, Keyb->NumNear);
            if (Key) {
                for (i = Keyb->NumNear - 1; i > 0; --i) {
                    if (Key[i] == CurChar)
                        break;
                }
            }
            if (i) {
                Turns += (i != Dir);
                Dir = i;
                ShiftCount += s;
            } else {
                break;
            }
        }
        PrevChar = CurChar;
    }
    if (Len >= MIN_SPATIAL_LEN) {
        Extra->Turns = Turns;
        Extra->Shifts = ShiftCount;
        return Len;
    }
    return 0;
}

/**********************************************************************************
 *  Try to match spatial patterns on the keyboard
 * Parameters:
 *  Result  Pointer head of linked list used to store results
 *  Passwd  The start of the password
 *  Start   Where in the password to start attempting to match
 *  MaxLen  Maximum number characters to consider
 */
static void SpatialMatch(ZxcMatch_t **Result, const uint8_t *Passwd, int Start, int MaxLen)
{
    unsigned int Indx;
    int Len, CurLen;
    SpatialMatchInfo_t Extra;
    const Keyboard_t *k;
    Passwd += Start;

    for (CurLen = MaxLen; CurLen >= MIN_SPATIAL_LEN; CurLen = Len - 1) {
        Len = 0;
        for (k = Keyboards, Indx = 0; Indx < (sizeof Keyboards / sizeof Keyboards[0]); ++Indx, ++k) {
            memset(&Extra, 0, sizeof Extra);
            Len = DoSptlMatch(Passwd, CurLen, k, &Extra);
            if (Len > 0) {
                /* Got a sequence of required length so add to result list */
                int i, j, s;
                double Degree, Entropy;
                ZxcMatch_t *p;
                Degree = (k->NumNear - 1) - (double)k->NumBlank / (double)k->NumKeys;
                s = k->NumKeys;
                if (k->Shifts)
                    s *= 2;

                /* Estimate the number of possible patterns with length ranging 2 to match length and */
                /* with turns ranging from 0 to match turns */
                Entropy = 0.0;
                for (i = 2; i <= Len; ++i) {
                    int PossTurns = Extra.Turns;
                    if (PossTurns >= i)
                        PossTurns = i - 1;
                    for (j = 1; j <= PossTurns; ++j)
                        Entropy += nCk(i - 1, j - 1) * pow(Degree, j) * s;
                }
                if (Entropy > 0.0)
                    Entropy = log(Entropy);
                if (Extra.Shifts) {
                    /* Add extra entropy for shifted keys. (% instead of 5, A instead of a etc.) */
                    /* Math is similar to extra entropy from uppercase letters in dictionary matches. */
                    int Shift = Extra.Shifts;
                    int Unshift = Len - Shift;

                    Degree = 0.0;
                    j = Shift;
                    if (j > Unshift)
                        j = Unshift;
                    for (i = 0; i <= j; ++i) {
                        Degree += nCk(Len, i);
                    }
                    if (Degree > 0.0)
                        Entropy += log(Degree);
                }
                p = AllocMatch();
                p->Type = SPATIAL_MATCH;
                p->Begin = Start;
                p->Entrpy = Entropy;
                p->Length = Len;
                AddMatchRepeats(Result, p, Passwd, MaxLen);
                AddResult(Result, p, MaxLen);
            }
        }
    }
}

/*################################################################################*
 *################################################################################*
 * Begin date matching code
 *################################################################################*
 *################################################################################*/

/* The possible date formats ordered by length (d for day, m for month, */
/*  y for year, ? for separator) */
static const char *Formats[] = {"yyyy",      "d?m?yy",    "ddmmyy",    "dmyyyy",     "dd?m?yy",    "d?mm?yy",  "ddmyyyy",  "dmmyyyy",
                                "yyyymmd",   "yyyymdd",   "d?m?yyyy",  "dd?mm?yy",   "ddmmyyyy",   "yyyy?m?d", "yyyymmdd", "dd?m?yyyy",
                                "d?mm?yyyy", "yyyy?mm?d", "yyyy?m?dd", "dd?mm?yyyy", "yyyy?mm?dd", 0};
/* Possible separator characters that could be used */
static const char DateSeperators[] = "/\\-_. ";

/**********************************************************************************
 * Try to match the password with the formats above.
 */
static void DateMatch(ZxcMatch_t **Result, const uint8_t *Passwd, int Start, int MaxLen)
{
    int CurFmt;
    int YrLen = 0;
    int PrevLen = 0;
    uint8_t Sep = 0;
    Passwd += Start;

    for (CurFmt = 0; Formats[CurFmt]; ++CurFmt) {
        int Len = 0;
        int Year = 0;
        int Mon = 0;
        int Day = 0;
        int Fail = 0;
        const uint8_t *p = Passwd;
        const char *Fmt;
        YrLen = 0;
        Sep = 0;
        /* Scan along the format, trying to match the password */
        for (Fmt = Formats[CurFmt]; *Fmt && !Fail; ++Fmt) {
            if (*Fmt == '?') {
                if (!Sep && strchr(DateSeperators, *p))
                    Sep = *p;
                Fail = (*p != Sep);
            } else if (isdigit(*p)) {
                if (*Fmt == 'd') {
                    Day = 10 * Day + *p - '0';
                } else if (*Fmt == 'm') {
                    Mon = 10 * Mon + *p - '0';
                } else {
                    Year = 10 * Year + *p - '0';
                    ++YrLen;
                }
            } else {
                Fail = 1;
            }
            ++p;
            ++Len;
            if (Len >= MaxLen)
                break;
        }
        if (Len < 4)
            Fail = 1;
        if (!Fail) {
            /* Character matching is OK, now check to see if valid date */
            if (((YrLen > 3) || (Len <= 4)) && ((Year < MIN_YEAR) || (Year > MAX_YEAR)))
                Fail = 1;
            else if (Len > 4) {
                if ((Mon > 12) && (Day < 13)) {
                    /* Swap day,month to try to make both in range */
                    int i = Mon;
                    Mon = Day;
                    Day = i;
                }
                /* Check for valid day, month. Currently assumes all months have 31 days. */
                if ((Mon < 1) || (Mon > 12))
                    Fail = 1;
                else if ((Day < 1) || (Day > 31))
                    Fail = 1;
            }
        }
        if (!Fail && (Len > PrevLen)) {
            /* String matched the date, store result */
            double e;
            ZxcMatch_t *match = AllocMatch();

            if (Len <= 4)
                e = log(MAX_YEAR - MIN_YEAR + 1.0);
            else if (YrLen > 3)
                e = log(31 * 12 * (MAX_YEAR - MIN_YEAR + 1.0));
            else
                e = log(31 * 12 * 100.0);
            if (Sep)
                e += log(4.0); /* Extra 2 bits for separator */
            match->Entrpy = e;
            match->Type = DATE_MATCH;
            match->Length = Len;
            match->Begin = Start;
            AddMatchRepeats(Result, match, Passwd, MaxLen);
            AddResult(Result, match, MaxLen);
            PrevLen = Len;
        }
    }
}

/*################################################################################*
 *################################################################################*
 * Begin repeated character matching code
 *################################################################################*
 *################################################################################*/

/**********************************************************************************
 * Try to match password part as a set of repeated characters.
 * Parameters:
 *  Result  Pointer head of linked list used to store results
 *  Passwd  The start of the password
 *  Start   Where in the password to start attempting to match
 *  MaxLen  Maximum number characters to consider
 */
static void RepeatMatch(ZxcMatch_t **Result, const uint8_t *Passwd, int Start, int MaxLen)
{
    int Len, i;
    uint8_t c;
    Passwd += Start;
    /* Remember first char and the count its occurrences */
    c = *Passwd;
    for (Len = 1; (Len < MaxLen) && (c == Passwd[Len]); ++Len) { }
    if (Len >= MIN_REPEAT_LEN) {
        /* Enough repeated char, so create results from number found down to min acceptable repeats */
        double Card = Cardinality(&c, 1);
        for (i = Len; i >= MIN_REPEAT_LEN; --i) {
            ZxcMatch_t *p = AllocMatch();
            p->Type = REPEATS_MATCH;
            p->Begin = Start;
            p->Length = i;
            p->Entrpy = log(Card * i);
            AddResult(Result, p, MaxLen);
        }
    }

    /* Try to match a repeated sequence e.g. qxno6qxno6 */
    for (Len = MaxLen / 2; Len >= MIN_REPEAT_LEN; --Len) {
        const uint8_t *Rpt = Passwd + Len;
        int RepeatCount = 2;
        while (MaxLen >= (Len * RepeatCount)) {
            if (strncmp((const char *)Passwd, (const char *)Rpt, Len) == 0) {
                /* Found a repeat */
                ZxcMatch_t *p = AllocMatch();
                p->Entrpy = log((double)Cardinality(Passwd, Len)) * Len + log(RepeatCount);
                p->Type = (ZxcTypeMatch_t)(BRUTE_MATCH + MULTIPLE_MATCH);
                p->Length = Len * RepeatCount;
                p->Begin = Start;
                AddResult(Result, p, MaxLen);
            } else
                break;
            ++RepeatCount;
            Rpt += Len;
        }
    }
}

/**********************************************************************************
 **********************************************************************************
 * Begin character sequence matching code
 **********************************************************************************
 *********************************************************************************/

#define MAX_SEQUENCE_STEP 5
/**********************************************************************************
 * Try to match password part as a set of incrementing or decrementing characters.
 * Parameters:
 *  Result  Pointer head of linked list used to store results
 *  Passwd  The start of the password
 *  Start   Where in the password to start attempting to match
 *  MaxLen  Maximum number characters to consider
 */
static void SequenceMatch(ZxcMatch_t **Result, const uint8_t *Passwd, int Start, int MaxLen)
{
    int Len = 0;
    int SetLow, SetHigh, Dir;
    uint8_t First, Next, IsDigits;
    const uint8_t *Pwd;
    Passwd += Start;
    Pwd = Passwd;
    First = Passwd[0];
    Dir = Passwd[1] - First;
    Len = 0;
    IsDigits = 0;
    /* Decide on min and max character code for sequence */
    if (islower(*Passwd)) {
        SetLow = 'a';
        SetHigh = 'z';
    } else if (isupper(*Passwd)) {
        SetLow = 'A';
        SetHigh = 'Z';
    } else if (isdigit(*Passwd)) {
        SetLow = '0';
        SetHigh = '9';
        if ((First == '0') && isdigit(Passwd[1]) && (Dir > MAX_SEQUENCE_STEP)) {
            /* Special case for decrementing sequence of digits, treat '0 as a 'ten' character */
            Dir = Passwd[1] - ('9' + 1);
        }
        IsDigits = 1;
    } else
        return;

    /* Only consider it a sequence if the character increment is not too large */
    if (Dir && (Dir <= MAX_SEQUENCE_STEP) && (Dir >= -MAX_SEQUENCE_STEP)) {
        ++Len;
        while (1) {
            Next = Passwd[0] + Dir;
            if (IsDigits && (Dir > 0) && (Next == ('9' + 1)) && (Passwd[1] == '0')) {
                /* Incrementing digits, consider '0' to be same as a 'ten' character */
                ++Len;
                ++Passwd;
                break;
            }
            if (IsDigits && (Dir < 0) && (Passwd[0] == '0') && (Passwd[1] == ('9' + 1 + Dir))) {
                ++Len;
                ++Passwd;
                break;
            }
            if ((Next > SetHigh) || (Next < SetLow) || (Passwd[1] != Next))
                break;
            ++Len;
            ++Passwd;
            if (Len >= MaxLen)
                break;
        }
    }
    if (Len >= MIN_SEQUENCE_LEN) {
        /* Enough repeated char, so create results from number found down to min acceptable length */
        int i;
        double e;
        if ((First == 'a') || (First == 'A') || (First == 'z') || (First == 'Z') || (First == '0') || (First == '1') || (First == '9'))
            e = log(2.0);
        else if (IsDigits)
            e = log(10.0);
        else if (isupper(First))
            e = log(26 * 2.0);
        else
            e = log(26.0);
        if (Dir < 0)
            e += log(2.0);

        for (i = Len; i >= MIN_SEQUENCE_LEN; --i) {
            ZxcMatch_t *p = AllocMatch();
            /* Add new result to head of list as it has lower entropy */
            p->Type = SEQUENCE_MATCH;
            p->Begin = Start;
            p->Length = i;
            p->Entrpy = e + log((double)i);
            AddMatchRepeats(Result, p, Pwd, MaxLen);
            AddResult(Result, p, MaxLen);
        }
    }
}

/**********************************************************************************
 **********************************************************************************
 * Begin top level zxcvbn code
 **********************************************************************************
 *********************************************************************************/

/**********************************************************************************
 * Matching a password is treated as a problem of finding the minimum distance
 * between two vertices in a graph. This is solved using Dijkstra's algorithm.
 *
 * There  are a series of nodes (or vertices in graph terminology) which correspond
 * to points between each character of the password. Also there is a start node
 * before the first character and an end node after the last character.
 *
 * The paths between the nodes (or edges in graph terminology) correspond to the
 * matched parts of the password (e.g. dictionary word, repeated characters etc).
 * The distance of the path is equal to the entropy of the matched part. A default
 * single character bruteforce match path is also added for all nodes except the
 * end node.
 *
 * Dijkstra's algorithm finds the combination of these part matches (or paths)
 * which gives the lowest entropy (or smallest distance) from beginning to end
 * of the password.
 */

/* Struct to hold the data of a node (imaginary point between password characters) */
typedef struct {
    ZxcMatch_t *Paths; /* Partial matches that lead to a following node */
    double Dist; /* Distance (or entropy) from start of password to this node */
    ZxcMatch_t *From; /* Which path was used to get to this node with lowest distance/entropy */
    int Visit; /* Non zero when node has been visited during Dijkstra evaluation */
} Node_t;

/**********************************************************************************
 * Main function of the zxcvbn password entropy estimation
 */
double ZxcvbnMatch(const char *Pwd, const char *UserDict[], ZxcMatch_t **Info)
{
    int i, j;
    ZxcMatch_t *Zp;
    Node_t *Np;
    double e;
    int Len = strlen(Pwd);
    const uint8_t *Passwd = (const uint8_t *)Pwd;
    uint8_t *RevPwd;
    /* Create the paths */
    Node_t *Nodes = MallocFn(Node_t, Len + 1);
    memset(Nodes, 0, (Len + 1) * sizeof *Nodes);
    i = Cardinality(Passwd, Len);
    e = log((double)i);

    /* Do matching for all parts of the password */
    for (i = 0; i < Len; ++i) {
        int MaxLen = Len - i;
        /* Add all the 'paths' between groups of chars in the password, for current starting char */
        UserMatch(&(Nodes[i].Paths), UserDict, Passwd, i, MaxLen);
        DictionaryMatch(&(Nodes[i].Paths), Passwd, i, MaxLen);
        DateMatch(&(Nodes[i].Paths), Passwd, i, MaxLen);
        SpatialMatch(&(Nodes[i].Paths), Passwd, i, MaxLen);
        SequenceMatch(&(Nodes[i].Paths), Passwd, i, MaxLen);
        RepeatMatch(&(Nodes[i].Paths), Passwd, i, MaxLen);

        /* Initially set distance to nearly infinite */
        Nodes[i].Dist = DBL_MAX;
    }

    /* Reverse dictionary words check */
    RevPwd = MallocFn(uint8_t, Len + 1);
    for (i = Len - 1, j = 0; i >= 0; --i, ++j)
        RevPwd[j] = Pwd[i];
    RevPwd[j] = 0;
    for (i = 0; i < Len; ++i) {
        ZxcMatch_t *Path = 0;
        int MaxLen = Len - i;
        DictionaryMatch(&Path, RevPwd, i, MaxLen);
        UserMatch(&Path, UserDict, RevPwd, i, MaxLen);

        /* Now transfer any reverse matches to the normal results */
        while (Path) {
            ZxcMatch_t *Nxt = Path->Next;
            Path->Next = 0;
            Path->Begin = Len - (Path->Begin + Path->Length);
            AddResult(&(Nodes[Path->Begin].Paths), Path, MaxLen);
            Path = Nxt;
        }
    }

    /* Add a set of brute force matches. Start by getting all the start points and all */
    /* points at character position after end of the matches.  */
    memset(RevPwd, 0, Len + 1);
    for (i = 0; i < Len; ++i) {
        ZxcMatch_t *Path = Nodes[i].Paths;
        while (Path) {
            RevPwd[Path->Begin] |= 1;
            RevPwd[Path->Begin + Path->Length] |= 2;
            Path = Path->Next;
        }
    }
    RevPwd[0] = 1;
    RevPwd[Len] = 2;

    /* Add the brute force matches */
    for (i = 0; i < Len; ++i) {
        int MaxLen = Len - i;
        int k;
        if (!RevPwd[i])
            continue;
        for (k = i + 1; k <= Len; ++k) {
            if (RevPwd[k]) {
                Zp = AllocMatch();
                Zp->Type = BRUTE_MATCH;
                Zp->Begin = i;
                Zp->Length = k - i;
                Zp->Entrpy = e * (k - i);
                AddResult(&(Nodes[i].Paths), Zp, MaxLen);
            }
        }
    }
    FreeFn(RevPwd);
    /* End node has infinite distance/entropy, start node has 0 distance */
    Nodes[i].Dist = DBL_MAX;
    Nodes[0].Dist = 0.0;

    /* Reduce the paths using Dijkstra's algorithm */
    for (i = 0; i < Len; ++i) {
        int k;
        double MinDist = DBL_MAX;
        int MinIdx = 0;
        /* Find the unvisited node with minimum distance or entropy */
        for (Np = Nodes, k = 0; k < Len; ++k, ++Np) {
            if (!Np->Visit && (Np->Dist < MinDist)) {
                MinIdx = k;
                MinDist = Np->Dist;
            }
        }
        /* Mark the minimum distance node as visited */
        Np = Nodes + MinIdx;
        Np->Visit = 1;
        e = Np->Dist;
        /* Update all unvisited neighbouring nodes with their new distance. A node is a */
        /* neighbour if there is a path/match from current node Np to it. The neighbour */
        /* distance is the current node distance plus the path distance/entropy. Only */
        /* update if the new distance is smaller. */
        for (Zp = Np->Paths; Zp; Zp = Zp->Next) {
            Node_t *Ep = Np + Zp->Length;
            double d = e + Zp->MltEnpy;
            if (!Ep->Visit && (d < Ep->Dist)) {
                /* Update as lower dist, also remember the 'from' node */
                Ep->Dist = d;
                Ep->From = Zp;
            }
        }
        /* If we got to the end node stop early */
        /*if (Nodes[Len].Dist < DBL_MAX/2.0) */
        /*  break; */
    }
    /* Make e hold entropy result and adjust to log base 2 */
    e = Nodes[Len].Dist / log(2.0);

    if (Info) {
        /* Construct info on password parts */
        *Info = 0;
        for (Zp = Nodes[Len].From; Zp;) {
            ZxcMatch_t *Xp;
            i = Zp->Begin;

            /* Remove all but required path */
            Xp = Nodes[i].Paths;
            Nodes[i].Paths = 0;
            while (Xp) {
                ZxcMatch_t *p = Xp->Next;
                if (Xp == Zp) {
                    /* Adjust the entropy to log to base 2 */
                    Xp->Entrpy /= log(2.0);
                    Xp->MltEnpy /= log(2.0);

                    /* Put previous part at head of info list */
                    Xp->Next = *Info;
                    *Info = Xp;
                } else {
                    /* Not going on info list, so free it */
                    FreeFn(Xp);
                }
                Xp = p;
            }
            Zp = Nodes[i].From;
        }
    }
    /* Free all paths. Any being returned to caller have already been freed */
    for (i = 0; i <= Len; ++i) {
        Zp = Nodes[i].Paths;
        while (Zp) {
            ZxcMatch_t *p = Zp->Next;
            FreeFn(Zp);
            Zp = p;
        }
    }
    FreeFn(Nodes);
    return e;
}

/**********************************************************************************
 * Free the path info returned by ZxcvbnMatch().
 */
void ZxcvbnFreeInfo(ZxcMatch_t *Info)
{
    ZxcMatch_t *p;
    while (Info) {
        p = Info->Next;
        FreeFn(Info);
        Info = p;
    }
}
