Initial commit

Makefile

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+
+gcaptchaz: gcaptchaz.c
+	gcc $^ -o $@ -lm -lfreetype -lpng -lgd -ggdb -Wall

gcaptchaz.c

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+#include <sys/time.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <gd.h>
+#include <gdfontl.h>
+
+/*
+  This code is only a C implementation (with some minor modifications) of this captcha generator :
+  http://logz.org/captchaz/
+
+  Copyright   November 2012    Grégory Soutadé
+  Copyright   July 2007        Loz
+
+  LICENCE : Copyleft, Licence Art Libre (http://artlibre.org/licence/lal)
+
+  Modifications : 
+  * Group letters 
+  * Add another layer for letter rendering (more confusing)
+  * Change start, not appropriate for big fonts
+  * Change min/max font size
+
+  You need libgd2-xpm-dev package
+
+  It's recommanded the included font "scrawl.ttf"
+ */
+
+#define MAX(a, b) (((a) >= (b)) ? (a) : (b))
+
+// If not defined
+/* int overflow2(int a, int b) */
+/* { */
+/* 	if(a < 0 || b < 0) { */
+/* 		fprintf(stderr, "gd warning: one parameter to a memory allocation multiplication is negative, failing operation gracefully\n"); */
+/* 		return 1; */
+/* 	} */
+/* 	if(b == 0) */
+/* 		return 0; */
+/* 	if(a > 0xFFFFFFFF / b) { */
+/* 		fprintf(stderr, "gd warning: product of memory allocation multiplication would exceed INT_MAX, failing operation gracefully\n"); */
+/* 		return 1; */
+/* 	} */
+/* 	return 0; */
+/* } */
+
+static int my_rand(int min, int max)
+{
+    int val;
+    struct timeval tv;
+    static unsigned int seed = 0;
+    int interval;
+
+    if (seed == 0)
+    {
+        gettimeofday(&tv, NULL);
+        seed = tv.tv_usec;
+    }
+    
+    val = rand_r(&seed);
+    
+    if (min < 0)
+    {
+        if (max < 0)
+            interval = -(min-max);
+        else
+            interval = max-min;
+    }
+    else
+        interval = max-min;
+
+    val = (int)(((double)val/(double)RAND_MAX)*(double)(interval));
+
+    val += min;
+
+    /* printf("rand [%d..%d] %d\n", min, max, val); */
+
+    return val;
+}
+
+static inline int random_color(gdImagePtr im, int a, int b) {
+    return gdImageColorAllocate(im, my_rand(a,b), my_rand(a,b), my_rand(a,b));
+}
+
+static int generate_captcha(int width, int height, int inverse, char* font, char* phrase, char* out)
+{
+    gdImagePtr im;
+    int R, c1, c2;
+    int wd, x, y, w1, w2, limit, n, p, r, g, b;
+    int size, half, len;
+    double rotation;
+    char letter[2] = {0, 0};
+    int brect[8];
+    char* error;
+    const double rad = 3.14/(double)180;
+
+// initialize in-memory image with gd library
+    im = gdImageCreateTrueColor(width, height);
+
+    R = (inverse) ? 0xFF : 0x00;
+
+    gdImageFilledRectangle(im, 0, 0, width, height, random_color(im, 222^R, 255^R));
+
+    c1 = my_rand(150^R, 185^R);
+    c2 = my_rand(195^R, 230^R);
+
+// encolour bg
+    wd=20; x=0;
+    while (x < width)
+    {
+        gdImageFilledRectangle(im, x, 0, x+wd, height, random_color(im, 222^R, 255^R));
+        x += wd;
+        wd += MAX(10, my_rand(0, 20) - 10);
+    }
+
+    // make interesting background I, lines
+    wd=4; w1=0; w2=0;
+    for(x=0; x<width; x+=wd)
+    {
+        if (x < width)
+            gdImageLine(im, x+w1, 0, x+w2, height-1, random_color(im, c1, c2));
+
+        if (x < height)
+            gdImageLine(im, 0, x-w2, width-1, x-w1, random_color(im, c1, c2));
+        
+        wd += my_rand(0, 8)-4;
+        if (wd < 1) wd = 2;
+        w1 += my_rand(0, 8)-4;
+        w2 += my_rand(0, 8)-4;
+        
+        if ((x > height) && (x > height)) // ???
+            break;
+    }
+
+    // more disturbing II, random letters
+    limit = my_rand(30, 90);
+    for(n=0; n<limit; n++)
+    {
+        letter[0] = my_rand(31, 125); // only one letter
+        size = my_rand(5, height/2);
+        half = size / 2;
+        x = my_rand(-half, width+half);
+        y = my_rand(half, height);
+        rotation = my_rand(60, 300);
+        c1 = random_color(im, 130^R, 240^R);
+        error = gdImageStringFT(im, brect, c1, font, size, rotation, x, y, letter);
+        if (error)
+        {
+            fprintf(stderr, "%s, font is %s\n", error, font);
+            return 1;
+        }
+    }
+
+    // add the real text to it
+    len = strlen(phrase);
+    w1 = 10;
+    w2 = width / (height/4); // Change start, not appropriate for big fonts
+    x = w2;
+
+    for(p=0; p<len; p++)
+    {
+        letter[0] = phrase[p];
+        size = my_rand(height/4, height/3); // Change min/max font size
+        half = size / 2;
+        rotation = (double)my_rand(-33, 33)*rad;
+        y = my_rand(size+3, height-3);
+        /* x = w1 + w2*p; */
+        w1 += my_rand(-width/90, width/40);
+        r = my_rand(30, 99) ; g = my_rand(30, 99) ; b = my_rand(30, 99);
+        c1 = gdImageColorAllocate(im, r*1^R, g*1^R, b*1^R);
+        c2 = gdImageColorAllocate(im, r*2^R, g*2^R, b*2^R);
+        gdImageStringFT(im, brect, c2, font, size, rotation, x+1, y, letter);
+        gdImageStringFT(im, brect, c1, font, size, rotation, x, y-1, letter);
+        // Add another layer
+        gdImageStringFT(im, brect, c1, font, size, rotation, x+2, y+2, letter);
+        // Group letters
+        x += size;
+    }
+
+    FILE* f= fopen(out, "wb");
+    
+    if (!f)
+    {
+        fprintf(stderr, "Error opening %s\n", out);
+        return 1;
+    }
+
+    gdImagePng(im, f);
+    fclose(f);
+
+    gdImageDestroy(im);
+
+    return 0;
+}
+
+static void usage()
+{
+    printf("gcpatchaz is a command line captcha generator\n\n");
+    printf("usage : gcpatchaz [options]\n");
+    printf("\t-w WIDTH\n");
+    printf("\t-h HEIGHT\n");
+    printf("\t-o OUT.PNG\n");
+    printf("\t-f FONT\n");
+    printf("\t-s STRING\n");    
+    printf("\t-i : inverse\n");    
+    printf("\t-h : help\n");
+}
+
+int main(int argc, char** argv)
+{
+    int opt;
+    int width=180, height=40;
+    char* out = "captcha.png", *font = "ttf-japanese-gothic.ttf", *string = NULL;
+    int inverse= 0;
+    int i, res;
+
+    while ((opt = getopt(argc, argv, "w:H:o:f:s:ih")) != -1)
+    {
+        switch(opt)
+        {
+        case 'w': width = atoi(optarg); break;
+        case 'H': height = atoi(optarg); break;
+        case 'o': out = optarg; break;
+        case 'f': font = optarg; break;
+        case 's': string = strdup(optarg); break;
+        case 'i': inverse = 1; break;
+        case 'h':
+            usage();
+            return 0;
+        default:
+            usage();
+            return 1;
+        }
+    }
+
+    if (string == NULL)
+    {
+        string = malloc(6);
+        for(i=0; i<5; i++)
+        {
+            string[i] = my_rand(65, 90);
+        }
+        string[i] = 0;
+    }
+
+    res = generate_captcha(width, height, inverse, font, string, out);
+
+    if (res == 0)
+        printf("Captcha generated for text \"%s\"\n", string);
+
+    free(string);
+
+    return 0;
+}

generate_captcha.sh

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+#!/bin/bash
+
+#
+# Simple script to generate a captcha and rename it with
+# the captcha's value encrypted (AES 128) with a md5 of the AES key.
+# This allow to retrieve captcha's value only with its name
+# if you have the right AES key and also to use a passphrase.
+#
+# The script also contains a visual verification to avoid
+# generating hard to resolve captchas.
+#
+# Parameters :
+# generate_captcha.sh OUT_DIR PASSPHRASE
+#
+
+# Get parameters
+out=$1
+pass=$2
+do_check=1
+
+# Verify parameters
+[ -z "$out" ] && out="."
+[ -z "$pass" ] && pass="AAA"
+[ ! -e $out ] && mkdir $out
+
+# Generate captcha
+res=`./gcaptchaz -f ./scrawl.ttf -o "$out/captcha.png"`
+echo $res | grep "Captcha generated" > /dev/null
+if [ ! $? -eq 0 ] ; then
+    echo $res
+    exit 1
+fi
+
+text=`echo $res | cut -d\" -f2`
+
+# Do verification
+if [ $do_check -eq 1 ] ; then
+    emacs "$out/captcha.png"
+
+    echo -n "Enter CAPTCHA value : "
+    read user
+
+    if [ "$user" != "$text" ] ; then
+	echo "CAPTCHA failed"
+	rm -f "$out/captcha.png"
+	exit 1
+    fi
+
+    echo "CAPTCHA OK"
+fi
+
+# Encrypt captcha's value to generate captcha's name
+key=`echo -n $pass | md5sum | cut -d' ' -f1`
+enc=`echo -n $text | openssl enc -aes-128-ecb -nosalt -K $key -iv $key`
+enc=`echo -n $enc | hexdump -e '"%02x"'`
+mv "$out/captcha.png" "$out/$enc.png"