{"id":5798,"date":"2025-12-13T17:52:15","date_gmt":"2025-12-13T16:52:15","guid":{"rendered":"https:\/\/workboot.fr\/ciela\/?page_id=5798"},"modified":"2025-12-13T18:28:06","modified_gmt":"2025-12-13T17:28:06","slug":"hachage-hash","status":"publish","type":"page","link":"https:\/\/workboot.fr\/ciela\/hachage-hash\/","title":{"rendered":"Hash"},"content":{"rendered":"\n

D\u00e9finition :<\/h2>\n\n\n\n

Un hash, c’est une empreinte digitale num\u00e9rique unique et de taille fixe cr\u00e9\u00e9e \u00e0 partir de n’importe quelle donn\u00e9e, qui permet de l’identifier et de v\u00e9rifier qu’elle n’a pas \u00e9t\u00e9 modifi\u00e9e.<\/strong><\/p>\n\n\n\n

<\/p>\n\n\n\n

Un exemple de code pour comprendre la notion de hash !<\/p>\n\n\n\n

hash_simple.c<\/p>\n\n\n\n

#include <stdio.h>\n\n\/* Fonction hash tr\u00e8s simple *\/\nint hash_simple(char *mot) \n{\n    int code = 0;    \n    while (*mot != '\\0') {\n        code = code + *mot;  \/* Additionne les codes des lettres *\/\n        mot++;\n    }    \n    return code % 100;  \/* Garde juste 2 chiffres *\/\n}\n\nint main() \n{\n    printf(\"Hash de 'chat' : %d\\n\", hash_simple(\"chat\"));\n    printf(\"Hash de 'chien' : %d\\n\", hash_simple(\"chien\"));\n    printf(\"Hash de 'chat' \u00e0 nouveau : %d\\n\", hash_simple(\"chat\"));   \n    return EXIT_SUCCESS;\n}<\/pre>\n\n\n\n
Hash de 'chat' : 42\nHash de 'chien' : 57  \nHash de 'chat' \u00e0 nouveau : 42  \u2190 Toujours pareil!<\/code><\/pre>\n\n\n\n
Sous Linux il existe des outils de Hash puissant :<\/h2>\n\n\n\n
# 1. Cr\u00e9e un fichier\necho \"Mon premier hash\" > test.txt\n\n# 2. Vois son empreinte\nmd5sum test.txt\n\n# 3. Modifie-le un tout petit peu\necho \"Mon premier hash!\" > test.txt  # Ajout d'un '!'\n\n# 4. Vois comme l'empreinte change compl\u00e8tement!\nmd5sum test.txt<\/code><\/pre>\n\n\n\n
Sous linux le fichier shadow  utilise le hash<\/h2>\n\n\n\n
etudiant:$y$j9T$PyMT0isnkPIZyB6gthk9r0$cGTbYOHh61zf3sRMnese.IZC0c7v5CCZCPMj8fO4MB5:20280:<\/mark>0:99999:7:::<\/code><\/pre>\n\n\n\n
pour information le mot de passe ici est \u00ab\u00a0etudiant\u00a0\u00bb<\/p>\n\n\n\n
Champ par champ :<\/strong><\/h3>\n\n\n\n
    \n
  1. etudiant:<\/code><\/strong> \u2192 Nom d’utilisateur<\/li>\n\n\n\n
  2. $y$j9T$PyMT0isnkPIZyB6gthk9r0$cGTbYOHh61zf3sRMnese.IZC0c7v5CCZCPMj8fO4MB5<\/code><\/strong> \u2192 Hash du mot de passe (d\u00e9taill\u00e9 ci-dessous)<\/li>\n\n\n\n
  3. 20280<\/mark><\/code><\/strong> \u2192 Date du dernier changement (en jours depuis le 1er janvier 1970)<\/li>\n\n\n\n
  4. 0<\/code><\/strong> \u2192 \u00c2ge minimum avant changement (0 = peut changer imm\u00e9diatement)<\/li>\n\n\n\n
  5. 99999<\/code><\/strong> \u2192 \u00c2ge maximum avant expiration (99999 = jamais)<\/li>\n\n\n\n
  6. 7<\/code><\/strong> \u2192 P\u00e9riode d’avertissement avant expiration (7 jours)<\/li>\n\n\n\n
  7. :<\/code><\/strong> \u2192 P\u00e9riode de gr\u00e2ce apr\u00e8s expiration (vide = aucune)<\/li>\n\n\n\n
  8. :<\/code><\/strong> \u2192 Date d’expiration absolue (vide = jamais)<\/li>\n\n\n\n
  9. :<\/code><\/strong> \u2192 R\u00e9serv\u00e9 pour usage futur<\/li>\n<\/ol>\n\n\n\n
    Analyse du Hash<\/p>\n\n\n\n
    $y$j9T$PyMT0isnkPIZyB6gthk9r0$cGTbYOHh61zf3sRMnese.IZC0c7v5CCZCPMj8fO4MB5<\/code><\/pre>\n\n\n\n
    $y$ : est l\u2019algorithme utilis\u00e9. Algorithme yescrypt (moderne, s\u00e9curis\u00e9)\nj9T : Sel (salt). Salt (3 caract\u00e8res - la partie \"publique\" pour rendre le hash unique)\n$   : s\u00e9parateur\n\nPyMT0isnkPIZyB6gthk9r0 : Sel compl\u00e9t\u00e9 (22 caract\u00e8res en base64)\nGTbYOHh61zf3sRMnese.IZC0c7v5CCZCPMj8fO4MB5 : Hash r\u00e9el (43 caract\u00e8res)<\/code><\/pre>\n\n\n\n
    Tester un mot de passe avec ce hash<\/h2>\n\n\n\n
    apt install whois<\/code><\/pre>\n\n\n\n
    echo -n \"etudiant\" | mkpasswd --method=yescrypt --salt='$y$j9T$PyMT0isnkPIZyB6gthk9r0' --stdin | grep -q '\\$y\\$j9T\\$PyMT0isnkPIZyB6gthk9r0\\$cGTbYOHh61zf3sRMnese.IZC0c7v5CCZCPMj8fO4MB5' && echo \"OK\" || echo \"KO\"<\/code><\/pre>\n\n\n\n
    on test  le hash en une ligne .<\/h2>\n\n\n\n
    etudiant@ordi:~\/Works\/hash_salt\/bash$ echo -n \"etudiant<\/mark>\" | mkpasswd --method=yescrypt --salt='$y$j9T$PyMT0isnkPIZyB6gthk9r0' --stdin | grep -q '\\$y\\$j9T\\$PyMT0isnkPIZyB6gthk9r0\\$cGTbYOHh61zf3sRMnese.IZC0c7v5CCZCPMj8fO4MB5' && echo \"OK\" || echo \"KO\"\nOK<\/mark>\netudiant@ordi:~\/Works\/hash_salt\/bash$ echo -n \"etodiant<\/mark>\" | mkpasswd --method=yescrypt --salt='$y$j9T$PyMT0isnkPIZyB6gthk9r0' --stdin | grep -q '\\$y\\$j9T\\$PyMT0isnkPIZyB6gthk9r0\\$cGTbYOHh61zf3sRMnese.IZC0c7v5CCZCPMj8fO4MB5' && echo \"OK\" || echo \"KO\"\nKO<\/mark>\netudiant@ordi:~\/Works\/hash_salt\/bash$ \n<\/code><\/pre>\n\n\n\n
    un petit script shell:<\/h2>\n\n\n\n
    #!\/bin\/bash\necho \"=== V\u00e9rificateur de Hash Yescrypt ===\"\necho\n\n# Demander le mot de passe (ne s'affiche pas \u00e0 l'\u00e9cran)\nread -sp \"Entrez le mot de passe: \" password\necho\n\n# Hash connu de \/etc\/shadow\nknown_hash=\"\\$y\\$j9T\\$PyMT0isnkPIZyB6gthk9r0\\$cGTbYOHh61zf3sRMnese.IZC0c7v5CCZCPMj8fO4MB5\"\n\n# Extraire le sel du hash connu\nsalt=$(echo \"$known_hash\" | cut -d'$' -f1-4)\n\necho \"Sel extrait: $salt\"\necho\n\n# G\u00e9n\u00e9rer le hash avec le m\u00eame sel\nif command -v mkpasswd >\/dev\/null 2>&1; then\n    generated_hash=$(echo -n \"$password\" | mkpasswd --method=yescrypt --salt=\"$salt\" --stdin)\nelif command -v python3 >\/dev\/null 2>&1; then\n    generated_hash=$(python3 -c \"import crypt; print(crypt.crypt('$password', '$salt'))\")\nelse\n    echo \"Erreur: ni mkpasswd ni python3 n'est install\u00e9\"\n    exit 1\nfi\n\necho \"Hash g\u00e9n\u00e9r\u00e9: $generated_hash\"\necho \"Hash connu:   $known_hash\"\necho\n\n# Comparaison\nif [ \"$generated_hash\" = \"$known_hash\" ]; then\n    echo \"\u2705 SUCC\u00c8S : Les hashs correspondent !\"\nelse\n    echo \"\u274c \u00c9CHEC : Les hashs sont diff\u00e9rents\"\n    echo \"Soit le mot de passe est incorrect, soit il y a un probl\u00e8me de sel\"\nfi\n<\/pre>\n\n\n\n
    etudiant@ordi:~\/Works\/hash_salt\/bash$ .\/test_hash.sh \n=== V\u00e9rificateur de Hash Yescrypt ===\n\nEntrez le mot de passe: \nSel extrait: $y$j9T$PyMT0isnkPIZyB6gthk9r0\n\nHash g\u00e9n\u00e9r\u00e9: $y$j9T$PyMT0isnkPIZyB6gthk9r0$cGTbYOHh61zf3sRMnese.IZC0c7v5CCZCPMj8fO4MB5\nHash connu:   $y$j9T$PyMT0isnkPIZyB6gthk9r0$cGTbYOHh61zf3sRMnese.IZC0c7v5CCZCPMj8fO4MB5\n\n\u2705 SUCC\u00c8S : Les hashs correspondent !\netudiant@ordi:~\/Works\/hash_salt\/bash$ \n\n<\/code><\/pre>\n\n\n\n
    <\/p>\n","protected":false},"excerpt":{"rendered":"
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