feat(auth): politique de complexite du mot de passe et flux de reinitialisation

Remplace la regle de longueur seule (12 caracteres) par une exigence de
composition (8 caracteres minimum, majuscule, minuscule, chiffre, caractere
special), non documentee dans les exigences officielles du projet, par une
regle explicite partagee entre le backend (validateur Pydantic) et le
frontend.

Ajoute un flux "mot de passe oublie" en libre-service, absent jusqu'ici :
jeton a usage unique hache en base (meme principe que les refresh tokens),
expirant a 15 minutes, envoye par email via un service SMTP (aiosmtplib,
Mailpit en dev), avec limitation de debit dediee et reponse generique pour
eviter l'enumeration des comptes.

Closes #87

apps/backend/app/api/deps.py

@@ -16,6 +16,7 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.config import Settings, get_settings
 from app.core.hashing import Argon2Hasher, build_hasher
+from app.core.mailer import Mailer, SmtpConfig
 from app.core.principal import Principal
 from app.core.roles import AccountKind, Role, has_at_least
 from app.core.security import TokenExpiredError, TokenInvalidError, TokenPolicy
@@ -24,13 +25,15 @@ from app.db.session import get_session
 from app.repositories.alert import AlertRepository
 from app.repositories.audit_log import AuditLogRepository
 from app.repositories.login_attempt import LoginAttemptRepository
+from app.repositories.password_reset_attempt import PasswordResetAttemptRepository
+from app.repositories.password_reset_token import PasswordResetTokenRepository
 from app.repositories.reading import ReadingRepository
 from app.repositories.recommendation import RecommendationRepository
 from app.repositories.refresh_token import RefreshTokenRepository
 from app.repositories.site import SiteRepository
 from app.repositories.user import UserRepository
 from app.services.alert import AlertService
-from app.services.auth import AuthService, LoginPolicy
+from app.services.auth import AuthService, LoginPolicy, PasswordResetPolicy
 from app.services.recommendation import RecommendationService
 from app.services.sensor import SensorService
 from app.services.site import SiteService
@@ -97,11 +100,27 @@ def get_client_ip(request: Request, settings: SettingsDep) -> str | None:
     return request.client.host if request.client else None
 
 
+def get_mailer(settings: SettingsDep) -> Mailer:
+    return Mailer(
+        SmtpConfig(
+            host=settings.smtp_host,
+            port=settings.smtp_port,
+            username=settings.smtp_username,
+            password=(
+                settings.smtp_password.get_secret_value() if settings.smtp_password else None
+            ),
+            use_tls=settings.smtp_use_tls,
+            from_address=settings.smtp_from_address,
+        )
+    )
+
+
 def get_auth_service(
     session: SessionDep,
     settings: SettingsDep,
     hasher: Annotated[Argon2Hasher, Depends(get_hasher)],
     token_policy: Annotated[TokenPolicy, Depends(get_token_policy)],
+    mailer: Annotated[Mailer, Depends(get_mailer)],
 ) -> AuthService:
     return AuthService(
         users=UserRepository(session),
@@ -118,6 +137,16 @@ def get_auth_service(
             max_failures_per_identifier=settings.login_max_failures_per_identifier,
         ),
         refresh_ttl=timedelta(seconds=settings.refresh_token_ttl_seconds),
+        reset_tokens=PasswordResetTokenRepository(session),
+        reset_attempts=PasswordResetAttemptRepository(session),
+        reset_policy=PasswordResetPolicy(
+            window_seconds=settings.password_reset_window_seconds,
+            max_requests_per_identifier=settings.password_reset_max_requests_per_identifier,
+            max_requests_per_ip=settings.password_reset_max_requests_per_ip,
+            token_ttl=timedelta(seconds=settings.password_reset_ttl_seconds),
+            frontend_reset_url=settings.frontend_reset_password_url,
+        ),
+        mailer=mailer,
     )
 
 

apps/backend/app/api/openapi.py

@@ -156,3 +156,16 @@ REPONSE_ORIGINE_REFUSEE: Final[Reponses] = {
         "description": "Origine non autorisée (protection CSRF de `require_trusted_origin`).",
     },
 }
+
+REPONSE_LIMITE: Final[Reponses] = {
+    429: {
+        "model": ErrorResponse,
+        "description": "Trop de demandes sur cette fenêtre glissante.",
+        "headers": {
+            "Retry-After": {
+                "description": "Secondes à attendre avant une nouvelle tentative.",
+                "schema": {"type": "integer"},
+            }
+        },
+    },
+}

apps/backend/app/api/v1/endpoints/auth.py

@@ -12,6 +12,7 @@ from app.api.deps import (
     require_trusted_origin,
 )
 from app.api.openapi import (
+    REPONSE_LIMITE,
     REPONSE_ORIGINE_REFUSEE,
     REPONSE_VALIDATION,
     REPONSES_AUTHENTIFIEES,
@@ -21,15 +22,18 @@ from app.api.openapi import (
 from app.core.cookies import RefreshCookie, cookie_name
 from app.core.logging import get_logger
 from app.schemas.auth import (
+    ForgotPasswordRequest,
     LoginRequest,
     PasswordChangeRequest,
     PrincipalResponse,
+    ResetPasswordRequest,
     TokenResponse,
 )
 from app.schemas.errors import ErrorResponse
 from app.services.auth import (
     AuthenticatedSession,
     InvalidCredentialsError,
+    InvalidOrExpiredResetTokenError,
     RateLimitedError,
     SessionRejectedError,
 )
@@ -39,6 +43,7 @@ logger = get_logger(__name__)
 
 DETAIL_IDENTIFIANTS = "Identifiants invalides"
 DETAIL_SESSION = "Session invalide"
+DETAIL_LIEN_RESET = "Lien invalide ou expiré"
 
 REPONSES_LOGIN: Reponses = {
     **REPONSE_VALIDATION,
@@ -85,6 +90,20 @@ REPONSES_MOT_DE_PASSE: Reponses = {
     },
 }
 
+REPONSES_FORGOT_PASSWORD: Reponses = {
+    **REPONSE_VALIDATION,
+    **REPONSE_LIMITE,
+}
+
+REPONSES_RESET_PASSWORD: Reponses = {
+    **REPONSE_VALIDATION,
+    **REPONSE_ORIGINE_REFUSEE,
+    400: {
+        "model": ErrorResponse,
+        "description": "Lien invalide, déjà utilisé, ou expiré (durée de vie : 15 minutes).",
+    },
+}
+
 
 def repond(
     response: Response, settings: SettingsDep, session: AuthenticatedSession
@@ -267,3 +286,67 @@ async def change_password(
 
     logger.info("auth.password_changed user_id=%s", principal.id)
     return repond(response, settings, session)
+
+
+@router.post(
+    "/forgot-password",
+    status_code=status.HTTP_202_ACCEPTED,
+    summary="Demande un lien de réinitialisation par email",
+    responses=REPONSES_FORGOT_PASSWORD,
+)
+async def forgot_password(
+    payload: ForgotPasswordRequest,
+    request: Request,
+    response: Response,
+    service: AuthServiceDep,
+    client_ip: str | None = Depends(get_client_ip),
+) -> None:
+    response.headers["Cache-Control"] = "no-store"
+
+    try:
+        await service.request_password_reset(
+            email=payload.email,
+            client_ip=client_ip,
+            user_agent=request.headers.get("user-agent"),
+        )
+    except RateLimitedError as erreur:
+        logger.warning("auth.password_reset.rate_limited ip=%s", client_ip)
+        raise HTTPException(
+            status_code=status.HTTP_429_TOO_MANY_REQUESTS,
+            detail="Trop de demandes, réessayez plus tard",
+            headers={"Retry-After": str(erreur.retry_after)},
+        ) from erreur
+
+
+@router.post(
+    "/reset-password",
+    response_model=TokenResponse,
+    summary="Choisit un nouveau mot de passe depuis un lien reçu par email",
+    dependencies=[Depends(require_trusted_origin)],
+    responses=REPONSES_RESET_PASSWORD,
+)
+async def reset_password(
+    payload: ResetPasswordRequest,
+    request: Request,
+    response: Response,
+    settings: SettingsDep,
+    service: AuthServiceDep,
+    client_ip: str | None = Depends(get_client_ip),
+) -> TokenResponse:
+    response.headers["Cache-Control"] = "no-store"
+
+    try:
+        session = await service.confirm_password_reset(
+            token=payload.token,
+            new_password=payload.new_password,
+            client_ip=client_ip,
+            user_agent=request.headers.get("user-agent"),
+        )
+    except InvalidOrExpiredResetTokenError as erreur:
+        logger.warning("auth.password_reset.invalid_token ip=%s", client_ip)
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST, detail=DETAIL_LIEN_RESET
+        ) from erreur
+
+    logger.info("auth.password_reset.success user_id=%s", session.principal.id)
+    return repond(response, settings, session)

apps/backend/app/cli.py

@@ -9,6 +9,7 @@ import argparse
 import asyncio
 import json
 import secrets
+import string
 import sys
 from getpass import getpass
 from pathlib import Path
@@ -22,9 +23,10 @@ from app.core.roles import Role
 from app.db.session import get_session_factory
 from app.main import create_app
 from app.repositories.user import UserRepository
+from app.schemas.auth import PASSWORD_MIN_LENGTH, valide_complexite
 
 LONGUEUR_MOT_DE_PASSE_GENERE = 24
-LONGUEUR_MINIMALE = 12
+CARACTERES_SPECIAUX = "!@#$%^&*()-_=+[]{};:,.?"
 CHEMIN_CONTRAT = Path(__file__).resolve().parent.parent / "openapi.json"
 
 
@@ -111,15 +113,36 @@ def build_parser() -> argparse.ArgumentParser:
     return parser
 
 
+def genere_mot_de_passe() -> str:
+    tirage = secrets.SystemRandom()
+    classes = [
+        string.ascii_uppercase,
+        string.ascii_lowercase,
+        string.digits,
+        CARACTERES_SPECIAUX,
+    ]
+    reste = LONGUEUR_MOT_DE_PASSE_GENERE - len(classes)
+    caracteres = [tirage.choice(classe) for classe in classes]
+    caracteres += [tirage.choice("".join(classes)) for _ in range(reste)]
+    tirage.shuffle(caracteres)
+    return "".join(caracteres)
+
+
 def read_password(*, generate: bool) -> str:
     if generate:
-        mot_de_passe = secrets.token_urlsafe(LONGUEUR_MOT_DE_PASSE_GENERE)
+        mot_de_passe = genere_mot_de_passe()
         print(f"Mot de passe généré, il ne sera plus affiché : {mot_de_passe}")
         return mot_de_passe
 
     mot_de_passe = getpass("Mot de passe : ")
-    if len(mot_de_passe) < LONGUEUR_MINIMALE:
-        raise SystemExit(f"Le mot de passe doit faire au moins {LONGUEUR_MINIMALE} caractères")
+    if len(mot_de_passe) < PASSWORD_MIN_LENGTH:
+        raise SystemExit(
+            f"Le mot de passe doit faire au moins {PASSWORD_MIN_LENGTH} caractères"
+        )
+    try:
+        valide_complexite(mot_de_passe)
+    except ValueError as erreur:
+        raise SystemExit(str(erreur)) from erreur
     if mot_de_passe != getpass("Confirmation : "):
         raise SystemExit("Les deux saisies diffèrent")
     return mot_de_passe

apps/backend/app/core/config.py

@@ -54,6 +54,19 @@ class Settings(BaseSettings):
     login_max_failures_per_ip: int = Field(default=20, ge=1)
     login_max_failures_per_identifier: int = Field(default=50, ge=1)
 
+    password_reset_ttl_seconds: int = Field(default=900, ge=60, le=3600)
+    password_reset_window_seconds: int = Field(default=900, ge=60)
+    password_reset_max_requests_per_identifier: int = Field(default=3, ge=1)
+    password_reset_max_requests_per_ip: int = Field(default=10, ge=1)
+
+    smtp_host: str = "localhost"
+    smtp_port: int = Field(default=587, ge=1, le=65535)
+    smtp_username: str | None = None
+    smtp_password: SecretStr | None = None
+    smtp_use_tls: bool = False
+    smtp_from_address: str = "no-reply@enervision.fr"
+    frontend_reset_password_url: str = "http://localhost:4200/reset-password"  # noqa: S105
+
     trust_proxy_headers: bool = False
     expose_api_docs: bool | None = None
     metrics_token: SecretStr | None = None

apps/backend/app/core/mailer.py

@@ -0,0 +1,48 @@
+# Piège : l'URL de réinitialisation porte le jeton en clair. Ne jamais la journaliser :
+# `send_password_reset_email()` ne logue que le destinataire, jamais `reset_url`.
+
+from dataclasses import dataclass
+from email.message import EmailMessage
+
+import aiosmtplib
+
+from app.core.logging import get_logger
+
+logger = get_logger(__name__)
+
+
+@dataclass(frozen=True, slots=True)
+class SmtpConfig:
+    host: str
+    port: int
+    username: str | None
+    password: str | None
+    use_tls: bool
+    from_address: str
+
+
+class Mailer:
+    def __init__(self, config: SmtpConfig) -> None:
+        self._config = config
+
+    async def send_password_reset_email(self, *, to: str, reset_url: str) -> None:
+        message = EmailMessage()
+        message["From"] = self._config.from_address
+        message["To"] = to
+        message["Subject"] = "Réinitialisation de votre mot de passe EnerVision"
+        message.set_content(
+            "Une réinitialisation de mot de passe a été demandée pour ce compte.\n\n"
+            f"Ouvrez ce lien dans les 15 minutes pour choisir un nouveau mot de passe : "
+            f"{reset_url}\n\n"
+            "Si vous n'êtes pas à l'origine de cette demande, ignorez cet email."
+        )
+
+        _, message_recu = await aiosmtplib.send(
+            message,
+            hostname=self._config.host,
+            port=self._config.port,
+            username=self._config.username,
+            password=self._config.password,
+            use_tls=self._config.use_tls,
+        )
+        logger.info("mailer.password_reset_sent to=%s smtp_response=%s", to, message_recu)

apps/backend/app/models/__init__.py

@@ -4,6 +4,8 @@
 from app.models.audit_log import AuditLog
 from app.models.energy import Alert, Dataset, Prediction, Reading, Recommendation, Site
 from app.models.login_attempt import LoginAttempt
+from app.models.password_reset_attempt import PasswordResetAttempt
+from app.models.password_reset_token import PasswordResetToken
 from app.models.refresh_token import RefreshToken
 from app.models.user import AppUser
 
@@ -13,6 +15,8 @@ __all__ = [
     "AuditLog",
     "Dataset",
     "LoginAttempt",
+    "PasswordResetAttempt",
+    "PasswordResetToken",
     "Prediction",
     "Reading",
     "Recommendation",

apps/backend/app/models/audit_log.py

@@ -29,6 +29,8 @@ class AuditAction(StrEnum):
     COMPTE_ACTIVE = "user.enabled"
     COMPTE_MOT_DE_PASSE_REINITIALISE = "user.password_reset_by_admin"
     COMPTE_MOT_DE_PASSE_CHANGE = "user.password_changed"
+    MOT_DE_PASSE_OUBLIE_DEMANDE = "auth.password_reset_requested"
+    MOT_DE_PASSE_REINITIALISE_PAR_SOI = "auth.password_reset_self_service"
     REFRESH_REUTILISE = "auth.refresh_reuse_detected"
     SESSIONS_REVOQUEES = "auth.all_sessions_revoked"
     LIMITE_PAR_IDENTIFIANT = "auth.identifier_throttled"

apps/backend/app/models/password_reset_attempt.py

@@ -0,0 +1,27 @@
+# Pourquoi : même séparation que `login_attempt` par rapport à `audit_log` : ce compteur est
+# piloté par l'attaquant (une campagne de demandes) et se purge, l'audit log est en ajout seul.
+# Piège : la tentative est enregistrée même quand l'email est inconnu, sinon le 429 apprendrait
+# qu'un compte existe.
+
+from datetime import datetime
+
+from sqlalchemy import BigInteger, DateTime, Identity, Index, String, func
+from sqlalchemy.dialects.postgresql import INET
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db.base import Base
+
+
+class PasswordResetAttempt(Base):
+    __tablename__ = "password_reset_attempt"
+    __table_args__ = (
+        Index("ix_password_reset_attempt_email_date", "email_tried", "occurred_at"),
+        Index("ix_password_reset_attempt_ip_date", "client_ip", "occurred_at"),
+    )
+
+    id: Mapped[int] = mapped_column(BigInteger, Identity(always=True), primary_key=True)
+    occurred_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now()
+    )
+    email_tried: Mapped[str] = mapped_column(String(320), nullable=False)
+    client_ip: Mapped[str | None] = mapped_column(INET, nullable=True)

apps/backend/app/models/password_reset_token.py

@@ -0,0 +1,40 @@
+# Pourquoi : même schéma que `refresh_token` (chaîne opaque, jamais un JWT) pour la même
+# raison : un jeton de réinitialisation doit être révocable d'un coup, et un JWT ne figure
+# dans aucune ligne à invalider.
+
+import uuid
+from datetime import datetime
+
+from sqlalchemy import DateTime, ForeignKey, Index, LargeBinary, Text, func
+from sqlalchemy.dialects.postgresql import INET
+from sqlalchemy.dialects.postgresql import UUID as PG_UUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db.base import Base
+
+
+class PasswordResetToken(Base):
+    __tablename__ = "password_reset_token"
+    __table_args__ = (
+        Index("ix_password_reset_token_user", "user_id"),
+        Index(
+            "ix_password_reset_token_vivants",
+            "user_id",
+            postgresql_where="consumed_at is null",
+        ),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PG_UUID(as_uuid=True), primary_key=True, server_default=func.gen_random_uuid()
+    )
+    user_id: Mapped[uuid.UUID] = mapped_column(
+        PG_UUID(as_uuid=True), ForeignKey("app_user.id", ondelete="CASCADE"), nullable=False
+    )
+    token_hash: Mapped[bytes] = mapped_column(LargeBinary, nullable=False, unique=True)
+    issued_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now()
+    )
+    expires_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
+    consumed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    client_ip: Mapped[str | None] = mapped_column(INET, nullable=True)
+    user_agent: Mapped[str | None] = mapped_column(Text, nullable=True)

apps/backend/app/repositories/password_reset_attempt.py

@@ -0,0 +1,42 @@
+from dataclasses import dataclass
+from datetime import UTC, datetime, timedelta
+
+from sqlalchemy import func, select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.password_reset_attempt import PasswordResetAttempt
+
+
+@dataclass(frozen=True, slots=True)
+class ResetRequestCounts:
+    per_identifier: int
+    per_ip: int
+
+
+class PasswordResetAttemptRepository:
+    def __init__(self, session: AsyncSession) -> None:
+        self._session = session
+
+    async def record(self, *, email: str, client_ip: str | None) -> None:
+        self._session.add(
+            PasswordResetAttempt(email_tried=email.strip().lower(), client_ip=client_ip)
+        )
+
+    async def count_recent(
+        self, *, email: str, client_ip: str | None, window_seconds: int
+    ) -> ResetRequestCounts:
+        identifiant = email.strip().lower()
+        meme_email = PasswordResetAttempt.email_tried == identifiant
+        meme_ip = PasswordResetAttempt.client_ip == client_ip
+
+        requete = select(
+            func.count().filter(meme_email),
+            func.count().filter(meme_ip),
+        ).where(
+            PasswordResetAttempt.occurred_at
+            > datetime.now(UTC) - timedelta(seconds=window_seconds),
+            meme_email | meme_ip,
+        )
+
+        par_identifiant, par_ip = (await self._session.execute(requete)).one()
+        return ResetRequestCounts(per_identifier=par_identifiant, per_ip=par_ip)

apps/backend/app/repositories/password_reset_token.py

@@ -0,0 +1,68 @@
+# Piège : `consume()` est une seule instruction, sur le modèle de `claim_for_rotation()` du
+# jeton de rafraîchissement. Un SELECT puis un UPDATE laisseraient une fenêtre où deux
+# soumissions concurrentes du même lien réussiraient toutes les deux.
+
+from dataclasses import dataclass
+from datetime import datetime
+from uuid import UUID
+
+from sqlalchemy import func, update
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.password_reset_token import PasswordResetToken
+
+
+@dataclass(frozen=True, slots=True)
+class ConsumedResetToken:
+    id: UUID
+    user_id: UUID
+
+
+class PasswordResetTokenRepository:
+    def __init__(self, session: AsyncSession) -> None:
+        self._session = session
+
+    async def create(
+        self,
+        *,
+        user_id: UUID,
+        token_hash: bytes,
+        expires_at: datetime,
+        client_ip: str | None,
+        user_agent: str | None,
+    ) -> PasswordResetToken:
+        jeton = PasswordResetToken(
+            user_id=user_id,
+            token_hash=token_hash,
+            expires_at=expires_at,
+            client_ip=client_ip,
+            user_agent=user_agent,
+        )
+        self._session.add(jeton)
+        await self._session.flush()
+        return jeton
+
+    async def consume(self, token_hash: bytes) -> ConsumedResetToken | None:
+        requete = (
+            update(PasswordResetToken)
+            .where(
+                PasswordResetToken.token_hash == token_hash,
+                PasswordResetToken.consumed_at.is_(None),
+                PasswordResetToken.expires_at > func.clock_timestamp(),
+            )
+            .values(consumed_at=func.clock_timestamp())
+            .returning(PasswordResetToken.id, PasswordResetToken.user_id)
+        )
+        ligne = (await self._session.execute(requete)).one_or_none()
+        if ligne is None:
+            return None
+        return ConsumedResetToken(id=ligne.id, user_id=ligne.user_id)
+
+    async def invalidate_all_for_user(self, user_id: UUID) -> int:
+        resultat = await self._session.execute(
+            update(PasswordResetToken)
+            .where(PasswordResetToken.user_id == user_id, PasswordResetToken.consumed_at.is_(None))
+            .values(consumed_at=func.clock_timestamp())
+            .returning(PasswordResetToken.id)
+        )
+        return len(resultat.all())

apps/backend/app/schemas/auth.py

@@ -1,17 +1,39 @@
 # Contrainte : le mot de passe est borné à 128 caractères. Sans plafond, une chaîne de dix
 # mégaoctets ferait travailler Argon2 gratuitement, à la charge du serveur.
 
+import re
 from typing import Literal, Self
 from uuid import UUID
 
-from pydantic import BaseModel, ConfigDict, EmailStr, Field
+from pydantic import BaseModel, ConfigDict, EmailStr, Field, field_validator
 
 from app.core.principal import Principal
 from app.core.roles import AccountKind, Role
 
-PASSWORD_MIN_LENGTH = 12
+PASSWORD_MIN_LENGTH = 8
 PASSWORD_MAX_LENGTH = 128
 
+_MAJUSCULE = re.compile(r"[A-ZÀ-Ý]")
+_MINUSCULE = re.compile(r"[a-zà-ÿ]")
+_CHIFFRE = re.compile(r"\d")
+_SPECIAL = re.compile(r"[^\w\s]")
+
+
+def valide_complexite(mot_de_passe: str) -> str:
+    manquants = [
+        nom
+        for nom, motif in (
+            ("une majuscule", _MAJUSCULE),
+            ("une minuscule", _MINUSCULE),
+            ("un chiffre", _CHIFFRE),
+            ("un caractère spécial", _SPECIAL),
+        )
+        if not motif.search(mot_de_passe)
+    ]
+    if manquants:
+        raise ValueError(f"Le mot de passe doit contenir au moins {', '.join(manquants)}")
+    return mot_de_passe
+
 
 class LoginRequest(BaseModel):
     email: EmailStr
@@ -22,6 +44,25 @@ class PasswordChangeRequest(BaseModel):
     current_password: str = Field(min_length=1, max_length=PASSWORD_MAX_LENGTH)
     new_password: str = Field(min_length=PASSWORD_MIN_LENGTH, max_length=PASSWORD_MAX_LENGTH)
 
+    @field_validator("new_password")
+    @classmethod
+    def _new_password_est_complexe(cls, valeur: str) -> str:
+        return valide_complexite(valeur)
+
+
+class ForgotPasswordRequest(BaseModel):
+    email: EmailStr
+
+
+class ResetPasswordRequest(BaseModel):
+    token: str = Field(min_length=1)
+    new_password: str = Field(min_length=PASSWORD_MIN_LENGTH, max_length=PASSWORD_MAX_LENGTH)
+
+    @field_validator("new_password")
+    @classmethod
+    def _new_password_est_complexe(cls, valeur: str) -> str:
+        return valide_complexite(valeur)
+
 
 class PrincipalResponse(BaseModel):
     model_config = ConfigDict(from_attributes=True)

apps/backend/app/services/auth.py

@@ -15,6 +15,7 @@ from typing import NoReturn, Protocol
 from uuid import UUID, uuid4
 
 from app.core.hashing import Argon2Hasher
+from app.core.mailer import Mailer
 from app.core.principal import Principal
 from app.core.roles import AccountKind, Role
 from app.core.security import (
@@ -28,6 +29,8 @@ from app.models.login_attempt import LoginOutcome
 from app.models.refresh_token import RevocationReason
 from app.repositories.audit_log import AuditLogRepository
 from app.repositories.login_attempt import LoginAttemptRepository
+from app.repositories.password_reset_attempt import PasswordResetAttemptRepository
+from app.repositories.password_reset_token import PasswordResetTokenRepository
 from app.repositories.refresh_token import RefreshTokenRepository
 from app.repositories.user import UserRepository
 
@@ -54,6 +57,10 @@ class RateLimitedError(AuthError):
         self.retry_after = retry_after
 
 
+class InvalidOrExpiredResetTokenError(AuthError):
+    pass
+
+
 @dataclass(frozen=True, slots=True)
 class LoginPolicy:
     window_seconds: int
@@ -62,6 +69,15 @@ class LoginPolicy:
     max_failures_per_identifier: int
 
 
+@dataclass(frozen=True, slots=True)
+class PasswordResetPolicy:
+    window_seconds: int
+    max_requests_per_identifier: int
+    max_requests_per_ip: int
+    token_ttl: timedelta
+    frontend_reset_url: str
+
+
 @dataclass(frozen=True, slots=True)
 class AuthenticatedSession:
     principal: Principal
@@ -83,6 +99,10 @@ class AuthService:
         token_policy: TokenPolicy,
         login_policy: LoginPolicy,
         refresh_ttl: timedelta,
+        reset_tokens: PasswordResetTokenRepository,
+        reset_attempts: PasswordResetAttemptRepository,
+        reset_policy: PasswordResetPolicy,
+        mailer: Mailer,
     ) -> None:
         self._users = users
         self._attempts = attempts
@@ -93,6 +113,10 @@ class AuthService:
         self._token_policy = token_policy
         self._login_policy = login_policy
         self._refresh_ttl = refresh_ttl
+        self._reset_tokens = reset_tokens
+        self._reset_attempts = reset_attempts
+        self._reset_policy = reset_policy
+        self._mailer = mailer
 
     async def authenticate(
         self, *, email: str, password: str, client_ip: str | None, user_agent: str | None
@@ -200,6 +224,75 @@ class AuthService:
         rafraichi = await self._users.get_by_id(principal.id)
         return self._session(self._en_principal(rafraichi or compte), secret)
 
+    async def request_password_reset(
+        self, *, email: str, client_ip: str | None, user_agent: str | None
+    ) -> None:
+        await self._refuse_si_limite_reset(email=email, client_ip=client_ip)
+
+        compte = await self._users.get_by_email(email)
+        # Piège : le hachage factice équilibre le temps de réponse sur un compte inconnu, comme
+        # `authenticate()`. La réponse et sa forme restent identiques dans tous les cas : compte
+        # inconnu, compte inactif, ou email envoyé avec succès.
+        if compte is None or not compte.is_active or compte.kind != AccountKind.HUMAIN.value:
+            await self._hasher.verify_dummy()
+            await self._reset_attempts.record(email=email, client_ip=client_ip)
+            await self._transaction.commit()
+            return
+
+        await self._reset_tokens.invalidate_all_for_user(compte.id)
+        secret = generate_refresh_secret()
+        await self._reset_tokens.create(
+            user_id=compte.id,
+            token_hash=fingerprint_refresh(secret),
+            expires_at=datetime.now(UTC) + self._reset_policy.token_ttl,
+            client_ip=client_ip,
+            user_agent=user_agent,
+        )
+        await self._reset_attempts.record(email=email, client_ip=client_ip)
+        await self._audit.record(
+            action=AuditAction.MOT_DE_PASSE_OUBLIE_DEMANDE,
+            actor_label=compte.email,
+            target_type="app_user",
+            target_id=str(compte.id),
+            client_ip=client_ip,
+            user_agent=user_agent,
+        )
+        await self._transaction.commit()
+
+        lien = f"{self._reset_policy.frontend_reset_url}?token={secret}"
+        await self._mailer.send_password_reset_email(to=compte.email, reset_url=lien)
+
+    async def confirm_password_reset(
+        self, *, token: str, new_password: str, client_ip: str | None, user_agent: str | None
+    ) -> AuthenticatedSession:
+        revendique = await self._reset_tokens.consume(fingerprint_refresh(token))
+        if revendique is None:
+            raise InvalidOrExpiredResetTokenError("Lien invalide ou expiré")
+
+        await self._users.update_password(
+            revendique.user_id, await self._hasher.hash(new_password), must_change_password=False
+        )
+        revoquees = await self._refresh.revoke_all_for_user(
+            revendique.user_id, RevocationReason.CHANGEMENT_MOT_DE_PASSE
+        )
+        secret = await self._ouvre_une_famille(
+            user_id=revendique.user_id, client_ip=client_ip, user_agent=user_agent
+        )
+        await self._audit.record(
+            action=AuditAction.MOT_DE_PASSE_REINITIALISE_PAR_SOI,
+            target_type="app_user",
+            target_id=str(revendique.user_id),
+            client_ip=client_ip,
+            user_agent=user_agent,
+            detail={"sessions_revoquees": revoquees},
+        )
+        await self._transaction.commit()
+
+        compte = await self._users.get_by_id(revendique.user_id)
+        if compte is None:
+            raise SessionRejectedError("Compte introuvable")
+        return self._session(self._en_principal(compte), secret)
+
     async def logout_all(self, principal: Principal) -> int:
         revoquees = await self._refresh.revoke_all_for_user(
             principal.id, RevocationReason.DECONNEXION
@@ -307,6 +400,23 @@ class AuthService:
         await self._transaction.commit()
         raise RateLimitedError(politique.window_seconds)
 
+    async def _refuse_si_limite_reset(self, *, email: str, client_ip: str | None) -> None:
+        politique = self._reset_policy
+        compteurs = await self._reset_attempts.count_recent(
+            email=email, client_ip=client_ip, window_seconds=politique.window_seconds
+        )
+
+        depasse = (
+            compteurs.per_identifier >= politique.max_requests_per_identifier
+            or compteurs.per_ip >= politique.max_requests_per_ip
+        )
+        if not depasse:
+            return
+
+        await self._reset_attempts.record(email=email, client_ip=client_ip)
+        await self._transaction.commit()
+        raise RateLimitedError(politique.window_seconds)
+
     async def _echoue(
         self,
         email: str,