使用密码（及哈希）的 OAuth2，基于 JWT 的 Bearer 令牌¶
🌐 Translation by AI and humans
This translation was made by AI guided by humans. 🤝
It could have mistakes of misunderstanding the original meaning, or looking unnatural, etc. 🤖
You can improve this translation by helping us guide the AI LLM better.
现在我们已经有了完整的安全流程，接下来用 JWT 令牌和安全的密码哈希，让应用真正安全起来。
这些代码可以直接用于你的应用，你可以把密码哈希保存到数据库中，等等。
我们将从上一章结束的地方继续，逐步完善。
关于 JWT¶
JWT 意为 “JSON Web Tokens”。
它是一种标准，把一个 JSON 对象编码成没有空格、很密集的一长串字符串。看起来像这样：
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c
它不是加密的，所以任何人都可以从内容中恢复信息。
但它是“签名”的。因此，当你收到一个自己签发的令牌时，你可以验证它确实是你签发的。
这样你就可以创建一个例如有效期为 1 周的令牌。然后当用户第二天带着这个令牌回来时，你能知道该用户仍然处于登录状态。
一周后令牌过期，用户将不再被授权，需要重新登录以获取新令牌。而如果用户（或第三方）尝试修改令牌来更改过期时间，你也能发现，因为签名将不匹配。
如果你想动手体验 JWT 令牌并了解它的工作方式，请访问 https://jwt.io。
安装 PyJWT¶
我们需要安装 PyJWT，以便在 Python 中生成和校验 JWT 令牌。
请确保创建并激活一个虚拟环境，然后安装 pyjwt：
$ pip install pyjwt
---> 100%
密码哈希¶
“哈希”是指把一些内容（这里是密码）转换成看起来像乱码的一串字节（其实就是字符串）。
当你每次传入完全相同的内容（完全相同的密码）时，都会得到完全相同的“乱码”。
但你无法从这个“乱码”反向还原出密码。
为什么使用密码哈希¶
如果你的数据库被盗，窃贼拿到的不会是用户的明文密码，而只是哈希值。
因此，窃贼无法把该密码拿去尝试登录另一个系统（很多用户在各处都用相同的密码，这将非常危险）。
安装 pwdlib¶
pwdlib 是一个用于处理密码哈希的优秀 Python 包。
它支持多种安全的哈希算法以及相关工具。
推荐的算法是 “Argon2”。
请确保创建并激活一个虚拟环境，然后安装带 Argon2 的 pwdlib：
$ pip install "pwdlib[argon2]"
---> 100%
提示
使用 pwdlib，你甚至可以把它配置为能够读取由 Django、Flask 安全插件或其他许多工具创建的密码。
例如，你可以在数据库中让一个 Django 应用和一个 FastAPI 应用共享同一份数据。或者在使用同一个数据库的前提下，逐步迁移一个 Django 应用到 FastAPI。
同时，你的用户既可以从 Django 应用登录，也可以从 FastAPI 应用登录。
哈希并校验密码¶
从 pwdlib 导入所需工具。
用推荐设置创建一个 PasswordHash 实例——它将用于哈希与校验密码。
提示
pwdlib 也支持 bcrypt 哈希算法，但不包含遗留算法——如果需要处理过时的哈希，建议使用 passlib 库。
例如，你可以用它读取并校验其他系统（如 Django）生成的密码，但对任何新密码使用不同的算法（如 Argon2 或 Bcrypt）进行哈希。
并且能够同时与它们全部兼容。
创建一个工具函数来哈希用户传入的密码。
再创建一个工具函数来校验接收的密码是否匹配已存储的哈希。
再创建一个工具函数来进行身份验证并返回用户。
from datetime import datetime, timedelta, timezone
from typing import Annotated
import jwt
from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jwt.exceptions import InvalidTokenError
from pwdlib import PasswordHash
from pydantic import BaseModel
# to get a string like this run:
# openssl rand -hex 32
SECRET_KEY = "09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30
fake_users_db = {
"johndoe": {
"username": "johndoe",
"full_name": "John Doe",
"email": "johndoe@example.com",
"hashed_password": "$argon2id$v=19$m=65536,t=3,p=4$wagCPXjifgvUFBzq4hqe3w$CYaIb8sB+wtD+Vu/P4uod1+Qof8h+1g7bbDlBID48Rc",
"disabled": False,
}
}
class Token(BaseModel):
access_token: str
token_type: str
class TokenData(BaseModel):
username: str | None = None
class User(BaseModel):
username: str
email: str | None = None
full_name: str | None = None
disabled: bool | None = None
class UserInDB(User):
hashed_password: str
password_hash = PasswordHash.recommended()
DUMMY_HASH = password_hash.hash("dummypassword")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")
app = FastAPI()
def verify_password(plain_password, hashed_password):
return password_hash.verify(plain_password, hashed_password)
def get_password_hash(password):
return password_hash.hash(password)
def get_user(db, username: str):
if username in db:
user_dict = db[username]
return UserInDB(**user_dict)
def authenticate_user(fake_db, username: str, password: str):
user = get_user(fake_db, username)
if not user:
verify_password(password, DUMMY_HASH)
return False
if not verify_password(password, user.hashed_password):
return False
return user
def create_access_token(data: dict, expires_delta: timedelta | None = None):
to_encode = data.copy()
if expires_delta:
expire = datetime.now(timezone.utc) + expires_delta
else:
expire = datetime.now(timezone.utc) + timedelta(minutes=15)
to_encode.update({"exp": expire})
encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
return encoded_jwt
async def get_current_user(token: Annotated[str, Depends(oauth2_scheme)]):
credentials_exception = HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Could not validate credentials",
headers={"WWW-Authenticate": "Bearer"},
)
try:
payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
username = payload.get("sub")
if username is None:
raise credentials_exception
token_data = TokenData(username=username)
except InvalidTokenError:
raise credentials_exception
user = get_user(fake_users_db, username=token_data.username)
if user is None:
raise credentials_exception
return user
async def get_current_active_user(
current_user: Annotated[User, Depends(get_current_user)],
):
if current_user.disabled:
raise HTTPException(status_code=400, detail="Inactive user")
return current_user
@app.post("/token")
async def login_for_access_token(
form_data: Annotated[OAuth2PasswordRequestForm, Depends()],
) -> Token:
user = authenticate_user(fake_users_db, form_data.username, form_data.password)
if not user:
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Incorrect username or password",
headers={"WWW-Authenticate": "Bearer"},
)
access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
access_token = create_access_token(
data={"sub": user.username}, expires_delta=access_token_expires
)
return Token(access_token=access_token, token_type="bearer")
@app.get("/users/me/")
async def read_users_me(
current_user: Annotated[User, Depends(get_current_active_user)],
) -> User:
return current_user
@app.get("/users/me/items/")
async def read_own_items(
current_user: Annotated[User, Depends(get_current_active_user)],
):
return [{"item_id": "Foo", "owner": current_user.username}]
🤓 Other versions and variants
Tip
Prefer to use the Annotated version if possible.
from datetime import datetime, timedelta, timezone
import jwt
from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jwt.exceptions import InvalidTokenError
from pwdlib import PasswordHash
from pydantic import BaseModel
# to get a string like this run:
# openssl rand -hex 32
SECRET_KEY = "09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30
fake_users_db = {
"johndoe": {
"username": "johndoe",
"full_name": "John Doe",
"email": "johndoe@example.com",
"hashed_password": "$argon2id$v=19$m=65536,t=3,p=4$wagCPXjifgvUFBzq4hqe3w$CYaIb8sB+wtD+Vu/P4uod1+Qof8h+1g7bbDlBID48Rc",
"disabled": False,
}
}
class Token(BaseModel):
access_token: str
token_type: str
class TokenData(BaseModel):
username: str | None = None
class User(BaseModel):
username: str
email: str | None = None
full_name: str | None = None
disabled: bool | None = None
class UserInDB(User):
hashed_password: str
password_hash = PasswordHash.recommended()
DUMMY_HASH = password_hash.hash("dummypassword")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")
app = FastAPI()
def verify_password(plain_password, hashed_password):
return password_hash.verify(plain_password, hashed_password)
def get_password_hash(password):
return password_hash.hash(password)
def get_user(db, username: str):
if username in db:
user_dict = db[username]
return UserInDB(**user_dict)
def authenticate_user(fake_db, username: str, password: str):
user = get_user(fake_db, username)
if not user:
verify_password(password, DUMMY_HASH)
return False
if not verify_password(password, user.hashed_password):
return False
return user
def create_access_token(data: dict, expires_delta: timedelta | None = None):
to_encode = data.copy()
if expires_delta:
expire = datetime.now(timezone.utc) + expires_delta
else:
expire = datetime.now(timezone.utc) + timedelta(minutes=15)
to_encode.update({"exp": expire})
encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
return encoded_jwt
async def get_current_user(token: str = Depends(oauth2_scheme)):
credentials_exception = HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Could not validate credentials",
headers={"WWW-Authenticate": "Bearer"},
)
try:
payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
username = payload.get("sub")
if username is None:
raise credentials_exception
token_data = TokenData(username=username)
except InvalidTokenError:
raise credentials_exception
user = get_user(fake_users_db, username=token_data.username)
if user is None:
raise credentials_exception
return user
async def get_current_active_user(current_user: User = Depends(get_current_user)):
if current_user.disabled:
raise HTTPException(status_code=400, detail="Inactive user")
return current_user
@app.post("/token")
async def login_for_access_token(
form_data: OAuth2PasswordRequestForm = Depends(),
) -> Token:
user = authenticate_user(fake_users_db, form_data.username, form_data.password)
if not user:
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Incorrect username or password",
headers={"WWW-Authenticate": "Bearer"},
)
access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
access_token = create_access_token(
data={"sub": user.username}, expires_delta=access_token_expires
)
return Token(access_token=access_token, token_type="bearer")
@app.get("/users/me/")
async def read_users_me(current_user: User = Depends(get_current_active_user)) -> User:
return current_user
@app.get("/users/me/items/")
async def read_own_items(current_user: User = Depends(get_current_active_user)):
return [{"item_id": "Foo", "owner": current_user.username}]
注意
如果你查看新的（伪）数据库 fake_users_db，现在你会看到哈希后的密码类似这样："$argon2id$v=19$m=65536,t=3,p=4$wagCPXjifgvUFBzq4hqe3w$CYaIb8sB+wtD+Vu/P4uod1+Qof8h+1g7bbDlBID48Rc"。
处理 JWT 令牌¶
导入已安装的模块。
创建一个用于对 JWT 令牌进行签名的随机密钥。
使用下列命令生成一个安全的随机密钥：
$ openssl rand -hex 32
09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7
把输出复制到变量 SECRET_KEY（不要使用示例中的那个）。
创建变量 ALGORITHM，设置用于签名 JWT 令牌的算法，这里设为 "HS256"。
创建一个变量用于设置令牌的过期时间。
定义一个用于令牌端点响应的 Pydantic 模型。
创建一个生成新访问令牌的工具函数。
from datetime import datetime, timedelta, timezone
from typing import Annotated
import jwt
from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jwt.exceptions import InvalidTokenError
from pwdlib import PasswordHash
from pydantic import BaseModel
# to get a string like this run:
# openssl rand -hex 32
SECRET_KEY = "09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30
fake_users_db = {
"johndoe": {
"username": "johndoe",
"full_name": "John Doe",
"email": "johndoe@example.com",
"hashed_password": "$argon2id$v=19$m=65536,t=3,p=4$wagCPXjifgvUFBzq4hqe3w$CYaIb8sB+wtD+Vu/P4uod1+Qof8h+1g7bbDlBID48Rc",
"disabled": False,
}
}
class Token(BaseModel):
access_token: str
token_type: str
class TokenData(BaseModel):
username: str | None = None
class User(BaseModel):
username: str
email: str | None = None
full_name: str | None = None
disabled: bool | None = None
class UserInDB(User):
hashed_password: str
password_hash = PasswordHash.recommended()
DUMMY_HASH = password_hash.hash("dummypassword")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")
app = FastAPI()
def verify_password(plain_password, hashed_password):
return password_hash.verify(plain_password, hashed_password)
def get_password_hash(password):
return password_hash.hash(password)
def get_user(db, username: str):
if username in db:
user_dict = db[username]
return UserInDB(**user_dict)
def authenticate_user(fake_db, username: str, password: str):
user = get_user(fake_db, username)
if not user:
verify_password(password, DUMMY_HASH)
return False
if not verify_password(password, user.hashed_password):
return False
return user
def create_access_token(data: dict, expires_delta: timedelta | None = None):
to_encode = data.copy()
if expires_delta:
expire = datetime.now(timezone.utc) + expires_delta
else:
expire = datetime.now(timezone.utc) + timedelta(minutes=15)
to_encode.update({"exp": expire})
encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
return encoded_jwt
async def get_current_user(token: Annotated[str, Depends(oauth2_scheme)]):
credentials_exception = HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Could not validate credentials",
headers={"WWW-Authenticate": "Bearer"},
)
try:
payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
username = payload.get("sub")
if username is None:
raise credentials_exception
token_data = TokenData(username=username)
except InvalidTokenError:
raise credentials_exception
user = get_user(fake_users_db, username=token_data.username)
if user is None:
raise credentials_exception
return user
async def get_current_active_user(
current_user: Annotated[User, Depends(get_current_user)],
):
if current_user.disabled:
raise HTTPException(status_code=400, detail="Inactive user")
return current_user
@app.post("/token")
async def login_for_access_token(
form_data: Annotated[OAuth2PasswordRequestForm, Depends()],
) -> Token:
user = authenticate_user(fake_users_db, form_data.username, form_data.password)
if not user:
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Incorrect username or password",
headers={"WWW-Authenticate": "Bearer"},
)
access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
access_token = create_access_token(
data={"sub": user.username}, expires_delta=access_token_expires
)
return Token(access_token=access_token, token_type="bearer")
@app.get("/users/me/")
async def read_users_me(
current_user: Annotated[User, Depends(get_current_active_user)],
) -> User:
return current_user
@app.get("/users/me/items/")
async def read_own_items(
current_user: Annotated[User, Depends(get_current_active_user)],
):
return [{"item_id": "Foo", "owner": current_user.username}]
🤓 Other versions and variants
Tip
Prefer to use the Annotated version if possible.
from datetime import datetime, timedelta, timezone
import jwt
from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jwt.exceptions import InvalidTokenError
from pwdlib import PasswordHash
from pydantic import BaseModel
# to get a string like this run:
# openssl rand -hex 32
SECRET_KEY = "09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30
fake_users_db = {
"johndoe": {
"username": "johndoe",
"full_name": "John Doe",
"email": "johndoe@example.com",
"hashed_password": "$argon2id$v=19$m=65536,t=3,p=4$wagCPXjifgvUFBzq4hqe3w$CYaIb8sB+wtD+Vu/P4uod1+Qof8h+1g7bbDlBID48Rc",
"disabled": False,
}
}
class Token(BaseModel):
access_token: str
token_type: str
class TokenData(BaseModel):
username: str | None = None
class User(BaseModel):
username: str
email: str | None = None
full_name: str | None = None
disabled: bool | None = None
class UserInDB(User):
hashed_password: str
password_hash = PasswordHash.recommended()
DUMMY_HASH = password_hash.hash("dummypassword")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")
app = FastAPI()
def verify_password(plain_password, hashed_password):
return password_hash.verify(plain_password, hashed_password)
def get_password_hash(password):
return password_hash.hash(password)
def get_user(db, username: str):
if username in db:
user_dict = db[username]
return UserInDB(**user_dict)
def authenticate_user(fake_db, username: str, password: str):
user = get_user(fake_db, username)
if not user:
verify_password(password, DUMMY_HASH)
return False
if not verify_password(password, user.hashed_password):
return False
return user
def create_access_token(data: dict, expires_delta: timedelta | None = None):
to_encode = data.copy()
if expires_delta:
expire = datetime.now(timezone.utc) + expires_delta
else:
expire = datetime.now(timezone.utc) + timedelta(minutes=15)
to_encode.update({"exp": expire})
encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
return encoded_jwt
async def get_current_user(token: str = Depends(oauth2_scheme)):
credentials_exception = HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Could not validate credentials",
headers={"WWW-Authenticate": "Bearer"},
)
try:
payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
username = payload.get("sub")
if username is None:
raise credentials_exception
token_data = TokenData(username=username)
except InvalidTokenError:
raise credentials_exception
user = get_user(fake_users_db, username=token_data.username)
if user is None:
raise credentials_exception
return user
async def get_current_active_user(current_user: User = Depends(get_current_user)):
if current_user.disabled:
raise HTTPException(status_code=400, detail="Inactive user")
return current_user
@app.post("/token")
async def login_for_access_token(
form_data: OAuth2PasswordRequestForm = Depends(),
) -> Token:
user = authenticate_user(fake_users_db, form_data.username, form_data.password)
if not user:
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Incorrect username or password",
headers={"WWW-Authenticate": "Bearer"},
)
access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
access_token = create_access_token(
data={"sub": user.username}, expires_delta=access_token_expires
)
return Token(access_token=access_token, token_type="bearer")
@app.get("/users/me/")
async def read_users_me(current_user: User = Depends(get_current_active_user)) -> User:
return current_user
@app.get("/users/me/items/")
async def read_own_items(current_user: User = Depends(get_current_active_user)):
return [{"item_id": "Foo", "owner": current_user.username}]
更新依赖项¶
更新 get_current_user 以接收与之前相同的令牌，但这次使用的是 JWT 令牌。
解码接收到的令牌，进行校验，并返回当前用户。
如果令牌无效，立即返回一个 HTTP 错误。
from datetime import datetime, timedelta, timezone
from typing import Annotated
import jwt
from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jwt.exceptions import InvalidTokenError
from pwdlib import PasswordHash
from pydantic import BaseModel
# to get a string like this run:
# openssl rand -hex 32
SECRET_KEY = "09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30
fake_users_db = {
"johndoe": {
"username": "johndoe",
"full_name": "John Doe",
"email": "johndoe@example.com",
"hashed_password": "$argon2id$v=19$m=65536,t=3,p=4$wagCPXjifgvUFBzq4hqe3w$CYaIb8sB+wtD+Vu/P4uod1+Qof8h+1g7bbDlBID48Rc",
"disabled": False,
}
}
class Token(BaseModel):
access_token: str
token_type: str
class TokenData(BaseModel):
username: str | None = None
class User(BaseModel):
username: str
email: str | None = None
full_name: str | None = None
disabled: bool | None = None
class UserInDB(User):
hashed_password: str
password_hash = PasswordHash.recommended()
DUMMY_HASH = password_hash.hash("dummypassword")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")
app = FastAPI()
def verify_password(plain_password, hashed_password):
return password_hash.verify(plain_password, hashed_password)
def get_password_hash(password):
return password_hash.hash(password)
def get_user(db, username: str):
if username in db:
user_dict = db[username]
return UserInDB(**user_dict)
def authenticate_user(fake_db, username: str, password: str):
user = get_user(fake_db, username)
if not user:
verify_password(password, DUMMY_HASH)
return False
if not verify_password(password, user.hashed_password):
return False
return user
def create_access_token(data: dict, expires_delta: timedelta | None = None):
to_encode = data.copy()
if expires_delta:
expire = datetime.now(timezone.utc) + expires_delta
else:
expire = datetime.now(timezone.utc) + timedelta(minutes=15)
to_encode.update({"exp": expire})
encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
return encoded_jwt
async def get_current_user(token: Annotated[str, Depends(oauth2_scheme)]):
credentials_exception = HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Could not validate credentials",
headers={"WWW-Authenticate": "Bearer"},
)
try:
payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
username = payload.get("sub")
if username is None:
raise credentials_exception
token_data = TokenData(username=username)
except InvalidTokenError:
raise credentials_exception
user = get_user(fake_users_db, username=token_data.username)
if user is None:
raise credentials_exception
return user
async def get_current_active_user(
current_user: Annotated[User, Depends(get_current_user)],
):
if current_user.disabled:
raise HTTPException(status_code=400, detail="Inactive user")
return current_user
@app.post("/token")
async def login_for_access_token(
form_data: Annotated[OAuth2PasswordRequestForm, Depends()],
) -> Token:
user = authenticate_user(fake_users_db, form_data.username, form_data.password)
if not user:
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Incorrect username or password",
headers={"WWW-Authenticate": "Bearer"},
)
access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
access_token = create_access_token(
data={"sub": user.username}, expires_delta=access_token_expires
)
return Token(access_token=access_token, token_type="bearer")
@app.get("/users/me/")
async def read_users_me(
current_user: Annotated[User, Depends(get_current_active_user)],
) -> User:
return current_user
@app.get("/users/me/items/")
async def read_own_items(
current_user: Annotated[User, Depends(get_current_active_user)],
):
return [{"item_id": "Foo", "owner": current_user.username}]
🤓 Other versions and variants
Tip
Prefer to use the Annotated version if possible.
from datetime import datetime, timedelta, timezone
import jwt
from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jwt.exceptions import InvalidTokenError
from pwdlib import PasswordHash
from pydantic import BaseModel
# to get a string like this run:
# openssl rand -hex 32
SECRET_KEY = "09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30
fake_users_db = {
"johndoe": {
"username": "johndoe",
"full_name": "John Doe",
"email": "johndoe@example.com",
"hashed_password": "$argon2id$v=19$m=65536,t=3,p=4$wagCPXjifgvUFBzq4hqe3w$CYaIb8sB+wtD+Vu/P4uod1+Qof8h+1g7bbDlBID48Rc",
"disabled": False,
}
}
class Token(BaseModel):
access_token: str
token_type: str
class TokenData(BaseModel):
username: str | None = None
class User(BaseModel):
username: str
email: str | None = None
full_name: str | None = None
disabled: bool | None = None
class UserInDB(User):
hashed_password: str
password_hash = PasswordHash.recommended()
DUMMY_HASH = password_hash.hash("dummypassword")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")
app = FastAPI()
def verify_password(plain_password, hashed_password):
return password_hash.verify(plain_password, hashed_password)
def get_password_hash(password):
return password_hash.hash(password)
def get_user(db, username: str):
if username in db:
user_dict = db[username]
return UserInDB(**user_dict)
def authenticate_user(fake_db, username: str, password: str):
user = get_user(fake_db, username)
if not user:
verify_password(password, DUMMY_HASH)
return False
if not verify_password(password, user.hashed_password):
return False
return user
def create_access_token(data: dict, expires_delta: timedelta | None = None):
to_encode = data.copy()
if expires_delta:
expire = datetime.now(timezone.utc) + expires_delta
else:
expire = datetime.now(timezone.utc) + timedelta(minutes=15)
to_encode.update({"exp": expire})
encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
return encoded_jwt
async def get_current_user(token: str = Depends(oauth2_scheme)):
credentials_exception = HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Could not validate credentials",
headers={"WWW-Authenticate": "Bearer"},
)
try:
payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
username = payload.get("sub")
if username is None:
raise credentials_exception
token_data = TokenData(username=username)
except InvalidTokenError:
raise credentials_exception
user = get_user(fake_users_db, username=token_data.username)
if user is None:
raise credentials_exception
return user
async def get_current_active_user(current_user: User = Depends(get_current_user)):
if current_user.disabled:
raise HTTPException(status_code=400, detail="Inactive user")
return current_user
@app.post("/token")
async def login_for_access_token(
form_data: OAuth2PasswordRequestForm = Depends(),
) -> Token:
user = authenticate_user(fake_users_db, form_data.username, form_data.password)
if not user:
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Incorrect username or password",
headers={"WWW-Authenticate": "Bearer"},
)
access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
access_token = create_access_token(
data={"sub": user.username}, expires_delta=access_token_expires
)
return Token(access_token=access_token, token_type="bearer")
@app.get("/users/me/")
async def read_users_me(current_user: User = Depends(get_current_active_user)) -> User:
return current_user
@app.get("/users/me/items/")
async def read_own_items(current_user: User = Depends(get_current_active_user)):
return [{"item_id": "Foo", "owner": current_user.username}]
更新 /token 路径操作¶
用令牌的过期时间创建一个 timedelta。
创建一个真正的 JWT 访问令牌并返回它。
from datetime import datetime, timedelta, timezone
from typing import Annotated
import jwt
from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jwt.exceptions import InvalidTokenError
from pwdlib import PasswordHash
from pydantic import BaseModel
# to get a string like this run:
# openssl rand -hex 32
SECRET_KEY = "09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30
fake_users_db = {
"johndoe": {
"username": "johndoe",
"full_name": "John Doe",
"email": "johndoe@example.com",
"hashed_password": "$argon2id$v=19$m=65536,t=3,p=4$wagCPXjifgvUFBzq4hqe3w$CYaIb8sB+wtD+Vu/P4uod1+Qof8h+1g7bbDlBID48Rc",
"disabled": False,
}
}
class Token(BaseModel):
access_token: str
token_type: str
class TokenData(BaseModel):
username: str | None = None
class User(BaseModel):
username: str
email: str | None = None
full_name: str | None = None
disabled: bool | None = None
class UserInDB(User):
hashed_password: str
password_hash = PasswordHash.recommended()
DUMMY_HASH = password_hash.hash("dummypassword")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")
app = FastAPI()
def verify_password(plain_password, hashed_password):
return password_hash.verify(plain_password, hashed_password)
def get_password_hash(password):
return password_hash.hash(password)
def get_user(db, username: str):
if username in db:
user_dict = db[username]
return UserInDB(**user_dict)
def authenticate_user(fake_db, username: str, password: str):
user = get_user(fake_db, username)
if not user:
verify_password(password, DUMMY_HASH)
return False
if not verify_password(password, user.hashed_password):
return False
return user
def create_access_token(data: dict, expires_delta: timedelta | None = None):
to_encode = data.copy()
if expires_delta:
expire = datetime.now(timezone.utc) + expires_delta
else:
expire = datetime.now(timezone.utc) + timedelta(minutes=15)
to_encode.update({"exp": expire})
encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
return encoded_jwt
async def get_current_user(token: Annotated[str, Depends(oauth2_scheme)]):
credentials_exception = HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Could not validate credentials",
headers={"WWW-Authenticate": "Bearer"},
)
try:
payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
username = payload.get("sub")
if username is None:
raise credentials_exception
token_data = TokenData(username=username)
except InvalidTokenError:
raise credentials_exception
user = get_user(fake_users_db, username=token_data.username)
if user is None:
raise credentials_exception
return user
async def get_current_active_user(
current_user: Annotated[User, Depends(get_current_user)],
):
if current_user.disabled:
raise HTTPException(status_code=400, detail="Inactive user")
return current_user
@app.post("/token")
async def login_for_access_token(
form_data: Annotated[OAuth2PasswordRequestForm, Depends()],
) -> Token:
user = authenticate_user(fake_users_db, form_data.username, form_data.password)
if not user:
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Incorrect username or password",
headers={"WWW-Authenticate": "Bearer"},
)
access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
access_token = create_access_token(
data={"sub": user.username}, expires_delta=access_token_expires
)
return Token(access_token=access_token, token_type="bearer")
@app.get("/users/me/")
async def read_users_me(
current_user: Annotated[User, Depends(get_current_active_user)],
) -> User:
return current_user
@app.get("/users/me/items/")
async def read_own_items(
current_user: Annotated[User, Depends(get_current_active_user)],
):
return [{"item_id": "Foo", "owner": current_user.username}]
🤓 Other versions and variants
Tip
Prefer to use the Annotated version if possible.
from datetime import datetime, timedelta, timezone
import jwt
from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jwt.exceptions import InvalidTokenError
from pwdlib import PasswordHash
from pydantic import BaseModel
# to get a string like this run:
# openssl rand -hex 32
SECRET_KEY = "09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30
fake_users_db = {
"johndoe": {
"username": "johndoe",
"full_name": "John Doe",
"email": "johndoe@example.com",
"hashed_password": "$argon2id$v=19$m=65536,t=3,p=4$wagCPXjifgvUFBzq4hqe3w$CYaIb8sB+wtD+Vu/P4uod1+Qof8h+1g7bbDlBID48Rc",
"disabled": False,
}
}
class Token(BaseModel):
access_token: str
token_type: str
class TokenData(BaseModel):
username: str | None = None
class User(BaseModel):
username: str
email: str | None = None
full_name: str | None = None
disabled: bool | None = None
class UserInDB(User):
hashed_password: str
password_hash = PasswordHash.recommended()
DUMMY_HASH = password_hash.hash("dummypassword")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")
app = FastAPI()
def verify_password(plain_password, hashed_password):
return password_hash.verify(plain_password, hashed_password)
def get_password_hash(password):
return password_hash.hash(password)
def get_user(db, username: str):
if username in db:
user_dict = db[username]
return UserInDB(**user_dict)
def authenticate_user(fake_db, username: str, password: str):
user = get_user(fake_db, username)
if not user:
verify_password(password, DUMMY_HASH)
return False
if not verify_password(password, user.hashed_password):
return False
return user
def create_access_token(data: dict, expires_delta: timedelta | None = None):
to_encode = data.copy()
if expires_delta:
expire = datetime.now(timezone.utc) + expires_delta
else:
expire = datetime.now(timezone.utc) + timedelta(minutes=15)
to_encode.update({"exp": expire})
encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
return encoded_jwt
async def get_current_user(token: str = Depends(oauth2_scheme)):
credentials_exception = HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Could not validate credentials",
headers={"WWW-Authenticate": "Bearer"},
)
try:
payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
username = payload.get("sub")
if username is None:
raise credentials_exception
token_data = TokenData(username=username)
except InvalidTokenError:
raise credentials_exception
user = get_user(fake_users_db, username=token_data.username)
if user is None:
raise credentials_exception
return user
async def get_current_active_user(current_user: User = Depends(get_current_user)):
if current_user.disabled:
raise HTTPException(status_code=400, detail="Inactive user")
return current_user
@app.post("/token")
async def login_for_access_token(
form_data: OAuth2PasswordRequestForm = Depends(),
) -> Token:
user = authenticate_user(fake_users_db, form_data.username, form_data.password)
if not user:
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail="Incorrect username or password",
headers={"WWW-Authenticate": "Bearer"},
)
access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
access_token = create_access_token(
data={"sub": user.username}, expires_delta=access_token_expires
)
return Token(access_token=access_token, token_type="bearer")
@app.get("/users/me/")
async def read_users_me(current_user: User = Depends(get_current_active_user)) -> User:
return current_user
@app.get("/users/me/items/")
async def read_own_items(current_user: User = Depends(get_current_active_user)):
return [{"item_id": "Foo", "owner": current_user.username}]
关于 JWT “主题” sub 的技术细节¶
JWT 规范中有一个 sub 键，表示令牌的“主题”（subject）。
使用它是可选的，但通常会把用户的标识放在这里，所以本例中我们使用它。
JWT 除了用于识别用户并允许其直接在你的 API 上执行操作之外，还可能用于其他场景。
例如，你可以用它来标识一辆“车”或一篇“博客文章”。
然后你可以为该实体添加权限，比如“drive”（用于车）或“edit”（用于博客）。
接着，你可以把这个 JWT 令牌交给一个用户（或机器人），他们就可以在没有账户的前提下，仅凭你的 API 生成的 JWT 令牌来执行这些操作（开车、编辑文章）。
基于这些想法，JWT 可以用于更复杂的场景。
在这些情况下，多个实体可能会有相同的 ID，比如都叫 foo（用户 foo、车 foo、博客文章 foo）。
因此，为了避免 ID 冲突，在为用户创建 JWT 令牌时，你可以给 sub 键的值加一个前缀，例如 username:。所以在这个例子中，sub 的值可以是：username:johndoe。
需要牢记的一点是，sub 键在整个应用中应该是一个唯一标识符，并且它应该是字符串。
检查¶
运行服务器并打开文档：http://127.0.0.1:8000/docs。
你会看到这样的用户界面：
像之前一样进行授权。
使用以下凭证：
用户名: johndoe
密码: secret
检查
注意，代码中的任何地方都没有明文密码 “secret”，我们只有它的哈希版本。
调用 /users/me/ 端点，你将得到如下响应：
{
"username": "johndoe",
"email": "johndoe@example.com",
"full_name": "John Doe",
"disabled": false
}
如果你打开开发者工具，你会看到发送的数据只包含令牌。密码只会在第一个请求中用于认证用户并获取访问令牌，之后就不会再发送密码了：
注意
注意 Authorization 请求头，其值以 Bearer 开头。
使用 scopes 的高级用法¶
OAuth2 支持 “scopes”（作用域）。
你可以用它们为 JWT 令牌添加一组特定的权限。
然后你可以把这个令牌直接交给用户或第三方，在一组限制条件下与 API 交互。
在高级用户指南中你将学习如何使用它们，以及它们如何集成进 FastAPI。
小结¶
通过目前所学内容，你可以使用 OAuth2 和 JWT 等标准来搭建一个安全的 FastAPI 应用。
在几乎任何框架中，处理安全问题都会很快变得相当复杂。
许多把安全流程大幅简化的包，往往要在数据模型、数据库和可用特性上做出大量妥协。而有些过度简化的包实际上在底层存在安全隐患。
FastAPI 不会在任何数据库、数据模型或工具上做妥协。
它给予你完全的灵活性，选择最适合你项目的方案。
而且你可以直接使用许多维护良好、广泛使用的包，比如 pwdlib 和 PyJWT，因为 FastAPI 不需要复杂机制来集成外部包。
同时它也为你提供尽可能简化流程的工具，而不牺牲灵活性、健壮性或安全性。
你可以以相对简单的方式使用和实现像 OAuth2 这样的安全、标准协议。
在高级用户指南中，你可以进一步了解如何使用 OAuth2 的 “scopes”，以遵循相同标准实现更细粒度的权限系统。带作用域的 OAuth2 是许多大型身份认证提供商（如 Facebook、Google、GitHub、Microsoft、X（Twitter）等）用来授权第三方应用代表其用户与其 API 交互的机制。