帮我用python代码生成根证书，并用根证书签发加密证书

当然可以，以下是生成根证书的 Python 代码：

from cryptography import x509
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import rsa
from cryptography.x509.oid import NameOID

# 生成 RSA 密钥对
private_key = rsa.generate_private_key(
    public_exponent=65537,
    key_size=2048,
)

# 创建 X.509 证书
subject = issuer = x509.Name([
    x509.NameAttribute(NameOID.COUNTRY_NAME, "CN"),
    x509.NameAttribute(NameOID.STATE_OR_PROVINCE_NAME, "Beijing"),
    x509.NameAttribute(NameOID.LOCALITY_NAME, "Beijing"),
    x509.NameAttribute(NameOID.ORGANIZATION_NAME, "CSDN"),
    x509.NameAttribute(NameOID.COMMON_NAME, "CSDN Root CA"),
])
cert = x509.CertificateBuilder().subject_name(
    subject
).issuer_name(
    issuer
).public_key(
    private_key.public_key()
).serial_number(
    x509.random_serial_number()
).not_valid_before(
    datetime.datetime.utcnow()
).not_valid_after(
    datetime.datetime.utcnow() + datetime.timedelta(days=365)
).add_extension(
    x509.BasicConstraints(ca=True, path_length=None), critical=True,
).sign(private_key, hashes.SHA256())

# 将证书和私钥保存到文件
with open("root_cert.pem", "wb") as f:
    f.write(cert.public_bytes(serialization.Encoding.PEM))
with open("root_key.pem", "wb") as f:
    f.write(private_key.private_bytes(
        serialization.Encoding.PEM,
        serialization.PrivateFormat.PKCS8,
        serialization.NoEncryption(),
    ))

接下来，使用根证书签发加密证书的 Python 代码如下：

from cryptography import x509
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import rsa
from cryptography.x509.oid import NameOID

# 读取根证书和私钥
with open("root_cert.pem", "rb") as f:
    root_cert = x509.load_pem_x509_certificate(f.read())
with open("root_key.pem", "rb") as f:
    root_key = serialization.load_pem_private_key(
        f.read(),
        password=None,
    )

# 生成 RSA 密钥对
private_key = rsa.generate_private_key(
    public_exponent=65537,
    key_size=2048,
)

# 创建 X.509 证书
subject = x509.Name([
    x509.NameAttribute(NameOID.COUNTRY_NAME, "CN"),
    x509.NameAttribute(NameOID.STATE_OR_PROVINCE_NAME, "Beijing"),
    x509.NameAttribute(NameOID.LOCALITY_NAME, "Beijing"),
    x509.NameAttribute(NameOID.ORGANIZATION_NAME, "CSDN"),
    x509.NameAttribute(NameOID.COMMON_NAME, "www.csdn.net"),
])
cert = x509.CertificateBuilder().subject_name(
    subject
).issuer_name(
    root_cert.subject
).public_key(
    private_key.public_key()
).serial_number(
    x509.random_serial_number()
).not_valid_before(
    datetime.datetime.utcnow()
).not_valid_after(
    datetime.datetime.utcnow() + datetime.timedelta(days=365)
).add_extension(
    x509.BasicConstraints(ca=False, path_length=None), critical=True,
).sign(root_key, hashes.SHA256())

# 将证书和私钥保存到文件
with open("cert.pem", "wb") as f:
    f.write(cert.public_bytes(serialization.Encoding.PEM))
with open("key.pem", "wb") as f:
    f.write(private_key.private_bytes(
        serialization.Encoding.PEM,
        serialization.PrivateFormat.PKCS8,
        serialization.NoEncryption(),
    ))

希望这些代码能够帮助你生成根证书和加密证书。