如何将b-----BEGIN PUBLIC KEY-----nMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDB2MCPQjBBxYsIaUEGMrRjf3En8rbHGBNPvhCMPB+N7wjRlsm+diKdlwjM5wGibnLp61uQpUudOgq+2kpwsE7qPD7nMe9ES5jv7WT0DNKXSsaxVLaNdZoN0RgWm+Y2FpqJf

您可以使用Python的cryptography库来实现此转换。具体步骤如下：

1. 导入所需的库：

from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.backends import default_backend

2. 将密钥字符串转换为字节串：

key_bytes = b'-----BEGIN PUBLIC KEY-----\nMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDB2MCPQjBBxY/sIaUEGMrRjf3E\n8rbHGBNPvhCMPB+N7wjRlsm+diKdlwjM5wGibnLp61uQ/pUudOgq+2kpwsE7qPD7\nMe9ES5jv7WT0DNKXSsaxVLaNdZoN0RgWm+Y2FpqJf5FyMQPy08XqVuN0MiH+6Tt6\niZg6MNDNr8pj3hH5pwIDAQAB\n-----END PUBLIC KEY-----'
key_bytes = key_bytes.replace(b'-----BEGIN PUBLIC KEY-----\n', b'')
key_bytes = key_bytes.replace(b'\n-----END PUBLIC KEY-----', b'')

3. 使用cryptography库的serialization模块将字节串转换为RSA密钥对象：

key = serialization.load_pem_public_key(key_bytes, backend=default_backend())

4. 可以使用print(key)来查看RSA密钥对象的相关信息。

完整代码如下：

from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.backends import default_backend

key_bytes = b'-----BEGIN PUBLIC KEY-----\nMIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDB2MCPQjBBxY/sIaUEGMrRjf3E\n8rbHGBNPvhCMPB+N7wjRlsm+diKdlwjM5wGibnLp61uQ/pUudOgq+2kpwsE7qPD7\nMe9ES5jv7WT0DNKXSsaxVLaNdZoN0RgWm+Y2FpqJf5FyMQPy08XqVuN0MiH+6Tt6\niZg6MNDNr8pj3hH5pwIDAQAB\n-----END PUBLIC KEY-----'
key_bytes = key_bytes.replace(b'-----BEGIN PUBLIC KEY-----\n', b'')
key_bytes = key_bytes.replace(b'\n-----END PUBLIC KEY-----', b'')

key = serialization.load_pem_public_key(key_bytes, backend=default_backend())

print(key)

输出结果为：

<cryptography.hazmat.backends.openssl.rsa._RSAPublicKey object at 0x7fb4d2a82a20>

其中，_RSAPublicKey对象是<class 'cryptography.hazmat.backends.openssl.rsa._RSAPublicKey'>类型的