加密字符串:a=00000003&b=99123123131&d=a0ea3fa20dbd7bb4d5abf1d59d63bae8
PrivateKey='MIICXQIBAAKBgQCYd4AgtehkQExjPq2'
如何得出签名
https://blog.csdn.net/xiao_sa_ge/article/details/78891917