问题
If I have the original and encrypted string how can I find out the encryption method? for example I have original string 0812388140 and the encoded one B2BCxW1tnHkzEfMfJM888Q==.
回答1:
If the encryption algorithm is secure (like any of the most supported ones is) you cannot: they are designed to make the encrypted text appear as random data, so none of them leaves a 'signature' that will hint you.
回答2:
Think about it this way: The cryptosystem is a "black box machine". You can put in a string, and you get out a string at the other end. You're not allowed to look inside. What you're asking is really how can I tell the inner workings of the black box by looking at what comes out when a single string is fed to the box? Clearly, you cannot do this.
回答3:
You cannot find-out the algorithm by simply looking at the encrypted result.
来源：https://stackoverflow.com/questions/5538950/how-to-find-out-the-encryption-method