cryptography - 识别成功解密不是很难吗？

Question

当我听说破解加密算法的方法时，我注意到通常关注如何非常快速地解密以及如何减少搜索空间。但是，我总是想知道如何识别成功的解密，以及为什么这不会形成瓶颈。还是通常假设加密/解密对是已知的？

Answer 1

来自 Cryptonomicon :

There is a compromise between the two extremes of, on the one hand, not knowing any of the plaintext at all, and, on the other, knowing all of it. In the Cryptonomicon that falls under the heading of cribs. A crib is an educated guess as to what words or phrases might be present in the message. For example if you were decrypting German messages from World War II, you might guess that the plaintext included the phrase "HElL HITLER" or "SIEG HElL." You might pick out a sequence of ten characters at random and say, "Let's assume that this represented HEIL HITLER. If that is the case, then what would it imply about the remainder of the message?"

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Sitting down in his office with the fresh Arethusa intercepts, he went to work, using FUNERAL as a crib: if this group of seven letters decrypts to FUNERAL, then what does the rest of the message look like? Gibberish? Okay, how about this group of seven letters?