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I realize servers such as Google, Yahoo, which use RSA has 2048 bits public key. After comparing those keys, I realize that the public keys share a common property, that is first 9 bytes and last 5 bytes are always the same. Since those public keys have 270 bytes altogether, this means there are only 256 useful bytes, which is 2048 bits. Is this 2048 bits of key secure? I google online and found that it takes a very long time to break 2048 bits of key as mentioned here. But I am not convincing enough. Can anyone explain to me?