A picture of RSA plus decryption and plus verification

RSA cryptographic Verification is a commonly used method for inter-agency communication with high security requirements, and the current computational power is not sufficient to decrypt it (but quantum computers ...), if the key is long enough. Who knows about the future. ）。 However, I find that there are still people who are smattering the process. For example, what your sign-up algorithm uses. Answer RSA ... For example, some organizations will be generated key pair re-use BASE64 encoding, so that the use of the corresponding decoding, the process is encapsulated in the tool class inside, so we look at the code as much as possible to go to see the source. RSA is just an encryption algorithm, the signature needs to hash and then encrypt the content, such as Sha1withrsa is a common RSA plus sign algorithm.

Many on the internet to explain the RSA article, this article does not say that the JDK has its own corresponding algorithm.

RSA plus sign, encrypted message why is safe.

A institution generates a key pair, gives the public key to B, and, similarly, B gives its own public key to a. In this case, a will encrypt the plaintext with the public key of B when generating the encrypted message, and then use A's private key to sign the plaintext. OK, at this point only B's private key can decrypt the message, and the private key only B, even if the message is intercepted, the third party can not decrypt. If the public key of a is public (and may not actually be public), then the third party can parse out the hash result of the message, just the hash result ... Unable to get clear text. b After receiving the request, with its own private key to decrypt the message, and then to check the message, if not consistent, then will not respond to the request, such a mode, the security of the communication process can be guaranteed. The process is shown in the following figure: