If this key agreement requires random bytes, they will be kept as a source of coincidence with the SecureRandom implementation of the installed vendor with the highest priority. (If none of the installed vendors provides an implementation of SecureRandom, a random source provided by the system is used.) Now Alice and Bob have the same sharedKey `bobPubKey` -alicePrivKey – alicePubKey – bobPrivKey. . There you go! Both parties now have the same derivative key that can be used for an AES code or an HMAC key, or as you like. A more sophisticated key bypass function, like HKDF. B, can be used to deduce other keys (for example.B. separate keys that send data in each direction, which is recommended). Excuse me, I have a NoSuchAlgorithmException error: The real ECDH key agreement is simple once we have exchanged the public keys. .
We use an example of the key ECDH protocol. The first step is to start it with our private key. Then we hand over the public key of the other part on the doPhase method (). We present the second argument that this is the last phase of the agreement (this is the only phase of the ECDH). Diffie-Hellman calculates a common secret based on our private key and the other party`s public key, so that`s all we need in this case. The magic of DH is that each party calculates the same value, although they have different sets of keys at their disposal. No one who listens to the exchange can calculate the common secret, unless they have access to one of the private keys (which are never disclosed). Original message in plain sight: Look, I`m a message! java.security.NoSuchProviderException: no such provider: BC at sun.security.jca.GetInstance.getService (Unknown Source) at sun.security.jca.GetInstance.getInstance (Unknown Source) at java.security.security..KeyPairGenerator.getInstance (Unknown Source) at Test.generateECKeys (Test.java:57) at Test.main (Test.java:36) java.security.NoSuchProvider: noSuchPro No dieser Anbieter: BC under sun.security.jca.GetInstance.getService (Unknown Source) under sun.security.jca.GetInstance.getInstance (Unknown Source) at java.security.KeyPairGenerator.getInstance (Unknown Source) at Test.generateECKeys (Test.java:57) at Test.main (Test.java:37) Exception in the thread „hand” java.lang.NullPointerException To use the example , compile and then run two instances (perhaps on different computers). An ephemeral public key value is printed in hex-coded, and then the public key of the other instance is waited. Simply copy these values from one to the other (and vice versa) and then the calculated common secret is printed again hex-coded and finally a secret key of the common secret.
There are a number of comprehensive protocols that build on this basic agreement mechanism and add authentication and other details: in the next section, we will implement the ECDH algorithm and demonstrate it for example code. Replace „BC” with the new org.bouncycastle.jce.provider.BouncyCastleProvider () and remove NoSuchProviderException Performs the next phase of this key agreement with the specified key received by one of the other parties to this key agreement. I`m trying to convert KeyPair into thong, but I can`t convert the channel into KeyPair. Can you help me? Downstairs, there is the one I am trying to do. KeyPair keyPairA – generateECKeys (); String p-keyPairA.toString (); You must again convert p to KeyPair The next step is to send our public key to the other party and get his public key.