question: public static void initKeys ( KeyStore keystore , Properties props ) { if ( props . containsKey ( Configuration . WEBCALL_KAFKA_AES ) ) { byte [ ] key = keystore . decodeKey ( props . getProperty ( Configuration . WEBCALL_KAFKA_AES ) ) ; Preconditions . checkArgument ( ( 16 == key . length || 24 == key . length || 32 == key . length ) , Configuration . WEBCALL_KAFKA_AES + " MUST be 128, 192 or 256 bits long." ) ; keystore . setKey ( KeyStore . AES_KAFKA_WEBCALL , key ) ; aesKey = key ; } if ( props . containsKey ( Configuration . WEBCALL_KAFKA_MAC ) ) { byte [ ] key = keystore . decodeKey ( props . getProperty ( Configuration . WEBCALL_KAFKA_MAC ) ) ; Preconditions . checkArgument ( ( 16 == key . length ) , Configuration . WEBCALL_KAFKA_MAC + " MUST be 128 bits long." ) ; keystore . setKey ( KeyStore . SIPHASH_KAFKA_WEBCALL , key ) ; siphashKey = key ; } }
target:  Extract the required keys if they exist