question: public boolean verifyServerEvidenceMessage ( BigInteger serverM2 ) throws CryptoException { if ( ( this . A == null ) || ( this . M1 == null ) || ( this . S == null ) ) { throw new CryptoException ( "Impossible to compute and verify M2: " + "some data are missing from the previous operations (A,M1,S)" ) ; } BigInteger computedM2 = SRP6Util . calculateM2 ( digest , N , A , M1 , S ) ; if ( computedM2 . equals ( serverM2 ) ) { this . M2 = serverM2 ; return true ; } return false ; }
target:  Authenticates the server evidence message M2 received and saves it only if correct.