单项选择题
Which algorithm was the first to be found suitable for both digital signing and encryption？（）
A.HMAC B.RSA C.MD5 D.SHA-1
单项选择题 Whichexampleisofafunctionintendedforcryptographichashing？（）
单项选择题 WhichoneofthefollowingitemsmaybeaddedtoapasswordstoredinMD5tomakeitmoresecure？（）
单项选择题 Whichitemisthegreatmajorityofsoftwarevulnerabilitiesthathavebeendiscovered？（）
