??????  BASE64 ???????????????????????????
??????  MD5(Message Digest algorithm 5?????????)
??????  SHA(Secure Hash Algorithm??????????)
??????  HMAC(Hash Message Authentication Code??????????????)???????????DES??PBE???????????????
??????  DES(Data Encryption Standard???????????)
??????  PBE(Password-based encryption?????????????)
??????  RSA(??????????????????????????Ron Rivest?? AdiShamir ??Leonard Adleman)
??????  DH(Diffie-Hellman??????????Э??)
??????  DSA(Digital Signature Algorithm?????????)
??????  ECC(Elliptic Curves Cryptography?????????????????)[/size]
????-------------------------------------------------------------------------------------------------------------------------------------------
?????????????????BASE64??MD5??SHA??HMAC???????????
????BASE64?????????????????????????
????MD5??SHA??HMAC???????????????ν??????????????????????????????????????????????????????????????????????????????????????????????????
????BASE64
????????RFC2045????壬Base64?????????Base64??????????????????????????е?8λ???????????????????????????????The Base64 Content-Transfer-Encoding is designed to represent arbitrary sequences of octets in a form that need not be humanly readable.??
???????????????http????????http???????????????????????????????????BASE64??????

?????????BASE64Encoder??BASE64Decoder??????????????????????????????ɡ????BASE?????????????λ????8??????????????λ????=???????
????sun?????????????????base64????????apache??????
????MD5
????MD5 -- message-digest algorithm 5 ?????-????????д?????????????????????????????У?顣У?飿??????????????MD5?????????MD5???????????ISOУ?飬????MD5У?顣????????????ISO????MD5?????MD5????????????linux-ISO?????????????????????????MD5??????????????????????μ??

??????????????????????MD5??????????MD5????????????齻??BASE64????????????????????????
????SHA
????SHA(Secure Hash Algorithm????????????????????????????????????????????????????????????????????????????SHA??MD5??????????????????????SHA??????????????????????MD5????????