function?outp?=?rsadec（inpkey）
%?RSADEC?-?rapidly?decrypt?a?short?message?using?RSA
%
%?pt=rsadec（ctkey）
%
%?ct??=?cyphertext?（uint8?vector）?created?by?RSAENC
%?key?=?private?or?public?key?created?by?the?RSAKEYS?function
%?pt??=?plaintext?message?（a?vector?of?type?uint8）?which?you?may
%???????wish?to?convert?to?text?using?“char（pt）“
%
%?Notes:?（1）?This?function?uses?Java?which?contains?the?calculation
%????????????routines
%????????（2）?The?usual?use?of?RSA?is?for?encryption?of?keys?in?a?“key
%????????????exchange“?so?the?plaintext?size?limits?provided?by?the?Java
%????????????routines?（which?are?adequate?for?that?purpose）?have?not?been
%????????????expanded?here.?（For?example?a?128-bit?AES?encryption?key
%????????????requires?only?16?bytes.）?See?the?RSAENC?function.
%????????（3）?An?RSA?“key“?consists?of?two?quatities:?a?modulus?and?an
%????????????exponent.?RSA?keys?always?come?in?pairs?with?one?key?denoted
%????????????“public“?and?the?other?as?“private.“?A?message?that?is
%????????????encrypted?using?EITHER?key?must?be?decrypted?using?the?OTHER
%????????????key.?You?keep?the?private?key?secret?and?broadcast?the?public
%????????????key.?Anyone?can?then?encrypt?any?message?to?you?using?the
%????????????public?key?but?no?one?but?you?can?decrypt?it?（not?even?the
%????????????sender）?since?only?you?have?the?secret?key.?Also?you?can
%????????????encrypt?a?message?using?your?private?key?and?anyone?can
%????????????decrypt?it?using?the?public?key.?The?benefit?is?that?they?then
%????????????know?for?sure?that?you?are?the?person?who?generated?the
%????????????message.
%????????（4）?RSA?modulus?and?exponent?selection?have?certain?nuances
%????????????beyond?the?basic?numerical?calculations.?In?particular
%????????????certain?values?for?various?components?of?the?key?generation
%????????????can?result?in?encryption?weaknesses.?For?this?reason?you
%????????????may?choose?to?avoid?generating?RSA?key?pairs?yourself?and
%????????????instead?rely?upon?“official“?key?generation?code?such?as?the
%????????????Java?routines?used?in?this?function.
%????????（5）?As?of?2005?“RSA?Laboratories?currently?recommends?key
%????????????sizes?of?1024?bits?for?corporate?use?and?2048?bits?for
%????????????extremely?valuable?keys....“?For?more?information?see
%????????????http://www.rsasecurity.com/rsalabs/node.asp?id=2218
%????????（6）?As?of?2005?the?US?National?Institue?of?Standards?and
%????????????Technology?claims?that?2048?bit?keys?for?RSA?will?remain
%????????????resistant?to?cracking?until?about?2030.
%????????（7）?Tested?but?no?warranty;?use?at?your?own?risk.
%????????（8）?Michael?Kleder?Nov?2005
%
%?EXAMPLE:
%
%?[pripub]=rsakeys（1024）;
%?char（rsadec（rsaenc（‘This?is?a?secret.‘pub）pri））
%?char（rsadec（rsaenc（‘This?is?a?secret.‘pri）pub））

if?ischar（inp）?|?islogical（inp）
????inp=uint8（inp（:））;
else
????inp=typecast（inp（:）‘uint8‘）;
end
modulus?=?java.math.BigInteger（key.modulus）;
pubexp?=?java.math.BigI

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????文件????????3442??2005-11-19?01:04??rsadec.m
?????文件????????3545??2005-11-19?01:04??rsaenc.m