problem with decryption using private key
liang wee
is wrong. I am unable to get back the original text
even though I am using the correct pair of
public/private key. Below is the snippet of my code. I
am using crypto++5.1 with g++ 3.3 on fbsd 5.1
AutoSeededRandomPool rng;
char *message = "Hello World";
unsigned int length = pub.CiphertextLength (strlen
(message));
char *outstr = new char [length];
pub.Encrypt (rng, (byte *)message, strlen (message),
(byte *)outstr);
int length2 = priv.MaxPlaintextLength (length);
char *plaintext = new char [length2];
priv.Decrypt (rng, (byte *)outstr, length2, (byte *)plaintext);
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key. If you want your message protected you then have to encrypt with the public key (from a
different key pair).
=====
Olga Sayenko
http://www.cs.uic.edu/~osayenko
Department of Computer Science
University of Illinois at Chicago
Wei Dai
> Crypto++ will not let you encrypt with the private key. It wants you to sign with the private
> key. If you want your message protected you then have to encrypt with the public key (from a
> different key pair).
You're right that Crypto++ won't let you encrypt with the private key, but
that's not what liang is trying to do. The actual problem is something
else.
> > priv.Decrypt (rng, (byte *)outstr, length2, (byte *)plaintext);
The second parameter here needs to be ciphertextLength, i.e., "length"
rather than "length2".
liang wee
After checking the code again, I notice that silly
mistake.
Just curius, is there any reason why crypto++ don't
support private key encryption ? If i am not wrong, a
message encrypted with a private key could only be
decrypted with the public key. Since only the owner
has the private key, this can be used to prove that
the message originated from the owner of this keypair.
It kind of serve the same purpose as signature.