[Botan-devel] need sample code for El Gamal Algorithm operations

[run zhang]

Thanks very much. It works!
According to the API reference, ElGamal can use
DSA-512 group. Which magic should I play to make it
run with this? 

--- Jack Lloyd <lloyd at randombit.net> wrote:

> 
> Some sample code is attached. It does basic key
> generation, encryption
> and decryption. Currently you cannot export ElGamal
> keys in any sort
> of PKCS #8 structure as no OIDs have been defined
> for it that I know
> of (I'll rectify this in 1.7.0, I've been assigned
> an OID arc by the
> IANA and will be allocating nodes for RW, NR, and
> ElGamal key
> formats). Until then, if you want to do import
> export you'll have to
> do it manually with the accessors in
> DL_Scheme_{PublicKey,PrivateKey}
> 
> -Jack
> 
> On Mon, Mar 19, 2007 at 08:42:38PM -0700, run zhang
> wrote:
> > Would someone post some sample code for El Gamal
> key generation and enc/dec?  Thanks a lot. 
> >    
> > 
> >  
> > ---------------------------------
> > Food fight? Enjoy some healthy debate
> > in the Yahoo! Answers Food & Drink Q&A.
> > _______________________________________________
> > botan-devel mailing list
> > botan-devel at randombit.net
> >
>
http://www.randombit.net/mailman/listinfo/botan-devel
> 
> > #include <botan/botan.h> // for libraryinitalizer,
> etc
> #include <botan/elgamal.h> // for the key info
> #include <botan/look_pk.h> // for get_pk_*
> using namespace Botan;
> 
> #include <iostream>
> #include <memory>
> 
> SecureVector<byte> do_encrypt(const SymmetricKey&
> key,
>                               const
> ElGamal_PublicKey& elg_key)
>    {
>    std::auto_ptr<PK_Encryptor>
> enc(get_pk_encryptor(elg_key, "PKCS1v15"));
>    return enc->encrypt(key.bits_of());
>    }
> 
> SecureVector<byte> do_decrypt(const
> SecureVector<byte>& ciphertext,
>                               const
> ElGamal_PrivateKey& elg_key)
>    {
>    std::auto_ptr<PK_Decryptor>
> dec(get_pk_decryptor(elg_key, "PKCS1v15"));
>    return dec->decrypt(ciphertext);
>    }
> 
> int main()
>    {
>    LibraryInitializer init;
> 
>    // generate a 2048 bit ElGamal key
>    ElGamal_PrivateKey
> priv_key(DL_Group("modp/ietf/1024"));
>    ElGamal_PrivateKey pub_key = priv_key;
> 
>    SymmetricKey sym_key(16); // 128 bits, for, eg
> AES-128
> 
>    SecureVector<byte> enc_key = do_encrypt(sym_key,
> pub_key);
>    SecureVector<byte> dec_key = do_decrypt(enc_key,
> priv_key);
> 
>    if(dec_key == sym_key.bits_of()) // check that it
> worked
>       std::cout << "Decrypted plaintext matches
> original\n";
>    else
>       std::cout << "Something went wrong, not
> identical\n";
>    return 0;
>    }
> > _______________________________________________
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> botan-devel at randombit.net
>
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> 



 
____________________________________________________________________________________
Food fight? Enjoy some healthy debate 
in the Yahoo! Answers Food & Drink Q&A.
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