term% cat index.txt ELGAMAL(2) System Calls Manual ELGAMAL(2)
NAME
eggen, egencrypt, egdecrypt, egsign, egverify, egpuballoc, egpubfree,
egprivalloc, egprivfree, egsigalloc, egsigfree, egprivtopub - elgamal
encryption
SYNOPSIS
#include <u.h>
#include <libc.h>
#include <mp.h>
#include <libsec.h>
EGpriv* eggen(int nlen, int nrep)
mpint* egencrypt(EGpub *k, mpint *in, mpint *out)
mpint* egdecrypt(EGpriv *k, mpint *in, mpint *out)
EGsig* egsign(EGpriv *k, mpint *m)
int egverify(EGpub *k, EGsig *sig, mpint *m)
EGpub* egpuballoc(void)
void egpubfree(EGpub*)
EGpriv* egprivalloc(void)
void egprivfree(EGpriv*)
EGsig* egsigalloc(void)
void egsigfree(EGsig*)
EGpub* egprivtopub(EGpriv*)
DESCRIPTION
Elgamal is a public key encryption and signature algorithm. The owner
of a key publishes the public part of the key:
struct EGpub
{
mpint *p; // modulus
mpint *alpha; // generator
mpint *key; // (encryption key) alpha**secret mod p
};
This part can be used for encrypting data (with egencrypt) to be sent
to the owner. The owner decrypts (with egdecrypt) using his private
key:
struct EGpriv
{
EGpub pub;
mpint *secret; // (decryption key)
};
Keys are generated using eggen. Eggen takes both bit length of the
modulus and the number of repetitions of the Miller-Rabin primality
test to run. If the latter is 0, it does the default number of rounds.
Egprivtopub returns a newly allocated copy of the public key corre‐
sponding to the private key.
The routines egpuballoc, egpubfree, egprivalloc, and egprivfree are
provided to manage key storage.
Egsign signs message m using a private key k yielding a
struct EGsig
{
mpint *r, *s;
};
Egverify returns 0 if the signature is valid and -1 if not.
The routines egsigalloc and egsigfree are provided to manage signature
storage.
SOURCE
/sys/src/libsec
SEE ALSO
mp(2), aes(2), blowfish(2), des(2), dsa(2), rc4(2), rsa(2), sechash(2),
prime(2), rand(2)
ELGAMAL(2)