9srv Manual Collection/plan9/elgamal(2) 9srv Manual Collection/plan9/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 corresponding 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)

9srv Manual Collection/plan9/elgamal(2) Rev:  Sun Dec 02 23:42:20 GMT 2007