#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*)
Elgamal is a public key encryption and signature algorithm. The owner of a key publishes the public part of the key: .EX 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: .EX 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 .EX 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.