126 lines
2.1 KiB
Plaintext
126 lines
2.1 KiB
Plaintext
|
.TH ELGAMAL 2
|
||
|
|
.SH NAME
|
||
|
|
eggen, egencrypt, egdecrypt, egsign, egverify, egpuballoc, egpubfree, egprivalloc, egprivfree, egsigalloc, egsigfree, egprivtopub - elgamal encryption
|
||
|
|
.SH SYNOPSIS
|
||
|
|
.B #include <u.h>
|
||
|
|
.br
|
||
|
|
.B #include <libc.h>
|
||
|
|
.br
|
||
|
|
.B #include <mp.h>
|
||
|
|
.br
|
||
|
|
.B #include <libsec.h>
|
||
|
|
.PP
|
||
|
|
.B
|
||
|
|
EGpriv* eggen(int nlen, int nrep)
|
||
|
|
.PP
|
||
|
|
.B
|
||
|
|
mpint* egencrypt(EGpub *k, mpint *in, mpint *out)
|
||
|
|
.PP
|
||
|
|
.B
|
||
|
|
mpint* egdecrypt(EGpriv *k, mpint *in, mpint *out)
|
||
|
|
.PP
|
||
|
|
.B
|
||
|
|
EGsig* egsign(EGpriv *k, mpint *m)
|
||
|
|
.PP
|
||
|
|
.B
|
||
|
|
int egverify(EGpub *k, EGsig *sig, mpint *m)
|
||
|
|
.PP
|
||
|
|
.B
|
||
|
|
EGpub* egpuballoc(void)
|
||
|
|
.PP
|
||
|
|
.B
|
||
|
|
void egpubfree(EGpub*)
|
||
|
|
.PP
|
||
|
|
.B
|
||
|
|
EGpriv* egprivalloc(void)
|
||
|
|
.PP
|
||
|
|
.B
|
||
|
|
void egprivfree(EGpriv*)
|
||
|
|
.PP
|
||
|
|
.B
|
||
|
|
EGsig* egsigalloc(void)
|
||
|
|
.PP
|
||
|
|
.B
|
||
|
|
void egsigfree(EGsig*)
|
||
|
|
.PP
|
||
|
|
.B
|
||
|
|
EGpub* egprivtopub(EGpriv*)
|
||
|
|
.SH DESCRIPTION
|
||
|
|
.PP
|
||
|
|
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
|
||
|
|
};
|
||
|
|
.EE
|
||
|
|
This part can be used for encrypting data (with
|
||
|
|
.IR egencrypt )
|
||
|
|
to be sent to the owner.
|
||
|
|
The owner decrypts (with
|
||
|
|
.IR egdecrypt )
|
||
|
|
using his private key:
|
||
|
|
.EX
|
||
|
|
struct EGpriv
|
||
|
|
{
|
||
|
|
EGpub pub;
|
||
|
|
mpint *secret; // (decryption key)
|
||
|
|
};
|
||
|
|
.EE
|
||
|
|
.PP
|
||
|
|
Keys are generated using
|
||
|
|
.IR eggen .
|
||
|
|
.I 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.
|
||
|
|
.I Egprivtopub
|
||
|
|
returns a newly allocated copy of the public key
|
||
|
|
corresponding to the private key.
|
||
|
|
.PP
|
||
|
|
The routines
|
||
|
|
.IR egpuballoc ,
|
||
|
|
.IR egpubfree ,
|
||
|
|
.IR egprivalloc ,
|
||
|
|
and
|
||
|
|
.I egprivfree
|
||
|
|
are provided to manage key storage.
|
||
|
|
.PP
|
||
|
|
.I Egsign
|
||
|
|
signs message
|
||
|
|
.I m
|
||
|
|
using a private key
|
||
|
|
.I k
|
||
|
|
yielding a
|
||
|
|
.EX
|
||
|
|
struct EGsig
|
||
|
|
{
|
||
|
|
mpint *r, *s;
|
||
|
|
};
|
||
|
|
.EE
|
||
|
|
.I Egverify
|
||
|
|
returns 0 if the signature is valid and \-1 if not.
|
||
|
|
.PP
|
||
|
|
The routines
|
||
|
|
.I egsigalloc
|
||
|
|
and
|
||
|
|
.I egsigfree
|
||
|
|
are provided to manage signature storage.
|
||
|
|
.SH SOURCE
|
||
|
|
.B /sys/src/libsec
|
||
|
|
.SH SEE ALSO
|
||
|
|
.IR mp (2),
|
||
|
|
.IR aes (2),
|
||
|
|
.IR blowfish (2),
|
||
|
|
.IR des (2),
|
||
|
|
.IR dsa (2),
|
||
|
|
.IR rc4 (2),
|
||
|
|
.IR rsa (2),
|
||
|
|
.IR sechash (2),
|
||
|
|
.IR prime (2),
|
||
|
|
.IR rand (2)
|