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125 lines
2.1 KiB
Groff
125 lines
2.1 KiB
Groff
.TH ELGAMAL 3
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.SH NAME
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eggen, egencrypt, egdecrypt, egsign, egverify, egpuballoc, egpubfree, egprivalloc, egprivfree, egsigalloc, egsigfree, egprivtopub - elgamal encryption
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.SH SYNOPSIS
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.B #include <u.h>
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.br
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.B #include <libc.h>
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.br
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.B #include <mp.h>
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.br
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.B #include <libsec.h>
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.PP
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.B
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EGpriv* eggen(int nlen, int nrep)
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.PP
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.B
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mpint* egencrypt(EGpub *k, mpint *in, mpint *out)
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.PP
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.B
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mpint* egdecrypt(EGpriv *k, mpint *in, mpint *out)
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.PP
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.B
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EGsig* egsign(EGpriv *k, mpint *m)
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.PP
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.B
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int egverify(EGpub *k, EGsig *sig, mpint *m)
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.PP
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.B
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EGpub* egpuballoc(void)
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.PP
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.B
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void egpubfree(EGpub*)
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.PP
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.B
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EGpriv* egprivalloc(void)
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.PP
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.B
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void egprivfree(EGpriv*)
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.PP
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.B
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EGsig* egsigalloc(void)
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.PP
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.B
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void egsigfree(EGsig*)
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.PP
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.B
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EGpub* egprivtopub(EGpriv*)
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.SH DESCRIPTION
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.PP
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Elgamal is a public key encryption and signature algorithm. The owner of a key publishes
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the public part of the key:
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.EX
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struct EGpub
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{
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mpint *p; // modulus
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mpint *alpha; // generator
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mpint *key; // (encryption key) alpha**secret mod p
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};
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.EE
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This part can be used for encrypting data (with
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.IR egencrypt )
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to be sent to the owner.
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The owner decrypts (with
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.IR egdecrypt )
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using his private key:
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.EX
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struct EGpriv
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{
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EGpub pub;
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mpint *secret; // (decryption key)
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};
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.EE
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.PP
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Keys are generated using
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.IR eggen .
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.I Eggen
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takes both bit length of the modulus
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and the number of repetitions of the Miller-Rabin
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primality test to run. If the latter is 0, it does the default number
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of rounds.
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.I Egprivtopub
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returns a newly allocated copy of the public key
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corresponding to the private key.
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.PP
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The routines
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.IR egpuballoc ,
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.IR egpubfree ,
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.IR egprivalloc ,
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and
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.I egprivfree
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are provided to manage key storage.
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.PP
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.I Egsign
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signs message
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.I m
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using a private key
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.I k
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yielding a
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.EX
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struct EGsig
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{
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mpint *r, *s;
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};
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.EE
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.I Egverify
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returns 0 if the signature is valid and \-1 if not.
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.PP
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The routines
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.I egsigalloc
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and
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.I egsigfree
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are provided to manage signature storage.
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.SH SOURCE
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.B \*9/src/libsec
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.SH SEE ALSO
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.MR mp (3) ,
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.MR aes (3) ,
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.MR blowfish (3) ,
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.MR des (3) ,
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.MR dsa (3) ,
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.MR rc4 (3) ,
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.MR rsa (3) ,
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.MR sechash (3) ,
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.MR prime (3) ,
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.MR rand (3)
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