ref: 75c92428225428c8fde2d015f010e608a0b12f1d
dir: purgatorio/man/2/crypt-dsagen
.TH CRYPT-DSAGEN 2
.SH NAME
crypt: dsagen, eggen, rsagen, rsafill, rsaencrypt, rsadecrypt \- specific public key systems
.SH SYNOPSIS
.EX
include "ipints.m";
ipints := load IPints IPints->PATH;
IPint: import ipints;
include "crypt.m";
crypt := load Crypt Crypt->PATH;
dsagen: fn(oldpk: ref PK.DSA): ref SK.DSA;
eggen: fn(nlen: int, nrep: int): ref SK.Elgamal;
rsagen: fn(nlen: int, elen: int, nrep: int): ref SK.RSA;
rsafill: fn(n: ref IPint, ek: ref IPint, dk: ref IPint,
p: ref IPint, q: ref IPint): ref SK.RSA;
rsaencrypt: fn(k: ref PK.RSA, m: ref IPint): ref IPint;
rsadecrypt: fn(k: ref SK.RSA, m: ref IPint): ref IPint;
.EE
.SH DESCRIPTION
.IR Crypt-gensk (2)
describes a set of functions that generate public/private key pairs given an algorithm name
and a key length.
Some key types allow further parameters for key generation or support further operations.
.PP
.B Dsagen
generates a DSA public/private key pair, represented by the pick adt
.BR SK.DSA ,
and compatible with the containing type
.BR SK .
If the parameter
.B oldpk
is not nil,
.B dsagen
takes the new key's modulus and group order from the existing key;
otherwise it generates a new pair of primes.
.PP
.B Eggen
generates a new El-Gamal key pair, represented by the pick adt
.BR SK.Elgamal .
.I Nlen
is the length of the modulus;
.I nrep
is the number of repetitions of the Miller-Rabin primality test (0 gives the default, currently 18).
.PP
.B Rsagen
generates an RSA public/private key pair, represented by the pick adt
.BR SK.RSA ,
and compatible with the containing type
.BR SK .
.I Nlen
gives the length of the key modulus in bits;
.I elen
gives the exponent length in bits; and
.I nrep
is as above.
.PP
The RSA private key representation used by Inferno includes some extra values to speed computation.
.B Rsagen
provides those values but keys imported from other systems might not.
Given the essential set of RSA private key parameters for a given key, represented as IPints,
.B rsafill
returns a suitable
.B SK.RSA
for that key, including the extra values.
.PP
The public key of type
.B PK.RSA
can be extracted from a given private key value
.I sk
by referencing the field
.BI sk .pk .
.PP
.B Rsaencrypt
encrypts a message
.IR m ,
represented by an IPint,
using the public key
.IR pk .
.PP
.B Rsadecrypt
decrypts
.I m
using private key
.IR sk .
The result is again returned as an IPint.
.SH SEE ALSO
.IR crypt-gensk (2),
.IR crypt-sha1 (2),
.IR security-auth (2),
.IR security-oldauth (2)