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#include <u.h>
#include <libc.h>
#include <mp.h>
#include <libsec.h>
#include <auth.h>
#include <thread.h>
#include <9pclient.h>
#include <bio.h>
void
usage(void)
{
fprint(2, "usage: 9 dsasign [-i id] [-v] key <data\n");
threadexitsall("usage");
}
static void doVerify(void);
static char *getline(int*);
char *id;
Biobuf b;
int nid;
char *key;
void
threadmain(int argc, char **argv)
{
int n, verify;
char *text, *p;
uchar digest[SHA1dlen];
AuthRpc *rpc;
Fmt fmt;
fmtinstall('[', encodefmt);
fmtinstall('H', encodefmt);
verify = 0;
id = "";
ARGBEGIN{
case 'i':
id = EARGF(usage());
break;
case 'v':
verify = 1;
break;
default:
usage();
}ARGEND
if(argc != 1)
usage();
key = argv[0];
nid = strlen(id);
Binit(&b, 0, OREAD);
if(verify) {
doVerify();
threadexitsall(nil);
}
if((rpc = auth_allocrpc()) == nil){
fprint(2, "dsasign: auth_allocrpc: %r\n");
threadexits("rpc");
}
key = smprint("proto=dsa role=sign %s", key);
if(auth_rpc(rpc, "start", key, strlen(key)) != ARok){
fprint(2, "dsasign: auth 'start' failed: %r\n");
auth_freerpc(rpc);
threadexits("rpc");
}
print("+%s\n", id);
Binit(&b, 0, OREAD);
fmtstrinit(&fmt);
while((p = getline(&n)) != nil) {
if(p[0] == '-' || p[0] == '+')
print("+");
print("%s\n", p);
fmtprint(&fmt, "%s\n", p);
}
text = fmtstrflush(&fmt);
sha1((uchar*)text, strlen(text), digest, nil);
if(auth_rpc(rpc, "write", digest, SHA1dlen) != ARok)
sysfatal("auth write in sign failed: %r");
if(auth_rpc(rpc, "read", nil, 0) != ARok)
sysfatal("auth read in sign failed: %r");
print("-%s %.*H\n", id, rpc->narg, rpc->arg);
threadexits(nil);
}
static mpint*
keytomp(Attr *a, char *name)
{
char *p;
mpint *m;
p = _strfindattr(a, name);
if(p == nil)
sysfatal("missing key attribute %s", name);
m = strtomp(p, nil, 16, nil);
if(m == nil)
sysfatal("malformed key attribute %s=%s", name, p);
return m;
}
static void
doVerify(void)
{
char *p;
int n, nsig;
Fmt fmt;
uchar digest[SHA1dlen], sig[1024];
char *text;
Attr *a;
DSAsig dsig;
DSApub dkey;
a = _parseattr(key);
if(a == nil)
sysfatal("invalid key");
dkey.alpha = keytomp(a, "alpha");
dkey.key = keytomp(a, "key");
dkey.p = keytomp(a, "p");
dkey.q = keytomp(a, "q");
if(!probably_prime(dkey.p, 20) && !probably_prime(dkey.q, 20))
sysfatal("p or q not prime");
while((p = getline(&n)) != nil)
if(p[0] == '+' && strcmp(p+1, id) == 0)
goto start;
sysfatal("no message found");
start:
fmtstrinit(&fmt);
while((p = getline(&n)) != nil) {
if(n >= 1+nid+1+16 && p[0] == '-' && strncmp(p+1, id, nid) == 0 && p[1+nid] == ' ') {
if((nsig = dec16(sig, sizeof sig, p+1+nid+1, n-(1+nid+1))) != 20+20)
sysfatal("malformed signture");
goto end;
}
if(p[0] == '+')
p++;
fmtprint(&fmt, "%s\n", p);
}
sysfatal("did not find end of message");
return; // silence clang warning
end:
text = fmtstrflush(&fmt);
sha1((uchar*)text, strlen(text), digest, nil);
if(nsig != 40)
sysfatal("malformed signature");
dsig.r = betomp(sig, 20, nil);
dsig.s = betomp(sig+20, 20, nil);
if(dsaverify(&dkey, &dsig, betomp(digest, sizeof digest, nil)) < 0)
sysfatal("signature failed to verify: %r");
write(1, text, strlen(text));
threadexitsall(0);
}
char*
getline(int *np)
{
char *p;
int n;
if((p = Brdline(&b, '\n')) == nil)
return nil;
n = Blinelen(&b);
while(n > 0 && (p[n-1] == '\n' || p[n-1] == ' ' || p[n-1] == '\t'))
n--;
p[n] = '\0';
*np = n;
return p;
}
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