new auth

src/cmd/auth/factotum/rsa.c

@@ -0,0 +1,191 @@
+#include "std.h"
+#include "dat.h"
+
+/*
+ * RSA authentication.
+ * 
+ * Client:
+ *	start n=xxx ek=xxx
+ *	write msg
+ *	read decrypt(msg)
+ *
+ * Sign (PKCS #1 using hash=sha1 or hash=md5)
+ *	start n=xxx ek=xxx
+ *	write hash(msg)
+ *	read signature(hash(msg))
+ * 
+ * all numbers are hexadecimal biginits parsable with strtomp.
+ * must be lower case for attribute matching in start.
+ */
+
+static int
+rsaclient(Conv *c)
+{
+	char *chal;
+	mpint *m;
+	Key *k;
+
+	k = keylookup("%A", c->attr);
+	if(k == nil)
+		return -1;
+	c->state = "read challenge";
+	if(convreadm(c, &chal) < 0){
+		keyclose(k);
+		return -1;
+	}
+	if(strlen(chal) < 32){
+	badchal:
+		free(chal);
+		convprint(c, "bad challenge");
+		keyclose(k);
+		return -1;
+	}
+	m = strtomp(chal, nil, 16, nil);
+	if(m == nil)
+		goto badchal;
+	free(chal);
+	m = rsadecrypt(k->priv, m, m);
+	convprint(c, "%B", m);
+	mpfree(m);
+	keyclose(k);
+	return 0;
+}
+
+static int
+xrsasign(Conv *c)
+{
+	char *hash;
+	int dlen, n;
+	DigestAlg *hashfn;
+	Key *k;
+	uchar sig[1024], digest[64];
+
+	k = keylookup("%A", c->attr);
+	if(k == nil)
+		return -1;
+	hash = strfindattr(k->attr, "hash");
+	if(hash == nil)
+		hash = "sha1";
+	if(strcmp(hash, "sha1") == 0){
+		hashfn = sha1;
+		dlen = SHA1dlen;
+	}else if(strcmp(hash, "md5") == 0){
+		hashfn = md5;
+		dlen = MD5dlen;
+	}else{
+		werrstr("unknown hash function %s", hash);
+		return -1;
+	}
+	c->state = "read data";
+	if((n=convread(c, digest, dlen)) < 0){
+		keyclose(k);
+		return -1;
+	}
+	memset(sig, 0xAA, sizeof sig);
+	n = rsasign(k->priv, hashfn, digest, dlen, sig, sizeof sig);
+	keyclose(k);
+	if(n < 0)
+		return -1;	
+	convwrite(c, sig, n);
+	return 0;
+}
+
+/*
+ * convert to canonical form (lower case) 
+ * for use in attribute matches.
+ */
+static void
+strlwr(char *a)
+{
+	for(; *a; a++){
+		if('A' <= *a && *a <= 'Z')
+			*a += 'a' - 'A';
+	}
+}
+
+static RSApriv*
+readrsapriv(Key *k)
+{
+	char *a;
+	RSApriv *priv;
+
+	priv = rsaprivalloc();
+
+	if((a=strfindattr(k->attr, "ek"))==nil 
+	|| (priv->pub.ek=strtomp(a, nil, 16, nil))==nil)
+		goto Error;
+	strlwr(a);
+	if((a=strfindattr(k->attr, "n"))==nil 
+	|| (priv->pub.n=strtomp(a, nil, 16, nil))==nil)
+		goto Error;
+	strlwr(a);
+	if((a=strfindattr(k->privattr, "!p"))==nil 
+	|| (priv->p=strtomp(a, nil, 16, nil))==nil)
+		goto Error;
+	strlwr(a);
+	if((a=strfindattr(k->privattr, "!q"))==nil 
+	|| (priv->q=strtomp(a, nil, 16, nil))==nil)
+		goto Error;
+	strlwr(a);
+	if((a=strfindattr(k->privattr, "!kp"))==nil 
+	|| (priv->kp=strtomp(a, nil, 16, nil))==nil)
+		goto Error;
+	strlwr(a);
+	if((a=strfindattr(k->privattr, "!kq"))==nil 
+	|| (priv->kq=strtomp(a, nil, 16, nil))==nil)
+		goto Error;
+	strlwr(a);
+	if((a=strfindattr(k->privattr, "!c2"))==nil 
+	|| (priv->c2=strtomp(a, nil, 16, nil))==nil)
+		goto Error;
+	strlwr(a);
+	if((a=strfindattr(k->privattr, "!dk"))==nil 
+	|| (priv->dk=strtomp(a, nil, 16, nil))==nil)
+		goto Error;
+	strlwr(a);
+	return priv;
+
+Error:
+	rsaprivfree(priv);
+	return nil;
+}
+
+static int
+rsacheck(Key *k)
+{
+	static int first = 1;
+	
+	if(first){
+		fmtinstall('B', mpfmt);
+		first = 0;
+	}
+
+	if((k->priv = readrsapriv(k)) == nil){
+		werrstr("malformed key data");
+		return -1;
+	}
+	return 0;
+}
+
+static void
+rsaclose(Key *k)
+{
+	rsaprivfree(k->priv);
+	k->priv = nil;
+}
+
+static Role
+rsaroles[] = 
+{
+	"client",	rsaclient,
+	"sign",	xrsasign,
+	0
+};
+
+Proto rsa = {
+	"rsa",
+	rsaroles,
+	nil,
+	rsacheck,
+	rsaclose
+};