From 12bb7bcfff4db1b122c4643859f3d4f1420fba38 Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Wed, 29 Apr 2015 02:58:10 +0200
Subject: [PATCH] libsec: remove aesCTRencrypt()/aesCTRdecrypt() (thanks
 mischief and qrstuv)

as mischief and qrstuv point out, these functions are not very usefull
and are even implemented wrong (incrementCTR()), so deleting the code.
---
 sys/include/libsec.h      |  3 ---
 sys/man/2/aes             | 15 +----------
 sys/src/libsec/port/aes.c | 55 ---------------------------------------
 3 files changed, 1 insertion(+), 72 deletions(-)

diff --git a/sys/include/libsec.h b/sys/include/libsec.h
index 4ab074fdb..ccebac087 100644
--- a/sys/include/libsec.h
+++ b/sys/include/libsec.h
@@ -23,7 +23,6 @@ struct AESstate
 	ulong	setup;
 	int	rounds;
 	int	keybytes;
-	uint	ctrsz;
 	uchar	key[AESmaxkey];			/* unexpanded key */
 	ulong	ekey[4*(AESmaxrounds + 1)];	/* encryption key */
 	ulong	dkey[4*(AESmaxrounds + 1)];	/* decryption key */
@@ -38,8 +37,6 @@ void	aes_decrypt(ulong rk[], int Nr, uchar ct[16], uchar pt[16]);
 void	setupAESstate(AESstate *s, uchar key[], int keybytes, uchar *ivec);
 void	aesCBCencrypt(uchar *p, int len, AESstate *s);
 void	aesCBCdecrypt(uchar *p, int len, AESstate *s);
-void	aesCTRdecrypt(uchar *p, int len, AESstate *s);
-void	aesCTRencrypt(uchar *p, int len, AESstate *s);
 
 void	setupAESXCBCstate(AESstate *s);
 uchar*	aesXCBCmac(uchar *p, int len, AESstate *s);
diff --git a/sys/man/2/aes b/sys/man/2/aes
index caae33630..fd5438bdf 100644
--- a/sys/man/2/aes
+++ b/sys/man/2/aes
@@ -1,6 +1,6 @@
 .TH AES 2
 .SH NAME
-setupAESstate, aesCBCencrypt, aesCBCdecrypt, aesCTRencrypt, aesCTRdecrypt, setupAESXCBCstate, aesXCBCmac - advanced encryption standard (rijndael)
+setupAESstate, aesCBCencrypt, aesCBCdecrypt, setupAESXCBCstate, aesXCBCmac - advanced encryption standard (rijndael)
 .SH SYNOPSIS
 .B #include <u.h>
 .br
@@ -28,12 +28,6 @@ void	aesCBCencrypt(uchar *p, int len, AESstate *s)
 void	aesCBCdecrypt(uchar *p, int len, AESstate *s)
 .PP
 .B
-void	aesCTRencrypt(uchar *p, int len, AESstate *s)
-.PP
-.B
-void	aesCTRdecrypt(uchar *p, int len, AESstate *s)
-.PP
-.B
 void	setupAESXCBCstate(AESstate *s)
 .PP
 .B
@@ -52,11 +46,6 @@ are the block ciphers, corresponding to
 and
 .I aesCBCdecrypt
 implement cipher-block-chaining encryption.
-.I AesCTRencrypt
-and
-.I aesCTRdecrypt
-implement counter mode, per RFC 3686;
-they are identical operations.
 .I setupAESXCBCstate
 and
 .I aesXCBCmac
@@ -93,8 +82,6 @@ in
 The functions
 .IR aes_encrypt ,
 .IR aes_decrypt ,
-.IR aesCTRencrypt ,
-.IR aesCTRdecrypt ,
 .IR setupAESXCBCstate ,
 and
 .IR aesXCBCmac
diff --git a/sys/src/libsec/port/aes.c b/sys/src/libsec/port/aes.c
index c90eb10ab..9dcf26547 100644
--- a/sys/src/libsec/port/aes.c
+++ b/sys/src/libsec/port/aes.c
@@ -220,61 +220,6 @@ aesCBCdecrypt(uchar *p, int len, AESstate *s)
 	}
 }
 
-/*
- * AES-CTR mode, per rfc3686.
- * CTRs could be precalculated for efficiency
- * and there would also be less back and forth mp
- */
-
-static void
-incrementCTR(uchar *p, uint ctrsz)
-{
-	int len;
-	uchar *ctr;
-	mpint *mpctr, *mpctrsz;
-
-	ctr = p + AESbsize - ctrsz;
-	mpctr = betomp(ctr, ctrsz, nil);
-	mpctrsz = itomp(1 << (ctrsz*8), nil);
-	mpadd(mpctr, mpone, mpctr);
-	mpmod(mpctr, mpctrsz, mpctr);
-	len = mptobe(mpctr, ctr, ctrsz, nil);
-	assert(len == ctrsz);
-	mpfree(mpctrsz);
-	mpfree(mpctr);
-}
-
-void
-aesCTRencrypt(uchar *p, int len, AESstate *s)
-{
-	uchar q[AESbsize];
-	uchar *ip, *eip, *ctr;
-
-	ctr = s->ivec;
-	for(; len >= AESbsize; len -= AESbsize){
-		ip = q;
-		aes_encrypt(s->ekey, s->rounds, ctr, q);
-		for(eip = p + AESbsize; p < eip; )
-			*p++ ^= *ip++;
-		incrementCTR(ctr, s->ctrsz);
-	}
-
-	if(len > 0){
-		ip = q;
-		aes_encrypt(s->ekey, s->rounds, ctr, q);
-		for(eip = p + len; p < eip; )
-			*p++ ^= *ip++;
-		incrementCTR(ctr, s->ctrsz);
-	}
-}
-
-void
-aesCTRdecrypt(uchar *p, int len, AESstate *s)
-{
-	aesCTRencrypt(p, len, s);
-}
-
-
 /* taken from sha1; TODO: verify suitability (esp. byte order) for aes */
 /*
  *	encodes input (ulong) into output (uchar). Assumes len is