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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.

--- a/sys/include/libsec.h

+++ b/sys/include/libsec.h

@@ -23,7 +23,6 @@

 	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	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);

--- 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	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 @@

 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 @@

 The functions

 .IR aes_encrypt ,

 .IR aes_decrypt ,

-.IR aesCTRencrypt ,

-.IR aesCTRdecrypt ,

 .IR setupAESXCBCstate ,

 and

 .IR aesXCBCmac

--- a/sys/src/libsec/port/aes.c

+++ b/sys/src/libsec/port/aes.c

@@ -220,61 +220,6 @@

 	}

 }

-/*

- * 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