From 0a651bdd5356560dba8c2d6fa9d48469da200337 Mon Sep 17 00:00:00 2001
From: Sean Colyer <sean@colyer.name>
Date: Thu, 2 Feb 2012 00:28:24 -0500
Subject: [PATCH] Optimized string concatenation in symmetric encryption. Slow
 large file encryption led to investigating that string concatenation used was
 inefficient(switched to an array).

---
 resources/openpgp.js       | 12 +++++++++---
 resources/openpgp.min.js   |  4 ++--
 src/ciphers/openpgp.cfb.js | 11 ++++++++---
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/resources/openpgp.js b/resources/openpgp.js
index 740d61aa..a01e0103 100644
--- a/resources/openpgp.js
+++ b/resources/openpgp.js
@@ -8957,10 +8957,13 @@ function openpgp_cfb_encrypt(prefixrandom, blockcipherencryptfn, plaintext, bloc
 	    //	   that we have finished encrypting the 10 octets of prefixed data.
 	    // 	   This produces C11-C18, the next 8 octets of ciphertext.
 		for (var i = 2; i < block_size; i++) ciphertext += String.fromCharCode(FRE[i] ^ plaintext.charCodeAt(i));
-
+		var tempCiphertext = ciphertext.substring(0,2*block_size).split('');
+		//var tempCiphertextHeader = ciphertext.substring(0,block_size);
+		var tempCiphertextString = ciphertext.substring(block_size);
 		for(n=block_size; n<plaintext.length; n+=block_size) {
 			// 10. FR is loaded with C11-C18
-			for (var i = 0; i < block_size; i++) FR[i] = ciphertext.charCodeAt(n+i);
+			for (var i = 0; i < block_size; i++) FR[i] = tempCiphertextString.charCodeAt(i);
+			tempCiphertextString='';
 			
 			// 11. FR is encrypted to produce FRE.
 			FRE = blockcipherencryptfn(FR, key);
@@ -8968,8 +8971,11 @@ function openpgp_cfb_encrypt(prefixrandom, blockcipherencryptfn, plaintext, bloc
 			// 12. FRE is xored with the next 8 octets of plaintext, to produce the
 			//     next 8 octets of ciphertext.  These are loaded into FR and the
 			//     process is repeated until the plaintext is used up.
-			for (var i = 0; i < block_size; i++) ciphertext += String.fromCharCode(FRE[i] ^ plaintext.charCodeAt(n+i));
+			for (var i = 0; i < block_size; i++){ tempCiphertext.push(String.fromCharCode(FRE[i] ^ plaintext.charCodeAt(n+i)));
+			tempCiphertextString += String.fromCharCode(FRE[i] ^ plaintext.charCodeAt(n+i));
+			}
 		}
+		ciphertext = tempCiphertext.join('');
 		
 	}
 	return ciphertext;
diff --git a/resources/openpgp.min.js b/resources/openpgp.min.js
index bcf0fc52..d1e1d341 100644
--- a/resources/openpgp.min.js
+++ b/resources/openpgp.min.js
@@ -343,8 +343,8 @@ BigInteger.prototype.modInt=bnpModInt;BigInteger.prototype.millerRabin=bnpMiller
 BigInteger.prototype.xor=bnXor;BigInteger.prototype.andNot=bnAndNot;BigInteger.prototype.not=bnNot;BigInteger.prototype.shiftLeft=bnShiftLeft;BigInteger.prototype.shiftRight=bnShiftRight;BigInteger.prototype.getLowestSetBit=bnGetLowestSetBit;BigInteger.prototype.bitCount=bnBitCount;BigInteger.prototype.testBit=bnTestBit;BigInteger.prototype.setBit=bnSetBit;BigInteger.prototype.clearBit=bnClearBit;BigInteger.prototype.flipBit=bnFlipBit;BigInteger.prototype.add=bnAdd;BigInteger.prototype.subtract=bnSubtract;
 BigInteger.prototype.multiply=bnMultiply;BigInteger.prototype.divide=bnDivide;BigInteger.prototype.remainder=bnRemainder;BigInteger.prototype.divideAndRemainder=bnDivideAndRemainder;BigInteger.prototype.modPow=bnModPow;BigInteger.prototype.modInverse=bnModInverse;BigInteger.prototype.pow=bnPow;BigInteger.prototype.gcd=bnGCD;BigInteger.prototype.isProbablePrime=bnIsProbablePrime;BigInteger.prototype.toMPI=bnToMPI;BigInteger.prototype.square=bnSquare;
 function openpgp_cfb_encrypt(a,b,c,d,e,f){var g=Array(d),h=Array(d),a=a+a.charAt(d-2)+a.charAt(d-1);util.print_debug("prefixrandom:"+util.hexstrdump(a));for(var k="",l=0;l<d;l++)g[l]=0;h=b(g,e);for(l=0;l<d;l++)k+=String.fromCharCode(h[l]^a.charCodeAt(l));for(l=0;l<d;l++)g[l]=k.charCodeAt(l);h=b(g,e);k+=String.fromCharCode(h[0]^a.charCodeAt(d));k+=String.fromCharCode(h[1]^a.charCodeAt(d+1));if(f)for(l=0;l<d;l++)g[l]=k.charCodeAt(l+2);else for(l=0;l<d;l++)g[l]=k.charCodeAt(l);h=b(g,e);if(f){for(l=0;l<
-d;l++)k+=String.fromCharCode(h[l]^c.charCodeAt(l));for(n=d+2;n<c.length;n+=d){for(l=0;l<d;l++)g[l]=k.charCodeAt(n+l);h=b(g,e);for(l=0;l<d;l++)k+=String.fromCharCode(h[l]^c.charCodeAt(n-2+l))}}else{c="  "+c;for(l=2;l<d;l++)k+=String.fromCharCode(h[l]^c.charCodeAt(l));for(n=d;n<c.length;n+=d){for(l=0;l<d;l++)g[l]=k.charCodeAt(n+l);h=b(g,e);for(l=0;l<d;l++)k+=String.fromCharCode(h[l]^c.charCodeAt(n+l))}}return k}
-function openpgp_cfb_mdc(a,b,c,d){var e=Array(b),f=Array(b),g;for(g=0;g<b;g++)e[g]=0;e=a(e,c);for(g=0;g<b;g++)f[g]=d.charCodeAt(g),e[g]^=f[g];f=a(f,c);return util.bin2str(e)+String.fromCharCode(f[0]^d.charCodeAt(b))+String.fromCharCode(f[1]^d.charCodeAt(b+1))}
+d;l++)k+=String.fromCharCode(h[l]^c.charCodeAt(l));for(n=d+2;n<c.length;n+=d){for(l=0;l<d;l++)g[l]=k.charCodeAt(n+l);h=b(g,e);for(l=0;l<d;l++)k+=String.fromCharCode(h[l]^c.charCodeAt(n-2+l))}}else{c="  "+c;for(l=2;l<d;l++)k+=String.fromCharCode(h[l]^c.charCodeAt(l));a=k.substring(0,2*d).split("");k=k.substring(d);for(n=d;n<c.length;n+=d){for(l=0;l<d;l++)g[l]=k.charCodeAt(l);k="";h=b(g,e);for(l=0;l<d;l++)a.push(String.fromCharCode(h[l]^c.charCodeAt(n+l))),k+=String.fromCharCode(h[l]^c.charCodeAt(n+
+l))}k=a.join("")}return k}function openpgp_cfb_mdc(a,b,c,d){var e=Array(b),f=Array(b),g;for(g=0;g<b;g++)e[g]=0;e=a(e,c);for(g=0;g<b;g++)f[g]=d.charCodeAt(g),e[g]^=f[g];f=a(f,c);return util.bin2str(e)+String.fromCharCode(f[0]^d.charCodeAt(b))+String.fromCharCode(f[1]^d.charCodeAt(b+1))}
 function openpgp_cfb_decrypt(a,b,c,d,e){util.print_debug("resync:"+e);var f=Array(b),g=Array(b),h,k="";for(h=0;h<b;h++)f[h]=0;f=a(f,c);for(h=0;h<b;h++)g[h]=d.charCodeAt(h),f[h]^=g[h];g=a(g,c);util.print_debug("openpgp_cfb_decrypt:\niblock:"+util.hexidump(f)+"\nablock:"+util.hexidump(g)+"\n");util.print_debug((g[0]^d.charCodeAt(b)).toString(16)+(g[1]^d.charCodeAt(b+1)).toString(16));if(f[b-2]!=(g[0]^d.charCodeAt(b))||f[b-1]!=(g[1]^d.charCodeAt(b+1)))return util.print_eror("error duding decryption. Symmectric encrypted data not valid."),
 k;if(e){for(h=0;h<b;h++)f[h]=d.charCodeAt(h+2);e=b+2}else{for(h=0;h<b;h++)f[h]=d.charCodeAt(h);e=b}for(;e<d.length;e+=b){g=a(f,c);for(h=0;h<b&&h+e<d.length;h++)f[h]=d.charCodeAt(e+h),k+=String.fromCharCode(g[h]^f[h])}return k}function normal_cfb_encrypt(a,b,c,d,e){var f=0,g="";for(""[h]=e.substring(0,b);d.length>b*f;){blocka=d.substring(f*b,f*b+b);a("",c);for(var h=0;h<blocka.size;h++)""[h]=blocka^enblock();g+="";f++}return g}
 function normal_cfb_decrypt(a,b,c,d,e){var f="",g=0,h="";if(null==e)for(e=0;e<b;e++)f+=String.fromCharCode(0);else f=e.substring(0,b);for(;d.length>b*g;){for(var k=a(f,c),f=d.substring(g*b+0,g*b+b+0),e=0;e<f.length;e++)h+=String.fromCharCode(f.charCodeAt(e)^k[e]);g++}return h}
diff --git a/src/ciphers/openpgp.cfb.js b/src/ciphers/openpgp.cfb.js
index 5078c6e6..118dc504 100644
--- a/src/ciphers/openpgp.cfb.js
+++ b/src/ciphers/openpgp.cfb.js
@@ -102,10 +102,12 @@ function openpgp_cfb_encrypt(prefixrandom, blockcipherencryptfn, plaintext, bloc
 	    //	   that we have finished encrypting the 10 octets of prefixed data.
 	    // 	   This produces C11-C18, the next 8 octets of ciphertext.
 		for (var i = 2; i < block_size; i++) ciphertext += String.fromCharCode(FRE[i] ^ plaintext.charCodeAt(i));
-
+		var tempCiphertext = ciphertext.substring(0,2*block_size).split('');
+		var tempCiphertextString = ciphertext.substring(block_size);
 		for(n=block_size; n<plaintext.length; n+=block_size) {
 			// 10. FR is loaded with C11-C18
-			for (var i = 0; i < block_size; i++) FR[i] = ciphertext.charCodeAt(n+i);
+			for (var i = 0; i < block_size; i++) FR[i] = tempCiphertextString.charCodeAt(i);
+			tempCiphertextString='';
 			
 			// 11. FR is encrypted to produce FRE.
 			FRE = blockcipherencryptfn(FR, key);
@@ -113,8 +115,11 @@ function openpgp_cfb_encrypt(prefixrandom, blockcipherencryptfn, plaintext, bloc
 			// 12. FRE is xored with the next 8 octets of plaintext, to produce the
 			//     next 8 octets of ciphertext.  These are loaded into FR and the
 			//     process is repeated until the plaintext is used up.
-			for (var i = 0; i < block_size; i++) ciphertext += String.fromCharCode(FRE[i] ^ plaintext.charCodeAt(n+i));
+			for (var i = 0; i < block_size; i++){ tempCiphertext.push(String.fromCharCode(FRE[i] ^ plaintext.charCodeAt(n+i)));
+			tempCiphertextString += String.fromCharCode(FRE[i] ^ plaintext.charCodeAt(n+i));
+			}
 		}
+		ciphertext = tempCiphertext.join('');
 		
 	}
 	return ciphertext;