From 68d8da485990e39de38300e9729e4d3e6dbee80c Mon Sep 17 00:00:00 2001
From: Martin Nilsson <nilsson@opera.com>
Date: Sat, 26 Jul 2014 02:07:48 +0200
Subject: [PATCH] Optimized rsa_unpad a bit.
---
src/post_modules/Nettle/hogweed.cmod | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/src/post_modules/Nettle/hogweed.cmod b/src/post_modules/Nettle/hogweed.cmod
index e37eec7831..5af48a54c6 100644
--- a/src/post_modules/Nettle/hogweed.cmod
+++ b/src/post_modules/Nettle/hogweed.cmod
@@ -187,9 +187,16 @@ PIKEFUN array(object(Gmp.mpz))
stack_pop_n_elems_keep_top(args); /* Remove bits, e and rnd. */
}
+/*! Unpads a message that has been padded according to
+ *! RSAES-PKCS1-V1_5-ENCODE(message) in PKCS#1 v2.2. The padding
+ *! method used on the original message must be provided in the
+ *! @[type] parameter. All content dependent processing is done in
+ *! constant time for the same padding type and @[data] length.
+ */
PIKEFUN int rsa_unpad(string(0..255) data, int type)
{
int i, pad=0, nonpad=0, pos=0;
+ unsigned char *str;
NO_WIDE_STRING(data);
@@ -197,10 +204,11 @@ PIKEFUN int rsa_unpad(string(0..255) data, int type)
without timing issue. 1 type + 8 padding + 1 delimiter + 1 value
= 11 bytes. */
if(data->len < 11 ) RETURN 0;
+ str = data->str + data->len - 1;
- for(i=data->len-1; i>0; i--)
+ for(i=data->len-1; i>0; i--,str--)
{
- switch((unsigned char)data->str[i])
+ switch(*str)
{
case 0: pos=i; break;
case 0xff: pad=i; break;
@@ -208,13 +216,13 @@ PIKEFUN int rsa_unpad(string(0..255) data, int type)
}
}
- if( data->str[0]==2 )
+ if( *str==2 )
{
nonpad=pos+1;
pad=1;
}
- if( (pad==1) + (nonpad>pos) + (data->str[0]==type) + (pos>8) == 4 )
+ if( (pad==1) + (nonpad>pos) + (*str==type) + (pos>8) == 4 )
RETURN pos+1;
RETURN 0;
}
--
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