From c4e0299bc4771356a19e29b33230033a2796bab2 Mon Sep 17 00:00:00 2001
From: Martin Nilsson <nilsson@opera.com>
Date: Sat, 26 Jul 2014 06:09:04 +0200
Subject: [PATCH] More internal documentation of rsa_pad.
---
lib/modules/Crypto.pmod/RSA.pike | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/lib/modules/Crypto.pmod/RSA.pike b/lib/modules/Crypto.pmod/RSA.pike
index 3e7d5b7896..181e02c4f5 100644
--- a/lib/modules/Crypto.pmod/RSA.pike
+++ b/lib/modules/Crypto.pmod/RSA.pike
@@ -374,9 +374,12 @@ int(0..) key_size() { return [int(0..)](size*8); }
Gmp.mpz rsa_pad(string(8bit) message, int(1..2) type,
function(int(0..):string(8bit))|void random)
{
- string(8bit) cookie = "";
+ string(8bit) padding = "";
- // Padding length. At least 8 bytes as security margin.
+ // Padding length: RSA size - message size - 3 bytes; delimiter,
+ // padding type and leading null (not explicitly coded, as Gmp.mpz
+ // does the right thing anyway). Require at least 8 bytes of padding
+ // as security margin.
int len = size - 3 - sizeof(message);
if (len < 8)
error( "Block too large. (%d>%d)\n", sizeof(message), size-11 );
@@ -384,18 +387,18 @@ Gmp.mpz rsa_pad(string(8bit) message, int(1..2) type,
switch(type)
{
case 1:
- cookie = sprintf("%@c", allocate(len, 0xff));
+ padding = sprintf("%@c", allocate(len, 0xff));
break;
case 2:
if( !random ) random = this_program::random;
do {
- cookie += random([int(0..)](len-sizeof(cookie))) - "\0";
- } while( sizeof(cookie)<len );
+ padding += random([int(0..)](len-sizeof(padding))) - "\0";
+ } while( sizeof(padding)<len );
break;
default:
error( "Unknown type.\n" );
}
- return Gmp.mpz(sprintf("%c", type) + cookie + "\0" + message, 256);
+ return Gmp.mpz(sprintf("%c", type) + padding + "\0" + message, 256);
}
//! Reverse the effect of @[rsa_pad].
--
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