Index: modules/aes/aes.tcl
==================================================================
--- modules/aes/aes.tcl
+++ modules/aes/aes.tcl
@@ -105,11 +105,14 @@
     }
 
     variable uid
     set Key [namespace current]::[incr uid]
     upvar #0 $Key state
-    array set state [list M $mode K $key I $iv Nk $Nk Nr $Nr Nb $Nb W {}]
+    if {[binary scan $iv Iu4 state(I)] != 1} {
+        return -code error "invalid initialization vector: must be 16 bytes"
+    }
+    array set state [list M $mode K $key Nk $Nk Nr $Nr Nb $Nb W {}]
     ExpandKey $Key
     return $Key
 }
 
 # aes::Reset --
@@ -118,11 +121,13 @@
 #	key to be reused for encryption or decryption without the expense of
 #	re-calculating the key schedule.
 #
 proc ::aes::Reset {Key iv} {
     upvar #0 $Key state
-    set state(I) $iv
+    if {[binary scan $iv Iu4 state(I)] != 1} {
+        return -code error "invalid initialization vector: must be 16 bytes"
+    }
     return
 }
     
 # aes::Final --
 #
@@ -136,20 +141,17 @@
 # -------------------------------------------------------------------------
 
 # 5.1 Cipher:  Encipher a single block of 128 bits.
 proc ::aes::EncryptBlock {Key block} {
     upvar #0 $Key state
-    if {[binary scan $block I4 data] != 1} {
+    if {[binary scan $block Iu4 data] != 1} {
         return -code error "invalid block size: blocks must be 16 bytes"
     }
 
     if {[string equal $state(M) cbc]} {
-        if {[binary scan $state(I) I4 iv] != 1} {
-            return -code error "invalid initialization vector: must be 16 bytes"
-        }
         for {set n 0} {$n < 4} {incr n} {
-            lappend data2 [expr {0xffffffff & ([lindex $data $n] ^ [lindex $iv $n])}]
+            lappend data2 [expr {0xffffffff & ([lindex $data $n] ^ [lindex $state(I) $n])}]
         }
         set data $data2
     }
 
     set data [AddRoundKey $Key 0 $data]
@@ -162,35 +164,33 @@
     # Force all elements of data into the 32bit range.
     set res {}
     foreach d $data {
         lappend res [expr {$d & 0xffffffff}]
     }
-    set data $res
-    
-    return [set state(I) [binary format I4 $data]]
-}
+
+    set state(I) $res
+    return [binary format Iu4 $res]
+#}
 
 # 5.3: Inverse Cipher: Decipher a single 128 bit block.
 proc ::aes::DecryptBlock {Key block} {
     upvar #0 $Key state
-    if {[binary scan $block I4 data] != 1} {
+    if {[binary scan $block Iu4 data] != 1} {
         return -code error "invalid block size: block must be 16 bytes"
     }
+    set iv $data
 
     set n $state(Nr)
     set data [AddRoundKey $Key $state(Nr) $data]
     for {incr n -1} {$n > 0} {incr n -1} {
         set data [InvMixColumns [AddRoundKey $Key $n [InvSubBytes [InvShiftRows $data]]]]
     }
     set data [AddRoundKey $Key $n [InvSubBytes [InvShiftRows $data]]]
     
     if {[string equal $state(M) cbc]} {
-        if {[binary scan $state(I) I4 iv] != 1} {
-            return -code error "invalid initialization vector: must be 16 bytes"
-        }
         for {set n 0} {$n < 4} {incr n} {
-            lappend data2 [expr {0xffffffff & ([lindex $data $n] ^ [lindex $iv $n])}]
+            lappend data2 [expr {0xffffffff & ([lindex $data $n] ^ [lindex $state(I) $n])}]
         }
         set data $data2
     } else {
         # Bug 2993029:
         # Force all elements of data into the 32bit range.
@@ -200,12 +200,12 @@
             lappend res [expr {$d & 0xffffffff}]
         }
         set data $res
     }
 
-    set state(I) $block
-    return [binary format I4 $data]
+    set state(I) $iv
+    return [binary format Iu4 $data]
 }
 
 # 5.2: KeyExpansion
 proc ::aes::ExpandKey {Key} {
     upvar #0 $Key state
@@ -433,13 +433,13 @@
         append result [EncryptBlock $Key $block]
     }
     return $result
 }
 
-# aes::DecryptBlock --
+# aes::Decrypt --
 #
-#	Decrypt a blocks of cipher text and returns blocks of plain text.
+#	Decrypt blocks of cipher text and returns blocks of plain text.
 #	The input data must be a multiple of the block size (16).
 #
 proc ::aes::Decrypt {Key data} {
     set len [string length $data]
     if {($len % 16) != 0} {
