Tcl Library Source Code

[comment {-*- tcl -*- doctools manpage}]
[vset AES_VERSION 1.2.1]
[manpage_begin aes n [vset AES_VERSION]]
[see_also blowfish(n)]
[see_also des(n)]
[see_also md5(n)]
[see_also sha1(n)]
[keywords aes]
[keywords {block cipher}]

# See the file "license.terms" for information on usage and redistribution
# of this file, and for a DISCLAIMER OF ALL WARRANTIES.
# -------------------------------------------------------------------------

package require Tcl 8.5

namespace eval ::aes {
    variable version 1.2.1
    variable rcsid {$Id: aes.tcl,v 1.7 2010/07/06 19:39:00 andreas_kupries Exp $}
    variable uid ; if {![info exists uid]} { set uid 0 }

    namespace export aes

    # constants

# 5.1 Cipher:  Encipher a single block of 128 bits.
proc ::aes::EncryptBlock {Key block} {
    upvar #0 $Key state
    if {[binary scan $block Iu4 data] != 1} {
        return -code error "invalid block size: blocks must be 16 bytes"
    }

    if {$state(M) eq {cbc}} {
        # Loop unrolled.
        lassign $data     d0 d1 d2 d3
        lassign $state(I) s0 s1 s2 s3

        set data [list \
                      [expr {$d0 ^ $s0}] \
                      [expr {$d1 ^ $s1}] \
                      [expr {$d2 ^ $s2}] \
                      [expr {$d3 ^ $s3}] ]
    }

    set data [AddRoundKey $Key 0 $data]
    for {set n 1} {$n < $state(Nr)} {incr n} {
        set data [AddRoundKey $Key $n [MixColumns [ShiftRows [SubBytes $data]]]]
    }
    set data [AddRoundKey $Key $n [ShiftRows [SubBytes $data]]]

    # Bug 2993029:
    # Force all elements of data into the 32bit range.
    # Loop unrolled
    set res [Clamp32 $data]




    set state(I) $res
    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 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 {$state(M) eq {cbc}} {
        lassign $data     d0 d1 d2 d3
        lassign $state(I) s0 s1 s2 s3

        set data [list \
                      [expr {($d0 ^ $s0) & 0xffffffff}] \
                      [expr {($d1 ^ $s1) & 0xffffffff}] \
                      [expr {($d2 ^ $s2) & 0xffffffff}] \
                      [expr {($d3 ^ $s3) & 0xffffffff}] ]
    } else {
        # Bug 2993029:

        # The integrated clamping we see above only happens for CBC mode.




        set data [Clamp32 $data]
    }

    set state(I) $iv
    binary format Iu4 $data
}

proc ::aes::Clamp32 {data} {
    # Force all elements into 32bit range.
    lassign $data d0 d1 d2 d3
    list \
        [expr {$d0 & 0xffffffff}] \
        [expr {$d1 & 0xffffffff}] \
        [expr {$d2 & 0xffffffff}] \
        [expr {$d3 & 0xffffffff}]
}

# 5.2: KeyExpansion
proc ::aes::ExpandKey {Key} {
    upvar #0 $Key state
    set Rcon [list 0x00000000 0x01000000 0x02000000 0x04000000 0x08000000 \
                   0x10000000 0x20000000 0x40000000 0x80000000 0x1b000000 \
                   0x36000000 0x6c000000 0xd8000000 0xab000000 0x4d000000]
    # Split the key into Nk big-endian words
    binary scan $state(K) I* W
    set max [expr {$state(Nb) * ($state(Nr) + 1)}]
    set i $state(Nk)
    set h [expr {$i - 1}]
    set j 0
    for {} {$i < $max} {incr i; incr h; incr j} {
        set temp [lindex $W $h]
        if {($i % $state(Nk)) == 0} {
            set sub [SubWord [RotWord $temp]]
            set rc [lindex $Rcon [expr {$i/$state(Nk)}]]
            set temp [expr {$sub ^ $rc}]
        } elseif {$state(Nk) > 6 && ($i % $state(Nk)) == 4} { 
            set temp [SubWord $temp]
        }
        lappend W [expr {[lindex $W $j] ^ $temp}]
    }
    set state(W) $W

}

# 5.2: Key Expansion: Apply S-box to each byte in the 32 bit word
proc ::aes::SubWord {w} {
    variable sbox
    set s3 [lindex $sbox [expr {($w >> 24) & 255}]]
    set s2 [lindex $sbox [expr {($w >> 16) & 255}]]
    set s1 [lindex $sbox [expr {($w >> 8 ) & 255}]]
    set s0 [lindex $sbox [expr { $w        & 255}]]
    return [expr {($s3 << 24) | ($s2 << 16) | ($s1 << 8) | $s0}]
}

proc ::aes::InvSubWord {w} {
    variable xobs
    set s3 [lindex $xobs [expr {($w >> 24) & 255}]]
    set s2 [lindex $xobs [expr {($w >> 16) & 255}]]
    set s1 [lindex $xobs [expr {($w >> 8 ) & 255}]]
    set s0 [lindex $xobs [expr { $w        & 255}]]
    return [expr {($s3 << 24) | ($s2 << 16) | ($s1 << 8) | $s0}]
}

# 5.2: Key Expansion: Rotate a 32bit word by 8 bits
proc ::aes::RotWord {w} {
    return [expr {(($w << 8) | (($w >> 24) & 0xff)) & 0xffffffff}]
}

# 5.1.1: SubBytes() Transformation
proc ::aes::SubBytes {words} {

    lassign $words w0 w1 w2 w3
    list [SubWord $w0] [SubWord $w1] [SubWord $w2] [SubWord $w3]


}

# 5.3.2: InvSubBytes() Transformation
proc ::aes::InvSubBytes {words} {

    lassign $words w0 w1 w2 w3
    list [InvSubWord $w0] [InvSubWord $w1] [InvSubWord $w2] [InvSubWord $w3]


}

# 5.1.2: ShiftRows() Transformation
proc ::aes::ShiftRows {words} {
    for {set n0 0} {$n0 < 4} {incr n0} {
        set n1 [expr {($n0 + 1) % 4}]
        set n2 [expr {($n0 + 2) % 4}]

        0x5b 0x59 0x5f 0x5d 0x53 0x51 0x57 0x55 0x4b 0x49 0x4f 0x4d 0x43 0x41 0x47 0x45 
        0x7b 0x79 0x7f 0x7d 0x73 0x71 0x77 0x75 0x6b 0x69 0x6f 0x6d 0x63 0x61 0x67 0x65 
        0x9b 0x99 0x9f 0x9d 0x93 0x91 0x97 0x95 0x8b 0x89 0x8f 0x8d 0x83 0x81 0x87 0x85 
        0xbb 0xb9 0xbf 0xbd 0xb3 0xb1 0xb7 0xb5 0xab 0xa9 0xaf 0xad 0xa3 0xa1 0xa7 0xa5 
        0xdb 0xd9 0xdf 0xdd 0xd3 0xd1 0xd7 0xd5 0xcb 0xc9 0xcf 0xcd 0xc3 0xc1 0xc7 0xc5 
        0xfb 0xf9 0xff 0xfd 0xf3 0xf1 0xf7 0xf5 0xeb 0xe9 0xef 0xed 0xe3 0xe1 0xe7 0xe5
    }
    lindex $xtime $number
}

proc ::aes::GFMult3 {number} {
    # multliply by 2 (via GFMult2) and add the number again on the result (via XOR)
    expr {$number ^ [GFMult2 $number]}
}

proc ::aes::GFMult09 {number} {
    # 09 is: (02*02*02) + 01
    expr {[GFMult2 [GFMult2 [GFMult2 $number]]] ^ $number}
}

proc ::aes::GFMult0b {number} {
    # 0b is: (02*02*02) + 02 + 01
    #return [expr [GFMult2 [GFMult2 [GFMult2 $number]]] ^ [GFMult2 $number] ^ $number]
    #set g0 [GFMult2 $number]
    expr {[GFMult09 $number] ^ [GFMult2 $number]}
}

proc ::aes::GFMult0d {number} {
    # 0d is: (02*02*02) + (02*02) + 01
    set temp [GFMult2 [GFMult2 $number]]
    expr {[GFMult2 $temp] ^ ($temp ^ $number)}
}

proc ::aes::GFMult0e {number} {
    # 0e is: (02*02*02) + (02*02) + 02
    set temp [GFMult2 [GFMult2 $number]]
    expr {[GFMult2 $temp] ^ ($temp ^ [GFMult2 $number])}
}

# -------------------------------------------------------------------------

# aes::Encrypt --
#
#	Encrypt a blocks of plain text and returns blocks of cipher text.

        set block [string range $data $i [incr i 15]]
        append result [DecryptBlock $Key $block]
    }
    return $result
}

# -------------------------------------------------------------------------
# chan event handler for chunked file reading.
#
proc ::aes::Chunk {Key in {out {}} {chunksize 4096}} {
    upvar #0 $Key state

    #puts ||CHUNK.X||i=$in|o=$out|c=$chunksize|eof=[eof $in]
    
    if {[eof $in]} {
        chan event $in readable {}
        set state(reading) 0
    }

    set data [read $in $chunksize]

    #puts ||CHUNK.R||i=$in|o=$out|c=$chunksize|eof=[eof $in]||[string length $data]||$data||

    # Do nothing when data was read at all.
    if {$data eq {}} return

    if {[eof $in]} {
        #puts CHUNK.Z
        set data [Pad $data 16]
    }

    #puts ||CHUNK.P||i=$in|o=$out|c=$chunksize|eof=[eof $in]||[string length $data]||$data||
    
    if {$out eq {}} {
        append state(output) [$state(cmd) $Key $data]
    } else {
        puts -nonewline $out [$state(cmd) $Key $data]
    }
}

proc ::aes::SetOneOf {lst item} {
    set ndx [lsearch -glob $lst "${item}*"]
    if {$ndx == -1} {
        set err [join $lst ", "]
        return -code error "invalid mode \"$item\": must be one of $err"
    }
    lindex $lst $ndx
}

proc ::aes::CheckSize {what size thing} {
    if {[string length $thing] != $size} {
        return -code error "invalid value for $what: must be $size bytes long"
    }
    return $thing

proc ::aes::Pop {varname {nth 0}} {
    upvar 1 $varname args
    set r [lindex $args $nth]
    set args [lreplace $args $nth $nth]
    return $r
}






proc ::aes::aes {args} {
    array set opts {-dir encrypt -mode cbc -key {} -in {} -out {} -chunksize 4096 -hex 0}
    set opts(-iv) [string repeat \0 16]
    set modes {ecb cbc}
    set dirs {encrypt decrypt}
    while {([llength $args] > 1) && [string match -* [set option [lindex $args 0]]]} {
        switch -exact -- $option {

                return -code error "bad option \"$option\":\
                    must be one of $err"
            }
        }
        Pop args
    }

    if {$opts(-key) eq {}} {
        return -code error "no key provided: the -key option is required"
    }

    set r {}
    if {$opts(-in) eq {}} {

        if {[llength $args] != 1} {
            return -code error "wrong \# args:\
                should be \"aes ?options...? -key keydata plaintext\""
        }

        set data [Pad [lindex $args 0] 16]
        set Key [Init $opts(-mode) $opts(-key) $opts(-iv)]
        if {[string equal $opts(-dir) "encrypt"]} {
            set r [Encrypt $Key $data]
        } else {
            set r [Decrypt $Key $data]
        }

        if {$opts(-out) ne {}} {
            puts -nonewline $opts(-out) $r
            set r {}
        }
        Final $Key

    } else {

        set state(reading) 1
        if {[string equal $opts(-dir) "encrypt"]} {
            set state(cmd) Encrypt
        } else {
            set state(cmd) Decrypt
        }
        set state(output) ""
        chan event $opts(-in) readable $readcmd
        if {[info commands ::tkwait] != {}} {
            tkwait variable [subst $Key](reading)
        } else {
            vwait [subst $Key](reading)
        }
        if {$opts(-out) == {}} {
            set r $state(output)
        }
        Final $Key
    }

    if {$opts(-hex)} {
        binary scan $r H* r
    }
    return $r
}

# -------------------------------------------------------------------------

package provide aes $::aes::version

# -------------------------------------------------------------------------
# Local variables:
# mode: tcl
# indent-tabs-mode: nil
# End:

if {![package vsatisfies [package provide Tcl] 8.5]} {
    # PRAGMA: returnok
    return
}
package ifneeded aes 1.2.1 [list source [file join $dir aes.tcl]]