blowfish.tcl

# Copyright Cyan Ogilvie <cyan@codeforge.co.za>
# License terms are the same as the Tcl core

# While I have been careful to adhere to the implementation guidelines as
# closely as possible, no cryptographic audit has been performed on this code
# and I make no warrenties as to its correctness or security.  You are
# encouraged to examine the code yourself or get a qualified cryptographer to
# audit this code before using it in an application with specific security
# requirements.
#
# In particular it should be noted that key privacy is poor - the limitations
# of working in a scripting language means that the keys could be leaked
# through freed memory, so this code should not be used in any situation where
# an attacker could have access to system memory.  Certain timing attacks
# are also probably made more feasible because the script runs more slowly
# than native code, magnifying the effects of taking different branches in
# the code.

namespace eval crypto::blowfish {
	namespace path {::tcl::mathop ::tcl::mathfunc}

	proc init_key {key} { #<<<
		set keylength	[string length $key]
		if {![<= 4 $keylength 56]} {
			throw {invalid_keysize} "key length in bytes must be in the range \[4, 56\]"
		}

		# Initial P and S arrays <<<
		set P	{
			0x243F6A88 0x85A308D3 0x13198A2E 0x03707344
			0xA4093822 0x299F31D0 0x082EFA98 0xEC4E6C89
			0x452821E6 0x38D01377 0xBE5466CF 0x34E90C6C
			0xC0AC29B7 0xC97C50DD 0x3F84D5B5 0xB5470917
			0x9216D5D9 0x8979FB1B
		}

		set S	{
			{
				0xD1310BA6 0x98DFB5AC 0x2FFD72DB 0xD01ADFB7
				0xB8E1AFED 0x6A267E96 0xBA7C9045 0xF12C7F99
				0x24A19947 0xB3916CF7 0x0801F2E2 0x858EFC16
				0x636920D8 0x71574E69 0xA458FEA3 0xF4933D7E
				0x0D95748F 0x728EB658 0x718BCD58 0x82154AEE
				0x7B54A41D 0xC25A59B5 0x9C30D539 0x2AF26013
				0xC5D1B023 0x286085F0 0xCA417918 0xB8DB38EF
				0x8E79DCB0 0x603A180E 0x6C9E0E8B 0xB01E8A3E
				0xD71577C1 0xBD314B27 0x78AF2FDA 0x55605C60
				0xE65525F3 0xAA55AB94 0x57489862 0x63E81440
				0x55CA396A 0x2AAB10B6 0xB4CC5C34 0x1141E8CE
				0xA15486AF 0x7C72E993 0xB3EE1411 0x636FBC2A
				0x2BA9C55D 0x741831F6 0xCE5C3E16 0x9B87931E
				0xAFD6BA33 0x6C24CF5C 0x7A325381 0x28958677
				0x3B8F4898 0x6B4BB9AF 0xC4BFE81B 0x66282193
				0x61D809CC 0xFB21A991 0x487CAC60 0x5DEC8032
				0xEF845D5D 0xE98575B1 0xDC262302 0xEB651B88
				0x23893E81 0xD396ACC5 0x0F6D6FF3 0x83F44239
				0x2E0B4482 0xA4842004 0x69C8F04A 0x9E1F9B5E
				0x21C66842 0xF6E96C9A 0x670C9C61 0xABD388F0
				0x6A51A0D2 0xD8542F68 0x960FA728 0xAB5133A3
				0x6EEF0B6C 0x137A3BE4 0xBA3BF050 0x7EFB2A98
				0xA1F1651D 0x39AF0176 0x66CA593E 0x82430E88
				0x8CEE8619 0x456F9FB4 0x7D84A5C3 0x3B8B5EBE
				0xE06F75D8 0x85C12073 0x401A449F 0x56C16AA6
				0x4ED3AA62 0x363F7706 0x1BFEDF72 0x429B023D
				0x37D0D724 0xD00A1248 0xDB0FEAD3 0x49F1C09B
				0x075372C9 0x80991B7B 0x25D479D8 0xF6E8DEF7
				0xE3FE501A 0xB6794C3B 0x976CE0BD 0x04C006BA
				0xC1A94FB6 0x409F60C4 0x5E5C9EC2 0x196A2463
				0x68FB6FAF 0x3E6C53B5 0x1339B2EB 0x3B52EC6F
				0x6DFC511F 0x9B30952C 0xCC814544 0xAF5EBD09
				0xBEE3D004 0xDE334AFD 0x660F2807 0x192E4BB3
				0xC0CBA857 0x45C8740F 0xD20B5F39 0xB9D3FBDB
				0x5579C0BD 0x1A60320A 0xD6A100C6 0x402C7279
				0x679F25FE 0xFB1FA3CC 0x8EA5E9F8 0xDB3222F8
				0x3C7516DF 0xFD616B15 0x2F501EC8 0xAD0552AB
				0x323DB5FA 0xFD238760 0x53317B48 0x3E00DF82
				0x9E5C57BB 0xCA6F8CA0 0x1A87562E 0xDF1769DB
				0xD542A8F6 0x287EFFC3 0xAC6732C6 0x8C4F5573
				0x695B27B0 0xBBCA58C8 0xE1FFA35D 0xB8F011A0
				0x10FA3D98 0xFD2183B8 0x4AFCB56C 0x2DD1D35B
				0x9A53E479 0xB6F84565 0xD28E49BC 0x4BFB9790
				0xE1DDF2DA 0xA4CB7E33 0x62FB1341 0xCEE4C6E8
				0xEF20CADA 0x36774C01 0xD07E9EFE 0x2BF11FB4
				0x95DBDA4D 0xAE909198 0xEAAD8E71 0x6B93D5A0
				0xD08ED1D0 0xAFC725E0 0x8E3C5B2F 0x8E7594B7
				0x8FF6E2FB 0xF2122B64 0x8888B812 0x900DF01C
				0x4FAD5EA0 0x688FC31C 0xD1CFF191 0xB3A8C1AD
				0x2F2F2218 0xBE0E1777 0xEA752DFE 0x8B021FA1
				0xE5A0CC0F 0xB56F74E8 0x18ACF3D6 0xCE89E299
				0xB4A84FE0 0xFD13E0B7 0x7CC43B81 0xD2ADA8D9
				0x165FA266 0x80957705 0x93CC7314 0x211A1477
				0xE6AD2065 0x77B5FA86 0xC75442F5 0xFB9D35CF
				0xEBCDAF0C 0x7B3E89A0 0xD6411BD3 0xAE1E7E49
				0x00250E2D 0x2071B35E 0x226800BB 0x57B8E0AF
				0x2464369B 0xF009B91E 0x5563911D 0x59DFA6AA
				0x78C14389 0xD95A537F 0x207D5BA2 0x02E5B9C5
				0x83260376 0x6295CFA9 0x11C81968 0x4E734A41
				0xB3472DCA 0x7B14A94A 0x1B510052 0x9A532915
				0xD60F573F 0xBC9BC6E4 0x2B60A476 0x81E67400
				0x08BA6FB5 0x571BE91F 0xF296EC6B 0x2A0DD915
				0xB6636521 0xE7B9F9B6 0xFF34052E 0xC5855664
				0x53B02D5D 0xA99F8FA1 0x08BA4799 0x6E85076A
			}
			{
				0x4B7A70E9 0xB5B32944 0xDB75092E 0xC4192623
				0xAD6EA6B0 0x49A7DF7D 0x9CEE60B8 0x8FEDB266
				0xECAA8C71 0x699A17FF 0x5664526C 0xC2B19EE1
				0x193602A5 0x75094C29 0xA0591340 0xE4183A3E
				0x3F54989A 0x5B429D65 0x6B8FE4D6 0x99F73FD6
				0xA1D29C07 0xEFE830F5 0x4D2D38E6 0xF0255DC1
				0x4CDD2086 0x8470EB26 0x6382E9C6 0x021ECC5E
				0x09686B3F 0x3EBAEFC9 0x3C971814 0x6B6A70A1
				0x687F3584 0x52A0E286 0xB79C5305 0xAA500737
				0x3E07841C 0x7FDEAE5C 0x8E7D44EC 0x5716F2B8
				0xB03ADA37 0xF0500C0D 0xF01C1F04 0x0200B3FF
				0xAE0CF51A 0x3CB574B2 0x25837A58 0xDC0921BD
				0xD19113F9 0x7CA92FF6 0x94324773 0x22F54701
				0x3AE5E581 0x37C2DADC 0xC8B57634 0x9AF3DDA7
				0xA9446146 0x0FD0030E 0xECC8C73E 0xA4751E41
				0xE238CD99 0x3BEA0E2F 0x3280BBA1 0x183EB331
				0x4E548B38 0x4F6DB908 0x6F420D03 0xF60A04BF
				0x2CB81290 0x24977C79 0x5679B072 0xBCAF89AF
				0xDE9A771F 0xD9930810 0xB38BAE12 0xDCCF3F2E
				0x5512721F 0x2E6B7124 0x501ADDE6 0x9F84CD87
				0x7A584718 0x7408DA17 0xBC9F9ABC 0xE94B7D8C
				0xEC7AEC3A 0xDB851DFA 0x63094366 0xC464C3D2
				0xEF1C1847 0x3215D908 0xDD433B37 0x24C2BA16
				0x12A14D43 0x2A65C451 0x50940002 0x133AE4DD
				0x71DFF89E 0x10314E55 0x81AC77D6 0x5F11199B
				0x043556F1 0xD7A3C76B 0x3C11183B 0x5924A509
				0xF28FE6ED 0x97F1FBFA 0x9EBABF2C 0x1E153C6E
				0x86E34570 0xEAE96FB1 0x860E5E0A 0x5A3E2AB3
				0x771FE71C 0x4E3D06FA 0x2965DCB9 0x99E71D0F
				0x803E89D6 0x5266C825 0x2E4CC978 0x9C10B36A
				0xC6150EBA 0x94E2EA78 0xA5FC3C53 0x1E0A2DF4
				0xF2F74EA7 0x361D2B3D 0x1939260F 0x19C27960
				0x5223A708 0xF71312B6 0xEBADFE6E 0xEAC31F66
				0xE3BC4595 0xA67BC883 0xB17F37D1 0x018CFF28
				0xC332DDEF 0xBE6C5AA5 0x65582185 0x68AB9802
				0xEECEA50F 0xDB2F953B 0x2AEF7DAD 0x5B6E2F84
				0x1521B628 0x29076170 0xECDD4775 0x619F1510
				0x13CCA830 0xEB61BD96 0x0334FE1E 0xAA0363CF
				0xB5735C90 0x4C70A239 0xD59E9E0B 0xCBAADE14
				0xEECC86BC 0x60622CA7 0x9CAB5CAB 0xB2F3846E
				0x648B1EAF 0x19BDF0CA 0xA02369B9 0x655ABB50
				0x40685A32 0x3C2AB4B3 0x319EE9D5 0xC021B8F7
				0x9B540B19 0x875FA099 0x95F7997E 0x623D7DA8
				0xF837889A 0x97E32D77 0x11ED935F 0x16681281
				0x0E358829 0xC7E61FD6 0x96DEDFA1 0x7858BA99
				0x57F584A5 0x1B227263 0x9B83C3FF 0x1AC24696
				0xCDB30AEB 0x532E3054 0x8FD948E4 0x6DBC3128
				0x58EBF2EF 0x34C6FFEA 0xFE28ED61 0xEE7C3C73
				0x5D4A14D9 0xE864B7E3 0x42105D14 0x203E13E0
				0x45EEE2B6 0xA3AAABEA 0xDB6C4F15 0xFACB4FD0
				0xC742F442 0xEF6ABBB5 0x654F3B1D 0x41CD2105
				0xD81E799E 0x86854DC7 0xE44B476A 0x3D816250
				0xCF62A1F2 0x5B8D2646 0xFC8883A0 0xC1C7B6A3
				0x7F1524C3 0x69CB7492 0x47848A0B 0x5692B285
				0x095BBF00 0xAD19489D 0x1462B174 0x23820E00
				0x58428D2A 0x0C55F5EA 0x1DADF43E 0x233F7061
				0x3372F092 0x8D937E41 0xD65FECF1 0x6C223BDB
				0x7CDE3759 0xCBEE7460 0x4085F2A7 0xCE77326E
				0xA6078084 0x19F8509E 0xE8EFD855 0x61D99735
				0xA969A7AA 0xC50C06C2 0x5A04ABFC 0x800BCADC
				0x9E447A2E 0xC3453484 0xFDD56705 0x0E1E9EC9
				0xDB73DBD3 0x105588CD 0x675FDA79 0xE3674340
				0xC5C43465 0x713E38D8 0x3D28F89E 0xF16DFF20
				0x153E21E7 0x8FB03D4A 0xE6E39F2B 0xDB83ADF7
			}
			{
				0xE93D5A68 0x948140F7 0xF64C261C 0x94692934
				0x411520F7 0x7602D4F7 0xBCF46B2E 0xD4A20068
				0xD4082471 0x3320F46A 0x43B7D4B7 0x500061AF
				0x1E39F62E 0x97244546 0x14214F74 0xBF8B8840
				0x4D95FC1D 0x96B591AF 0x70F4DDD3 0x66A02F45
				0xBFBC09EC 0x03BD9785 0x7FAC6DD0 0x31CB8504
				0x96EB27B3 0x55FD3941 0xDA2547E6 0xABCA0A9A
				0x28507825 0x530429F4 0x0A2C86DA 0xE9B66DFB
				0x68DC1462 0xD7486900 0x680EC0A4 0x27A18DEE
				0x4F3FFEA2 0xE887AD8C 0xB58CE006 0x7AF4D6B6
				0xAACE1E7C 0xD3375FEC 0xCE78A399 0x406B2A42
				0x20FE9E35 0xD9F385B9 0xEE39D7AB 0x3B124E8B
				0x1DC9FAF7 0x4B6D1856 0x26A36631 0xEAE397B2
				0x3A6EFA74 0xDD5B4332 0x6841E7F7 0xCA7820FB
				0xFB0AF54E 0xD8FEB397 0x454056AC 0xBA489527
				0x55533A3A 0x20838D87 0xFE6BA9B7 0xD096954B
				0x55A867BC 0xA1159A58 0xCCA92963 0x99E1DB33
				0xA62A4A56 0x3F3125F9 0x5EF47E1C 0x9029317C
				0xFDF8E802 0x04272F70 0x80BB155C 0x05282CE3
				0x95C11548 0xE4C66D22 0x48C1133F 0xC70F86DC
				0x07F9C9EE 0x41041F0F 0x404779A4 0x5D886E17
				0x325F51EB 0xD59BC0D1 0xF2BCC18F 0x41113564
				0x257B7834 0x602A9C60 0xDFF8E8A3 0x1F636C1B
				0x0E12B4C2 0x02E1329E 0xAF664FD1 0xCAD18115
				0x6B2395E0 0x333E92E1 0x3B240B62 0xEEBEB922
				0x85B2A20E 0xE6BA0D99 0xDE720C8C 0x2DA2F728
				0xD0127845 0x95B794FD 0x647D0862 0xE7CCF5F0
				0x5449A36F 0x877D48FA 0xC39DFD27 0xF33E8D1E
				0x0A476341 0x992EFF74 0x3A6F6EAB 0xF4F8FD37
				0xA812DC60 0xA1EBDDF8 0x991BE14C 0xDB6E6B0D
				0xC67B5510 0x6D672C37 0x2765D43B 0xDCD0E804
				0xF1290DC7 0xCC00FFA3 0xB5390F92 0x690FED0B
				0x667B9FFB 0xCEDB7D9C 0xA091CF0B 0xD9155EA3
				0xBB132F88 0x515BAD24 0x7B9479BF 0x763BD6EB
				0x37392EB3 0xCC115979 0x8026E297 0xF42E312D
				0x6842ADA7 0xC66A2B3B 0x12754CCC 0x782EF11C
				0x6A124237 0xB79251E7 0x06A1BBE6 0x4BFB6350
				0x1A6B1018 0x11CAEDFA 0x3D25BDD8 0xE2E1C3C9
				0x44421659 0x0A121386 0xD90CEC6E 0xD5ABEA2A
				0x64AF674E 0xDA86A85F 0xBEBFE988 0x64E4C3FE
				0x9DBC8057 0xF0F7C086 0x60787BF8 0x6003604D
				0xD1FD8346 0xF6381FB0 0x7745AE04 0xD736FCCC
				0x83426B33 0xF01EAB71 0xB0804187 0x3C005E5F
				0x77A057BE 0xBDE8AE24 0x55464299 0xBF582E61
				0x4E58F48F 0xF2DDFDA2 0xF474EF38 0x8789BDC2
				0x5366F9C3 0xC8B38E74 0xB475F255 0x46FCD9B9
				0x7AEB2661 0x8B1DDF84 0x846A0E79 0x915F95E2
				0x466E598E 0x20B45770 0x8CD55591 0xC902DE4C
				0xB90BACE1 0xBB8205D0 0x11A86248 0x7574A99E
				0xB77F19B6 0xE0A9DC09 0x662D09A1 0xC4324633
				0xE85A1F02 0x09F0BE8C 0x4A99A025 0x1D6EFE10
				0x1AB93D1D 0x0BA5A4DF 0xA186F20F 0x2868F169
				0xDCB7DA83 0x573906FE 0xA1E2CE9B 0x4FCD7F52
				0x50115E01 0xA70683FA 0xA002B5C4 0x0DE6D027
				0x9AF88C27 0x773F8641 0xC3604C06 0x61A806B5
				0xF0177A28 0xC0F586E0 0x006058AA 0x30DC7D62
				0x11E69ED7 0x2338EA63 0x53C2DD94 0xC2C21634
				0xBBCBEE56 0x90BCB6DE 0xEBFC7DA1 0xCE591D76
				0x6F05E409 0x4B7C0188 0x39720A3D 0x7C927C24
				0x86E3725F 0x724D9DB9 0x1AC15BB4 0xD39EB8FC
				0xED545578 0x08FCA5B5 0xD83D7CD3 0x4DAD0FC4
				0x1E50EF5E 0xB161E6F8 0xA28514D9 0x6C51133C
				0x6FD5C7E7 0x56E14EC4 0x362ABFCE 0xDDC6C837
				0xD79A3234 0x92638212 0x670EFA8E 0x406000E0
			}
			{
				0x3A39CE37 0xD3FAF5CF 0xABC27737 0x5AC52D1B
				0x5CB0679E 0x4FA33742 0xD3822740 0x99BC9BBE
				0xD5118E9D 0xBF0F7315 0xD62D1C7E 0xC700C47B
				0xB78C1B6B 0x21A19045 0xB26EB1BE 0x6A366EB4
				0x5748AB2F 0xBC946E79 0xC6A376D2 0x6549C2C8
				0x530FF8EE 0x468DDE7D 0xD5730A1D 0x4CD04DC6
				0x2939BBDB 0xA9BA4650 0xAC9526E8 0xBE5EE304
				0xA1FAD5F0 0x6A2D519A 0x63EF8CE2 0x9A86EE22
				0xC089C2B8 0x43242EF6 0xA51E03AA 0x9CF2D0A4
				0x83C061BA 0x9BE96A4D 0x8FE51550 0xBA645BD6
				0x2826A2F9 0xA73A3AE1 0x4BA99586 0xEF5562E9
				0xC72FEFD3 0xF752F7DA 0x3F046F69 0x77FA0A59
				0x80E4A915 0x87B08601 0x9B09E6AD 0x3B3EE593
				0xE990FD5A 0x9E34D797 0x2CF0B7D9 0x022B8B51
				0x96D5AC3A 0x017DA67D 0xD1CF3ED6 0x7C7D2D28
				0x1F9F25CF 0xADF2B89B 0x5AD6B472 0x5A88F54C
				0xE029AC71 0xE019A5E6 0x47B0ACFD 0xED93FA9B
				0xE8D3C48D 0x283B57CC 0xF8D56629 0x79132E28
				0x785F0191 0xED756055 0xF7960E44 0xE3D35E8C
				0x15056DD4 0x88F46DBA 0x03A16125 0x0564F0BD
				0xC3EB9E15 0x3C9057A2 0x97271AEC 0xA93A072A
				0x1B3F6D9B 0x1E6321F5 0xF59C66FB 0x26DCF319
				0x7533D928 0xB155FDF5 0x03563482 0x8ABA3CBB
				0x28517711 0xC20AD9F8 0xABCC5167 0xCCAD925F
				0x4DE81751 0x3830DC8E 0x379D5862 0x9320F991
				0xEA7A90C2 0xFB3E7BCE 0x5121CE64 0x774FBE32
				0xA8B6E37E 0xC3293D46 0x48DE5369 0x6413E680
				0xA2AE0810 0xDD6DB224 0x69852DFD 0x09072166
				0xB39A460A 0x6445C0DD 0x586CDECF 0x1C20C8AE
				0x5BBEF7DD 0x1B588D40 0xCCD2017F 0x6BB4E3BB
				0xDDA26A7E 0x3A59FF45 0x3E350A44 0xBCB4CDD5
				0x72EACEA8 0xFA6484BB 0x8D6612AE 0xBF3C6F47
				0xD29BE463 0x542F5D9E 0xAEC2771B 0xF64E6370
				0x740E0D8D 0xE75B1357 0xF8721671 0xAF537D5D
				0x4040CB08 0x4EB4E2CC 0x34D2466A 0x0115AF84
				0xE1B00428 0x95983A1D 0x06B89FB4 0xCE6EA048
				0x6F3F3B82 0x3520AB82 0x011A1D4B 0x277227F8
				0x611560B1 0xE7933FDC 0xBB3A792B 0x344525BD
				0xA08839E1 0x51CE794B 0x2F32C9B7 0xA01FBAC9
				0xE01CC87E 0xBCC7D1F6 0xCF0111C3 0xA1E8AAC7
				0x1A908749 0xD44FBD9A 0xD0DADECB 0xD50ADA38
				0x0339C32A 0xC6913667 0x8DF9317C 0xE0B12B4F
				0xF79E59B7 0x43F5BB3A 0xF2D519FF 0x27D9459C
				0xBF97222C 0x15E6FC2A 0x0F91FC71 0x9B941525
				0xFAE59361 0xCEB69CEB 0xC2A86459 0x12BAA8D1
				0xB6C1075E 0xE3056A0C 0x10D25065 0xCB03A442
				0xE0EC6E0E 0x1698DB3B 0x4C98A0BE 0x3278E964
				0x9F1F9532 0xE0D392DF 0xD3A0342B 0x8971F21E
				0x1B0A7441 0x4BA3348C 0xC5BE7120 0xC37632D8
				0xDF359F8D 0x9B992F2E 0xE60B6F47 0x0FE3F11D
				0xE54CDA54 0x1EDAD891 0xCE6279CF 0xCD3E7E6F
				0x1618B166 0xFD2C1D05 0x848FD2C5 0xF6FB2299
				0xF523F357 0xA6327623 0x93A83531 0x56CCCD02
				0xACF08162 0x5A75EBB5 0x6E163697 0x88D273CC
				0xDE966292 0x81B949D0 0x4C50901B 0x71C65614
				0xE6C6C7BD 0x327A140A 0x45E1D006 0xC3F27B9A
				0xC9AA53FD 0x62A80F00 0xBB25BFE2 0x35BDD2F6
				0x71126905 0xB2040222 0xB6CBCF7C 0xCD769C2B
				0x53113EC0 0x1640E3D3 0x38ABBD60 0x2547ADF0
				0xBA38209C 0xF746CE76 0x77AFA1C5 0x20756060
				0x85CBFE4E 0x8AE88DD8 0x7AAAF9B0 0x4CF9AA7E
				0x1948C25C 0x02FB8A8C 0x01C36AE4 0xD6EBE1F9
				0x90D4F869 0xA65CDEA0 0x3F09252D 0xC208E69F
				0xB74E6132 0xCE77E25B 0x578FDFE3 0x3AC372E6
			}
		}
		# Initial P and S arrays >>>

		set reqbytes	[expr {4 * [llength $P]}]
		set cycledkey	[string repeat $key [expr {
			int(ceil( double($reqbytes) / [string length $key] ))
		}]]
		for {set i 0} {$i < [llength $P]} {incr i} {
			set a	[lindex $P $i]
			set o	[expr {$i * 4}]
			binary scan $cycledkey @${o}I keyportion
			lset P $i [expr {$keyportion ^ $a}]
		}

		set l		0
		set r		0
		for {set i 0} {$i < [llength $P]} {} {
			lassign [_transform_block $P $S $l $r] l r
			lset P $i $l
			incr i
			lset P $i $r
			incr i
		}

		for {set i 0} {$i < 4} {incr i} {
			for {set j 0} {$j < 256} {} {
				lassign [_transform_block $P $S $l $r] l r
				lset S $i $j $l
				incr j
				lset S $i $j $r
				incr j
			}
		}

		list $P $S
	}

	#>>>
	proc encrypt {schedule bytes} { #<<<
		lassign $schedule P S
		_apply $P $S $bytes
	}

	#>>>
	proc decrypt {schedule bytes} { #<<<
		lassign $schedule P S
		_apply [lreverse $P] $S $bytes
	}

	#>>>
	proc encrypt_cbc {schedule bytes iv} { #<<<
		lassign $schedule P S
		_apply_cbc_e $P $S [_pad $bytes] $iv
	}

	#>>>
	proc decrypt_cbc {schedule bytes iv} { #<<<
		lassign $schedule P S
		_unpad [_apply_cbc_d [lreverse $P] $S $bytes $iv]
	}

	#>>>
	proc _apply {P S bytes} { #<<<
		set bytelen	[string length $bytes]
		if {$bytelen % 8 != 0} {
			throw {invalid_plaintext_length} "ECB mode requires input to be a multiple of blocksize (64 bits): $bytelen"
		}

		if {$bytelen < 8192} {
			binary scan $bytes Iu* ints
			set oints	{}
			foreach {l r} $ints {
				lappend oints {*}[_transform_block $P $S $l $r]
			}

			binary format I* $oints
		} else {
			# Use a less memory intesive method - the faster one above would
			# use more than 1.5MB for a 50kb message
			set O	""
			set o	0
			while {$o + $bs <= $bytelen} {
				binary scan $bytes @${o}Iu2048 ints
				set oints	{}
				foreach {l r} $ints {
					lappend oints	{*}[_transform_block $P $S $l $r]
				}
				append O	[binary format I* $oints]
			}
			if {$o < $bytelen} {
				binary scan $bytes @${o}Iu[expr {($bytelen-$o)/4}] ints
				set oints	{}
				foreach {l r} $ints {
					lappend oints	{*}[_transform_block $P $S $l $r]
				}
				append O	[binary format I* $oints]
			}
			set O
		}
	}

	#>>>
	proc _apply_cbc_e {P S bytes iv} { #<<<
		if {[binary scan $iv IuIu ivl ivr] != 2} {
			throw {invalid_iv_length} "Invalid IV length, must be one block (64 bits)"
		}

		set bytelen	[string length $bytes]
		if {$bytelen % 8 != 0} {
			throw {invalid_plaintext_length} "ECB mode requires input to be a multiple of blocksize (64 bits): $bytelen"
		}

		if {$bytelen < 8192} {
			binary scan $bytes Iu* ints
			set oints	{}
			foreach {l r} $ints {
				set l	[^ $l $ivl]
				set r	[^ $r $ivr]
				lassign [_transform_block $P $S $l $r] l r
				set ivl	$l
				set ivr	$r
				lappend oints	$l $r
			}

			return [binary format I* $oints]
		} else {
			# Use a less memory intesive method - the faster one above would be
			# using more than 1.5MB for a 50kb message
			set O	""
			for {set o 0} {$o < $bytelen} {incr o 8192} {
				binary scan $bytes @${o}Iu[expr {min($bs, $bytelen-$o)/4}] ints
				set oints	{}
				foreach {l r} $ints {
					set l	[^ $l $ivl]
					set r	[^ $r $ivr]
					lassign [_transform_block $P $S $l $r] l r
					set ivl	$l
					set ivr	$r
					lappend oints	$l $r
				}
				append O	[binary format I* $oints]
			}
			return $O
		}
	}

	#>>>
	proc _apply_cbc_d {P S bytes iv} { #<<<
		if {[binary scan $iv IuIu ivl ivr] != 2} {
			throw {invalid_iv_length} "Invalid IV length, must be one block (64 bits)"
		}


		set bytelen	[string length $bytes]
		if {$bytelen % 8 != 0} {
			throw {invalid_plaintext_length} "ECB mode requires input to be a multiple of blocksize (64 bits): $bytelen"
		}

		if {$bytelen < 8192} {
			binary scan $bytes Iu* ints
			set oints	{}
			foreach {l r} $ints {
				lassign [_transform_block $P $S $l $r] ol or
				set ol	[^ $ol $ivl]
				set or	[^ $or $ivr]
				set ivl	$l
				set ivr	$r
				lappend oints	$ol $or
			}

			return [binary format I* $oints]
		} else {
			# Use a less memory intesive method - the faster one above would be
			# using more than 1.5MB for a 50kb message
			set O	""
			for {set o 0} {$o < $bytelen} {incr o 8192} {
				binary scan $bytes @${o}Iu[expr {min($bs, $bytelen-$o)/4}] ints
				set oints	{}
				foreach {l r} $ints {
					lassign [_transform_block $P $S $l $r] ol or
					set ol	[^ $ol $ivl]
					set or	[^ $or $ivr]
					set ivl	$l
					set ivr	$r
					lappend oints	$ol $or
				}
				append O	[binary format I* $oints]
			}
			return $O
		}
	}

	#>>>
	proc _transform_block {P S l r} { #<<<
		lassign $S S1 S2 S3 S4
		foreach p [lrange $P 0 end-2] {
			set l		[expr {$l ^ $p}]

			set s1	[lindex $S1 [expr {($l >> 24) & 0xff}]]
			set s2	[lindex $S2 [expr {($l >> 16) & 0xff}]]
			set s3	[lindex $S3 [expr {($l >>  8) & 0xff}]]
			set s4	[lindex $S4 [expr { $l        & 0xff}]]

			set hold	$l
			set l	[expr {(((($s1 + $s2) ^ $s3) + $s4) & 0xffffffff) ^ $r}]
			set r	$hold
		}

		list \
				[expr {($r ^ [lindex $P end])   & 0xffffffff}] \
				[expr {($l ^ [lindex $P end-1]) & 0xffffffff}]
	}

	#>>>
	proc _pad {bytes} { #<<<
		set bytelen		[string length $bytes]
		set lastbyte	[string index $bytes end]
		set padlen		[expr {8-($bytelen % 8)}]

		set padchar	[csprng 1]
		while {$padchar eq $lastbyte} {
			set padchar	[csprng 1]
		}

		append bytes [string repeat $padchar $padlen]
		return $bytes
	}

	#>>>
	proc _unpad {bytes} { #<<<
		set paddedlen	[string length $bytes]
		set last		[string index $bytes end]
		set i			[expr {$paddedlen - 2}]
		while {[string index $bytes $i] eq $last} {incr i -1}
		string range $bytes 0 $i
	}

	#>>>
	proc csprng {bytes} { #<<<
		variable _csprngstate

		# Based on blowfish run in counter mode, with cbc
		#
		# Setup consumes 72 bytes (576 bits) of entropy.
		# This effectively selects one of 2⁵¹² sequences, each with a
		# period of 2⁶⁷ bytes, initialized to a random block aligned
		# (8 byte) point within their period (ie, one of 2⁶⁴ points)
		#
		# TODO: does this satisfy the next bit test (assuming no knowledge
		# of initial key, iv and i)?
		# Since blowfish at full 16 rounds cannot currently be distinguished
		# from a random number source even with weak keys to the best of
		# my knowledge as of April 2009, this should be ok.
		#
		# Basic testing seems to indicate uniform distribution

		if {![info exists _csprngstate]} {
			set rand	[randbytes 72]
			lassign [init_key [string range $rand 0 55]] P S
			binary scan [string range $rand 56 63] W i
			binary scan [string range $rand 64 71] II ivl ivr
			dict set _csprngstate P		$P
			dict set _csprngstate S		$S
			dict set _csprngstate i		$i
			dict set _csprngstate ivl	$ivl
			dict set _csprngstate ivr	$ivr
			dict set _csprngstate O		""
		}

		dict with _csprngstate {
			while {[string length $O] < $bytes} {
				set i	[expr {($i + 1) & 0xffffffffffffffff}]

				set l	[expr {(($i >> 32) & 0xffffffff) ^ $ivl}]
				set r	[expr {( $i        & 0xffffffff) ^ $ivr}]

				lassign [_transform_block $P $S $l $r] l r
				set ivl		$l
				set ivr		$r
				append O	[binary format II $l $r]
			}
			set res	[string range $O 0 $bytes-1]
			set O	[string range $O $bytes end]
			set res
		}
	}

	#>>>
	proc randbytes {bytecount} { #<<<
		#set h	[open /dev/random r]
		set h	[open /dev/urandom r]
		try {
			chan configure $h -translation binary -encoding binary -blocking 1
			chan read $h $bytecount
		} finally {
			catch {chan close $h}
		}
	}

	#>>>
}

# vim: ft=tcl foldmethod=marker foldmarker=<<<,>>> ts=4 shiftwidth=4