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8b577828f6
Cryptol 2.3-alpha couldn't math, but thanks to @yav's hard work, Cryptol 2.3 and later can math! So with our new found powers comes great simplification. Not all is perfect, much like Dori-Mic's situation, but things are much better. See the width constraints in SCrypt.cry for areas that could be improved with some semi-obvious statements (forall x. 1 + width x >= width (x - 1)).
93 lines
3.5 KiB
Plaintext
93 lines
3.5 KiB
Plaintext
/*
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* Copyright (c) 2013-2016 Galois, Inc.
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* Distributed under the terms of the BSD3 license (see LICENSE file)
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*/
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module SCrypt where
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import Salsa20
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import PBKDF2
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// SCrypt paper page 10: BlockMix specialized to Salsa20
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BlockMix : {r} (fin r, r >= 1) => [2*r][64*8] -> [2*r][64*8]
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BlockMix B = ys @@ ([0,2..2*r-2] # [1,3..2*r-1])
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where
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rs = [B!0] # [ join (Salsa20 `{r=8} (split (X ^ bi))) | X <- rs | bi <- B ]
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ys = drop `{1} rs
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// SMix with the ROMix algorithm (section 5) inlined (specialized to BlockMix)
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// N = 2^^17
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SMix : {N,r} ( fin r
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, r >= 1
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, N >= 1
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, 512 >= width N
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, 1 + width N >= width (N-1)
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) => [128 * 8 * r] -> [128 * 8 * r]
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SMix B = join (Xs ! 0)
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where
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Vs = [split B] # [ BlockMix x | x <- Vs | _ <- [0..N-1] : [_][width N + 1]]
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V = take `{front=N} Vs
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Xs : [N+1][2*r][64*8]
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Xs = [Vs!0] # [ (x' where
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j = integerify x
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T = x ^ (V@j)
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x' = BlockMix T)
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| x <- Xs | _ <- [0..N-1] : [_][width N + 1] ]
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integerify w = (join (reverse (split `{each=8} (w!0)))) % `N
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// SCrypt paper, page 11: MFCrypt specialized to sha256 (see the 'pbkdf2' function)
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// p = 1
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MFcrypt : { pwBytes, saltBytes, dkLen, r, N }
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( 4*r >= 1
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, 16 >= width (4*r)
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, ((dkLen*8 + 255) / 256) >= 1
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, 32 >= width (8*pwBytes)
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, 32 >= width (4 + saltBytes)
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, 16 >= width ((255 + 8 * dkLen) / 256)
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, N >= 1, 512 >= width N, 1+width N >= width (N-1)
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)
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=> [pwBytes][8] -> [saltBytes][8] -> [dkLen][8]
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MFcrypt P S = split DK
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where
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B = pbkdf2 `{C=1} P S
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B' = SMix `{N=N,r=r} B
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DK = pbkdf2 `{dkLenBits=dkLen*8, C=1} P (split B')
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SCrypt : {pwBytes, saltBytes, dkBytes, r, N}
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( 4*r >= 1, 16 >= width (4*r)
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, (dkBytes * 8 + 255) / 256 >= 1
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, 16 >= width ((255 + 8 * dkBytes) / 256)
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, 8 * dkBytes == 256 * ((255 + 8 * dkBytes) / 256)
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, 32 >= width (8 * pwBytes)
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, 32 >= width (4 * saltBytes)
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, N >= 1, 512 >= width N, 1+width N >= width (N-1)
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)
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=> [pwBytes][8] -> [saltBytes][8] -> [dkBytes][8]
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SCrypt P S = MFcrypt `{r=r,N=N} P S
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property kats_pass = ~zero ==
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[ SCrypt `{N=2^^4,r=1} "" "" ==
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[ 0x77, 0xd6, 0x57, 0x62, 0x38, 0x65, 0x7b, 0x20
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, 0x3b, 0x19, 0xca, 0x42, 0xc1, 0x8a, 0x04, 0x97
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, 0xf1, 0x6b, 0x48, 0x44, 0xe3, 0x07, 0x4a, 0xe8
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, 0xdf, 0xdf, 0xfa, 0x3f, 0xed, 0xe2, 0x14, 0x42
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, 0xfc, 0xd0, 0x06, 0x9d, 0xed, 0x09, 0x48, 0xf8
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, 0x32, 0x6a, 0x75, 0x3a, 0x0f, 0xc8, 0x1f, 0x17
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, 0xe8, 0xd3, 0xe0, 0xfb, 0x2e, 0x0d, 0x36, 0x28
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, 0xcf, 0x35, 0xe2, 0x0c, 0x38, 0xd1, 0x89, 0x06
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]
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// This tests takes too long in the Cryptol interpreter. Run once, comment it
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// out and be happy.
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// , SCrypt {N=2^^14, r=8} "pleaseletmein" "SodiumChloride" ==
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// [ 0x70, 0x23, 0xbd, 0xcb, 0x3a, 0xfd, 0x73, 0x48
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// , 0x46, 0x1c, 0x06, 0xcd, 0x81, 0xfd, 0x38, 0xeb
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// , 0xfd, 0xa8, 0xfb, 0xba, 0x90, 0x4f, 0x8e, 0x3e
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// , 0xa9, 0xb5, 0x43, 0xf6, 0x54, 0x5d, 0xa1, 0xf2
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// , 0xd5, 0x43, 0x29, 0x55, 0x61, 0x3f, 0x0f, 0xcf
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// , 0x62, 0xd4, 0x97, 0x05, 0x24, 0x2a, 0x9a, 0xf9
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// , 0xe6, 0x1e, 0x85, 0xdc, 0x0d, 0x65, 0x1e, 0x40
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// , 0xdf, 0xcf, 0x01, 0x7b, 0x45, 0x57, 0x58, 0x87
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// ]
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]
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