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81 lines
2.0 KiB
Plaintext
81 lines
2.0 KiB
Plaintext
// WORK IN PROGRESS
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/*
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Implementation of the algorithms from the paper
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"Automated Analysis and Synthesis of Authenticated Encryption Schemes"
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by Viet Tung Hoang, Jonathan Katz, and Alex J. Malozemoff
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*/
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parameter
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type A : * // State type
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type K : * // Key type
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type n : # // Block size
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type p : # // Number of blocks to process at once
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type tagAmount : #
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type constraint (fin p, fin n, n >= tagAmount)
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// Process a single block using this key and tweak
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tweak_cipher : K -> Tweak -> [n] -> [n]
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// Cost for using the tweak
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Cost : Int
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Enc : K -> Tweak -> Node -> Node
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Dec : K -> Tweak -> Node -> Node
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Tag : K -> Tweak -> State -> [n]
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// The unit at which `Enc` operates
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type Node = { message : WorkBlock, state : State }
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// Some encryption schemes process multiple blocks at once
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type WorkBlock = [p*n]
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type State = [p*n] // The state for `p` blocks
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type Tweak = { nonce : Nonce, state : A, z : Int }
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type Nonce = [n]
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/*
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property
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// The tweak in the `i`th query to the tweak_cipher
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tweak_prop i { nonce = n, state = a, z = v } =
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{ nonce = n, state = a, z = v + i - 1 }
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// Property of decrypt
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Dec_prop : Tweak -> Node -> Bit
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Dec_prop t { message = m, state = x } =
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Dec t { message = c, state = x } == { message = m, state = y }
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where { message = c, state = y } = Enc t x m
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*/
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type Int = [64]
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encrypt :
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{m} fin m => K -> Nonce -> A -> [m * (p * n)] -> [m * (p * n) + tagAmount]
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encrypt key nonce state inputMsg = encMsg # tag
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where
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encMsg = join rest.0.message
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tag = take (Tag key (tweak (1 - final.1)) final.0.state)
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final = steps ! 0
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steps = [ ({ message = undefined, state = zero }, 1) ] # rest
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rest = [ (Enc key (tweak v) { message = m, state = prev.state }, v + Cost)
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| (prev,v) <- steps
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| m <- chunks
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]
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// XXX: isn't v i just 1 + i * Cost
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chunks : [m] [p * n]
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chunks = split inputMsg
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tweak : Int -> Tweak
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tweak v = { nonce = nonce, state = state, z = v }
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