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https://github.com/logos-storage/logos-storage-nim.git
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adding more comments
Signed-off-by: Csaba Kiraly <csaba.kiraly@gmail.com>
This commit is contained in:
Csaba Kiraly
Dmitriy Ryajov
parent
8693453cc9
commit
6a03fbac29
@ -37,7 +37,9 @@
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#
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# Implementation:
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# Our implementation uses additive cyclic groups instead of the multiplicative
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# cyclic group in the paper, thus changing operations as in blscurve and blst.
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# cyclic group in the paper, thus changing the name of the group operation as in
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# blscurve and blst. Thus, point multiplication becomes point addition, and scalar
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# exponentiation becomes scalar multiplicaiton.
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#
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# Number of operations:
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# The following table summarizes the number of operations in different phases
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@ -80,32 +82,41 @@ import blscurve
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import blscurve/blst/blst_abi
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import ../rng
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const bytespersector = 31 # r is 255 bits long
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# sector size in bytes. Must be smaller than the subgroup order r
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# which is 255 bits long for BLS12-381
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const bytespersector = 31
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# a single sector
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type ZChar = array[bytespersector, byte]
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# secret key combining the metadata signing key and the POR generation key
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type SecretKey = object
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signkey: blscurve.SecretKey
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key: blst_scalar
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# public key combining the metadata signing key and the POR validation key
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type PublicKey = object
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signkey: blscurve.PublicKey
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key: blst_p2
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# POR metadata
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type TauZero = object
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name: array[512,byte]
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n: int64
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u: seq[blst_p1]
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# signed POR metadata
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type Tau = object
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t: TauZero
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signature: array[96, byte]
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proc fromBytesBE(a: array[32, byte]): blst_scalar =
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## Convert data to blst native form
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blst_scalar_from_bendian(result, a)
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doAssert(blst_scalar_fr_check(result).bool)
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proc fromBytesBE(a: openArray[byte]): blst_scalar =
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## Convert data to blst native form
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var b: array[32, byte]
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doAssert(a.len <= b.len)
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let d = b.len - a.len
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@ -115,10 +126,12 @@ proc fromBytesBE(a: openArray[byte]): blst_scalar =
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doAssert(blst_scalar_fr_check(result).bool)
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proc getSector(f: File, blockid: int64, sectorid: int64, spb: int64): ZChar =
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## Read file sector at given <blockid, sectorid> postion
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f.setFilePos((blockid * spb + sectorid) * sizeof(result))
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let r = f.readBytes(result, 0, sizeof(result))
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proc rndScalar(): blst_scalar =
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## Generate random scalar within the subroup order r
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var scal{.noInit.}: array[32, byte]
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var scalar{.noInit.}: blst_scalar
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@ -132,6 +145,7 @@ proc rndScalar(): blst_scalar =
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return scalar
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proc rndP2(): (blst_p2, blst_scalar) =
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## Generate random point on G2
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var x{.noInit.}: blst_p2
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x.blst_p2_from_affine(BLS12_381_G2) # init from generator
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let scalar = rndScalar()
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@ -139,6 +153,7 @@ proc rndP2(): (blst_p2, blst_scalar) =
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return (x, scalar)
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proc rndP1(): (blst_p1, blst_scalar) =
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## Generate random point on G1
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var x{.noInit.}: blst_p1
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x.blst_p1_from_affine(BLS12_381_G1) # init from generator
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let scalar = rndScalar()
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@ -146,9 +161,11 @@ proc rndP1(): (blst_p1, blst_scalar) =
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return (x, scalar)
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proc posKeygen(): (blst_p2, blst_scalar) =
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## Generate POS key pair
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rndP2()
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proc keygen*(): (PublicKey, SecretKey) =
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## Generate key pair for signing metadata and for POS tags
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var pk: PublicKey
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var sk: SecretKey
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var ikm: array[32, byte]
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@ -161,6 +178,7 @@ proc keygen*(): (PublicKey, SecretKey) =
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return (pk, sk)
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proc split(f: File, s: int64): int64 =
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## Calculate number of blocks for a file
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let size = f.getFileSize()
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let n = ((size - 1) div (s * sizeof(ZChar))) + 1
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echo "File size=", size, " bytes",
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@ -171,17 +189,18 @@ proc split(f: File, s: int64): int64 =
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return n
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proc hashToG1(msg: string): blst_p1 =
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## Hash to curve with Dagger specific domain separation
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const dst = "DAGGER-PROOF-OF-CONCEPT"
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result.blst_hash_to_g1(msg, dst, aug = "")
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proc hashNameI(name: openArray[byte], i: int64): blst_p1 =
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## Calculate unique filname and block index based hash
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return hashToG1($name & $i)
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proc generateAuthenticatorNaive(i: int64, s: int64, t: TauZero, f: File, ssk: SecretKey): blst_p1 =
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## Naive implementation of authenticator as in the S&W paper.
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## With the paper's multiplicative notation:
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## \sigmai=\(H(file||i)\cdot\prod{j=0}^{s-1}{uj^{m[i][j]}})^{\alpha}
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var sum: blst_p1
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for j in 0 ..< s:
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var prod: blst_p1
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@ -199,7 +218,6 @@ proc generateAuthenticatorOpt(i: int64, s: int64, t: TauZero, ubase: openArray[b
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##
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## With the paper's multiplicative notation, we use:
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## (H(file||i)\cdot g^{\sum{j=0}^{s-1}{r_j \cdot m[i][j]}})^{\alpha}
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var sum: blst_fr
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var sums: blst_scalar
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for j in 0 ..< s:
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@ -217,12 +235,15 @@ proc generateAuthenticatorOpt(i: int64, s: int64, t: TauZero, ubase: openArray[b
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result.blst_p1_mult(result, ssk.key, 255)
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proc generateAuthenticator(i: int64, s: int64, t: TauZero, ubase: openArray[blst_scalar], f: File, ssk: SecretKey): blst_p1 =
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## Wrapper to select tag generator implementation
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# let a = generateAuthenticatorNaive(i, s, t, f, ssk)
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let b = generateAuthenticatorOpt(i, s, t, ubase, f, ssk)
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# doAssert(a.blst_p1_is_equal(b).bool)
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return b
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proc setup*(ssk: SecretKey, s:int64, filename: string): (Tau, seq[blst_p1]) =
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## Set up the POR scheme by generating tags and metadata
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let file = open(filename)
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let n = split(file, s)
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var t = TauZero(n: n)
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@ -254,13 +275,8 @@ type QElement = object
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I: int64
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V: blst_scalar
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proc generateQuery*(
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tau: Tau,
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spk: PublicKey,
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l: int # query elements
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): seq[QElement] =
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# verify signature on Tau
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proc generateQuery*(tau: Tau, spk: PublicKey, l: int): seq[QElement] =
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## Generata a random BLS query of given sizxe
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let n = tau.t.n # number of blocks
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for i in 0 ..< l :
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@ -270,6 +286,7 @@ proc generateQuery*(
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result.add(q)
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proc generateProof*(q: openArray[QElement], authenticators: openArray[blst_p1], spk: PublicKey, s: int64, filename: string): (seq[blst_scalar], blst_p1) =
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## Generata BLS proofs for a given query
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let file = open(filename)
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var mu: seq[blst_scalar]
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@ -296,6 +313,7 @@ proc generateProof*(q: openArray[QElement], authenticators: openArray[blst_p1],
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return (mu, sigma)
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proc pairing(a: blst_p1, b: blst_p2): blst_fp12 =
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## Calculate pairing G_1,G_2 -> G_T
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var aa: blst_p1_affine
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var bb: blst_p2_affine
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blst_p1_to_affine(aa, a)
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@ -310,7 +328,8 @@ proc verifyPairingsNaive(a1: blst_p1, a2: blst_p2, b1: blst_p1, b2: blst_p2) : b
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return e1 == e2
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proc verifyPairingsNeg(a1: blst_p1, a2: blst_p2, b1: blst_p1, b2: blst_p2) : bool =
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# based on https://github.com/benjaminion/c-kzg/blob/main/src/bls12_381.c
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## Faster pairing verification using 2 miller loops but ony one final exponentiation
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## based on https://github.com/benjaminion/c-kzg/blob/main/src/bls12_381.c
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var
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loop0, loop1, gt_point: blst_fp12
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aa1, bb1: blst_p1_affine
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@ -333,9 +352,12 @@ proc verifyPairingsNeg(a1: blst_p1, a2: blst_p2, b1: blst_p1, b2: blst_p2) : boo
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return blst_fp12_is_one(gt_point).bool
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proc verifyPairings(a1: blst_p1, a2: blst_p2, b1: blst_p1, b2: blst_p2) : bool =
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## Wrapper to select verify pairings implementation
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verifyPairingsNaive(a1, a2, b1, b2)
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#verifyPairingsNeg(a1, a2, b1, b2)
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proc verifyProof*(tau: Tau, q: openArray[QElement], mus: openArray[blst_scalar], sigma: blst_p1, spk: PublicKey): bool =
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## Verify a BLS proof given a query
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# verify signature on Tau
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var signature: Signature
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