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generateAuthenticator: add some more explanation

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Signed-off-by: Csaba Kiraly <csaba.kiraly@gmail.com>
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Csaba Kiraly 2021-10-22 15:48:14 +02:00 committed by Dmitriy Ryajov
parent 8158ecf892
commit 680c0a54b6
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1 changed files with 10 additions and 0 deletions
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dagger/storageproofs/bls.nim
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@ -178,6 +178,9 @@ proc hashNameI(name: openArray[byte], i: int64): blst_p1 =
return hashToG1($name & $i)
proc generateAuthenticatorNaive(i: int64, s: int64, t: TauZero, f: File, ssk: SecretKey): blst_p1 =
## Naive implementation of authenticator as in the S&W paper.
## With the paper's multiplicative notation:
## \sigmai=\(H(file||i)\cdot\prod{j=0}^{s-1}{uj^{m[i][j]}})^{\alpha}
var sum: blst_p1
for j in 0 ..< s:
@ -189,6 +192,13 @@ proc generateAuthenticatorNaive(i: int64, s: int64, t: TauZero, f: File, ssk: Se
result.blst_p1_mult(result, ssk.key, 255)
proc generateAuthenticatorOpt(i: int64, s: int64, t: TauZero, ubase: openArray[blst_scalar], f: File, ssk: SecretKey): blst_p1 =
## Optimized implementation of authenticator generation
## This implementation is reduces the number of scalar multiplications
## from s+1 to 1+1 , using knowledge about the scalars (r_j)
## used to generate u_j as u_j = g^{r_j}
##
## With the paper's multiplicative notation, we use:
## (H(file||i)\cdot g^{\sum{j=0}^{s-1}{r_j \cdot m[i][j]}})^{\alpha}
var sum: blst_fr
var sums: blst_scalar