54 lines
1.5 KiB
Nim
54 lines
1.5 KiB
Nim
## nim-ws
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## Copyright (c) 2021 Status Research & Development GmbH
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## Licensed under either of
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## * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
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## * MIT license ([LICENSE-MIT](LICENSE-MIT))
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## at your option.
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## This file may not be copied, modified, or distributed except according to
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## those terms.
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import bearssl
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export bearssl
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## Random helpers: similar as in stdlib, but with BrHmacDrbgContext rng
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const randMax = 18_446_744_073_709_551_615'u64
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type
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Rng* = ref BrHmacDrbgContext
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proc newRng*(): Rng =
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# You should only create one instance of the RNG per application / library
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# Ref is used so that it can be shared between components
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# TODO consider moving to bearssl
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var seeder = brPrngSeederSystem(nil)
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if seeder == nil:
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return nil
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var rng = Rng()
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brHmacDrbgInit(addr rng[], addr sha256Vtable, nil, 0)
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if seeder(addr rng.vtable) == 0:
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return nil
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rng
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proc rand*(rng: Rng, max: Natural): int =
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if max == 0: return 0
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var x: uint64
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while true:
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brHmacDrbgGenerate(addr rng[], addr x, csize_t(sizeof(x)))
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if x < randMax - (randMax mod (uint64(max) + 1'u64)): # against modulo bias
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return int(x mod (uint64(max) + 1'u64))
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proc genMaskKey*(rng: Rng): array[4, char] =
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## Generates a random key of 4 random chars.
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proc r(): char = char(rand(rng, 255))
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return [r(), r(), r(), r()]
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proc genWebSecKey*(rng: Rng): seq[byte] =
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var key = newSeq[byte](16)
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proc r(): byte = byte(rand(rng, 255))
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## Generates a random key of 16 random chars.
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for i in 0..15:
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key[i] = r()
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return key
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