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https://github.com/logos-storage/logos-storage-nim.git
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72 lines
2.3 KiB
Nim
72 lines
2.3 KiB
Nim
## Nim-Codex
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## Copyright (c) 2025 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 std/sequtils
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import bearssl/[blockx, hash]
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import stew/[byteutils, endians2]
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import ../rng
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import ./bearsslhash
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{.push raises: [].}
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const
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MasterKeySize = 32 # 256 bits
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KeySize = 24 # 192 bits for AES-192
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IvSize = 16 # 128 bits
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KeyDerivationIdentifier = "aes192_block_key".toBytes
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IvDerivationIdentifier = "aes192_block_iv".toBytes
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type CodexEncryption* = ref object
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masterKey: seq[byte]
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proc newCodexEncryption*(): CodexEncryption =
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let masterKey = newSeqWith(MasterKeySize, Rng.instance.rand(uint8.high).byte)
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CodexEncryption(masterKey: masterKey)
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proc newCodexEncryption*(masterKey: seq[byte]): CodexEncryption =
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CodexEncryption(masterKey: masterKey)
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proc getKeyHexEncoded*(self: CodexEncryption): string =
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self.masterKey.toHex()
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proc deriveKeyForBlockIndex(self: CodexEncryption, blockIndex: uint32): seq[byte] =
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let blockIndexArray = toBytes(blockIndex, bigEndian)
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bearSslHash(
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addr sha256Vtable, self.masterKey & KeyDerivationIdentifier & blockIndexArray.toSeq
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)[0 ..< KeySize]
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proc deriveIvForBlockIndex(self: CodexEncryption, blockIndex: uint32): seq[byte] =
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let blockIndexArray = toBytes(blockIndex, bigEndian)
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bearSslHash(
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addr sha256Vtable, self.masterKey & IvDerivationIdentifier & blockIndexArray.toSeq
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)[0 ..< IvSize]
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proc encryptBlock*(
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self: CodexEncryption, blockData: seq[byte], blockIndex: uint32
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): seq[byte] =
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let key = self.deriveKeyForBlockIndex(blockIndex)
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let iv = self.deriveIvForBlockIndex(blockIndex)
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result = blockData
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var encCtx: AesBigCbcencKeys
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aesBigCbcencInit(encCtx, addr key[0], key.len.uint)
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aesBigCbcencRun(encCtx, addr iv[0], addr result[0], iv.len.uint)
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proc decryptBlock*(
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self: CodexEncryption, encryptedBlockData: seq[byte], blockIndex: uint32
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): seq[byte] =
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let key = self.deriveKeyForBlockIndex(blockIndex)
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let iv = self.deriveIvForBlockIndex(blockIndex)
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result = encryptedBlockData
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var decCtx: AesBigCbcdecKeys
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aesBigCbcdecInit(decCtx, addr key[0], key.len.uint)
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aesBigCbcdecRun(decCtx, addr iv[0], addr result[0], iv.len.uint)
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