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Improve Sealed Box construction #132

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Merged
Lukasa merged 4 commits into from
Jan 23, 2023
Merged

Improve Sealed Box construction #132

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d5b2a93
Improve Sealed Box construction
Lukasa Jan 23, 2023
d9952eb
Prefer nonce.count
Lukasa Jan 23, 2023
64ab437
Lower alloc limits
Lukasa Jan 23, 2023
dba31fc
Merge branch 'main' into cb-improve-sealed-box-construction
Lukasa Jan 23, 2023
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17 changes: 16 additions & 1 deletion Sources/NIOSSH/TransportProtection/AESGCM.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -99,7 +99,7 @@ extension AESGCMTransportProtection: NIOSSHTransportProtection {
}

// Ok, let's try to decrypt this data.
let sealedBox = try AES.GCM.SealedBox(nonce: AES.GCM.Nonce(data: self.inboundNonce), ciphertext: ciphertextView, tag: tagView)
let sealedBox = try AES.GCM.SealedBox(nonce: self.inboundNonce, ciphertext: ciphertextView, tag: tagView)
plaintext = try AES.GCM.open(sealedBox, using: self.inboundEncryptionKey, authenticating: lengthView)

// All good! A quick soundness check to verify that the length of the plaintext is ok.
Expand Down Expand Up @@ -342,3 +342,18 @@ extension Data {
self = self[contentStartIndex ..< contentEndIndex]
}
}

extension AES.GCM.SealedBox {
fileprivate init(nonce: SSHAESGCMNonce, ciphertext: ByteBufferView, tag: ByteBufferView) throws {
// As a workaround for a Swift Crypto inefficiency, we create the combined representation
// directly.
var combined: [UInt8] = []
combined.reserveCapacity(12 + ciphertext.count + tag.count)
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@dnadoba dnadoba Jan 23, 2023

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can we add a comment that 12 is the size of nonce or can we make it a static property on SSHAESGCMNonce?

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@Lukasa Lukasa Jan 23, 2023

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Done.


combined.append(contentsOf: nonce)
combined.append(contentsOf: ciphertext)
combined.append(contentsOf: tag)

try self.init(combined: combined)
}
}