//
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// AEAD.swift
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// CryptoSwift
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//
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// Copyright (C) 2014-2022 Marcin Krzyżanowski <marcin@krzyzanowskim.com>
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// This software is provided 'as-is', without any express or implied warranty.
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//
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// In no event will the authors be held liable for any damages arising from the use of this software.
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//
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// Permission is granted to anyone to use this software for any purpose,including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions:
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//
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// - The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation is required.
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// - Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
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// - This notice may not be removed or altered from any source or binary distribution.
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//
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//
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// https://www.iana.org/assignments/aead-parameters/aead-parameters.xhtml
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/// Authenticated Encryption with Associated Data (AEAD)
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public protocol AEAD {
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static var kLen: Int { get } // key length
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static var ivRange: Range<Int> { get } // nonce length
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}
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extension AEAD {
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static func calculateAuthenticationTag(authenticator: Authenticator, cipherText: Array<UInt8>, authenticationHeader: Array<UInt8>) throws -> Array<UInt8> {
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let headerPadding = ((16 - (authenticationHeader.count & 0xf)) & 0xf)
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let cipherPadding = ((16 - (cipherText.count & 0xf)) & 0xf)
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var mac = authenticationHeader
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mac += Array<UInt8>(repeating: 0, count: headerPadding)
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mac += cipherText
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mac += Array<UInt8>(repeating: 0, count: cipherPadding)
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mac += UInt64(bigEndian: UInt64(authenticationHeader.count)).bytes()
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mac += UInt64(bigEndian: UInt64(cipherText.count)).bytes()
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return try authenticator.authenticate(mac)
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}
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}
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