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//===----------------------------------------------------------------------===//
//
// This source file is part of the SwiftCrypto open source project
//
// Copyright (c) 2019-2020 Apple Inc. and the SwiftCrypto project authors
// Licensed under Apache License v2.0
//
// See LICENSE.txt for license information
// See CONTRIBUTORS.md for the list of SwiftCrypto project authors
//
// SPDX-License-Identifier: Apache-2.0
//
//===----------------------------------------------------------------------===//
#if CRYPTO_IN_SWIFTPM && !CRYPTO_IN_SWIFTPM_FORCE_BUILD_API
@_exported import CryptoKit
#else
import Foundation
private let protocolLabel = Data("HPKE-v1".utf8)
private let eaePRKLabel = Data("eae_prk".utf8)
private let sharedSecretLabel = Data("shared_secret".utf8)
extension Data {
internal init(unsafeFromContiguousBytes cb: ContiguousBytes) {
self = cb.withUnsafeBytes { return Data($0) }
}
}
internal func ExtractAndExpand(zz: ContiguousBytes, kemContext: Data, suiteID: Data, kem: HPKE.KEM, kdf: HPKE.KDF) -> SymmetricKey {
let eaePrk = LabeledExtract(salt: Data(), label: eaePRKLabel, ikm: zz, suiteID: suiteID, kdf: kdf)
return LabeledExpand(prk: eaePrk, label: sharedSecretLabel,
info: kemContext, outputByteCount: kem.nSecret, suiteID: suiteID, kdf: kdf)
}
internal func LabeledExtract(salt: Data?, label: Data, ikm: ContiguousBytes?, suiteID: Data, kdf: HPKE.KDF) -> SymmetricKey {
var labeled_ikm = protocolLabel
labeled_ikm.append(suiteID)
labeled_ikm.append(label)
ikm.map { labeled_ikm.append(Data(unsafeFromContiguousBytes: $0)) }
return kdf.extract(salt: salt ?? Data(), ikm: SymmetricKey(data: labeled_ikm))
}
internal func LabeledExpand<Info: DataProtocol>(prk: SymmetricKey, label: Data, info: Info, outputByteCount: UInt16, suiteID: Data, kdf: HPKE.KDF) -> SymmetricKey {
var labeled_info = I2OSP(value: Int(outputByteCount), outputByteCount: 2)
labeled_info.append(protocolLabel)
labeled_info.append(suiteID)
labeled_info.append(label)
labeled_info.append(contentsOf: info)
return kdf.expand(prk: prk, info: labeled_info, outputByteCount: Int(outputByteCount))
}
internal func NonSecretOutputLabeledExtract(salt: Data?, label: Data, ikm: ContiguousBytes?, suiteID: Data, kdf: HPKE.KDF) -> Data {
return Data(unsafeFromContiguousBytes: LabeledExtract(salt: salt, label: label, ikm: ikm, suiteID: suiteID, kdf: kdf))
}
internal func NonSecretOutputLabeledExpand(prk: SymmetricKey, label: Data, info: Data, outputByteCount: UInt16, suiteID: Data, kdf: HPKE.KDF) -> Data {
return Data(unsafeFromContiguousBytes: LabeledExpand(prk: prk, label: label, info: info, outputByteCount: outputByteCount, suiteID: suiteID, kdf: kdf))
}
#endif // Linux or !SwiftPM
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