//
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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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public extension PKCS5 {
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/// A key derivation function.
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///
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/// PBKDF1 is recommended only for compatibility with existing
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/// applications since the keys it produces may not be large enough for
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/// some applications.
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struct PBKDF1 {
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public enum Error: Swift.Error {
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case invalidInput
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case derivedKeyTooLong
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}
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public enum Variant {
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case md5, sha1
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@usableFromInline
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var size: Int {
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switch self {
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case .md5:
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return MD5.digestLength
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case .sha1:
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return SHA1.digestLength
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}
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}
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@usableFromInline
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func calculateHash(_ bytes: Array<UInt8>) -> Array<UInt8> {
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switch self {
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case .sha1:
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return Digest.sha1(bytes)
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case .md5:
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return Digest.md5(bytes)
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}
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}
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}
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@usableFromInline
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let iterations: Int // c
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@usableFromInline
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let variant: Variant
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@usableFromInline
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let keyLength: Int
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@usableFromInline
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let t1: Array<UInt8>
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/// - parameters:
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/// - salt: salt, an eight-bytes
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/// - variant: hash variant
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/// - iterations: iteration count, a positive integer
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/// - keyLength: intended length of derived key
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public init(password: Array<UInt8>, salt: Array<UInt8>, variant: Variant = .sha1, iterations: Int = 4096 /* c */, keyLength: Int? = nil /* dkLen */ ) throws {
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precondition(iterations > 0)
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precondition(salt.count == 8)
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let keyLength = keyLength ?? variant.size
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if keyLength > variant.size {
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throw Error.derivedKeyTooLong
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}
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let t1 = variant.calculateHash(password + salt)
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self.iterations = iterations
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self.variant = variant
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self.keyLength = keyLength
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self.t1 = t1
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}
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/// Apply the underlying hash function Hash for c iterations
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@inlinable
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public func calculate() -> Array<UInt8> {
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var t = self.t1
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for _ in 2...self.iterations {
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t = self.variant.calculateHash(t)
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}
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return Array(t[0..<self.keyLength])
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}
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public func callAsFunction() -> Array<UInt8> {
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calculate()
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}
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}
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}
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