Merge pull request krzyzanowskim#887 from NathanFallet/rsa

RSA

README.md

@@ -522,6 +522,33 @@ let encrypt = try AEADChaCha20Poly1305.encrypt(plaintext, key: key, iv: nonce, a
 let decrypt = try AEADChaCha20Poly1305.decrypt(ciphertext, key: key, iv: nonce, authenticationHeader: header, authenticationTag: tagArr: tag)
 ```
 
+##### RSA
+
+RSA initialization from parameters
+
+```swift
+let input: Array<UInt8> = [0,1,2,3,4,5,6,7,8,9]
+
+let n: Array<UInt8> = // RSA modulus
+let e: Array<UInt8> = // RSA public exponent
+let d: Array<UInt8> = // RSA private exponent
+
+let rsa = RSA(n: n, e: e, d: d)
+
+do {
+    let encrypted = try rsa.encrypt(input)
+    let decrypted = try rsa.decrypt(encrypted)
+} catch {
+    print(error)
+}
+```
+
+RSA key generation
+
+```swift
+let rsa = RSA(keySize: 2048) // This generates a modulus, public exponent and private exponent with the given size
+```
+
 ## Author
 
 CryptoSwift is owned and maintained by [Marcin Krzyżanowski](http://www.krzyzanowskim.com)

Sources/CryptoSwift/Array+Extension.swift

@@ -24,6 +24,11 @@ extension Array {
   var slice: ArraySlice<Element> {
     self[self.startIndex ..< self.endIndex]
   }
+
+  @inlinable
+  subscript (safe index: Index) -> Element? {
+    return indices.contains(index) ? self[index] : nil
+  }
 }
 
 extension Array where Element == UInt8 {

Sources/CryptoSwift/BigInt/Addition.swift

@@ -0,0 +1,126 @@
+//
+//  Addition.swift
+//  BigInt
+//
+//  Created by Károly Lőrentey on 2016-01-03.
+//  Copyright © 2016-2017 Károly Lőrentey.
+//
+
+extension BigUInt {
+    //MARK: Addition
+
+    /// Add `word` to this integer in place.
+    /// `word` is shifted `shift` words to the left before being added.
+    ///
+    /// - Complexity: O(max(count, shift))
+    internal mutating func addWord(_ word: Word, shiftedBy shift: Int = 0) {
+        precondition(shift >= 0)
+        var carry = word
+        var i = shift
+        while carry > 0 {
+            let (d, c) = self[i].addingReportingOverflow(carry)
+            self[i] = d
+            carry = (c ? 1 : 0)
+            i += 1
+        }
+    }
+
+    /// Add the digit `d` to this integer and return the result.
+    /// `d` is shifted `shift` words to the left before being added.
+    ///
+    /// - Complexity: O(max(count, shift))
+    internal func addingWord(_ word: Word, shiftedBy shift: Int = 0) -> BigUInt {
+        var r = self
+        r.addWord(word, shiftedBy: shift)
+        return r
+    }
+
+    /// Add `b` to this integer in place.
+    /// `b` is shifted `shift` words to the left before being added.
+    ///
+    /// - Complexity: O(max(count, b.count + shift))
+    internal mutating func add(_ b: BigUInt, shiftedBy shift: Int = 0) {
+        precondition(shift >= 0)
+        var carry = false
+        var bi = 0
+        let bc = b.count
+        while bi < bc || carry {
+            let ai = shift + bi
+            let (d, c) = self[ai].addingReportingOverflow(b[bi])
+            if carry {
+                let (d2, c2) = d.addingReportingOverflow(1)
+                self[ai] = d2
+                carry = c || c2
+            }
+            else {
+                self[ai] = d
+                carry = c
+            }
+            bi += 1
+        }
+    }
+
+    /// Add `b` to this integer and return the result.
+    /// `b` is shifted `shift` words to the left before being added.
+    ///
+    /// - Complexity: O(max(count, b.count + shift))
+    internal func adding(_ b: BigUInt, shiftedBy shift: Int = 0) -> BigUInt {
+        var r = self
+        r.add(b, shiftedBy: shift)
+        return r
+    }
+
+    /// Increment this integer by one. If `shift` is non-zero, it selects
+    /// the word that is to be incremented.
+    ///
+    /// - Complexity: O(count + shift)
+    internal mutating func increment(shiftedBy shift: Int = 0) {
+        self.addWord(1, shiftedBy: shift)
+    }
+
+    /// Add `a` and `b` together and return the result.
+    ///
+    /// - Complexity: O(max(a.count, b.count))
+    public static func +(a: BigUInt, b: BigUInt) -> BigUInt {
+        return a.adding(b)
+    }
+
+    /// Add `a` and `b` together, and store the sum in `a`.
+    ///
+    /// - Complexity: O(max(a.count, b.count))
+    public static func +=(a: inout BigUInt, b: BigUInt) {
+        a.add(b, shiftedBy: 0)
+    }
+}
+
+extension BigInt {
+    /// Add `a` to `b` and return the result.
+    public static func +(a: BigInt, b: BigInt) -> BigInt {
+        switch (a.sign, b.sign) {
+        case (.plus, .plus):
+            return BigInt(sign: .plus, magnitude: a.magnitude + b.magnitude)
+        case (.minus, .minus):
+            return BigInt(sign: .minus, magnitude: a.magnitude + b.magnitude)
+        case (.plus, .minus):
+            if a.magnitude >= b.magnitude {
+                return BigInt(sign: .plus, magnitude: a.magnitude - b.magnitude)
+            }
+            else {
+                return BigInt(sign: .minus, magnitude: b.magnitude - a.magnitude)
+            }
+        case (.minus, .plus):
+            if b.magnitude >= a.magnitude {
+                return BigInt(sign: .plus, magnitude: b.magnitude - a.magnitude)
+            }
+            else {
+                return BigInt(sign: .minus, magnitude: a.magnitude - b.magnitude)
+            }
+        }
+    }
+
+    /// Add `b` to `a` in place.
+    public static func +=(a: inout BigInt, b: BigInt) {
+        a = a + b
+    }
+}
+

Sources/CryptoSwift/BigInt/BigInt.swift

@@ -0,0 +1,74 @@
+//
+//  BigInt.swift
+//  BigInt
+//
+//  Created by Károly Lőrentey on 2015-12-27.
+//  Copyright © 2016-2017 Károly Lőrentey.
+//
+
+//MARK: BigInt
+
+/// An arbitary precision signed integer type, also known as a "big integer".
+///
+/// Operations on big integers never overflow, but they might take a long time to execute.
+/// The amount of memory (and address space) available is the only constraint to the magnitude of these numbers.
+///
+/// This particular big integer type uses base-2^64 digits to represent integers.
+///
+/// `BigInt` is essentially a tiny wrapper that extends `BigUInt` with a sign bit and provides signed integer
+/// operations. Both the underlying absolute value and the negative/positive flag are available as read-write 
+/// properties.
+///
+/// Not all algorithms of `BigUInt` are available for `BigInt` values; for example, there is no square root or
+/// primality test for signed integers. When you need to call one of these, just extract the absolute value:
+///
+/// ```Swift
+/// BigInt(255).abs.isPrime()   // Returns false
+/// ```
+///
+public struct BigInt: SignedInteger {
+    public enum Sign {
+        case plus
+        case minus
+    }
+
+    public typealias Magnitude = BigUInt
+
+    /// The type representing a digit in `BigInt`'s underlying number system.
+    public typealias Word = BigUInt.Word
+
+    public static var isSigned: Bool {
+        return true
+    }
+
+    /// The absolute value of this integer.
+    public var magnitude: BigUInt
+
+    /// True iff the value of this integer is negative.
+    public var sign: Sign
+
+    /// Initializes a new big integer with the provided absolute number and sign flag.
+    public init(sign: Sign, magnitude: BigUInt) {
+        self.sign = (magnitude.isZero ? .plus : sign)
+        self.magnitude = magnitude
+    }
+
+    /// Return true iff this integer is zero.
+    ///
+    /// - Complexity: O(1)
+    public var isZero: Bool {
+        return magnitude.isZero
+    }
+
+    /// Returns `-1` if this value is negative and `1` if it’s positive; otherwise, `0`.
+    ///
+    /// - Returns: The sign of this number, expressed as an integer of the same type.
+    public func signum() -> BigInt {
+        switch sign {
+        case .plus:
+            return isZero ? 0 : 1
+        case .minus:
+            return -1
+        }
+    }
+}