feat: Make base64url Data utilities public (#75)

Sources/SwiftJWT/BlueECDSA.swift

@@ -39,7 +39,7 @@ class BlueECSigner: SignerAlgorithm {
             throw JWTError.invalidJWTString
         }
         let signature = try sign(unsignedData)
-        let signatureString = signature.base64urlEncodedString()
+        let signatureString = JWTEncoder.base64urlEncodedString(data: signature)
         return header + "." + claims + "." + signatureString
     }
 
@@ -76,7 +76,7 @@ class BlueECVerifier: VerifierAlgorithm {
     func verify(jwt: String) -> Bool {
         let components = jwt.components(separatedBy: ".")
         if components.count == 3 {
-            guard let signature = Data(base64urlEncoded: components[2]),
+            guard let signature = JWTDecoder.data(base64urlEncoded: components[2]),
                 let jwtData = (components[0] + "." + components[1]).data(using: .utf8)
                 else {
                     return false

Sources/SwiftJWT/BlueHMAC.swift

@@ -35,7 +35,7 @@ class BlueHMAC: SignerAlgorithm, VerifierAlgorithm {
             throw JWTError.invalidJWTString
         }
         let signature = try sign(unsignedData)
-        let signatureString = signature.base64urlEncodedString()
+        let signatureString = JWTEncoder.base64urlEncodedString(data: signature)
         return header + "." + claims + "." + signatureString
     }
 
@@ -58,7 +58,7 @@ class BlueHMAC: SignerAlgorithm, VerifierAlgorithm {
     func verify(jwt: String) -> Bool {
         let components = jwt.components(separatedBy: ".")
         if components.count == 3 {
-            guard let signature = Data(base64urlEncoded: components[2]),
+            guard let signature = JWTDecoder.data(base64urlEncoded: components[2]),
                 let jwtData = (components[0] + "." + components[1]).data(using: .utf8)
                 else {
                     return false

Sources/SwiftJWT/BlueRSA.swift

@@ -40,7 +40,7 @@ class BlueRSA: SignerAlgorithm, VerifierAlgorithm {
             throw JWTError.invalidJWTString
         }
         let signature = try sign(unsignedData)
-        let signatureString = signature.base64urlEncodedString()
+        let signatureString = JWTEncoder.base64urlEncodedString(data: signature)
         return header + "." + claims + "." + signatureString
     }
 
@@ -76,7 +76,7 @@ class BlueRSA: SignerAlgorithm, VerifierAlgorithm {
     func verify(jwt: String) -> Bool {
         let components = jwt.components(separatedBy: ".")
         if components.count == 3 {
-            guard let signature = Data(base64urlEncoded: components[2]),
+            guard let signature = JWTDecoder.data(base64urlEncoded: components[2]),
                 let jwtData = (components[0] + "." + components[1]).data(using: .utf8)
                 else {
                     return false

Sources/SwiftJWT/Claims.swift

@@ -79,6 +79,6 @@ public extension Claims {
         let jsonEncoder = JSONEncoder()
         jsonEncoder.dateEncodingStrategy = .secondsSince1970
         let data = try jsonEncoder.encode(self)
-        return data.base64urlEncodedString()
+        return JWTEncoder.base64urlEncodedString(data: data)
     }
 }

Sources/SwiftJWT/Data+Base64URLEncoded.swift

@@ -1,5 +1,5 @@
 /**
- * Copyright IBM Corporation 2017
+ * Copyright IBM Corporation 2017-2019
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,22 +16,35 @@
 
 import Foundation
 
+/// Convenience extension for encoding a `Data` as a base64url-encoded `String`.
+extension JWTEncoder {
 
-extension Data {
-    func base64urlEncodedString() -> String {
-        let result = self.base64EncodedString()
+    /// Returns a `String` representation of this data, encoded in base64url format
+    /// as defined in RFC4648 (https://tools.ietf.org/html/rfc4648).
+    ///
+    /// This is the appropriate format for encoding the header and claims of a JWT.
+    public static func base64urlEncodedString(data: Data) -> String {
+        let result = data.base64EncodedString()
         return result.replacingOccurrences(of: "+", with: "-")
             .replacingOccurrences(of: "/", with: "_")
             .replacingOccurrences(of: "=", with: "")
     }
+}
+
+/// Convenience extension for decoding a `Data` from a base64url-encoded `String`.
+extension JWTDecoder {
 
-    init?(base64urlEncoded: String) {
+    /// Initializes a new `Data` from the base64url-encoded `String` provided. The
+    /// base64url encoding is defined in RFC4648 (https://tools.ietf.org/html/rfc4648).
+    ///
+    /// This is appropriate for reading the header or claims portion of a JWT string.
+    public static func data(base64urlEncoded: String) -> Data? {
         let paddingLength = 4 - base64urlEncoded.count % 4
         let padding = (paddingLength < 4) ? String(repeating: "=", count: paddingLength) : ""
         let base64EncodedString = base64urlEncoded
             .replacingOccurrences(of: "-", with: "+")
             .replacingOccurrences(of: "_", with: "/")
             + padding
-        self.init(base64Encoded: base64EncodedString)
+        return Data(base64Encoded: base64EncodedString)
     }
 }

Sources/SwiftJWT/Header.swift

@@ -97,6 +97,6 @@ public struct Header: Codable {
         let jsonEncoder = JSONEncoder()
         jsonEncoder.dateEncodingStrategy = .secondsSince1970
         let data = try jsonEncoder.encode(self)
-        return data.base64urlEncodedString()
+        return JWTEncoder.base64urlEncodedString(data: data)
     }
 }

Sources/SwiftJWT/JWT.swift

@@ -65,8 +65,8 @@ public struct JWT<T: Claims>: Codable {
     public init(jwtString: String, verifier: JWTVerifier = .none ) throws {
         let components = jwtString.components(separatedBy: ".")
         guard components.count == 2 || components.count == 3,
-            let headerData = Data(base64urlEncoded: components[0]),
-            let claimsData = Data(base64urlEncoded: components[1])
+            let headerData = JWTDecoder.data(base64urlEncoded: components[0]),
+            let claimsData = JWTDecoder.data(base64urlEncoded: components[1])
         else {
             throw JWTError.invalidJWTString
         }

Sources/SwiftJWT/JWTDecoder.swift

@@ -75,8 +75,8 @@ public class JWTDecoder: BodyDecoder {
     public func decode<T : Decodable>(_ type: T.Type, fromString: String) throws -> T {
         // Seperate the JWT into the headers and claims.
         let components = fromString.components(separatedBy: ".")
-        guard let headerData = Data(base64urlEncoded: components[0]),
-              let claimsData = Data(base64urlEncoded: components[1])
+        guard let headerData = JWTDecoder.data(base64urlEncoded: components[0]),
+            let claimsData = JWTDecoder.data(base64urlEncoded: components[1])
         else {
             throw JWTError.invalidJWTString
         }

Sources/SwiftJWT/JWTEncoder.swift

@@ -166,10 +166,10 @@ fileprivate class _JWTEncoder: Encoder {
                 }
                 _header.alg = encoder.jwtSigner?.name
                 let data = try jsonEncoder.encode(_header)
-                encoder.header = data.base64urlEncodedString()
+                encoder.header = JWTEncoder.base64urlEncodedString(data: data)
             } else if fieldName == "claims" {
                 let data = try jsonEncoder.encode(value)
-                encoder.claims = data.base64urlEncodedString()
+                encoder.claims = JWTEncoder.base64urlEncodedString(data: data)
             }
         }