Revert previous commit, instead add SRPKey.unpaddedBytes

Author: adam-fowler

Sources/SRP/client.swift

@@ -96,7 +96,6 @@ public struct SRPClient<H: HashFunction> {
     ) -> [UInt8] {
         let clientPublicKey = clientPublicKey.with(padding: configuration.sizeN)
         let serverPublicKey = serverPublicKey.with(padding: configuration.sizeN)
-        let sharedSecret = sharedSecret.with(padding: configuration.sizeN)
         let hashSharedSecret = [UInt8](H.hash(data: sharedSecret.bytes))
         // get verification code
         return SRP<H>.calculateClientProof(
@@ -198,7 +197,7 @@ public extension SRPClient {
         // calculate S = (B - k*g^x)^(a+u*x)
         let S = (serverPublicKey.number - configuration.k * configuration.g.power(x, modulus: configuration.N)).power(clientKeys.private.number + u * x, modulus: configuration.N)
 
-        return SRPKey(S)
+        return SRPKey(S, padding: configuration.sizeN)
     }
 
     /// generate password verifier

Sources/SRP/keys.swift

@@ -10,8 +10,12 @@ public struct SRPKey {
     public let padding: Int
     /// Representation as a byte array
     public var bytes: [UInt8] { number.bytes.pad(to: padding) }
+    /// Representation as a byte array without padding
+    public var unpaddedBytes: [UInt8] { number.bytes }
     /// Representation as a hex string
     public var hex: String { number.bytes.pad(to: padding).hexdigest() }
+    /// Representation as a hex string without padding
+    public var unpaddedHex: String { number.bytes.hexdigest() }
 
     /// Initialize with an array of bytes
     @inlinable public init<C: Collection & ContiguousBytes>(_ bytes: C, padding: Int? = nil) {

Sources/SRP/server.swift

@@ -59,7 +59,7 @@ public struct SRPServer<H: HashFunction> {
         // calculate S
         let S = ((clientPublicKey.number * verifier.number.power(u, modulus: configuration.N)).power(serverKeys.private.number, modulus: configuration.N))
 
-        return SRPKey(S)
+        return SRPKey(S, padding: configuration.sizeN)
     }
 
     /// verify proof that client has shared secret and return a server verification proof. If verification fails a `invalidClientCode` error is thrown