Add verification

Author: ptoffy

Sources/Bcrypt/BcryptVersion.swift

@@ -27,6 +27,14 @@ public enum BcryptVersion {
     var identifier: [UInt8] {
         [.separator, majorVersion, minorVersion, .separator]  // $2x$
     }
+    
+    init(identifier: [UInt8]) {
+        switch identifier {
+        case [0x32, 0x61]: self = .v2a
+        case [0x32, 0x62]: self = .v2b
+        default: fatalError("Invalid identifier")
+        }
+    }
 }
 
 extension UInt8 {

Sources/Bcrypt/Verifier.swift

@@ -1,16 +1,17 @@
 struct Verifier {
-    private let version: BcryptVersion
-    private let hasher: Hasher
-
-    init(version: BcryptVersion) {
-        self.version = version
-        self.hasher = Hasher(version: version)
-    }
-
     @inlinable
     public func verify(password: [UInt8], hash goodHash: [UInt8]) throws -> Bool {
-        let hash = try hasher.hash(password: password, cost: 6, salt: goodHash)
-        return hash == goodHash
+        let prefix = goodHash.prefix(7)
+            
+        let version = BcryptVersion(identifier: Array(prefix[1...2]))
+        let cost = prefix[4...5].reduce(0) { $0 * 10 + Int($1 - 48) }
+        
+        let salt = Array(goodHash[7...28])
+        
+        let hasher = Hasher(version: version)
+        let newHash = try hasher.hash(password: password, cost: cost, salt: salt)
+
+        return newHash == goodHash
     }
 
 }

Tests/BcryptTests/BcryptTests.swift

@@ -64,6 +64,16 @@ struct BcryptTests {
                 "Expected: \(testVector.expectedHash), got: \(String(decoding: hash, as: UTF8.self))")
         }
     }
+    
+    @Test("End to end")
+    func endToEnd() throws {
+        let password = "password"
+        let cost = 12
+        
+        let hash = try Hasher().hash(password: Array(password.utf8), cost: cost)
+        let verifier = Verifier()
+        #expect(try verifier.verify(password: Array(password.utf8), hash: hash))
+    }
 
     @Test("Correct Version")
     func correctVersion() throws {