Add overloaded methods in SignatureVerifier

These are methods that replaces the signature parameter
with a SessionToken parameter.

Author: MasterJ93

Sources/ATCryptography/SignatureVerifier.swift

@@ -65,4 +65,65 @@ public struct SignatureVerifier {
 
         return try await verifySignature(didKey: didKey, data: dataBytes, signature: signatureBytes, options: options)
     }
+
+    // MARK: - With SessionToken
+    /// Verifies a digital signature from a session token using a `did:key`.
+    ///
+    /// This is essentially the same as creating a ``SessionToken`` object, grabbing the signature,
+    /// and inserting it into ``verifySignature(didKey:data:signature:options:jwtAlgorithm:)``.
+    ///
+    /// - Parameters:
+    ///   - didKey: The `did:key` string associated with the signer.
+    ///   - data: The original message that was signed.
+    ///   - sessionToken: The session token to verify.
+    ///   - options: Options for signature verification. Optional. Defaults to `nil`.
+    ///   - jwtAlgorithm: The JWT algorithm used. Optional. Defaults to `nil`.
+    /// - Returns: `true` if the signature is valid, or `false` if not.
+    ///
+    /// - Throws: An error if the key type is unsupported or the JWT algorithm does not match.
+    public static func verifySignature(
+        didKey: String,
+        data: [UInt8],
+        sessionToken: SessionToken,
+        options: VerifyOptions? = nil,
+        jwtAlgorithm: String? = nil
+    ) async throws -> Bool {
+        let jwt = sessionToken
+
+        guard let signature = jwt.signature else {
+            throw SignatureVerificationError.invalidEncoding(reason: "Invalid session token.")
+        }
+
+        return try await SignatureVerifier.verifySignature(
+            didKey: didKey,
+            data: data,
+            signature: [UInt8](signature),
+            options: options,
+            jwtAlgorithm: jwtAlgorithm
+        )
+    }
+
+    /// Verifies a digital signature where the data and signature are given as UTF-8 and Base64URL strings.
+    ///
+    /// This is essentially the same as creating a ``SessionToken`` object, grabbing the signature,
+    /// and inserting it into ``verifySignatureUTF8(didKey:data:signature:options:)``.
+    ///
+    /// - Parameters:
+    ///   - didKey: The `did:key` string associated with the signer.
+    ///   - data: The original message in UTF-8 string format.
+    ///   - sessionToken: The session token to verify.
+    ///   - options: Options for signature verification. Optional. Defaults to `nil`.
+    /// - Returns: `true` if the signature is valid, otherwise `false`.
+    ///
+    /// - Throws: An error if decoding fails or signature verification fails.
+    public static func verifySignatureUTF8(didKey: String, data: String, sessionToken: SessionToken, options: VerifyOptions? = nil) async throws -> Bool {
+        let jwt = sessionToken
+
+        guard let signature = jwt.signature,
+              let encodedSignatureString = String(data: signature, encoding: .utf8) else {
+            throw SignatureVerificationError.invalidEncoding(reason: "Invalid session token.")
+        }
+
+        return try await verifySignatureUTF8(didKey: didKey, data: data, signature: encodedSignatureString, options: options)
+    }
 }