feat: add sncrypto client side packages

packages/sncrypto-common/src/Base64/CryptoBase64Interface.ts

@@ -0,0 +1,25 @@
+import { Base64String } from '../Types/Base64String'
+import { Utf8String } from '../Types/Utf8String'
+
+export interface CryptoBase64Interface {
+  /**
+   * Converts a plain string into base64
+   * @param text - A plain string
+   * @returns  A base64 encoded string
+   */
+  base64Encode(text: Utf8String): Base64String
+
+  /**
+   * Converts a plain string into url-safe base64
+   * @param text - A plain string
+   * @returns  A base64 encoded string
+   */
+  base64URLEncode(text: Utf8String): Base64String
+
+  /**
+   * Converts a base64 string into a plain string
+   * @param base64String - A base64 encoded string
+   * @returns A plain string
+   */
+  base64Decode(base64String: Base64String): Utf8String
+}