Base64 implemented.

Author: Zen0x7

lib/headers/base64url/container.hpp

@@ -6,6 +6,13 @@
 #include <regex>
 
 namespace base64url {
+    static const std::string chars =
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+        "abcdefghijklmnopqrstuvwxyz"
+        "0123456789-_";
+
     struct container {
+        std::string static encode(const std::string & input, bool padding = true);
+        std::string static decode(const std::string & input);
     };
 }

lib/sources/container.cpp

@@ -1,4 +1,43 @@
 #include <base64url/container.hpp>
 
 namespace base64url {
+    std::string container::encode(const std::string &input, bool padding) {
+        std::string output;
+        int value = 0;
+        int value_b = -6;
+
+        for (const unsigned char character : input) {
+            value = (value << 8) + character;
+            value_b += 8;
+            while (value_b >= 0) {
+                output.push_back(chars[(value >> value_b) & 0x3F]);
+                value_b -= 6;
+            }
+        }
+        if (value_b > -6)
+            output.push_back(chars[((value << 8) >> (value_b + 8)) & 0x3F]);
+
+        if (padding)
+            while (output.size() % 4 != 0)
+                output.push_back('=');
+
+        return output;
+    }
+
+    std::string container::decode(const std::string &input) {
+        std::string output;
+        int value = 0;
+        int value_b = -8;
+        for (const char character : input) {
+            if (character == '=') break;
+            auto position = chars.find(character);
+            value = (value << 6) + position;
+            value_b += 6;
+            if (value_b >= 0) {
+                output.push_back(static_cast<char>((value >> value_b) & 0xFF));
+                value_b -= 8;
+            }
+        }
+        return output;
+    }
 }

tests/implementation_test.cc

@@ -1,6 +1,23 @@
 #include <gtest/gtest.h>
 #include <base64url/container.hpp>
 
-TEST(Base64URL, Assertions) {
+TEST(Base64URL, Encode) {
     using namespace base64url;
+    const std::string input = "hello world";
+    const std::string output = container::encode(input);
+    ASSERT_EQ(output, "aGVsbG8gd29ybGQ=");
+
+    const std::string output_no_padding = container::encode(input, false);
+    ASSERT_EQ(output_no_padding, "aGVsbG8gd29ybGQ");
+}
+
+TEST(Base64URL, Decode) {
+    using namespace base64url;
+    const std::string input = "aGVsbG8gd29ybGQ=";
+    const std::string output = container::decode(input);
+    ASSERT_EQ(output, "hello world");
+
+    const std::string input_no_padding = "aGVsbG8gd29ybGQ";
+    const std::string output_no_padding = container::decode(input_no_padding);
+    ASSERT_EQ(output_no_padding, "hello world");
 }