Merge pull request #161 from jamdotdev/petar/decode-multiline-base64

fix: decode multiline base64 input correctly

Author: peckz

components/utils/base-64.utils.test.ts

@@ -16,6 +16,26 @@ describe("base-64.utils", () => {
       expect(fromBase64("aGVsbG8=")).toBe("hello");
     });
 
+    test("should decode base64 with line breaks and surrounding whitespace", () => {
+      expect(fromBase64("aGVs\nbG8=")).toBe("hello");
+      expect(fromBase64("aGVs\r\nbG8=")).toBe("hello");
+      expect(fromBase64("  aGVsbG8=  ")).toBe("hello");
+    });
+
+    test("should decode multiple base64 strings, one per line", () => {
+      expect(fromBase64("aGVsbG8=\nd29ybGQ=")).toBe("hello\nworld");
+    });
+
+    test("should decode PEM-style wrapped base64 as a single message", () => {
+      const message =
+        "hello world this is a longer message for testing pem wrap";
+      const wrapped = Buffer.from(message)
+        .toString("base64")
+        .match(/.{1,20}/g)!
+        .join("\n");
+      expect(fromBase64(wrapped)).toBe(message);
+    });
+
     test("should throw an error for an invalid Base64 string", () => {
       expect(() => fromBase64("invalid_base64")).toThrow(
         "Invalid Base64 input"

components/utils/base-64.utils.ts

@@ -6,13 +6,39 @@ export function toBase64(value: string) {
   }
 }
 
+function decodeBase64Chunk(value: string): string {
+  const decoded = Buffer.from(value, "base64").toString("utf-8");
+  if (!isPrintableASCII(decoded)) {
+    throw new Error("Decoded string contains non-printable characters");
+  }
+  return decoded;
+}
+
 export function fromBase64(value: string): string {
   try {
-    const decoded = Buffer.from(value, "base64").toString("utf-8");
-    if (!isPrintableASCII(decoded)) {
-      throw new Error("Decoded string contains non-printable characters");
+    const trimmed = value.trim();
+    if (!trimmed) {
+      return "";
+    }
+
+    const lines = trimmed
+      .split(/\r?\n/)
+      .map((line) => line.trim())
+      .filter(Boolean);
+
+    if (lines.length > 1) {
+      const stripped = trimmed.replace(/\s/g, "");
+      const singleDecoded = decodeBase64Chunk(stripped);
+      const firstLineDecoded = decodeBase64Chunk(lines[0]);
+
+      // Multiple independent base64 strings (one per line) decode to the same
+      // output as the first line when joined; PEM-style wrapped input does not.
+      if (singleDecoded === firstLineDecoded) {
+        return lines.map((line) => decodeBase64Chunk(line)).join("\n");
+      }
     }
-    return decoded;
+
+    return decodeBase64Chunk(trimmed.replace(/\s/g, ""));
   } catch {
     throw new Error("Invalid Base64 input");
   }