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diff --git a/Userland/Libraries/LibCrypto/ASN1/PEM.h b/Userland/Libraries/LibCrypto/ASN1/PEM.h
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+++ b/Userland/Libraries/LibCrypto/ASN1/PEM.h
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+/*
+ * Copyright (c) 2020, Ali Mohammad Pur <ali.mpfard@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Span.h>
+#include <LibCrypto/ASN1/ASN1.h>
+#include <LibCrypto/ASN1/DER.h>
+
+namespace Crypto {
+
+static ByteBuffer decode_pem(ReadonlyBytes data_in, size_t cert_index = 0)
+{
+    size_t i { 0 };
+    size_t start_at { 0 };
+    size_t idx { 0 };
+    size_t input_length = data_in.size();
+    auto alloc_len = input_length / 4 * 3;
+    auto output = ByteBuffer::create_uninitialized(alloc_len);
+
+    for (i = 0; i < input_length; i++) {
+        if ((data_in[i] == '\n') || (data_in[i] == '\r'))
+            continue;
+
+        if (data_in[i] != '-') {
+            // Read entire line.
+            while ((i < input_length) && (data_in[i] != '\n'))
+                i++;
+            continue;
+        }
+
+        if (data_in[i] == '-') {
+            auto end_idx = i;
+            // Read until end of line.
+            while ((i < input_length) && (data_in[i] != '\n'))
+                i++;
+            if (start_at) {
+                if (cert_index > 0) {
+                    cert_index--;
+                    start_at = 0;
+                } else {
+                    idx = decode_b64(data_in.offset(start_at), end_idx - start_at, output);
+                    break;
+                }
+            } else
+                start_at = i + 1;
+        }
+    }
+    return output.slice(0, idx);
+}
+
+}