1 files changed, 86 insertions, 0 deletions
diff --git a/Userland/Libraries/LibCrypt/crypt.cpp b/Userland/Libraries/LibCrypt/crypt.cpp
new file mode 100644
index 0000000000..0a789bfe6a
--- /dev/null
+++ b/Userland/Libraries/LibCrypt/crypt.cpp
@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2020, Peter Elliott <pelliott@ualberta.ca>
+ * 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.
+ */
+#include <AK/Base64.h>
+#include <AK/Types.h>
+#include <LibCrypto/Hash/SHA2.h>
+#include <string.h>
+#include <unistd.h>
+
+extern "C" {
+
+static struct crypt_data crypt_data;
+
+char* crypt(const char* key, const char* salt)
+{
+    crypt_data.initialized = true;
+    return crypt_r(key, salt, &crypt_data);
+}
+
+static constexpr size_t crypt_salt_max = 16;
+static constexpr size_t sha_string_length = 44;
+
+char* crypt_r(const char* key, const char* salt, struct crypt_data* data)
+{
+    if (!data->initialized) {
+        errno = EINVAL;
+        return nullptr;
+    }
+
+    if (salt[0] == '$') {
+        if (salt[1] == '5') {
+            const char* salt_value = salt + 3;
+            size_t salt_len = min(strcspn(salt_value, "$"), crypt_salt_max);
+            size_t header_len = salt_len + 3;
+
+            bool fits = String(salt, header_len).copy_characters_to_buffer(data->result, sizeof(data->result));
+            if (!fits) {
+                errno = EINVAL;
+                return nullptr;
+            }
+            data->result[header_len] = '$';
+
+            Crypto::Hash::SHA256 sha;
+            sha.update(key);
+            sha.update((const u8*)salt_value, salt_len);
+
+            auto digest = sha.digest();
+            auto string = encode_base64(ReadonlyBytes(digest.immutable_data(), digest.data_length()));
+
+            fits = string.copy_characters_to_buffer(data->result + header_len + 1, sizeof(data->result) - header_len - 1);
+            if (!fits) {
+                errno = EINVAL;
+                return nullptr;
+            }
+
+            return data->result;
+        }
+    }
+
+    // DES crypt is not available.
+    errno = EINVAL;
+    return nullptr;
+}
+}