diff --git a/fpdfsdk/fpdfattachment.cpp b/fpdfsdk/fpdfattachment.cpp
index e07d15b..337ab35 100644
--- a/fpdfsdk/fpdfattachment.cpp
+++ b/fpdfsdk/fpdfattachment.cpp
@@ -4,7 +4,10 @@
 
 #include "public/fpdf_attachment.h"
 
+#include "core/fpdfapi/page/cpdf_streamparser.h"
 #include "core/fpdfapi/parser/cpdf_document.h"
+#include "core/fpdfapi/parser/cpdf_string.h"
+#include "core/fpdfapi/parser/fpdf_parser_decode.h"
 #include "core/fpdfdoc/cpdf_filespec.h"
 #include "core/fpdfdoc/cpdf_nametree.h"
 #include "fpdfsdk/fsdk_define.h"
@@ -17,28 +20,119 @@
   return CPDF_NameTree(pDoc, "EmbeddedFiles").GetCount();
 }
 
-DLLEXPORT unsigned long STDCALL
-FPDFDoc_GetAttachmentName(FPDF_DOCUMENT document,
-                          int index,
-                          void* buffer,
-                          unsigned long buflen) {
+DLLEXPORT FPDF_ATTACHMENT STDCALL FPDFDoc_GetAttachment(FPDF_DOCUMENT document,
+                                                        int index) {
   CPDF_Document* pDoc = CPDFDocumentFromFPDFDocument(document);
   if (!pDoc || index < 0)
-    return 0;
+    return nullptr;
 
   CPDF_NameTree nameTree(pDoc, "EmbeddedFiles");
   if (static_cast<size_t>(index) >= nameTree.GetCount())
-    return 0;
+    return nullptr;
 
   CFX_ByteString csName;
-  CPDF_Object* pFile = nameTree.LookupValueAndName(index, &csName);
+  return nameTree.LookupValueAndName(index, &csName);
+}
+
+DLLEXPORT unsigned long STDCALL
+FPDFAttachment_GetName(FPDF_ATTACHMENT attachment,
+                       void* buffer,
+                       unsigned long buflen) {
+  CPDF_Object* pFile = CPDFObjectFromFPDFAttachment(attachment);
   if (!pFile)
     return 0;
 
-  CFX_ByteString name = CPDF_FileSpec(pFile).GetFileName().UTF16LE_Encode();
-  unsigned long len = name.GetLength();
-  if (buffer && buflen >= len)
-    memcpy(buffer, name.c_str(), len);
+  return Utf16EncodeMaybeCopyAndReturnLength(CPDF_FileSpec(pFile).GetFileName(),
+                                             buffer, buflen);
+}
 
-  return len;
+DLLEXPORT FPDF_BOOL STDCALL FPDFAttachment_HasKey(FPDF_ATTACHMENT attachment,
+                                                  FPDF_WIDESTRING key) {
+  CPDF_Object* pFile = CPDFObjectFromFPDFAttachment(attachment);
+  if (!pFile)
+    return 0;
+
+  CPDF_Dictionary* pParamsDict = CPDF_FileSpec(pFile).GetParamsDict();
+  if (!pParamsDict)
+    return 0;
+
+  return pParamsDict->KeyExist(CFXByteStringFromFPDFWideString(key));
+}
+
+DLLEXPORT FPDF_OBJECT_TYPE STDCALL
+FPDFAttachment_GetValueType(FPDF_ATTACHMENT attachment, FPDF_WIDESTRING key) {
+  if (!FPDFAttachment_HasKey(attachment, key))
+    return FPDF_OBJECT_UNKNOWN;
+
+  CPDF_Object* pObj = CPDF_FileSpec(CPDFObjectFromFPDFAttachment(attachment))
+                          .GetParamsDict()
+                          ->GetObjectFor(CFXByteStringFromFPDFWideString(key));
+  if (!pObj)
+    return FPDF_OBJECT_UNKNOWN;
+
+  return pObj->GetType();
+}
+
+DLLEXPORT unsigned long STDCALL
+FPDFAttachment_GetStringValue(FPDF_ATTACHMENT attachment,
+                              FPDF_WIDESTRING key,
+                              void* buffer,
+                              unsigned long buflen) {
+  CPDF_Object* pFile = CPDFObjectFromFPDFAttachment(attachment);
+  if (!pFile)
+    return 0;
+
+  CPDF_Dictionary* pParamsDict = CPDF_FileSpec(pFile).GetParamsDict();
+  if (!pParamsDict)
+    return 0;
+
+  CFX_ByteString bsKey = CFXByteStringFromFPDFWideString(key);
+  CFX_WideString value = pParamsDict->GetUnicodeTextFor(bsKey);
+  if (bsKey == "CheckSum") {
+    CPDF_String* stringValue = pParamsDict->GetObjectFor(bsKey)->AsString();
+    if (stringValue->IsHex()) {
+      value =
+          CPDF_String(nullptr, PDF_EncodeString(stringValue->GetString(), true),
+                      false)
+              .GetUnicodeText();
+    }
+  }
+
+  return Utf16EncodeMaybeCopyAndReturnLength(value, buffer, buflen);
+}
+
+DLLEXPORT unsigned long STDCALL
+FPDFAttachment_GetFile(FPDF_ATTACHMENT attachment,
+                       void* buffer,
+                       unsigned long buflen) {
+  CPDF_Object* pFile = CPDFObjectFromFPDFAttachment(attachment);
+  if (!pFile)
+    return 0;
+
+  CPDF_Stream* pFileStream = CPDF_FileSpec(pFile).GetFileStream();
+  if (!pFileStream)
+    return 0;
+
+  uint8_t* data = pFileStream->GetRawData();
+  uint32_t len = pFileStream->GetRawSize();
+  CPDF_Dictionary* pFileDict = pFileStream->GetDict();
+  if (!pFileDict || pFileDict->GetStringFor("Filter").IsEmpty()) {
+    if (buffer && buflen >= len)
+      memcpy(buffer, data, len);
+
+    return len;
+  }
+
+  // Decode the stream if a stream filter is specified.
+  uint8_t* decodedData = nullptr;
+  uint32_t decodedLen = 0;
+  CPDF_StreamParser::DecodeInlineStream(
+      data, len, pFileDict->GetIntegerFor("Width"),
+      pFileDict->GetIntegerFor("Height"), pFileDict->GetStringFor("Filter"),
+      pFileDict->GetDictFor("DecodeParms"), &decodedData, &decodedLen);
+  if (buffer && buflen >= decodedLen)
+    memcpy(buffer, decodedData, decodedLen);
+
+  FX_Free(decodedData);
+  return decodedLen;
 }