implement CryptoAPI RC4+SHA1 encryption scheme for xls import

there might be other variants out there in practice, but this
works for default encrypted xls of excel 2013

Change-Id: I91c0e1d1d95fbd1c68966650e7ac7d23276bcbe3

5 files changed, 347 insertions, 134 deletions

diff --git a/filter/source/msfilter/mscodec.cxx b/filter/source/msfilter/mscodec.cxx
index 20a1f4aa8fc4..ffbbd0992275 100644
--- a/filter/source/msfilter/mscodec.cxx
+++ b/filter/source/msfilter/mscodec.cxx
@@ -245,30 +245,36 @@ void MSCodec_Xor95::Skip( std::size_t nBytes )
     mnOffset = (mnOffset + nBytes) & 0x0F;
 }
 
-MSCodec97::MSCodec97(rtlCipher hCipher)
-    : m_hCipher(hCipher)
+MSCodec97::MSCodec97(size_t nHashLen)
+    : m_nHashLen(nHashLen)
+    , m_hCipher(rtl_cipher_create(rtl_Cipher_AlgorithmARCFOUR, rtl_Cipher_ModeStream))
+    , m_aDigestValue(nHashLen, 0)
 {
+    assert(m_hCipher != nullptr);
+    (void)memset (m_pDocId, 0, sizeof(m_pDocId));
 }
 
 MSCodec_Std97::MSCodec_Std97()
-    : MSCodec97(rtl_cipher_create(rtl_Cipher_AlgorithmARCFOUR, rtl_Cipher_ModeStream))
+    : MSCodec97(RTL_DIGEST_LENGTH_MD5)
 {
-    assert(m_hCipher != nullptr);
     m_hDigest = rtl_digest_create(rtl_Digest_AlgorithmMD5);
     assert(m_hDigest != nullptr);
-    (void)memset (m_pDigestValue, 0, sizeof(m_pDigestValue));
-    (void)memset (m_pDocId, 0, sizeof(m_pDocId));
+}
+
+MSCodec_CryptoAPI::MSCodec_CryptoAPI()
+    : MSCodec97(RTL_DIGEST_LENGTH_SHA1)
+{
 }
 
 MSCodec97::~MSCodec97()
 {
+    (void)memset(m_aDigestValue.data(), 0, m_aDigestValue.size());
+    (void)memset(m_pDocId, 0, sizeof(m_pDocId));
     rtl_cipher_destroy(m_hCipher);
 }
 
 MSCodec_Std97::~MSCodec_Std97()
 {
-    (void)memset (m_pDigestValue, 0, sizeof(m_pDigestValue));
-    (void)memset (m_pDocId, 0, sizeof(m_pDocId));
     rtl_digest_destroy(m_hDigest);
 }
 
@@ -286,7 +292,7 @@ static inline void lcl_PrintDigest(const sal_uInt8* /*pDigest*/, const char* /*m
 }
 #endif
 
-bool MSCodec_Std97::InitCodec( const uno::Sequence< beans::NamedValue >& aData )
+bool MSCodec97::InitCodec( const uno::Sequence< beans::NamedValue >& aData )
 {
 #if DEBUG_MSO_ENCRYPTION_STD97
     fprintf(stdout, "MSCodec_Std97::InitCodec: --begin\n");fflush(stdout);
@@ -295,16 +301,17 @@ bool MSCodec_Std97::InitCodec( const uno::Sequence< beans::NamedValue >& aData )
 
     ::comphelper::SequenceAsHashMap aHashData( aData );
     uno::Sequence< sal_Int8 > aKey = aHashData.getUnpackedValueOrDefault("STD97EncryptionKey", uno::Sequence< sal_Int8 >() );
-
-    if ( aKey.getLength() == RTL_DIGEST_LENGTH_MD5 )
+    const size_t nKeyLen = aKey.getLength();
+    if (nKeyLen == m_nHashLen)
     {
-        (void)memcpy( m_pDigestValue, aKey.getConstArray(), RTL_DIGEST_LENGTH_MD5 );
+        assert(m_aDigestValue.size() == m_nHashLen);
+        (void)memcpy(m_aDigestValue.data(), aKey.getConstArray(), m_nHashLen);
         uno::Sequence< sal_Int8 > aUniqueID = aHashData.getUnpackedValueOrDefault("STD97UniqueID", uno::Sequence< sal_Int8 >() );
         if ( aUniqueID.getLength() == 16 )
         {
             (void)memcpy( m_pDocId, aUniqueID.getConstArray(), 16 );
             bResult = true;
-            lcl_PrintDigest(m_pDigestValue, "digest value");
+            lcl_PrintDigest(m_aDigestValue.data(), "digest value");
             lcl_PrintDigest(m_pDocId, "DocId value");
         }
         else
@@ -316,10 +323,11 @@ bool MSCodec_Std97::InitCodec( const uno::Sequence< beans::NamedValue >& aData )
     return bResult;
 }
 
-uno::Sequence< beans::NamedValue > MSCodec_Std97::GetEncryptionData()
+uno::Sequence< beans::NamedValue > MSCodec97::GetEncryptionData()
 {
     ::comphelper::SequenceAsHashMap aHashData;
-    aHashData[ OUString( "STD97EncryptionKey" ) ] <<= uno::Sequence< sal_Int8 >( reinterpret_cast<sal_Int8*>(m_pDigestValue), RTL_DIGEST_LENGTH_MD5 );
+    assert(m_aDigestValue.size() == m_nHashLen);
+    aHashData[ OUString( "STD97EncryptionKey" ) ] <<= uno::Sequence< sal_Int8 >( reinterpret_cast<sal_Int8*>(m_aDigestValue.data()), m_nHashLen );
     aHashData[ OUString( "STD97UniqueID" ) ] <<= uno::Sequence< sal_Int8 >( reinterpret_cast<sal_Int8*>(m_pDocId), 16 );
 
     return aHashData.getAsConstNamedValueList();
@@ -335,26 +343,51 @@ void MSCodec_Std97::InitKey (
     uno::Sequence< sal_Int8 > aKey = ::comphelper::DocPasswordHelper::GenerateStd97Key(pPassData, pDocId);
     // Fill raw digest of above updates into DigestValue.
 
-    if ( aKey.getLength() == sizeof(m_pDigestValue) )
-        (void)memcpy ( m_pDigestValue, aKey.getConstArray(), sizeof(m_pDigestValue) );
+    const size_t nKeyLen = aKey.getLength();
+    if (m_aDigestValue.size() == nKeyLen)
+        (void)memcpy(m_aDigestValue.data(), aKey.getConstArray(), m_aDigestValue.size());
     else
-        memset( m_pDigestValue, 0, sizeof(m_pDigestValue) );
+        memset(m_aDigestValue.data(), 0, m_aDigestValue.size());
+
+    lcl_PrintDigest(m_aDigestValue.data(), "digest value");
+
+    (void)memcpy (m_pDocId, pDocId, 16);
+
+    lcl_PrintDigest(m_pDocId, "DocId value");
+}
+
+void MSCodec_CryptoAPI::InitKey (
+    const sal_uInt16 pPassData[16],
+    const sal_uInt8  pDocId[16])
+{
+    sal_uInt32 saltSize = 16;
+
+    // Prepare initial data -> salt + password (in 16-bit chars)
+    std::vector<sal_uInt8> initialData(pDocId, pDocId + saltSize);
+
+    // Fill PassData into KeyData.
+    for (sal_Int32 nInd = 0; nInd < 16 && pPassData[nInd]; ++nInd)
+    {
+        initialData.push_back(sal::static_int_cast<sal_uInt8>((pPassData[nInd] >> 0) & 0xff));
+        initialData.push_back(sal::static_int_cast<sal_uInt8>((pPassData[nInd] >> 8) & 0xff));
+    }
+
+    // calculate SHA1 hash of initialData
+    rtl_digest_SHA1(initialData.data(), initialData.size(), m_aDigestValue.data(), m_aDigestValue.size());
 
-    lcl_PrintDigest(m_pDigestValue, "digest value");
+    lcl_PrintDigest(m_aDigestValue.data(), "digest value");
 
     (void)memcpy (m_pDocId, pDocId, 16);
 
     lcl_PrintDigest(m_pDocId, "DocId value");
 }
 
-bool MSCodec_Std97::VerifyKey (
-    const sal_uInt8 pSaltData[16],
-    const sal_uInt8 pSaltDigest[16])
+bool MSCodec97::VerifyKey(const sal_uInt8* pSaltData, const sal_uInt8* pSaltDigest)
 {
     // both the salt data and salt digest (hash) come from the document being imported.
 
 #if DEBUG_MSO_ENCRYPTION_STD97
-    fprintf(stdout, "MSCodec_Std97::VerifyKey: \n");
+    fprintf(stdout, "MSCodec97::VerifyKey: \n");
     lcl_PrintDigest(pSaltData, "salt data");
     lcl_PrintDigest(pSaltDigest, "salt hash");
 #endif
@@ -362,35 +395,42 @@ bool MSCodec_Std97::VerifyKey (
 
     if (InitCipher(0))
     {
-        sal_uInt8 pDigest[RTL_DIGEST_LENGTH_MD5];
-        GetDigestFromSalt(pSaltData, pDigest);
+        std::vector<sal_uInt8> aDigest(m_nHashLen);
+        GetDigestFromSalt(pSaltData, aDigest.data());
 
-        sal_uInt8 pBuffer[16];
+        std::vector<sal_uInt8> aBuffer(m_nHashLen);
         // Decode original SaltDigest into Buffer.
-        rtl_cipher_decode (
-            m_hCipher, pSaltDigest, 16, pBuffer, sizeof(pBuffer));
+        rtl_cipher_decode(m_hCipher, pSaltDigest, m_nHashLen, aBuffer.data(), m_nHashLen);
 
         // Compare Buffer with computed Digest.
-        result = (memcmp (pBuffer, pDigest, sizeof(pDigest)) == 0);
+        result = (memcmp(aBuffer.data(), aDigest.data(), m_nHashLen) == 0);
 
         // Erase Buffer and Digest arrays.
-        rtl_secureZeroMemory (pBuffer, sizeof(pBuffer));
-        rtl_secureZeroMemory (pDigest, sizeof(pDigest));
+        rtl_secureZeroMemory(aBuffer.data(), m_nHashLen);
+        rtl_secureZeroMemory(aDigest.data(), m_nHashLen);
     }
 
     return result;
 }
 
-bool MSCodec_Std97::InitCipher (sal_uInt32 nCounter)
+void MSCodec_CryptoAPI::GetDigestFromSalt(const sal_uInt8* pSaltData, sal_uInt8* pDigest)
+{
+    std::vector<sal_uInt8> verifier(16);
+    rtl_cipher_decode(m_hCipher,
+        pSaltData, 16, verifier.data(), verifier.size());
+
+    rtl_digest_SHA1(verifier.data(), verifier.size(), pDigest, RTL_DIGEST_LENGTH_SHA1);
+}
+
+bool MSCodec_Std97::InitCipher(sal_uInt32 nCounter)
 {
-    rtlCipherError result;
     sal_uInt8      pKeyData[64]; // 512-bit message block
 
     // Initialize KeyData array.
     (void)memset (pKeyData, 0, sizeof(pKeyData));
 
     // Fill 40 bit of DigestValue into [0..4].
-    (void)memcpy (pKeyData, m_pDigestValue, 5);
+    (void)memcpy (pKeyData, m_aDigestValue.data(), 5);
 
     // Fill counter into [5..8].
     pKeyData[ 5] = sal_uInt8((nCounter >>  0) & 0xff);
@@ -408,7 +448,7 @@ bool MSCodec_Std97::InitCipher (sal_uInt32 nCounter)
         m_hDigest, pKeyData, RTL_DIGEST_LENGTH_MD5);
 
     // Initialize Cipher with KeyData (for decoding).
-    result = rtl_cipher_init (
+    rtlCipherError result = rtl_cipher_init (
         m_hCipher, rtl_Cipher_DirectionBoth,
         pKeyData, RTL_DIGEST_LENGTH_MD5, nullptr, 0);
 
@@ -418,6 +458,25 @@ bool MSCodec_Std97::InitCipher (sal_uInt32 nCounter)
     return (result == rtl_Cipher_E_None);
 }
 
+bool MSCodec_CryptoAPI::InitCipher(sal_uInt32 nCounter)
+{
+    // data = hash + iterator (4bytes)
+    std::vector<sal_uInt8> aKeyData(m_aDigestValue);
+    aKeyData.push_back(sal_uInt8((nCounter >>  0) & 0xff));
+    aKeyData.push_back(sal_uInt8((nCounter >>  8) & 0xff));
+    aKeyData.push_back(sal_uInt8((nCounter >> 16) & 0xff));
+    aKeyData.push_back(sal_uInt8((nCounter >> 24) & 0xff));
+
+    std::vector<sal_uInt8> hash(RTL_DIGEST_LENGTH_SHA1);
+    rtl_digest_SHA1(aKeyData.data(), aKeyData.size(), hash.data(), RTL_DIGEST_LENGTH_SHA1);
+
+    rtlCipherError result =
+        rtl_cipher_init(m_hCipher, rtl_Cipher_DirectionDecode,
+                        hash.data(), ENCRYPT_KEY_SIZE_AES_128/8, nullptr, 0);
+
+    return (result == rtl_Cipher_E_None);
+}
+
 void MSCodec_Std97::CreateSaltDigest( const sal_uInt8 nSaltData[16], sal_uInt8 nSaltDigest[16] )
 {
 #if DEBUG_MSO_ENCRYPTION_STD97
@@ -471,7 +530,7 @@ bool MSCodec97::Skip(std::size_t nDatLen)
     return bResult;
 }
 
-void MSCodec_Std97::GetDigestFromSalt( const sal_uInt8 pSaltData[16], sal_uInt8 pDigest[16] )
+void MSCodec_Std97::GetDigestFromSalt(const sal_uInt8* pSaltData, sal_uInt8* pDigest)
 {
     sal_uInt8 pBuffer[64];
     sal_uInt8 pDigestLocal[16];
@@ -530,7 +589,7 @@ void MSCodec_Std97::GetEncryptKey (
     }
 }
 
-void MSCodec_Std97::GetDocId( sal_uInt8 pDocId[16] )
+void MSCodec97::GetDocId( sal_uInt8 pDocId[16] )
 {
     if ( sizeof( m_pDocId ) == 16 )
         (void)memcpy( pDocId, m_pDocId, 16 );
@@ -557,6 +616,15 @@ EncryptionVerifierAES::EncryptionVerifierAES()
     memset(encryptedVerifierHash, 0, sizeof(encryptedVerifierHash));
 }
 
+EncryptionVerifierRC4::EncryptionVerifierRC4()
+    : saltSize(SALT_LENGTH)
+    , encryptedVerifierHashSize(SHA1_HASH_LENGTH)
+{
+    memset(salt, 0, sizeof(salt));
+    memset(encryptedVerifier, 0, sizeof(encryptedVerifier));
+    memset(encryptedVerifierHash, 0, sizeof(encryptedVerifierHash));
+}
+
 }
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/include/filter/msfilter/mscodec.hxx b/include/filter/msfilter/mscodec.hxx
index afdf163b747b..52846f8899f6 100644
--- a/include/filter/msfilter/mscodec.hxx
+++ b/include/filter/msfilter/mscodec.hxx
@@ -25,6 +25,7 @@
 #include <rtl/cipher.h>
 #include <rtl/digest.h>
 #include <sal/types.h>
+#include <vector>
 
 namespace com { namespace sun { namespace star {
     namespace beans { struct NamedValue; }
@@ -177,7 +178,7 @@ public:
 class MSFILTER_DLLPUBLIC MSCodec97
 {
 public:
-    MSCodec97(rtlCipher m_hCipher);
+    MSCodec97(size_t nHashLen);
     virtual ~MSCodec97();
 
     /** Initializes the algorithm with the encryption data.
@@ -186,7 +187,7 @@ public:
             The sequence contains the necessary data to initialize
             the codec.
      */
-    virtual bool InitCodec(const css::uno::Sequence< css::beans::NamedValue >& aData) = 0;
+    bool InitCodec(const css::uno::Sequence< css::beans::NamedValue >& aData);
 
     /** Retrieves the encryption data
 
@@ -194,8 +195,37 @@ public:
             The sequence contains the necessary data to initialize
             the codec.
      */
-    virtual css::uno::Sequence< css::beans::NamedValue > GetEncryptionData() = 0;
+    css::uno::Sequence< css::beans::NamedValue > GetEncryptionData();
+
+    /** Initializes the algorithm with the specified password and document ID.
+
+        @param pPassData
+            Wide character array containing the password. Must be zero
+            terminated, which results in a maximum length of 15 characters.
+        @param pDocId
+            Unique document identifier read from or written to the file.
+     */
+    virtual void InitKey(const sal_uInt16 pPassData[16],
+                         const sal_uInt8 pDocId[16]) = 0;
+
+
+    /** Verifies the validity of the password using the passed salt data.
+
+        @precond
+            The codec must be initialized with InitKey() before this function
+            can be used.
+
+        @param pSaltData
+            Salt data block read from the file.
+        @param pSaltDigest
+            Salt digest read from the file.
+
+        @return
+            true = Test was successful.
+     */
+    bool VerifyKey(const sal_uInt8* pSaltData, const sal_uInt8* pSaltDigest);
 
+    virtual void GetDigestFromSalt(const sal_uInt8* pSaltData, sal_uInt8* pDigest) = 0;
 
     /** Rekeys the codec using the specified counter.
 
@@ -278,12 +308,19 @@ public:
      */
     bool                Skip(std::size_t nDatLen);
 
+    /* allows to get the unique document id from the codec
+     */
+    void                GetDocId( sal_uInt8 pDocId[16] );
+
 private:
                         MSCodec97(const MSCodec97&) = delete;
     MSCodec97&          operator=(const MSCodec97&) = delete;
 
 protected:
+    size_t              m_nHashLen;
     rtlCipher           m_hCipher;
+    sal_uInt8           m_pDocId[16];
+    std::vector<sal_uInt8> m_aDigestValue;
 };
 
 /** Encodes and decodes data from protected MSO 97+ documents.
@@ -295,25 +332,8 @@ protected:
 class MSFILTER_DLLPUBLIC MSCodec_Std97 :  public MSCodec97
 {
 public:
-    explicit            MSCodec_Std97();
-                        ~MSCodec_Std97();
-
-    /** Initializes the algorithm with the encryption data.
-
-        @param aData
-            The sequence contains the necessary data to initialize
-            the codec.
-     */
-    virtual bool InitCodec(const css::uno::Sequence< css::beans::NamedValue >& aData) override;
-
-    /** Retrieves the encryption data
-
-        @return
-            The sequence contains the necessary data to initialize
-            the codec.
-     */
-    virtual css::uno::Sequence<css::beans::NamedValue> GetEncryptionData() override;
-
+    MSCodec_Std97();
+    virtual ~MSCodec_Std97() override;
 
     /** Initializes the algorithm with the specified password and document ID.
 
@@ -323,27 +343,8 @@ public:
         @param pDocId
             Unique document identifier read from or written to the file.
      */
-    void                InitKey(
-                            const sal_uInt16 pPassData[ 16 ],
-                            const sal_uInt8 pDocId[ 16 ] );
-
-    /** Verifies the validity of the password using the passed salt data.
-
-        @precond
-            The codec must be initialized with InitKey() before this function
-            can be used.
-
-        @param pSaltData
-            Salt data block read from the file.
-        @param pSaltDigest
-            Salt digest read from the file.
-
-        @return
-            true = Test was successful.
-     */
-    bool                VerifyKey(
-                            const sal_uInt8 pSaltData[ 16 ],
-                            const sal_uInt8 pSaltDigest[ 16 ] );
+    virtual void InitKey(const sal_uInt16 pPassData[16],
+                         const sal_uInt8 pDocId[16]) override;
 
     /** Rekeys the codec using the specified counter.
 
@@ -384,19 +385,24 @@ public:
                             sal_uInt8 pSaltData[16],
                             sal_uInt8 pSaltDigest[16]);
 
-    /* allows to get the unique document id from the codec
-     */
-    void                GetDocId( sal_uInt8 pDocId[16] );
-
-    void                GetDigestFromSalt( const sal_uInt8 pSaltData[16], sal_uInt8 pDigest[16] );
+    virtual void        GetDigestFromSalt(const sal_uInt8* pSaltData, sal_uInt8* pDigest) override;
 
 private:
                         MSCodec_Std97( const MSCodec_Std97& ) = delete;
     MSCodec_Std97&      operator=( const MSCodec_Std97& ) = delete;
 
     rtlDigest           m_hDigest;
-    sal_uInt8           m_pDigestValue[ RTL_DIGEST_LENGTH_MD5 ];
-    sal_uInt8           m_pDocId[16];
+};
+
+class MSFILTER_DLLPUBLIC MSCodec_CryptoAPI :  public MSCodec97
+{
+public:
+    MSCodec_CryptoAPI();
+
+    virtual void InitKey(const sal_uInt16 pPassData[16],
+                         const sal_uInt8 pDocId[16]) override;
+    virtual bool InitCipher(sal_uInt32 nCounter) override;
+    virtual void GetDigestFromSalt(const sal_uInt8* pSaltData, sal_uInt8* pDigest) override;
 };
 
 const sal_uInt32 ENCRYPTINFO_CRYPTOAPI      = 0x00000004;
@@ -459,12 +465,28 @@ struct MSFILTER_DLLPUBLIC EncryptionVerifierAES
     EncryptionVerifierAES();
 };
 
+struct MSFILTER_DLLPUBLIC EncryptionVerifierRC4
+{
+    sal_uInt32 saltSize;                                                // must be 0x00000010
+    sal_uInt8  salt[SALT_LENGTH];                                       // random generated salt value
+    sal_uInt8  encryptedVerifier[ENCRYPTED_VERIFIER_LENGTH];            // randomly generated verifier value
+    sal_uInt32 encryptedVerifierHashSize;                               // actually written hash size - depends on algorithm
+    sal_uInt8  encryptedVerifierHash[SHA1_HASH_LENGTH];                 // verifier value hash - itself also encrypted
+
+    EncryptionVerifierRC4();
+};
+
 struct MSFILTER_DLLPUBLIC StandardEncryptionInfo
 {
     EncryptionStandardHeader header;
     EncryptionVerifierAES    verifier;
 };
 
+struct MSFILTER_DLLPUBLIC RC4EncryptionInfo
+{
+    EncryptionStandardHeader header;
+    EncryptionVerifierRC4 verifier;
+};
 
 } // namespace msfilter
 
diff --git a/sc/source/filter/excel/xicontent.cxx b/sc/source/filter/excel/xicontent.cxx
index fdd43aef03e6..c854d75af154 100644
--- a/sc/source/filter/excel/xicontent.cxx
+++ b/sc/source/filter/excel/xicontent.cxx
@@ -64,6 +64,7 @@
 #include <memory>
 #include <utility>
 #include <o3tl/make_unique.hxx>
+#include <oox/helper/helper.hxx>
 
 using ::com::sun::star::uno::Sequence;
 using ::std::unique_ptr;
@@ -1110,21 +1111,80 @@ XclImpDecrypterRef lclReadFilepass8_Standard( XclImpStream& rStrm )
     OSL_ENSURE( rStrm.GetRecLeft() == 48, "lclReadFilepass8 - wrong record size" );
     if( rStrm.GetRecLeft() == 48 )
     {
-        sal_uInt8 pnSalt[ 16 ];
-        sal_uInt8 pnVerifier[ 16 ];
-        sal_uInt8 pnVerifierHash[ 16 ];
-        rStrm.Read( pnSalt, 16 );
-        rStrm.Read( pnVerifier, 16 );
-        rStrm.Read( pnVerifierHash, 16 );
-        xDecr.reset( new XclImpBiff8Decrypter( pnSalt, pnVerifier, pnVerifierHash ) );
+        std::vector<sal_uInt8> aSalt(16);
+        std::vector<sal_uInt8> aVerifier(16);
+        std::vector<sal_uInt8> aVerifierHash(16);
+        rStrm.Read(aSalt.data(), 16);
+        rStrm.Read(aVerifier.data(), 16);
+        rStrm.Read(aVerifierHash.data(), 16);
+        xDecr.reset(new XclImpBiff8StdDecrypter(aSalt, aVerifier, aVerifierHash));
     }
     return xDecr;
 }
 
-XclImpDecrypterRef lclReadFilepass8_Strong( XclImpStream& /*rStrm*/ )
+XclImpDecrypterRef lclReadFilepass8_Strong(XclImpStream& rStream)
 {
-    // not supported
-    return XclImpDecrypterRef();
+    //Its possible there are other variants in existance but these
+    //are the defaults I get with Excel 2013
+    XclImpDecrypterRef xDecr;
+
+    msfilter::RC4EncryptionInfo info;
+
+    info.header.flags = rStream.ReaduInt32();
+    if (oox::getFlag( info.header.flags, msfilter::ENCRYPTINFO_EXTERNAL))
+        return xDecr;
+
+    sal_uInt32 nHeaderSize = rStream.ReaduInt32();
+    sal_uInt32 actualHeaderSize = sizeof(info.header);
+
+    if( (nHeaderSize < actualHeaderSize) )
+        return xDecr;
+
+    info.header.flags = rStream.ReaduInt32();
+    info.header.sizeExtra = rStream.ReaduInt32();
+    info.header.algId = rStream.ReaduInt32();
+    info.header.algIdHash = rStream.ReaduInt32();
+    info.header.keyBits = rStream.ReaduInt32();
+    info.header.providedType = rStream.ReaduInt32();
+    info.header.reserved1 = rStream.ReaduInt32();
+    info.header.reserved2 = rStream.ReaduInt32();
+
+    rStream.Ignore(nHeaderSize - actualHeaderSize);
+
+    info.verifier.saltSize = rStream.ReaduInt32();
+    if (info.verifier.saltSize != 16)
+        return xDecr;
+    rStream.Read(&info.verifier.salt, sizeof(info.verifier.salt));
+    rStream.Read(&info.verifier.encryptedVerifier, sizeof(info.verifier.encryptedVerifier));
+
+    info.verifier.encryptedVerifierHashSize = rStream.ReaduInt32();
+    if (info.verifier.encryptedVerifierHashSize != RTL_DIGEST_LENGTH_SHA1)
+        return xDecr;
+    rStream.Read(&info.verifier.encryptedVerifierHash, info.verifier.encryptedVerifierHashSize);
+
+    // check flags and algorithm IDs, required are AES128 and SHA-1
+    if (!oox::getFlag(info.header.flags, msfilter::ENCRYPTINFO_CRYPTOAPI))
+        return xDecr;
+
+    if (oox::getFlag(info.header.flags, msfilter::ENCRYPTINFO_AES))
+        return xDecr;
+
+    if (info.header.algId != msfilter::ENCRYPT_ALGO_RC4)
+        return xDecr;
+
+    // hash algorithm ID 0 defaults to SHA-1 too
+    if (info.header.algIdHash != 0 && info.header.algIdHash != msfilter::ENCRYPT_HASH_SHA1)
+        return xDecr;
+
+    xDecr.reset(new XclImpBiff8CryptoAPIDecrypter(
+        std::vector<sal_uInt8>(info.verifier.salt,
+            info.verifier.salt + SAL_N_ELEMENTS(info.verifier.salt)),
+        std::vector<sal_uInt8>(info.verifier.encryptedVerifier,
+            info.verifier.encryptedVerifier + SAL_N_ELEMENTS(info.verifier.encryptedVerifier)),
+        std::vector<sal_uInt8>(info.verifier.encryptedVerifierHash,
+            info.verifier.encryptedVerifierHash + SAL_N_ELEMENTS(info.verifier.encryptedVerifierHash))));
+
+    return xDecr;
 }
 
 XclImpDecrypterRef lclReadFilepass8( XclImpStream& rStrm )
diff --git a/sc/source/filter/excel/xistream.cxx b/sc/source/filter/excel/xistream.cxx
index 31cf3d5ced08..4f28d9c5101f 100644
--- a/sc/source/filter/excel/xistream.cxx
+++ b/sc/source/filter/excel/xistream.cxx
@@ -192,28 +192,50 @@ sal_uInt16 XclImpBiff5Decrypter::OnRead( SvStream& rStrm, sal_uInt8* pnData, sal
     return nRet;
 }
 
-XclImpBiff8Decrypter::XclImpBiff8Decrypter( sal_uInt8 pnSalt[ 16 ],
-        sal_uInt8 pnVerifier[ 16 ], sal_uInt8 pnVerifierHash[ 16 ] ) :
-    maSalt( pnSalt, pnSalt + 16 ),
-    maVerifier( pnVerifier, pnVerifier + 16 ),
-    maVerifierHash( pnVerifierHash, pnVerifierHash + 16 )
+XclImpBiff8Decrypter::XclImpBiff8Decrypter(const std::vector<sal_uInt8>& rSalt,
+                                           const std::vector<sal_uInt8>& rVerifier,
+                                           const std::vector<sal_uInt8>& rVerifierHash)
+    : maSalt(rSalt)
+    , maVerifier(rVerifier)
+    , maVerifierHash(rVerifierHash)
+    , mpCodec(nullptr)
 {
 }
 
-XclImpBiff8Decrypter::XclImpBiff8Decrypter( const XclImpBiff8Decrypter& rSrc ) :
-    XclImpDecrypter( rSrc ),
-    maEncryptionData( rSrc.maEncryptionData ),
-    maSalt( rSrc.maSalt ),
-    maVerifier( rSrc.maVerifier ),
-    maVerifierHash( rSrc.maVerifierHash )
+XclImpBiff8Decrypter::XclImpBiff8Decrypter(const XclImpBiff8Decrypter& rSrc)
+    : XclImpDecrypter(rSrc)
+    , maEncryptionData(rSrc.maEncryptionData)
+    , maSalt(rSrc.maSalt)
+    , maVerifier(rSrc.maVerifier)
+    , maVerifierHash(rSrc.maVerifierHash)
+    , mpCodec(nullptr)
 {
-    if( IsValid() )
-        maCodec.InitCodec( maEncryptionData );
 }
 
-XclImpBiff8Decrypter* XclImpBiff8Decrypter::OnClone() const
+XclImpBiff8StdDecrypter::XclImpBiff8StdDecrypter(const XclImpBiff8StdDecrypter& rSrc)
+    : XclImpBiff8Decrypter(rSrc)
 {
-    return new XclImpBiff8Decrypter( *this );
+    mpCodec = &maCodec;
+    if (IsValid())
+        maCodec.InitCodec(maEncryptionData);
+}
+
+XclImpBiff8StdDecrypter* XclImpBiff8StdDecrypter::OnClone() const
+{
+    return new XclImpBiff8StdDecrypter(*this);
+}
+
+XclImpBiff8CryptoAPIDecrypter::XclImpBiff8CryptoAPIDecrypter(const XclImpBiff8CryptoAPIDecrypter& rSrc)
+    : XclImpBiff8Decrypter(rSrc)
+{
+    mpCodec = &maCodec;
+    if (IsValid())
+        maCodec.InitCodec(maEncryptionData);
+}
+
+XclImpBiff8CryptoAPIDecrypter* XclImpBiff8CryptoAPIDecrypter::OnClone() const
+{
+    return new XclImpBiff8CryptoAPIDecrypter(*this);
 }
 
 uno::Sequence< beans::NamedValue > XclImpBiff8Decrypter::OnVerifyPassword( const OUString& rPassword )
@@ -232,9 +254,9 @@ uno::Sequence< beans::NamedValue > XclImpBiff8Decrypter::OnVerifyPassword( const
             *aIt = static_cast< sal_uInt16 >( *pcChar );
 
         // init codec
-        maCodec.InitKey( &aPassVect.front(), &maSalt.front() );
-        if ( maCodec.VerifyKey( &maVerifier.front(), &maVerifierHash.front() ) )
-            maEncryptionData = maCodec.GetEncryptionData();
+        mpCodec->InitKey( &aPassVect.front(), &maSalt.front() );
+        if ( mpCodec->VerifyKey( &maVerifier.front(), &maVerifierHash.front() ) )
+            maEncryptionData = mpCodec->GetEncryptionData();
     }
 
     return maEncryptionData;
@@ -247,9 +269,9 @@ bool XclImpBiff8Decrypter::OnVerifyEncryptionData( const uno::Sequence< beans::N
     if( rEncryptionData.getLength() )
     {
         // init codec
-        maCodec.InitCodec( rEncryptionData );
+        mpCodec->InitCodec( rEncryptionData );
 
-        if ( maCodec.VerifyKey( &maVerifier.front(), &maVerifierHash.front() ) )
+        if ( mpCodec->VerifyKey( &maVerifier.front(), &maVerifierHash.front() ) )
             maEncryptionData = rEncryptionData;
     }
 
@@ -269,13 +291,13 @@ void XclImpBiff8Decrypter::OnUpdate( std::size_t nOldStrmPos, std::size_t nNewSt
         /*  Rekey cipher, if block changed or if previous offset in same block. */
         if( (nNewBlock != nOldBlock) || (nNewOffset < nOldOffset) )
         {
-            maCodec.InitCipher( nNewBlock );
+            mpCodec->InitCipher( nNewBlock );
             nOldOffset = 0;     // reset nOldOffset for next if() statement
         }
 
         /*  Seek to correct offset. */
         if( nNewOffset > nOldOffset )
-            maCodec.Skip( nNewOffset - nOldOffset );
+            mpCodec->Skip( nNewOffset - nOldOffset );
     }
 }
 
@@ -293,9 +315,9 @@ sal_uInt16 XclImpBiff8Decrypter::OnRead( SvStream& rStrm, sal_uInt8* pnData, sal
         // read the block from stream
         nRet = nRet + static_cast<sal_uInt16>(rStrm.ReadBytes(pnCurrData, nDecBytes));
         // decode the block inplace
-        maCodec.Decode( pnCurrData, nDecBytes, pnCurrData, nDecBytes );
+        mpCodec->Decode( pnCurrData, nDecBytes, pnCurrData, nDecBytes );
         if( GetOffset( rStrm.Tell() ) == 0 )
-            maCodec.InitCipher( GetBlock( rStrm.Tell() ) );
+            mpCodec->InitCipher( GetBlock( rStrm.Tell() ) );
 
         pnCurrData += nDecBytes;
         nBytesLeft = nBytesLeft - nDecBytes;
diff --git a/sc/source/filter/inc/xistream.hxx b/sc/source/filter/inc/xistream.hxx
index 4e0e63bd84e5..3a53643ef1cf 100644
--- a/sc/source/filter/inc/xistream.hxx
+++ b/sc/source/filter/inc/xistream.hxx
@@ -119,16 +119,7 @@ private:
 /** Decrypts BIFF8 stream contents using the given document identifier. */
 class XclImpBiff8Decrypter : public XclImpDecrypter
 {
-public:
-    explicit            XclImpBiff8Decrypter( sal_uInt8 pnSalt[ 16 ],
-                            sal_uInt8 pnVerifier[ 16 ], sal_uInt8 pnVerifierHash[ 16 ] );
-
 private:
-    /** Private copy c'tor for OnClone(). */
-    explicit            XclImpBiff8Decrypter( const XclImpBiff8Decrypter& rSrc );
-
-    /** Implementation of cloning this object. */
-    virtual XclImpBiff8Decrypter* OnClone() const override;
     /** Implements password verification and initialization of the decoder. */
     virtual css::uno::Sequence< css::beans::NamedValue >
         OnVerifyPassword( const OUString& rPassword ) override;
@@ -143,12 +134,62 @@ private:
     /** Returns the block offset corresponding to the passed stream position. */
     static sal_uInt16   GetOffset( std::size_t nStrmPos );
 
+protected:
+    explicit  XclImpBiff8Decrypter(const std::vector<sal_uInt8>& rSalt,
+                                   const std::vector<sal_uInt8>& rVerifier,
+                                   const std::vector<sal_uInt8>& rVerifierHash);
+
+    explicit  XclImpBiff8Decrypter(const XclImpBiff8Decrypter& rSrc);
+
+    css::uno::Sequence< css::beans::NamedValue > maEncryptionData;
+    std::vector< sal_uInt8 > maSalt;
+    std::vector< sal_uInt8 > maVerifier;
+    std::vector< sal_uInt8 > maVerifierHash;
+    msfilter::MSCodec97* mpCodec;       /// Crypto algorithm implementation.
+};
+
+class XclImpBiff8StdDecrypter : public XclImpBiff8Decrypter
+{
+public:
+    explicit XclImpBiff8StdDecrypter(const std::vector<sal_uInt8>& rSalt,
+                                     const std::vector<sal_uInt8>& rVerifier,
+                                     const std::vector<sal_uInt8>& rVerifierHash)
+        : XclImpBiff8Decrypter(rSalt, rVerifier, rVerifierHash)
+    {
+        mpCodec = &maCodec;
+    }
+
+private:
+    /** Private copy c'tor for OnClone(). */
+    explicit XclImpBiff8StdDecrypter(const XclImpBiff8StdDecrypter& rSrc);
+
+    /** Implementation of cloning this object. */
+    virtual XclImpBiff8StdDecrypter* OnClone() const override;
+
 private:
     ::msfilter::MSCodec_Std97 maCodec;       /// Crypto algorithm implementation.
-    css::uno::Sequence< css::beans::NamedValue > maEncryptionData;
-    ::std::vector< sal_uInt8 > maSalt;
-    ::std::vector< sal_uInt8 > maVerifier;
-    ::std::vector< sal_uInt8 > maVerifierHash;
+};
+
+class XclImpBiff8CryptoAPIDecrypter : public XclImpBiff8Decrypter
+{
+public:
+    explicit XclImpBiff8CryptoAPIDecrypter(const std::vector<sal_uInt8>& rSalt,
+                                           const std::vector<sal_uInt8>& rVerifier,
+                                           const std::vector<sal_uInt8>& rVerifierHash)
+        : XclImpBiff8Decrypter(rSalt, rVerifier, rVerifierHash)
+    {
+        mpCodec = &maCodec;
+    }
+
+private:
+    /** Private copy c'tor for OnClone(). */
+    explicit XclImpBiff8CryptoAPIDecrypter(const XclImpBiff8CryptoAPIDecrypter& rSrc);
+
+    /** Implementation of cloning this object. */
+    virtual XclImpBiff8CryptoAPIDecrypter* OnClone() const override;
+
+private:
+    ::msfilter::MSCodec_CryptoAPI maCodec;       /// Crypto algorithm implementation.
 };
 
 // Stream