Re: [edk2-devel] [PATCH v3 1/3] CryptoPkg/BaseCryptLib: Add EVP (Envelope) Digest interface

["Laszlo Ersek" <lersek@redhat.com>]

On 09/16/20 13:44, Yao, Jiewen wrote:
> Hi Laszlo
> I disagree to put OPTIONAL for DigestValue, just because NULL is checked.
> If we need follow this, then we need add OPTIONAL to almost all pointer, which is unnecessary.

I'm not suggesting OPTIONAL *only* because NULL is checked. I'm
suggesting OPTIONAL because there is a specific use case related to
that. Please see the comments on the function:

"If DigestValue is NULL, free the Context then return FALSE."

But, anyway, I don't insist. It's not a huge deal. Feel free to ignore
my comment regarding OPTIONAL.

Thanks
Laszlo


> 
>> +BOOLEAN
>> +EFIAPI
>> +EvpMdFinal (
>> +  IN OUT  VOID   *EvpMdContext,
>> +  OUT     UINT8  *DigestValue
> 
> (3) DigestValue should be marked OPTIONAL in my opinion, as NULL is
> deliberately permitted (for just freeing the context).
> 
> 
> 
> 
>> -----Original Message-----
>> From: Laszlo Ersek <lersek@redhat.com>
>> Sent: Wednesday, September 16, 2020 7:07 PM
>> To: devel@edk2.groups.io; Zurcher, Christopher J
>> <christopher.j.zurcher@intel.com>
>> Cc: Yao, Jiewen <jiewen.yao@intel.com>; Wang, Jian J <jian.j.wang@intel.com>;
>> Lu, XiaoyuX <xiaoyux.lu@intel.com>
>> Subject: Re: [edk2-devel] [PATCH v3 1/3] CryptoPkg/BaseCryptLib: Add EVP
>> (Envelope) Digest interface
>>
>> Hello Christopher,
>>
>> On 09/16/20 02:59, Zurcher, Christopher J wrote:
>>> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2545
>>>
>>> The EVP interface should be used in place of discrete digest function
>>> calls.
>>>
>>> Cc: Laszlo Ersek <lersek@redhat.com>
>>> Cc: Jiewen Yao <jiewen.yao@intel.com>
>>> Cc: Jian J Wang <jian.j.wang@intel.com>
>>> Cc: Xiaoyu Lu <xiaoyux.lu@intel.com>
>>> Signed-off-by: Christopher J Zurcher <christopher.j.zurcher@intel.com>
>>> ---
>>>  CryptoPkg/Library/BaseCryptLib/BaseCryptLib.inf         |   1 +
>>>  CryptoPkg/Library/BaseCryptLib/PeiCryptLib.inf          |   1 +
>>>  CryptoPkg/Library/BaseCryptLib/RuntimeCryptLib.inf      |   1 +
>>>  CryptoPkg/Library/BaseCryptLib/SmmCryptLib.inf          |   1 +
>>>  CryptoPkg/Library/BaseCryptLibNull/BaseCryptLibNull.inf |   1 +
>>>  CryptoPkg/Include/Library/BaseCryptLib.h                | 129 ++++++++++
>>>  CryptoPkg/Library/BaseCryptLib/Evp/CryptEvpMd.c         | 257
>> ++++++++++++++++++++
>>>  CryptoPkg/Library/BaseCryptLib/Evp/CryptEvpMdNull.c     | 128 ++++++++++
>>>  CryptoPkg/Library/BaseCryptLibNull/Evp/CryptEvpMdNull.c | 128 ++++++++++
>>>  9 files changed, 647 insertions(+)
>>
>> I agree that "CryptoPkg/Library/BaseCryptLibNull/Evp/CryptEvpMdNull.c"
>> is necessary. (If I understand correctly, that file was missing from
>> your v2 posting.)
>>
>> But "CryptoPkg/Library/BaseCryptLib/Evp/CryptEvpMdNull.c" seems
>> superfluous. This file is never referenced in the INF files.
>>
>> The point of this file would be to allow *some* of the Base / Pei /
>> Runtime / Smm instances to "stub out" the EVP MD functions (i.e. provide
>> only stub implementations). But this isn't what's happening -- all of
>> the Base / Pei / Runtime / Smm instances are getting the real deal
>> ("CryptoPkg/Library/BaseCryptLib/Evp/CryptEvpMd.c").
>>
>> (1) So I think "CryptoPkg/Library/BaseCryptLib/Evp/CryptEvpMdNull.c"
>> should be dropped. Only the Null instance of the library needs null
>> versions of the new functions. The Base / Pei / Runtime / Smm instances
>> don't.
>>
>>>
>>> diff --git a/CryptoPkg/Library/BaseCryptLib/BaseCryptLib.inf
>> b/CryptoPkg/Library/BaseCryptLib/BaseCryptLib.inf
>>> index 4aae2aba95..3968f29412 100644
>>> --- a/CryptoPkg/Library/BaseCryptLib/BaseCryptLib.inf
>>> +++ b/CryptoPkg/Library/BaseCryptLib/BaseCryptLib.inf
>>> @@ -50,6 +50,7 @@
>>>    Pk/CryptAuthenticode.c
>>>    Pk/CryptTs.c
>>>    Pem/CryptPem.c
>>> +  Evp/CryptEvpMd.c
>>>
>>>    SysCall/CrtWrapper.c
>>>    SysCall/TimerWrapper.c
>>> diff --git a/CryptoPkg/Library/BaseCryptLib/PeiCryptLib.inf
>> b/CryptoPkg/Library/BaseCryptLib/PeiCryptLib.inf
>>> index dc28e3a11d..d0b91716d0 100644
>>> --- a/CryptoPkg/Library/BaseCryptLib/PeiCryptLib.inf
>>> +++ b/CryptoPkg/Library/BaseCryptLib/PeiCryptLib.inf
>>> @@ -57,6 +57,7 @@
>>>    Pk/CryptTsNull.c
>>>    Pem/CryptPemNull.c
>>>    Rand/CryptRandNull.c
>>> +  Evp/CryptEvpMd.c
>>>
>>>    SysCall/CrtWrapper.c
>>>    SysCall/ConstantTimeClock.c
>>> diff --git a/CryptoPkg/Library/BaseCryptLib/RuntimeCryptLib.inf
>> b/CryptoPkg/Library/BaseCryptLib/RuntimeCryptLib.inf
>>> index 5005beed02..9f3accd35b 100644
>>> --- a/CryptoPkg/Library/BaseCryptLib/RuntimeCryptLib.inf
>>> +++ b/CryptoPkg/Library/BaseCryptLib/RuntimeCryptLib.inf
>>> @@ -56,6 +56,7 @@
>>>    Pk/CryptAuthenticodeNull.c
>>>    Pk/CryptTsNull.c
>>>    Pem/CryptPem.c
>>> +  Evp/CryptEvpMd.c
>>>
>>>    SysCall/CrtWrapper.c
>>>    SysCall/TimerWrapper.c
>>> diff --git a/CryptoPkg/Library/BaseCryptLib/SmmCryptLib.inf
>> b/CryptoPkg/Library/BaseCryptLib/SmmCryptLib.inf
>>> index 91ec3e03bf..420623cdc6 100644
>>> --- a/CryptoPkg/Library/BaseCryptLib/SmmCryptLib.inf
>>> +++ b/CryptoPkg/Library/BaseCryptLib/SmmCryptLib.inf
>>> @@ -54,6 +54,7 @@
>>>    Pk/CryptAuthenticodeNull.c
>>>    Pk/CryptTsNull.c
>>>    Pem/CryptPem.c
>>> +  Evp/CryptEvpMd.c
>>>
>>>    SysCall/CrtWrapper.c
>>>    SysCall/ConstantTimeClock.c
>>> diff --git a/CryptoPkg/Library/BaseCryptLibNull/BaseCryptLibNull.inf
>> b/CryptoPkg/Library/BaseCryptLibNull/BaseCryptLibNull.inf
>>> index 689af4fedd..542ac2e2e1 100644
>>> --- a/CryptoPkg/Library/BaseCryptLibNull/BaseCryptLibNull.inf
>>> +++ b/CryptoPkg/Library/BaseCryptLibNull/BaseCryptLibNull.inf
>>> @@ -50,6 +50,7 @@
>>>    Pk/CryptTsNull.c
>>>    Pem/CryptPemNull.c
>>>    Rand/CryptRandNull.c
>>> +  Evp/CryptEvpMdNull.c
>>>
>>>  [Packages]
>>>    MdePkg/MdePkg.dec
>>> diff --git a/CryptoPkg/Include/Library/BaseCryptLib.h
>> b/CryptoPkg/Include/Library/BaseCryptLib.h
>>> index ae9bde9e37..5e1b408b54 100644
>>> --- a/CryptoPkg/Include/Library/BaseCryptLib.h
>>> +++ b/CryptoPkg/Include/Library/BaseCryptLib.h
>>> @@ -1012,6 +1012,135 @@ HmacSha256Final (
>>>    OUT     UINT8  *HmacValue
>>>    );
>>>
>>>
>> +//==============================================================
>> =======================
>>> +//    EVP (Envelope) Primitive
>>>
>> +//==============================================================
>> =======================
>>> +
>>> +/**
>>> +  Allocates and initializes one EVP_MD_CTX context for subsequent EVP_MD
>> use.
>>> +
>>> +  If DigestName is NULL, then return FALSE.
>>> +
>>> +  @param[in]    DigestName    Pointer to the digest name as a NULL-
>> terminated ASCII string.
>>> +                              Valid digest names are:
>>> +                              MD5, SHA1, SHA224, SHA256, SHA384, SHA512
>>> +                              SHA3-224, SHA3-256, SHA3-384, SHA3-512
>>> +                              SM3
>>> +
>>> +  @return  Pointer to the EVP_MD_CTX context that has been allocated and
>> initialized.
>>> +           If DigestName is invalid, returns NULL.
>>> +           If the allocations fails, returns NULL.
>>> +           If initialization fails, returns NULL.
>>> +
>>> +**/
>>> +VOID *
>>> +EFIAPI
>>> +EvpMdInit (
>>> +  IN  CONST CHAR8   *DigestName
>>> +  );
>>> +
>>> +/**
>>> +  Makes a copy of an existing EVP_MD context.
>>> +
>>> +  If EvpMdContext is NULL, then return FALSE.
>>> +  If NewEvpMdContext is NULL, then return FALSE.
>>> +
>>> +  @param[in]  EvpMdContext     Pointer to EVP_MD context being copied.
>>> +  @param[out] NewEvpMdContext  Pointer to new EVP_MD context.
>>> +
>>> +  @retval TRUE   EVP_MD context copy succeeded.
>>> +  @retval FALSE  EVP_MD context copy failed.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdDuplicate (
>>> +  IN  CONST VOID    *EvpMdContext,
>>> +  OUT VOID          *NewEvpMdContext
>>> +  );
>>> +
>>> +/**
>>> +  Digests the input data and updates EVP_MD context.
>>> +
>>> +  This function performs EVP digest on a data buffer of the specified size.
>>> +  It can be called multiple times to compute the digest of long or
>> discontinuous data streams.
>>> +  EVP_MD context should be already correctly initialized by EvpMdInit(), and
>> should not
>>> +  be finalized by EvpMdFinal(). Behavior with invalid context is undefined.
>>> +
>>> +  If EvpMdContext is NULL, then return FALSE.
>>> +  If Data is NULL and DataSize is not zero, return FALSE.
>>> +
>>> +  @param[in, out]  EvpMdContext       Pointer to the EVP_MD context.
>>> +  @param[in]       Data               Pointer to the buffer containing the data to be
>> digested.
>>> +  @param[in]       DataSize           Size of Data buffer in bytes.
>>> +
>>> +  @retval TRUE   EVP data digest succeeded.
>>> +  @retval FALSE  EVP data digest failed.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdUpdate (
>>> +  IN OUT  VOID        *EvpMdContext,
>>> +  IN      CONST VOID  *Data,
>>> +  IN      UINTN       DataSize
>>> +  );
>>> +
>>> +/**
>>> +  Completes computation of the EVP digest value.
>>> +  Releases the specified EVP_MD_CTX context.
>>> +
>>> +  This function completes EVP hash computation and retrieves the digest
>> value into
>>> +  the specified memory. After this function has been called, the EVP context
>> cannot
>>> +  be used again.
>>> +  EVP context should be already correctly initialized by EvpMdInit(), and
>> should
>>> +  not be finalized by EvpMdFinal(). Behavior with invalid EVP context is
>> undefined.
>>> +
>>> +  If EvpMdContext is NULL, then return FALSE.
>>> +  If DigestValue is NULL, free the Context then return FALSE.
>>> +
>>> +  @param[in, out]  EvpMdContext   Pointer to the EVP context.
>>> +  @param[out]      Digest         Pointer to a buffer that receives the EVP digest
>> value.
>>
>> (2) Please extend the comment on Digest with the following:
>>
>>   The caller is responsible for providing enough storage for the digest
>>   algorithm selected with EvpMdInit(). Providing EVP_MAX_MD_SIZE bytes
>>   will suffice for storing the digest regardless of the algorithm chosen
>>   in EvpMdInit().
>>
>> (EVP_MAX_MD_SIZE is a public OpenSSL macro and I think we should openly
>> advertise it to consumers in edk2.)
>>
>>> +
>>> +  @retval TRUE   EVP digest computation succeeded.
>>> +  @retval FALSE  EVP digest computation failed.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdFinal (
>>> +  IN OUT  VOID   *EvpMdContext,
>>> +  OUT     UINT8  *DigestValue
>>
>> (3) DigestValue should be marked OPTIONAL in my opinion, as NULL is
>> deliberately permitted (for just freeing the context).
>>
>>> +  );
>>> +
>>> +/**
>>> +  Computes the message digest of an input data buffer.
>>> +
>>> +  This function performs the message digest of a given data buffer, and places
>>> +  the digest value into the specified memory.
>>> +
>>> +  If DigestName is NULL, return FALSE.
>>> +  If Data is NULL and DataSize is not zero, return FALSE.
>>> +  If HashValue is NULL, return FALSE.
>>> +
>>> +  @param[in]    DigestName    Pointer to the digest name.
>>> +  @param[in]    Data          Pointer to the buffer containing the data to be
>> hashed.
>>> +  @param[in]    DataSize      Size of Data buffer in bytes.
>>> +  @param[out]   HashValue     Pointer to a buffer that receives the digest
>> value.
>>> +
>>> +  @retval TRUE   Digest computation succeeded.
>>> +  @retval FALSE  Digest computation failed.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdHashAll (
>>> +  IN  CONST CHAR8   *DigestName,
>>> +  IN  CONST VOID    *Data,
>>> +  IN  UINTN         DataSize,
>>> +  OUT UINT8         *HashValue
>>> +  );
>>> +
>>>
>> //===============================================================
>> ======================
>>>  //    Symmetric Cryptography Primitive
>>>
>> //===============================================================
>> ======================
>>> diff --git a/CryptoPkg/Library/BaseCryptLib/Evp/CryptEvpMd.c
>> b/CryptoPkg/Library/BaseCryptLib/Evp/CryptEvpMd.c
>>> new file mode 100644
>>> index 0000000000..b2770a9186
>>> --- /dev/null
>>> +++ b/CryptoPkg/Library/BaseCryptLib/Evp/CryptEvpMd.c
>>> @@ -0,0 +1,257 @@
>>> +/** @file
>>> +  EVP MD Wrapper Implementation for OpenSSL.
>>> +
>>> +Copyright (c) 2020, Intel Corporation. All rights reserved.<BR>
>>> +SPDX-License-Identifier: BSD-2-Clause-Patent
>>> +
>>> +**/
>>> +
>>> +#include "InternalCryptLib.h"
>>> +#include <openssl/evp.h>
>>> +
>>> +/**
>>> +  Allocates and initializes one EVP_MD_CTX context for subsequent EVP_MD
>> use.
>>> +
>>> +  If DigestName is NULL, then return FALSE.
>>> +
>>> +  @param[in]    DigestName    Pointer to the digest name as a NULL-
>> terminated ASCII string.
>>> +                              Valid digest names are:
>>> +                              MD5, SHA1, SHA224, SHA256, SHA384, SHA512
>>> +                              SHA3-224, SHA3-256, SHA3-384, SHA3-512
>>> +                              SM3
>>> +
>>> +  @return  Pointer to the EVP_MD_CTX context that has been allocated and
>> initialized.
>>> +           If DigestName is invalid, returns NULL.
>>> +           If the allocations fails, returns NULL.
>>> +           If initialization fails, returns NULL.
>>> +
>>> +**/
>>> +VOID *
>>> +EFIAPI
>>> +EvpMdInit (
>>> +  IN  CONST CHAR8   *DigestName
>>> +  )
>>> +{
>>> +  EVP_MD    *Digest;
>>> +  VOID      *EvpMdContext;
>>> +
>>> +  //
>>> +  // Check input parameters.
>>> +  //
>>> +  if (DigestName == NULL) {
>>> +    return NULL;
>>> +  }
>>> +
>>> +  //
>>> +  // Allocate EVP_MD_CTX Context
>>> +  //
>>> +  EvpMdContext = EVP_MD_CTX_new ();
>>> +  if (EvpMdContext == NULL) {
>>> +    return NULL;
>>> +  }
>>> +
>>> +  Digest = EVP_get_digestbyname (DigestName);
>>
>> I think this may not compile with gcc (and correctly so). The pointer
>> returned by EVP_get_digestbyname() is const-qualified, but with the
>> assignment, we're throwing away the const-ness.
>>
>> (4) Please const-qualify the "Digest" local pointer.
>>
>>> +  if (Digest == NULL) {
>>> +    return NULL;
>>> +  }
>>
>> (5) This is a memory leak I believe; "EvpMdContext" is leaked.
>>
>> For keeping the control flow simple, consider moving
>> EVP_get_digestbyname() above EVP_MD_CTX_new().
>>
>>> +
>>> +  //
>>> +  // Initialize Context
>>> +  //
>>> +  if (EVP_DigestInit_ex (EvpMdContext, Digest, NULL) != 1) {
>>> +    EVP_MD_CTX_free (EvpMdContext);
>>> +    return NULL;
>>> +  }
>>> +
>>> +  return EvpMdContext;
>>> +}
>>> +
>>> +/**
>>> +  Makes a copy of an existing EVP_MD context.
>>> +
>>> +  If EvpMdContext is NULL, then return FALSE.
>>> +  If NewEvpMdContext is NULL, then return FALSE.
>>> +
>>> +  @param[in]  EvpMdContext     Pointer to EVP_MD context being copied.
>>> +  @param[out] NewEvpMdContext  Pointer to new EVP_MD context.
>>> +
>>> +  @retval TRUE   EVP_MD context copy succeeded.
>>> +  @retval FALSE  EVP_MD context copy failed.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdDuplicate (
>>> +  IN  CONST VOID    *EvpMdContext,
>>> +  OUT VOID          *NewEvpMdContext
>>> +  )
>>> +{
>>> +  //
>>> +  // Check input parameters.
>>> +  //
>>> +  if (EvpMdContext == NULL || NewEvpMdContext == NULL) {
>>> +    return FALSE;
>>> +  }
>>> +
>>> +  if (EVP_MD_CTX_copy (NewEvpMdContext, EvpMdContext) != 1) {
>>> +    return FALSE;
>>> +  }
>>> +
>>> +  return TRUE;
>>> +}
>>
>> (6) Can you please confirm that the caller is supposed to initialize
>> "NewEvpMdContext" with EvpMdInit() first, before calling EvpMdDuplicate()?
>>
>>> +
>>> +/**
>>> +  Digests the input data and updates EVP_MD context.
>>> +
>>> +  This function performs EVP digest on a data buffer of the specified size.
>>> +  It can be called multiple times to compute the digest of long or
>> discontinuous data streams.
>>> +  EVP_MD context should be already correctly initialized by EvpMdInit(), and
>> should not
>>> +  be finalized by EvpMdFinal(). Behavior with invalid context is undefined.
>>> +
>>> +  If EvpMdContext is NULL, then return FALSE.
>>> +  If Data is NULL and DataSize is not zero, return FALSE.
>>> +
>>> +  @param[in, out]  EvpMdContext       Pointer to the EVP_MD context.
>>> +  @param[in]       Data               Pointer to the buffer containing the data to be
>> digested.
>>> +  @param[in]       DataSize           Size of Data buffer in bytes.
>>> +
>>> +  @retval TRUE   EVP data digest succeeded.
>>> +  @retval FALSE  EVP data digest failed.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdUpdate (
>>> +  IN OUT  VOID        *EvpMdContext,
>>> +  IN      CONST VOID  *Data,
>>> +  IN      UINTN       DataSize
>>> +  )
>>> +{
>>> +  //
>>> +  // Check input parameters.
>>> +  //
>>> +  if (EvpMdContext == NULL) {
>>> +    return FALSE;
>>> +  }
>>> +
>>> +  //
>>> +  // Check invalid parameters, in case only DataLength was checked in
>> OpenSSL
>>> +  //
>>> +  if (Data == NULL && DataSize != 0) {
>>> +    return FALSE;
>>> +  }
>>> +
>>> +  //
>>> +  // OpenSSL EVP digest update
>>> +  //
>>> +  if (EVP_DigestUpdate (EvpMdContext, Data, DataSize) != 1) {
>>> +    return FALSE;
>>> +  }
>>> +
>>> +  return TRUE;
>>> +}
>>> +
>>> +/**
>>> +  Completes computation of the EVP digest value.
>>> +  Releases the specified EVP_MD_CTX context.
>>> +
>>> +  This function completes EVP hash computation and retrieves the digest
>> value into
>>> +  the specified memory. After this function has been called, the EVP context
>> cannot
>>> +  be used again.
>>> +  EVP context should be already correctly initialized by EvpMdInit(), and
>> should
>>> +  not be finalized by EvpMdFinal(). Behavior with invalid EVP context is
>> undefined.
>>> +
>>> +  If EvpMdContext is NULL, then return FALSE.
>>> +  If DigestValue is NULL, free the Context then return FALSE.
>>> +
>>> +  @param[in, out]  EvpMdContext   Pointer to the EVP context.
>>> +  @param[out]      Digest         Pointer to a buffer that receives the EVP digest
>> value.
>>> +
>>> +  @retval TRUE   EVP digest computation succeeded.
>>> +  @retval FALSE  EVP digest computation failed.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdFinal (
>>> +  IN OUT  VOID   *EvpMdContext,
>>> +  OUT     UINT8  *DigestValue
>>> +  )
>>> +{
>>> +  UINT32    Length;
>>> +  BOOLEAN   ReturnValue;
>>> +
>>> +  ReturnValue = TRUE;
>>> +
>>> +  //
>>> +  // Check input parameters.
>>> +  //
>>> +  if (EvpMdContext == NULL) {
>>> +    return FALSE;
>>> +  }
>>> +  if (DigestValue == NULL) {
>>> +    EVP_MD_CTX_free (EvpMdContext);
>>> +    return FALSE;
>>> +  }
>>> +
>>> +  //
>>> +  // OpenSSL EVP digest finalization
>>> +  //
>>> +  if (EVP_DigestFinal_ex (EvpMdContext, DigestValue, &Length) != 1) {
>>> +    ReturnValue = FALSE;
>>> +  }
>>
>>
>> (7) I suggest dropping the "Length" local variable. EVP_DigestFinal_ex()
>> deals fine with the third parameter being NULL, according to the docs
>> (and the code).
>>
>>
>>> +
>>> +  //
>>> +  // Free OpenSSL EVP_MD_CTX Context
>>> +  //
>>> +  EVP_MD_CTX_free (EvpMdContext);
>>> +
>>> +  return ReturnValue;
>>> +}
>>> +
>>> +/**
>>> +  Computes the message digest of an input data buffer.
>>> +
>>> +  This function performs the message digest of a given data buffer, and places
>>> +  the digest value into the specified memory.
>>> +
>>> +  If DigestName is NULL, return FALSE.
>>> +  If Data is NULL and DataSize is not zero, return FALSE.
>>> +  If HashValue is NULL, return FALSE.
>>> +
>>> +  @param[in]    DigestName    Pointer to the digest name.
>>> +  @param[in]    Data          Pointer to the buffer containing the data to be
>> hashed.
>>> +  @param[in]    DataSize      Size of Data buffer in bytes.
>>> +  @param[out]   HashValue     Pointer to a buffer that receives the digest
>> value.
>>> +
>>> +  @retval TRUE   Digest computation succeeded.
>>> +  @retval FALSE  Digest computation failed.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdHashAll (
>>> +  IN  CONST CHAR8   *DigestName,
>>> +  IN  CONST VOID    *Data,
>>> +  IN  UINTN         DataSize,
>>> +  OUT UINT8         *HashValue
>>> +  )
>>> +{
>>> +  BOOLEAN   Result;
>>> +  VOID      *EvpMdContext;
>>> +
>>> +  EvpMdContext = EvpMdInit (DigestName);
>>> +  if (EvpMdContext == NULL) {
>>> +    return FALSE;
>>> +  }
>>> +
>>> +  Result = EvpMdUpdate (EvpMdContext, Data, DataSize);
>>> +  if (Result == FALSE) {
>>
>> (8) Style: please write (!Result).
>>
>>
>>> +    EvpMdFinal (EvpMdContext, NULL);
>>> +    return FALSE;
>>> +  }
>>> +
>>> +  Result = EvpMdFinal (EvpMdContext, HashValue);
>>> +
>>> +  return Result;
>>> +}
>>> diff --git a/CryptoPkg/Library/BaseCryptLib/Evp/CryptEvpMdNull.c
>> b/CryptoPkg/Library/BaseCryptLib/Evp/CryptEvpMdNull.c
>>> new file mode 100644
>>> index 0000000000..038f63801f
>>> --- /dev/null
>>> +++ b/CryptoPkg/Library/BaseCryptLib/Evp/CryptEvpMdNull.c
>>> @@ -0,0 +1,128 @@
>>> +/** @file
>>> +  EVP MD Wrapper Null Library.
>>> +
>>> +Copyright (c) 2020, Intel Corporation. All rights reserved.<BR>
>>> +SPDX-License-Identifier: BSD-2-Clause-Patent
>>> +
>>> +**/
>>> +
>>> +#include "InternalCryptLib.h"
>>> +
>>> +/**
>>> +  Allocates and initializes one EVP_MD_CTX context for subsequent EVP_MD
>> use.
>>> +
>>> +  Return FALSE to indicate this interface is not supported.
>>> +
>>> +  @param[in]    DigestName    Pointer to the digest name as a NULL-
>> terminated ASCII string.
>>> +                              Valid digest names are:
>>> +                              MD5, SHA1, SHA224, SHA256, SHA384, SHA512
>>> +                              SHA3-224, SHA3-256, SHA3-384, SHA3-512
>>> +                              SM3
>>> +
>>> +  @return NULL  This interface is not supported.
>>> +
>>> +**/
>>> +VOID *
>>> +EFIAPI
>>> +EvpMdInit (
>>> +  IN  CONST CHAR8   *DigestName
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return NULL;
>>> +}
>>> +
>>> +/**
>>> +  Makes a copy of an existing EVP_MD context.
>>> +
>>> +  Return FALSE to indicate this interface is not supported.
>>> +
>>> +  @param[in]  EvpMdContext     Pointer to EVP_MD context being copied.
>>> +  @param[out] NewEvpMdContext  Pointer to new EVP_MD context.
>>> +
>>> +  @retval FALSE  This interface is not supported.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdDuplicate (
>>> +  IN  CONST VOID    *EvpMdContext,
>>> +  OUT VOID          *NewEvpMdContext
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return FALSE;
>>> +}
>>> +
>>> +/**
>>> +  Digests the input data and updates EVP_MD context.
>>> +
>>> +  Return FALSE to indicate this interface is not supported.
>>> +
>>> +  @param[in, out]  EvpMdContext       Pointer to the EVP_MD context.
>>> +  @param[in]       Data               Pointer to the buffer containing the data to be
>> digested.
>>> +  @param[in]       DataSize           Size of Data buffer in bytes.
>>> +
>>> +  @retval FALSE  This interface is not supported.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdUpdate (
>>> +  IN OUT  VOID        *EvpMdContext,
>>> +  IN      CONST VOID  *Data,
>>> +  IN      UINTN       DataSize
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return FALSE;
>>> +}
>>> +
>>> +/**
>>> +  Completes computation of the EVP digest value.
>>> +  Releases the specified EVP_MD_CTX context.
>>> +
>>> +  Return FALSE to indicate this interface is not supported.
>>> +
>>> +  @param[in, out]  EvpMdContext   Pointer to the EVP context.
>>> +  @param[out]      Digest         Pointer to a buffer that receives the EVP digest
>> value.
>>> +
>>> +  @retval FALSE  This interface is not supported.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdFinal (
>>> +  IN OUT  VOID   *EvpMdContext,
>>> +  OUT     UINT8  *DigestValue
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return FALSE;
>>> +}
>>> +
>>> +/**
>>> +  Computes the message digest of an input data buffer.
>>> +
>>> +  Return FALSE to indicate this interface is not supported.
>>> +
>>> +  @param[in]    DigestName    Pointer to the digest name.
>>> +  @param[in]    Data          Pointer to the buffer containing the data to be
>> hashed.
>>> +  @param[in]    DataSize      Size of Data buffer in bytes.
>>> +  @param[out]   HashValue     Pointer to a buffer that receives the digest
>> value.
>>> +
>>> +  @retval FALSE  This interface is not supported.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdHashAll (
>>> +  IN  CONST CHAR8   *DigestName,
>>> +  IN  CONST VOID    *Data,
>>> +  IN  UINTN         DataSize,
>>> +  OUT UINT8         *HashValue
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return FALSE;
>>> +}
>>> diff --git a/CryptoPkg/Library/BaseCryptLibNull/Evp/CryptEvpMdNull.c
>> b/CryptoPkg/Library/BaseCryptLibNull/Evp/CryptEvpMdNull.c
>>> new file mode 100644
>>> index 0000000000..038f63801f
>>> --- /dev/null
>>> +++ b/CryptoPkg/Library/BaseCryptLibNull/Evp/CryptEvpMdNull.c
>>> @@ -0,0 +1,128 @@
>>> +/** @file
>>> +  EVP MD Wrapper Null Library.
>>> +
>>> +Copyright (c) 2020, Intel Corporation. All rights reserved.<BR>
>>> +SPDX-License-Identifier: BSD-2-Clause-Patent
>>> +
>>> +**/
>>> +
>>> +#include "InternalCryptLib.h"
>>> +
>>> +/**
>>> +  Allocates and initializes one EVP_MD_CTX context for subsequent EVP_MD
>> use.
>>> +
>>> +  Return FALSE to indicate this interface is not supported.
>>> +
>>> +  @param[in]    DigestName    Pointer to the digest name as a NULL-
>> terminated ASCII string.
>>> +                              Valid digest names are:
>>> +                              MD5, SHA1, SHA224, SHA256, SHA384, SHA512
>>> +                              SHA3-224, SHA3-256, SHA3-384, SHA3-512
>>> +                              SM3
>>> +
>>> +  @return NULL  This interface is not supported.
>>> +
>>> +**/
>>> +VOID *
>>> +EFIAPI
>>> +EvpMdInit (
>>> +  IN  CONST CHAR8   *DigestName
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return NULL;
>>> +}
>>> +
>>> +/**
>>> +  Makes a copy of an existing EVP_MD context.
>>> +
>>> +  Return FALSE to indicate this interface is not supported.
>>> +
>>> +  @param[in]  EvpMdContext     Pointer to EVP_MD context being copied.
>>> +  @param[out] NewEvpMdContext  Pointer to new EVP_MD context.
>>> +
>>> +  @retval FALSE  This interface is not supported.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdDuplicate (
>>> +  IN  CONST VOID    *EvpMdContext,
>>> +  OUT VOID          *NewEvpMdContext
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return FALSE;
>>> +}
>>> +
>>> +/**
>>> +  Digests the input data and updates EVP_MD context.
>>> +
>>> +  Return FALSE to indicate this interface is not supported.
>>> +
>>> +  @param[in, out]  EvpMdContext       Pointer to the EVP_MD context.
>>> +  @param[in]       Data               Pointer to the buffer containing the data to be
>> digested.
>>> +  @param[in]       DataSize           Size of Data buffer in bytes.
>>> +
>>> +  @retval FALSE  This interface is not supported.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdUpdate (
>>> +  IN OUT  VOID        *EvpMdContext,
>>> +  IN      CONST VOID  *Data,
>>> +  IN      UINTN       DataSize
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return FALSE;
>>> +}
>>> +
>>> +/**
>>> +  Completes computation of the EVP digest value.
>>> +  Releases the specified EVP_MD_CTX context.
>>> +
>>> +  Return FALSE to indicate this interface is not supported.
>>> +
>>> +  @param[in, out]  EvpMdContext   Pointer to the EVP context.
>>> +  @param[out]      Digest         Pointer to a buffer that receives the EVP digest
>> value.
>>> +
>>> +  @retval FALSE  This interface is not supported.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdFinal (
>>> +  IN OUT  VOID   *EvpMdContext,
>>> +  OUT     UINT8  *DigestValue
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return FALSE;
>>> +}
>>> +
>>> +/**
>>> +  Computes the message digest of an input data buffer.
>>> +
>>> +  Return FALSE to indicate this interface is not supported.
>>> +
>>> +  @param[in]    DigestName    Pointer to the digest name.
>>> +  @param[in]    Data          Pointer to the buffer containing the data to be
>> hashed.
>>> +  @param[in]    DataSize      Size of Data buffer in bytes.
>>> +  @param[out]   HashValue     Pointer to a buffer that receives the digest
>> value.
>>> +
>>> +  @retval FALSE  This interface is not supported.
>>> +
>>> +**/
>>> +BOOLEAN
>>> +EFIAPI
>>> +EvpMdHashAll (
>>> +  IN  CONST CHAR8   *DigestName,
>>> +  IN  CONST VOID    *Data,
>>> +  IN  UINTN         DataSize,
>>> +  OUT UINT8         *HashValue
>>> +  )
>>> +{
>>> +  ASSERT (FALSE);
>>> +  return FALSE;
>>> +}
>>>
>>
>> Thanks,
>> Laszlo
>