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

["Yao, Jiewen" <jiewen.yao@intel.com>]

I try to understand what is the use case to EvpMdFinal without DigestValue and only Free the EvpMdContext.

A normal usage will be:
1) EvpMdHashAll (Digest) - get digest.
2) EvpMdInit, EvpMdUpdate, EvpMdUpdate, ... , EvpMdFinal (Digest) - get digest

Why we need support the case to use EvpMdFinal (NULL) in the end to free context?


Thank you
Yao Jiewen

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Laszlo Ersek
> Sent: Wednesday, September 16, 2020 8:40 PM
> To: Yao, Jiewen <jiewen.yao@intel.com>; devel@edk2.groups.io; Zurcher,
> Christopher J <christopher.j.zurcher@intel.com>
> Cc: 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
> 
> On 09/16/20 14:07, Yao, Jiewen wrote:
> > I overlooked the behavior that NULL DigestValue will take side effect to free
> Context.
> >
> > Hi Christopher
> > May I understand why we need free the context?
> > This does not align with other existing HASH or HMAC functions.
> 
> I requested that.
> 
> It makes no sense to keep a finalized context.
> 
> In other words, it makes no sense to separate finalization from freeing.
> A context that has been finalized is unusable for anything except freeing.
> 
> Thanks
> Laszlo
> 
> >
> > Thank you
> > Yao Jiewen
> >
> >> -----Original Message-----
> >> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Yao,
> Jiewen
> >> Sent: Wednesday, September 16, 2020 7:45 PM
> >> To: Laszlo Ersek <lersek@redhat.com>; devel@edk2.groups.io; Zurcher,
> >> Christopher J <christopher.j.zurcher@intel.com>
> >> Cc: 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
> >>
> >> 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.
> >>
> >>> +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
> >>
> >>
> >>
> >
> 
> 
>