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

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

On 09/16/20 14:56, Yao, Jiewen wrote:
> I try to understand what is the use case to EvpMdFinal without DigestValue and only Free the EvpMdContext.

Error paths. You got some hashing going, detect an error condition
(related to the hashing itself, or to something else), and want to abort
/ clean up the hashing. You need to release the context, but don't care
about the digest calculated thus far.
> 
> 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?

We don't strictly need it. In the above (error path) use case, we can
still pass a pointer to an actual digest-receiving object, and then go
on to ignore the contents of that object. Passing NULL in that case
improves readability though.

Thanks
Laszlo

> 
> 
> 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
>>>>
>>>>
>>>>
>>>
>>
>>
>> 
>