Re: [PATCH v1 1/1] CryptoPkg: BaseCryptLib: Add RSA PSS verify support

["Agrawal, Sachin" <sachin.agrawal@intel.com>]

Hi Jiewen,

>From Section 9.1 in RFC 8017:
" Note that the verification operation follows reverse steps to recover
   salt and then forward steps to recompute and compare H."

Therefore, salt length can be inferred from the PSS block structure during verification operation.

I opted for 'RSA_PSS_SALTLEN_AUTO' as it will allow Edk2 to verify PSS signatures of any salt lengths.

Thanks
Sachin

-----Original Message-----
From: Yao, Jiewen <jiewen.yao@intel.com> 
Sent: Monday, April 19, 2021 7:30 PM
To: Agrawal, Sachin <sachin.agrawal@intel.com>; devel@edk2.groups.io
Cc: Wang, Jian J <jian.j.wang@intel.com>; Lu, XiaoyuX <xiaoyux.lu@intel.com>; Jiang, Guomin <guomin.jiang@intel.com>
Subject: RE: [PATCH v1 1/1] CryptoPkg: BaseCryptLib: Add RSA PSS verify support

Hi Sachin
May I know why you hardcode PSS salt length to be RSA_PSS_SALTLEN_AUTO ?

Thank you
Yao Jiewen


> -----Original Message-----
> From: Agrawal, Sachin <sachin.agrawal@intel.com>
> Sent: Tuesday, April 20, 2021 10:02 AM
> To: devel@edk2.groups.io
> Cc: Yao, Jiewen <jiewen.yao@intel.com>; Wang, Jian J 
> <jian.j.wang@intel.com>; Lu, XiaoyuX <xiaoyux.lu@intel.com>; Jiang, 
> Guomin <guomin.jiang@intel.com>; Agrawal, Sachin 
> <sachin.agrawal@intel.com>
> Subject: [PATCH v1 1/1] CryptoPkg: BaseCryptLib: Add RSA PSS verify 
> support
> 
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3314
> 
> This patch uses Openssl's EVP API's to perform RSASSA-PSS verification 
> of a binary blob.
> 
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Jian J Wang <jian.j.wang@intel.com>
> Cc: Xiaoyu Lu <xiaoyux.lu@intel.com>
> Cc: Guomin Jiang <guomin.jiang@intel.com>
> 
> Signed-off-by: Sachin Agrawal <sachin.agrawal@intel.com>
> ---
>  CryptoPkg/Library/BaseCryptLib/Pk/CryptRsaPss.c     | 139
> ++++++++++++++++++++
>  CryptoPkg/Library/BaseCryptLib/Pk/CryptRsaPssNull.c |  43 ++++++
>  CryptoPkg/Include/Library/BaseCryptLib.h            |  27 ++++
>  CryptoPkg/Library/BaseCryptLib/BaseCryptLib.inf     |   1 +
>  CryptoPkg/Library/BaseCryptLib/PeiCryptLib.inf      |   1 +
>  CryptoPkg/Library/BaseCryptLib/RuntimeCryptLib.inf  |   1 +
>  CryptoPkg/Library/BaseCryptLib/SmmCryptLib.inf      |   1 +
>  7 files changed, 213 insertions(+)
> 
> diff --git a/CryptoPkg/Library/BaseCryptLib/Pk/CryptRsaPss.c
> b/CryptoPkg/Library/BaseCryptLib/Pk/CryptRsaPss.c
> new file mode 100644
> index 000000000000..acf5eb689cd8
> --- /dev/null
> +++ b/CryptoPkg/Library/BaseCryptLib/Pk/CryptRsaPss.c
> @@ -0,0 +1,139 @@
> +/** @file
> +  RSA Asymmetric Cipher Wrapper Implementation over OpenSSL.
> +
> +  This file implements following APIs which provide basic capabilities for RSA:
> +  1) RsaPssVerify
> +
> +Copyright (c) 2021, Intel Corporation. All rights reserved.<BR>
> +SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +**/
> +
> +#include "InternalCryptLib.h"
> +
> +#include <openssl/bn.h>
> +#include <openssl/rsa.h>
> +#include <openssl/objects.h>
> +#include <openssl/evp.h>
> +
> +
> +/**
> +  Retrieve a pointer to EVP message digest object.
> +
> +  @param[in]  DigestLen   Length of the message digest.
> +
> +**/
> +static
> +EVP_MD*
> +GetEvpMD (
> +  IN UINT16 DigestLen
> +  )
> +{
> +  switch (DigestLen){
> +    case SHA256_DIGEST_SIZE:
> +      return EVP_sha256();
> +      break;
> +    case SHA384_DIGEST_SIZE:
> +      return EVP_sha384();
> +      break;
> +    case SHA512_DIGEST_SIZE:
> +      return EVP_sha512();
> +      break;
> +    default:
> +      return NULL;
> +  }
> +}
> +
> +
> +/**
> +  Verifies the RSA signature with RSASSA-PSS signature scheme defined 
> +in RFC
> 8017.
> +  Implementation determines salt length automatically from the 
> + signature
> encoding.
> +  Mask generation function is the same as the message digest algorithm.
> +
> +  @param[in]  RsaContext      Pointer to RSA context for signature verification.
> +  @param[in]  Message         Pointer to octet message to be verified.
> +  @param[in]  MsgSize         Size of the message in bytes.
> +  @param[in]  Signature       Pointer to RSASSA-PSS signature to be verified.
> +  @param[in]  SigSize         Size of signature in bytes.
> +  @param[in]  DigestLen       Length of digest for RSA operation.
> +
> +  @retval  TRUE   Valid signature encoded in RSASSA-PSS.
> +  @retval  FALSE  Invalid signature or invalid RSA context.
> +
> +**/
> +BOOLEAN
> +EFIAPI
> +RsaPssVerify (
> +  IN  VOID         *RsaContext,
> +  IN  CONST UINT8  *Message,
> +  IN  UINTN        MsgSize,
> +  IN  CONST UINT8  *Signature,
> +  IN  UINTN        SigSize,
> +  IN  UINT16       DigestLen
> +  )
> +{
> +  BOOLEAN Result;
> +  EVP_PKEY *pEvpRsaKey = NULL;
> +  EVP_MD_CTX *pEvpVerifyCtx = NULL;
> +  EVP_PKEY_CTX *pKeyCtx = NULL;
> +  CONST EVP_MD  *HashAlg = NULL;
> +
> +  if (RsaContext == NULL) {
> +    return FALSE;
> +  }
> +  if (Message == NULL || MsgSize == 0 || MsgSize > INT_MAX) {
> +    return FALSE;
> +  }
> +  if (Signature == NULL || SigSize == 0 || SigSize > INT_MAX) {
> +    return FALSE;
> +  }
> +
> +  HashAlg = GetEvpMD(DigestLen);
> +
> +  if (HashAlg == NULL) {
> +    return FALSE;
> +  }
> +
> +  pEvpRsaKey = EVP_PKEY_new();
> +  if (pEvpRsaKey == NULL) {
> +    goto _Exit;
> +  }
> +
> +  EVP_PKEY_set1_RSA(pEvpRsaKey, RsaContext);
> +
> +  pEvpVerifyCtx = EVP_MD_CTX_create();  if (pEvpVerifyCtx == NULL) {
> +    goto _Exit;
> +  }
> +
> +  Result = EVP_DigestVerifyInit(pEvpVerifyCtx, &pKeyCtx, HashAlg, 
> + NULL,
> pEvpRsaKey) > 0;
> +  if (pKeyCtx == NULL) {
> +    goto _Exit;
> +  }
> +
> +  if (Result) {
> +    Result = EVP_PKEY_CTX_set_rsa_padding(pKeyCtx,
> RSA_PKCS1_PSS_PADDING) > 0;
> +  }
> +  if (Result) {
> +    Result = EVP_PKEY_CTX_set_rsa_pss_saltlen(pKeyCtx,
> RSA_PSS_SALTLEN_AUTO) > 0;
> +  }
> +  if (Result) {
> +    Result = EVP_PKEY_CTX_set_rsa_mgf1_md(pKeyCtx, HashAlg) > 0;  }  
> + if (Result) {
> +    Result = EVP_DigestVerifyUpdate(pEvpVerifyCtx, Message,
> (UINT32)MsgSize) > 0;
> +  }
> +  if (Result) {
> +    Result = EVP_DigestVerifyFinal(pEvpVerifyCtx, Signature, 
> + (UINT32)SigSize) > 0;  }
> +
> +_Exit :
> +  if (pEvpRsaKey) {
> +    EVP_PKEY_free(pEvpRsaKey);
> +  }
> +  if (pEvpVerifyCtx) {
> +    EVP_MD_CTX_destroy(pEvpVerifyCtx);
> +  }
> +
> +  return Result;
> +}
> diff --git a/CryptoPkg/Library/BaseCryptLib/Pk/CryptRsaPssNull.c
> b/CryptoPkg/Library/BaseCryptLib/Pk/CryptRsaPssNull.c
> new file mode 100644
> index 000000000000..8d84b4c1426c
> --- /dev/null
> +++ b/CryptoPkg/Library/BaseCryptLib/Pk/CryptRsaPssNull.c
> @@ -0,0 +1,43 @@
> +/** @file
> +  RSA-PSS Asymmetric Cipher Wrapper Implementation over OpenSSL.
> +
> +  This file does not provide real capabilities for following APIs in RSA handling:
> +  1) RsaPssVerify
> +
> +Copyright (c) 2021, Intel Corporation. All rights reserved.<BR>
> +SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +**/
> +
> +#include "InternalCryptLib.h"
> +
> +/**
> +  Verifies the RSA signature with RSASSA-PSS signature scheme defined 
> +in RFC
> 8017.
> +  Implementation determines salt length automatically from the 
> + signature
> encoding.
> +  Mask generation function is the same as the message digest algorithm.
> +
> +  @param[in]  RsaContext      Pointer to RSA context for signature verification.
> +  @param[in]  Message         Pointer to octet message to be verified.
> +  @param[in]  MsgSize         Size of the message in bytes.
> +  @param[in]  Signature       Pointer to RSASSA-PSS signature to be verified.
> +  @param[in]  SigSize         Size of signature in bytes.
> +  @param[in]  DigestLen       Length of digest for RSA operation.
> +
> +  @retval  TRUE   Valid signature encoded in RSASSA-PSS.
> +  @retval  FALSE  Invalid signature or invalid RSA context.
> +
> +**/
> +BOOLEAN
> +EFIAPI
> +RsaPssVerify (
> +  IN  VOID         *RsaContext,
> +  IN  CONST UINT8  *Message,
> +  IN  UINTN        MsgSize,
> +  IN  CONST UINT8  *Signature,
> +  IN  UINTN        SigSize,
> +  IN  UINT16       DigestLen
> +  )
> +{
> +  ASSERT (FALSE);
> +  return FALSE;
> +}
> diff --git a/CryptoPkg/Include/Library/BaseCryptLib.h
> b/CryptoPkg/Include/Library/BaseCryptLib.h
> index 496121e6a4ed..36d560b8d691 100644
> --- a/CryptoPkg/Include/Library/BaseCryptLib.h
> +++ b/CryptoPkg/Include/Library/BaseCryptLib.h
> @@ -1363,6 +1363,33 @@ RsaPkcs1Verify (
>    IN  UINTN        SigSize
>    );
> 
> +/**
> +  Verifies the RSA signature with RSASSA-PSS signature scheme defined 
> +in RFC
> 8017.
> +  Implementation determines salt length automatically from the 
> + signature
> encoding.
> +  Mask generation function is the same as the message digest algorithm.
> +
> +  @param[in]  RsaContext      Pointer to RSA context for signature verification.
> +  @param[in]  Message         Pointer to octet message to be verified.
> +  @param[in]  MsgSize         Size of the message in bytes.
> +  @param[in]  Signature       Pointer to RSASSA-PSS signature to be verified.
> +  @param[in]  SigSize         Size of signature in bytes.
> +  @param[in]  DigestLen       Length of digest for RSA operation.
> +
> +  @retval  TRUE   Valid signature encoded in RSASSA-PSS.
> +  @retval  FALSE  Invalid signature or invalid RSA context.
> +
> +**/
> +BOOLEAN
> +EFIAPI
> +RsaPssVerify (
> +  IN  VOID         *RsaContext,
> +  IN  CONST UINT8  *Message,
> +  IN  UINTN        MsgSize,
> +  IN  CONST UINT8  *Signature,
> +  IN  UINTN        SigSize,
> +  IN  UINT16       DigestLen
> +  );
> +
>  /**
>    Retrieve the RSA Private Key from the password-protected PEM key data.
>