uses jwawincrypt
const   
  szOID_CRL_NEXT_PUBLISH = '1.3.6.1.4.1.311.21.4';
  
var
  Context: PCCRL_CONTEXT; 
  pExtension: PCERT_EXTENSION;
  cbStructInfo: DWORD;
  pvStructInfo: POINTER;
  FileTime: PFileTime; 
  lpszStructType: LPCSTR;
  
  

чтение из файла (или переделать на чтение из хранилища)

CryptQueryObject(CERT_QUERY_OBJECT_FILE,  CRLFileName, CERT_QUERY_CONTENT_FLAG_CRL, CERT_QUERY_FORMAT_FLAG_ALL , 0, 0, 0, 0, 0, 0, @CRL_CONTEXT)
 
  
pExtension := CertFindExtension(szOID_CRL_NEXT_PUBLISH, Context^.pCrlInfo^.cExtension, Context^.pCrlInfo^.rgExtension);
  
  CryptDecodeObject(ENCODING_TYPE, lpszStructType, pExtension^.Value.pbData, pExtension^.Value.cbData, 0 , nil, cbStructInfo) 
  
  GetMem(pvStructInfo, cbStructInfo);
  
  CryptDecodeObject(ENCODING_TYPE, lpszStructType, pExtension^.Value.pbData, pExtension^.Value.cbData, 0, pvStructInfo, cbStructInfo) 
 
  FileTime := PFileTime(pvStructInfo);
  DT := DecodeFileTime(FileTime^);
  FreeMem(pvStructInfo);