Botan::BER Namespace Reference

Functions
void	decode (BER_Decoder &source, Key_Constraints &key_usage)

Detailed Description

BER Decoding Function for key constraints

Function Documentation

decode()

void BOTAN_DLL Botan::BER::decode	(	BER_Decoder &	source,
		Key_Constraints &	key_usage )

Definition at line 18 of file pubkey_enums.cpp.

   {
   BER_Object obj = source.get_next_object();
 
   if(obj.type_tag != BIT_STRING || obj.class_tag != UNIVERSAL)
      throw BER_Bad_Tag("Bad tag for usage constraint",
                        obj.type_tag, obj.class_tag);
   if(obj.value.size() != 2 && obj.value.size() != 3)
      throw BER_Decoding_Error("Bad size for BITSTRING in usage constraint");
   if(obj.value[0] >= 8)
      throw BER_Decoding_Error("Invalid unused bits in usage constraint");
 
   const byte mask = (0xFF << obj.value[0]);
   obj.value[obj.value.size()-1] &= mask;
 
   u16bit usage = 0;
   for(size_t j = 1; j != obj.value.size(); ++j)
      usage = (obj.value[j] << 8) | usage;
 
   key_usage = Key_Constraints(usage);
   }

References Botan::BER_Bad_Tag::BER_Bad_Tag(), Botan::BER_Decoding_Error::BER_Decoding_Error(), Botan::BIT_STRING, Botan::BER_Object::class_tag, decode(), Botan::BER_Decoder::get_next_object(), Botan::MemoryRegion< T >::size(), Botan::BER_Object::type_tag, Botan::UNIVERSAL, and Botan::BER_Object::value.

Referenced by decode().