target = "https://tools.ietf.org/rfc/rfc4492#section-5.1.2" # 5.1.2. Supported Point Formats Extension # # enum { uncompressed (0), ansiX962_compressed_prime (1), # ansiX962_compressed_char2 (2), reserved (248..255) # } ECPointFormat; # # struct { # ECPointFormat ec_point_format_list<1..2^8-1> # } ECPointFormatList; # # Three point formats are included in the definition of ECPointFormat # above. The uncompressed point format is the default format in that # implementations of this document MUST support it for all of their # supported curves. Compressed point formats reduce bandwidth by # including only the x-coordinate and a single bit of the y-coordinate # of the point. Implementations of this document MAY support the # ansiX962_compressed_prime and ansiX962_compressed_char2 formats, # where the former applies only to prime curves and the latter applies # only to characteristic-2 curves. (These formats are specified in # [7].) Values 248 through 255 are reserved for private use. # # The ECPointFormat name space is maintained by IANA. See Section 8 # for information on how new value assignments are added. # # Items in ec_point_format_list are ordered according to the client's # preferences (favorite choice first). # # A client that can parse only the uncompressed point format (value 0) # includes an extension consisting of the following octets; note that # the first two octets indicate the extension type (Supported Point # Formats Extension): # # 00 0B 00 02 01 00 # # A client that in the case of prime fields prefers the compressed # format (ansiX962_compressed_prime, value 1) over the uncompressed # format (value 0), but in the case of characteristic-2 fields prefers # the uncompressed format (value 0) over the compressed format # (ansiX962_compressed_char2, value 2), may indicate these preferences # by including an extension consisting of the following octets: # # 00 0B 00 04 03 01 00 02 [[spec]] level = "MUST" quote = ''' The uncompressed point format is the default format in that implementations of this document MUST support it for all of their supported curves. ''' [[spec]] level = "MAY" quote = ''' Implementations of this document MAY support the ansiX962_compressed_prime and ansiX962_compressed_char2 formats, where the former applies only to prime curves and the latter applies only to characteristic-2 curves. '''