OID
A object identifier (also called a OID) is a kind of hierarchical unique identifiers for many things, which is usable with ASN.1.
Decimal format
The decimal format consists if a sequence of natural numbers, normally written with dots in between. There must be at least two numbers, and the first number must be not greater than 2, and if the first number is less than 2 then the second number must be not greater than 39 (although the second number can be greater than 39 if the first number is 2). There is no limit of how big each number can be or how many numbers are allowed in the sequence.
The first number indicates if it is ITU or ISO, where 0 means ITU, 1 means ISO, and 2 means both.
Binary format
The binary format is a nonempty sequence of bytes, such that: the last byte must have the high bit clear, the first byte cannot be 0x80, and any 0x80 cannot be immediately preceded by a byte with the high bit clear. This can also be written as a regular expression: /^(([\x81-\xFF][\x80-\xFF]*)?[\x00-\x7F])+$/
To convert from the decimal format to the binary format, you must first combine the first two numbers into one number by multiplying the first number by forty and adding the second number, and then convert them to big-endian base 128, with the high bit set of each byte of a number other than the last byte.
