Description
Inspect any BER initial length octet, including reserved FF.
ASN.1 encodings separate identifiers, lengths and contents, with DER applying stricter canonical forms than BER. One leading octet or terminal-bit check covers only part of the complete value.
Inspect any BER initial length octet, including reserved FF.
When to use this tool
Use Decoding: Ber Length Initial Octet when inspecting a stated ASN.1 field or canonical-content condition.
How to use the tool and how it works
- Enter octet. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read result. Expand result to inspect the returned fields.
Inspect any BER initial length octet, including reserved FF. Return short/indefinite/long/reserved, a shortLength only for values below 128, and followingOctets only for 129-254.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| octet | One numeric octet, from 0 through 255. | Required. Safe integer. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| result | Returned object; expand its named members below. | Required. Object. |
| result.kind | Kind | Calculated result member: string. |
| result.shortLength | Short-form length, or zero placeholder for all other kinds. | Calculated result member: number. |
| result.followingOctets | Number of subsequent length octets for long form; zero for other kinds. | Calculated result member: number. |
{
"input": {
"octet": 130
},
"output": {
"result": {
"kind": "long",
"shortLength": 0,
"followingOctets": 2
}
}
}Limitations and assumptions
- Zero shortLength in other modes is a placeholder; no full value length or DER validity is established.
- Outputs are nested inside result. Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use an ASN.1 schema and complete BER/DER parser for nested values, canonicality and application meaning.
References
Similar or alternative tools
- BER Length Short Long Discriminator
Classify an initial BER length octet.
- BER Tag First Octet Fields
Split a BER identifier's first octet.