X.509 Serial Hex Length Parity Check
X.509 serial hex layout screen up to 20 unsigned octets; DER signed integer padding reported separately, not full certificate validation.
Description
Check selected hexadecimal serial-number layout and DER sign-padding properties.
Certificate serial numbers are integers whose written hexadecimal width differs from their minimal DER representation. This checker reports selected properties of a supplied hexadecimal spelling.
When to use this tool
Check selected hexadecimal serial-number layout and DER sign-padding properties. Use it when the input measurements and conventions below match the operation you need.
- Prepare serialHex, respecting the measurement basis and boundaries below.
- Compare the worked example with your intended operation before reusing its result.
How to use the tool and how it works
- Enter every field in the input table using the stated units and exact supported selector spelling where applicable.
- Run the tool. Correct input errors before interpreting an output.
- Read the result fields below; use accompanying flags and the stated sign, boundary or model convention when interpreting a number.
The input must contain 1 to 40 hexadecimal digits. The tool converts it to an integer, reports even written length, positivity and ceil(written digits/2) as unsignedOctets, and determines whether the minimal positive integer representation would need a DER sign-padding octet. certificateValidityVerified is always false.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| serialHex | Serial hex. | Text |
| Output field | Interpretation |
|---|---|
| result | Object containing the following named result fields. |
| result.evenHexLength | Even hex length flag under the exact conditions described above. |
| result.positive | Positive flag under the exact conditions described above. |
| result.unsignedOctets | Unsigned octets; use the stated units and sign convention. |
| result.derSignPaddingNeeded | Der sign padding needed flag under the exact conditions described above. |
| result.certificateValidityVerified | Always false; no certificate is parsed or authenticated. |
{
"input": {
"serialHex": "80"
},
"output": {
"result": {
"evenHexLength": true,
"positive": true,
"unsignedOctets": 1,
"derSignPaddingNeeded": true,
"certificateValidityVerified": false
}
}
}Limitations and assumptions
- Leading zeros affect written width but not the minimal integer's high bit. The tool does not parse a certificate or verify issuance, uniqueness, chain, signature or full DER conformance.
- Every declared field is required and unexpected fields are rejected. Numeric inputs must be finite; input errors are distinct from a valid false result or an explicitly qualified output.
- Extremely large inputs and nonfinite or excessively large outputs are rejected. List positions reported by the tool use zero-based indices unless stated otherwise.
Alternative or Complementary methods
Use the applicable protocol specification and a reviewed implementation for real verification, hashing or key management. A format label, probability model or tentative text mapping does not replace that operation. Compare the scope of the nearby tools below before substituting one.
References
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