ASN.1 DER / PEM Text Structure Report

Produce a locally generated indented text report for ASN.1 DER or PEM, showing Tag, Length and value summaries for encoded objects.

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What is ASN.1 DER / PEM Text Structure Report?

Certificates, CSRs and many key formats use ASN.1. DER uses deterministic binary Tag-Length-Value encoding, while PEM is usually a Base64 wrapper around DER. This tool creates an indented local text report listing tags, lengths, value summaries and nesting, making it practical to copy into debugging records and compare. The report is not an expandable interactive tree and does not establish business trust: readable structure does not make a certificate trusted, unrevoked or chain-complete.

How to Use

  1. Paste PEM/Base64 or import a DER binary file or Base64 text (.txt/.b64/.base64)
  2. Generate and read the indented text report with Tag, Length, value summaries and nesting
  3. Copy the report for debugging and use a dedicated X.509 or CSR tool to confirm field semantics

FAQ

What is the difference between PEM and DER?
DER is binary encoding. PEM is commonly Base64 text bounded by BEGIN/END lines that carries DER bytes.
Why does the report contain many SEQUENCE and OID entries?
ASN.1 organizes fields with SEQUENCE and identifies algorithms, extensions and attributes with OIDs; the report shows encoding structure, while format documentation defines the semantics.
Does parsing ASN.1 prove a certificate is valid?
No. Structural parsing does not establish trusted signatures, hostname matching, revocation or a valid certificate chain.

Related Tools

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Last updated 2026-10-09