ASN.1 encoder/decoder on JavaScript (v0.3)

Free access counter with access analysis
ASN.1 to Binary is now under construction! Binary to ASN.1 is available.

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  1. Input ASN.1 object into [Input] field.
    You can choose one of these formats:
    • 30 03 02 01 ff .. (HEX string)
    • 30030201ff.. (HEX string, without space)
    • 30 03 02 01 FF .. (HEX string, upper case)
    • 30030201FF.. (HEX string, without space, upper case)
    • Q2hhbmdlIHRoZSBzY3J.. (BASE64)
  2. Any carriage-returns, line-feeds, and tabs can be used instead of space. They'll be ignored.
  3. (In case of HEX string with space) Each token must have 2 digits even if being less than 16.
  4. Press [Convert] button to show ASN.1 dump in [Output] field.
  5. If you describe what each OID numbers mean at [OID] field, those descriptions will be appended to OID number in ASN.1 dump.
  6. If you are using Internet Explorer on Windows, press [Send to Clipboard] button to fetch the clipboard your result from [Output] field.
How to use this off line?
23 Mar, 2004 (v0.3)
  • The bug has been fixed; "The previous VALUE field is reused in case VALUE has zero length."
  • OID description is equiped.
  • Now it can run on Mozilla Firefox 0.8, as well as Internet Explorer 5.
2 Apr, 2003 (v0.2)
  • Decoding routine for BASE64 has been equiped.
28 Mar, 2003 (v0.1)
  • Strange indent for beginning of sequencial object has been deleted.
  • v0.0 couldn't process ASN.1 when the length of LENGTH field is longer than 1 octet. This bug has been fixed in this version(v0.1).
  • These problems were found by Mr.(or Ms.) T @ OCN. Japan
someday of 2002 (v0.0)
© 2002 -
I wish your pointing and suggestion for bugs and my poor English skill.