TOOLS / PARSERS & VALIDATORS

ASN.1 Decoder

Decode ASN.1 DER/BER encoded data structures.

DER and BER

Shows tag classes, constructed values, integers, object identifiers, text and raw HEX. Supports definite lengths and constructed BER indefinite lengths.

PEM is Base64 around the encoded bytes. An encrypted PEM payload must be decrypted before its inner ASN.1 can be inspected.

Interpretation

This is a structural decoder, not a complete DER validator. Schema constraints, SET ordering, all string/time rules and certificate signatures are not verified. Context-specific tags need the relevant schema.

ITU-T X.690 encoding rules ↗

Limits

65,536 decoded bytes, 2,048 nodes and 32 nesting levels. Offsets start at zero. Malformed boundaries produce an error rather than a partial result.

Worked example

The example decodes a SEQUENCE containing INTEGER 42, OID 1.2.840.113549.1.1.1 and UTF8String “Hello!”.

ASN.1 Decoder

Decoded structure