Aspose.PDF FOSS
Aspose.PDF FOSS for Java
Developer Guide
ASN.1 Encoding

ASN.1 Encoding

ASN.1

ASN.1 (Abstract Syntax Notation One) is used in PDF digital signatures for encoding cryptographic data structures such as certificate chains, signature values, and algorithm identifiers.

DEREncoder

DEREncoder provides utilities for encoding ASN.1 DER (Distinguished Encoding Rules) structures used in PDF digital signature workflows:

  • encodeSequence() — encodes an ASN.1 SEQUENCE structure to a byte array
  • encodeSet() — encodes an ASN.1 SET structure
  • encodeOID(oid) — encodes an OID string into its DER byte representation
DEREncoder encoder = new DEREncoder();
byte[] oidBytes = encoder.encodeOID("1.2.840.113549.1.1.11"); // SHA-256 with RSA

Usage Context

DER encoding is required when working with:

  • PDF digital signatures (PKCS#7 / CMS signature containers)
  • Certificate encoding in signature dictionaries
  • Algorithm identifier structures in cryptographic operations

See the Signatures and PKCS7 pages for usage in digital signature workflows.

See Also