Supported cryptographic formats
PSPDFKit supports the following signing methods:

PAdES
(PDF Advanced Electronic Signatures, ETSI.CAdES.detached) 
CMS
(adbe.pkcs7.detached)
Supported signing algorithms are:

RSA

ECDSA
Supported hashing algorithms include:

MD4

MD5

SHA2 (SHA224, SHA256, SHA384, SHA512, SHA512256)
A hashing algorithm is an algorithm that converts a large amount of data (your PDF document) to a fixedlength string. If someone changes one bit of data in your PDF document, the hashing algorithm produces a different string, so if you store that hash inside the PDF document, you could potentially know when it has been changed by a third party. However, as easy as it sounds, this approach is insecure. If someone knows the hashing algorithm that was used to sign the PDF, they could replace the hash inside the PDF so that it validates as authentic. To avoid this, PSPDFKit works with encryption algorithms.
More specifically, PSPDFKit supports RSA
, one of the most popular public key encryption algorithms. ECDSA
, an algorithm based on elliptic curve cryptography, is also supported. Cryptographic systems based on ECDSA
are becoming the de facto standard for messaging and systems security.