Why digital signature
Why digital signature
- integrity: if the document is tampered after my signing, it will get detected
- authenticity: we want assurance that the author of the document is who we think it is (and not somebody else),
- non-repudiation: we want assurance that the author can’t deny his or her authorship.
Cryptography behind DS
- Asymmetric cryptography
- Cryptographic Hash
- Digital Signature
Asymmetric cryptography
- Public Key (feel free to distribute to anyone)
- Private Key (keep it secret)
- Examples
- RSA
- ECC(Elliptic-curve cryptography)
Asymmetric cryptography applications
- Encrypting communication
Asymmetric cryptography applications
- Digital Signature
Cryptographic Hash
Digital Signature
PKI: to build the chain of trust
a set of roles, policies, and procedures needed to create, manage, distribute, use, store and revoke digital certificates and manage public-key encryption.
Certificate
How DS works in PDF
Live demo https://lapo.it/asn1js/
Multi signatures in a single PDF
Understanding the NDI flow diagram
