PKCS 1

PKCS #1 (Public-Key Cryptography Standards #1) is part of a suite of Public-Key Cryptography Standards (PKCS) developed by RSA Laboratories. It defines the mathematical formats and cryptographic techniques for RSA public-key cryptography. Specifically, it details the implementation of RSA encryption, signature, and key generation algorithms.

The standard covers several versions and specifies different encoding methods and padding schemes to ensure the security and interoperability of RSA implementations. Key aspects defined within PKCS #1 include:

• Key Generation: Procedures for generating RSA key pairs, including the selection of prime numbers and the calculation of the public and private exponents.

• Encryption Schemes: Algorithms and padding methods for encrypting data using the RSA public key, such as Optimal Asymmetric Encryption Padding (OAEP) and Probabilistic Signature Scheme (PSS). Older schemes like PKCS #1 v1.5 padding are also specified, although generally considered less secure for modern applications.

• Signature Schemes: Methods for creating digital signatures using the RSA private key. These schemes typically involve hashing the data to be signed and then applying RSA operations with appropriate padding, again including options like PSS and the less secure PKCS #1 v1.5 signature padding.

• Data Structures: Formats for representing RSA public and private keys, including the Abstract Syntax Notation One (ASN.1) structures commonly used in X.509 certificates.

PKCS #1 is a fundamental standard for RSA cryptography, providing a framework for secure communication and data protection. However, due to vulnerabilities discovered in older padding schemes (like PKCS #1 v1.5), it's crucial to use the recommended and more robust schemes like OAEP and PSS in modern applications. Updated versions of PKCS #1 continue to refine and strengthen the specification to address evolving security threats.