Public-Key Cryptography Standards (PKCS) is a set of informal intervendor standards developed since 1991 by RSA Laboratories with representatives of other vendors. Since its publication, PKCS has been used in many standards and products. These standards cover RSA encryption, Diffie-Hellman key agreement, password-based encryption, extended-certificate syntax, cryptographic message syntax, private-key information syntax, and certification request syntax, as well as selected attributes. The standards that form part of PKCS include: - PKCS #1: RSA Encryption Standard - PKCS #3: Diffie-Hellman Key-Agreement Standard - PKCS #5: Password-Based Cryptography Standard - PKCS #6: Extended-Certificate Syntax Standard - PKCS #7: Cryptographic Message Syntax Standard - PKCS #8: Private-Key Information Syntax Standard - PKCS #9: Selected Attribute Types - PKCS #10: Certification Request Syntax Standard - PKCS #11: Cryptographic Token Interface Standard - PKCS #12: Personal Information Exchange Syntax Standard - PKCS #13: Elliptic Curve Cryptography Standard - PKCS #15: Cryptographic Token Information Format Standard