Public Key Cryptography Standards (PKCS)

Public Key Cryptography Standards (PKCS):

PKCS model was initially developed by RSA Laboratories. The main purpose of PKCS is to standardize Public Key Infrastructure (PKI). The standardization is in many respects, such as formatting, algorithms and APIs. This would help organizations to develop and implement inter-operable PKI solutions, rather than everyone choosing their own standard.

Standard	Purpose	Details
PKCS#1	RSA Encryption Standard	Defines the basic formatting rules for RSA public key functions, more specifically the digital signature. It defines how digital signatures should be calculated, including the structure of the data to be signed as well as the format of the signature. The standard also defines the syntax for RSA private and public keys.
PKCS#2	RSA Encryption Standard for Message Digests	This standard outlined the message digest calculation. However, this is now merged with PKCS#1 and does not have an independent existence.
PKCS#3	Diffie-Hellman Key Agreement Standard	Defines a mechanism to implement Diffe-Hellman Key Agreement protocol.
PKCS#4	NA	Merged with PKCS#1
PKCS#5	Password Based Encryption (PBE)	Describes a method for encrypting an octet string with a symmetric key. The symmetric key is derived from a password.
PKCS#6	Extended Certificate Syntax Standard	Defines syntax for extending the basic attributes of an X.509 digital certificate.
PKCS#7	Cryptographic Message Syntax Standard	Specifies a format/syntax for data that is the result of a cryptographic operation. Examples of this are digital signatures and digital envelopes. This standard provides many formatting options, such as messages that are only signed, only enveloped, signed and enveloped, etc.
PKCS#8	Private Key Information Standard	Describes the syntax for private key information (i.e. the algorithm and attributes used to generate the private key).
PKCS#9	Selected Attribute Types	Defines selected attribute types for use in PKCS#6 extended certificates (e.g. email address, unstructured name and address).
PKCS#10	Certificate Request Syntax Standard	Defines syntax for requesting for digital certificates. A certificate request contains a Distinguished Name (DN) and public key.
PKCS#11	Cryptographic Token Interface Standard	This standard, also called as Cryptoki , specifies an API for the single-user devices that contain cryptographic information, such as private keys and digital certificates. These devices are also capable of performing cryptographic functions. Smart cards are examples of such devices.
PKCS#12	Personal Information Exchange Syntax Standard	Defines syntax for personal identity information, such as private keys, digital certificates, etc. This allows the users to transfer their certificates and other personal identity information from one device to another, using a standard mechanism.
PKCS#13	Elliptic Curve Cryptography Standard	Currently under development, this standard deals with a new cryptographic mechanism called as Elliptic Curve Cryptography.
PKCS#14	Pseudo-Random Number Generation Standard	Currently under development, this standard will specify the requirements and process of random number generation. Since random numbers are extensively used in cryptography, standardizing their generation is important.
PKCS#15	Cryptographic Token Information Syntax Standard	Defines a standard for cryptographic tokens, so that they can interoperate.