PKCS Standards

Here is a list of active PKCS standards. You will notice that there are gaps in the numbered sequence of these standards, and that is due to the retiring of standards over time since they were first introduced.

PKCS #1: RSA Cryptography Standard Outlines the encryption of data using the RSA algorithm. The purpose of the RSA Cryptography Standard is in the development of digital signatures and digital envelopes. PKCS#1 also describes a syntax for RSA public keys and private keys. The public-key syntax is used for certificates, while the private-key syntax is used for encrypting private keys.

PKCS #3: Diffie-Hellman Key Agreement Standard Outlines the use of the Diffie-Hellman Key Agreement, a method of sharing a secret key between two parties. The secret key used to encrypt ongoing data transfer between the two parties. Whitefield Diffie and Martin Hellman developed the Diffie-Hellman algorithm in the 1970s as the first public asymmetric cryptographic system (asymmetric cryptography was invented in the United Kingdom earlier in the same decade, but was classified as a military secret). Diffie-Hellman overcomes the issue of symmetric key system, because management of the keys is less difficult.

PKCS #5: Password-based Cryptography Standard A method for encrypting a string with a secret key that is derived from a password. The result of the method is an octet string (a sequence of 8-bit values). PKCS #8 is primarily used for encrypting private keys when they are being transmitted between computers.

PKCS #6: Extended-certificate Syntax Standard Deals with extended certificates. Extended certificates are made up of the X.509 certificate plus additional attributes. The additional attributes and the X.509 certificate can be verified using a single public-key operation. The issuer that signs the extended certificate is the same as the one that signs the X.509 certificate.

PKCS #7: Cryptographic Message Syntax Standard The foundation for Secure/Multipurpose Internet Mail Extensions (S/MIME) standard. It is also compatible with Privacy-Enhanced Mail (PEM) and can be used in several different architectures of key management.

PKCS #8: Private-key Information Syntax Standard Describes a method of communication for private-key information that includes the use of public-key algorithm and additional attributes (similar to PKCS #6). In this case, the attributes can be a DN or a root CA’s public key.

PKCS #9: Selected Attribute Types Defines the types of attributes for use in extended certificates (PKCS #6), digitally signed messages (PKCS #7), and private-key information (PKCS #8).

PKCS #10: Certification Request Syntax Standard Describes a syntax for certification request. A certification request consists of a DN, a public key, and additional attributes. Certification requests are sent to a CA, which then issues the certificate.

PKCS #11: Cryptographic Token Interface Standard Specifies an application program interface (API) for token devices that hold encrypted information and perform cryptographic functions, such as smart cards and Universal Serial Bus (USB) pigtails.

PKCS #12: Personal Information Exchange Syntax Standard Specifies a portable format for storing or transporting a user’s private keys and certificates. Ties into both PKCS #8 (communication of private-key information) and PKCS #11 (Cryptographic Token Interface Standard). Portable formats include diskettes, smart cards, and Personal Computer Memory Card International Association (PCMCIA) cards. On Microsoft Windows platforms, PKCS #12 format files are generally given the extension .pfx. PKCS #12 is the best standard format to use when exchanging private keys and certificates between systems.

RSA-derived technology in its various forms is used extensively by Windows Server 2008 for such things as Kerberos authentication and S/MIME. In practice, the use of the PKI technology goes something like this: Two users, Dave and Dixine, wish to communicate privately. Dave and Dixine each own a key pair consisting of a public key and a private key. If Dave wants Dixine to send him an encrypted message, he first transmits his public key to Dixine. She then uses Dave’s public key to encrypt the message. Fundamentally, since Dave’s public key was used to encrypt, only Dave’s private key can be used to decrypt. When he receives the message, only he is able to read it. Security is maintained because only public keys are transmitted—the private keys are kept secret and are known only to their owners.

In a Windows Server 2008 PKI, a user’s public and private keys are stored under the user’s profile. For the administrator, the public keys would be under Documents and Settings\Administrator\System Certificates\My\Certificates and the private keys would be under Documents and Settings\Administrator\Crypto\RSA (where they are double encrypted by Microsoft’s Data Protection API, or DPAPI). Although a copy of the public keys is kept in the registry, and can even be kept in Active Directory, the private keys are vulnerable to deletion. If you delete a user profile, the private keys will be lost!

Source of Information : Syngress The Best Damn Windows Server 2008 Book Period 2nd Edition

No comments:

The many complications and risks of tape

Magnetic tape technology was adopted for backup many years ago because it met most of the physical storage requirements, primarily by being ...