1.1 Notations

In these guidelines, assertions, attribute bundles, and other elements of the federation protocol are verified by an asymmetric digital signature or a symmetric message authentication code (MAC). When either asymmetric or symmetric cryptography is specifically required, the terms sign and signature will be qualified as appropriate to indicate the requirement, such as symmetric signature or asymmetric signature. When either option is possible, the terms sign and signature are used without a qualifier.

For both symmetric and asymmetric signatures, the key used to create a signature is known as the signing key. With asymmetric cryptography, the signing key refers to the private key of the cryptographic key pair. Likewise, the key used to verify the signature is known as the verification key. For asymmetric cryptography, the verification key refers to the public key of the cryptographic key pair. With symmetric cryptography, the symmetric key is both the signing key and verification key.

For both symmetric and asymmetric encryption, the key used to encrypt a payload is known as the encryption key. With asymmetric cryptography, the encryption key refers to the public key of the cryptographic key pair, which is used to encapsulate a symmetric key that encrypts the payload. Likewise, the key used to decrypt the encrypted payload is known as the decryption key. With asymmetric cryptography, the decryption key refers to the private key of the cryptographic key pair. With symmetric cryptography, the symmetric key is both the encryption key and the decryption key.

Some cryptographic processes use multiple keys in combination, such as using a public-private key pair to derive a shared key for actual use. Unless otherwise specified, these guidelines focus on the initial key material that is known or transferred by the parties taking part in the federation protocol and not the cryptographic material derived from those keys.

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