Table 1 Cryptographic notation
From: A lightweight payment scheme for real-time services based on SIP
Notation | Meaning |
|---|---|
Data | This indicates that this piece of data is optional, and may not be in the message. |
H(Data) | A message digest of Data, obtained using a secure hash algorithm such as SHA2 [35]. |
E K (Data) | Data, encrypted by a symmetric cipher such as Advanced Encryption Standard (AES) [54] using the symmetric key K. |
H K (Data) | Data is authenticated using a HMAC algorithm using a secure hash function such as SHA-2 with a cryptographic key K. |
EK,K'(Data) | E K (Data, HK'(Data)). Data that is authenticated using a HMAC function with key K' and then encrypted using a symmetric cipher using the key K. |
S X (Data) | Data is signed using the private key of entity X. As a signature algorithm we could use RSA, DSA, ECDSA, etc. |
E X (Data) | Data, encrypted for entity X using public key cryptography (RSA) or elliptic curve cryptography--ECC--(ECDH, ECMQH, . . .). For computational efficiency, this is implemented using either a digital envelope (in RSA) or the ephemeral-static Elliptic Curve Diffie-Hellman (ECDH) key agreement algorithm (in ECC) as specified in [55, 56]. |
X → Y | This indicates that X sends a message to Y. |