Remote Audio Output Protocol
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|This article's introduction section may not adequately summarize its contents. (December 2015)|
- computing the hash of the message
- decrypting the signature with the signer's public key
- comparing the computed digest with the decrypted digest
- Public-key encryption, in which a message is encrypted with a recipient's public key. The message cannot be decrypted by anyone who does not possess the matching private key, who is thus presumed to be the owner of that key and the person associated with the public key. This is used in an attempt to ensure confidentiality.
- Digital signatures, in which a message is signed with the sender's private key and can be verified by anyone who has access to the sender's public key. This verification proves that the sender had access to the private key, and therefore is likely to be the person associated with the public key. This also ensures that the message has not been tampered with, as any manipulation of the message will result in changes to the encoded message digest, which otherwise remains unchanged between the sender and receiver.
Enveloped Public Key Encryption
- Every participant in the communication has their own unique pair of keys. The first key that is required is a public key and the second key that is required is a private key.
- Each person's own private and public keys must be mathematically related where the private key is used to decrypt a communication sent using a public key and vice versa. Some well-known asymmetric encryption algorithms are based on the RSA cryptosystem.
- The private key must be kept absolutely private by the owner, though the public key can be published in a public directory such as with a certification authority.
Public Key Encryption
A*B*C = A*C*B = C*B*A). This method is secure for certain choices of commutative ciphers, but insecure for others (e.g., a simple
XOR). For example, let
E2()be two encryption functions, and let "
M" be the message so that if Alice encrypts it using
E1(M)to Bob. Bob then again encrypts the message as
E2(E1(M))and sends it to Alice. Now, Alice decrypts
E1(). Alice will now get
E2(M), meaning when she sends this again to Bob, he will be able to decrypt the message using
E2()and get "
M". Although none of the keys were ever exchanged, the message "
M" may well be a key (e.g., Alice's Public key). This three-pass protocol is typically used during key exchange.
Associating public keys with identities
Relation to real world events
Privilege of key revocation
Distribution of a new key
Spreading the revocation
Recovery from a leaked key
- Diffie–Hellman key exchange protocol
- DSS (Digital Signature Standard), which incorporates the Digital Signature Algorithm
- Various elliptic curve techniques
- Various password-authenticated key agreement techniques
- Paillier cryptosystem
- RSA encryption algorithm (PKCS#1)
- Cramer–Shoup cryptosystem
- YAK authenticated key agreement protocol