Asymmetric Cryptography - Introduction: Public Key Encryption
3 important questions on Asymmetric Cryptography - Introduction: Public Key Encryption
What is a key pair?
the padlock and the key together. The lock itself is called the public key and the key is called the private key. The public key can be used for encryption, and the private key for decryption.
Out of which three components does an Asymmetric encryption consist?
·A key pair generation algorithm, which outputs a key pair (p, k) consisting of:
oA public key K
oA private key P
·An encryption algorithm AE, which has as inputs the public key p and a plaintext m, and outputs ciphertext c=AEp (m)
·A decryption algorithm AD, which has as inputs the private key k and a ciphertext c, and outputs a decrypted text m’= ADk (c).
oA public key K
oA private key P
·An encryption algorithm AE, which has as inputs the public key p and a plaintext m, and outputs ciphertext c=AEp (m)
·A decryption algorithm AD, which has as inputs the private key k and a ciphertext c, and outputs a decrypted text m’= ADk (c).
What is the man in the middle problem?
The problem really is one of lack of authentication. What is needed is that Alice knows for sure that the public key she receives is Bob’s, and not somebody else’s. This is an authentication problem. So to make public key systems work, we need authentication of public keys.
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