“Meet in the middle attack” is an attack

An X.509 public key certificate is a digital document that contains a user's public key and a name for the user. X.509 certificates are used in many security protocols and applications to verify the identity of individuals, devices, or entities in a digital communication or transaction.  X.509 certificates are a standardized format for encoding and exchanging public key certificates.  They contain the following fields: The distinguished name of the owner of the public key The distinguished name of the issuer of the certificate The public key itself The validity period of the... Show more

An X.509 public key certificate is a digital document that contains a user's public key and a name for the user. X.509 certificates are used in many security protocols and applications to verify the identity of individuals, devices, or entities in a digital communication or transaction. 

X.509 certificates are a standardized format for encoding and exchanging public key certificates. 
They contain the following fields:
The distinguished name of the owner of the public key
The distinguished name of the issuer of the certificate
The public key itself
The validity period of the certificate
The certificate's serial number
The issuer's digital signature 

X.509 certificates use a public and private key pair to encrypt and decrypt content. The keys are mathematically related, and content encrypted by one key can only be decrypted by the other. The private key is kept secret, and the public key is typically embedded in a binary certificate. 
X.509 certificates are widely used in various applications like secure email, web browsing, online banking, and electronic transactions. 

Show less