Open SSL is an open source implementation of SSL and TLS . SSL is basically written in C programming language and developed by Netscape for transmitting crucial document and information over internet. There are different versions of SSL available according to the Operating System such as UNIX and Windows .
Some of the history of Open SSL are this was developed in 1998 with a few set of encryption which is implemented in 2/3rd of webservices . Open SSL supports a number of cryptographic algorithm .Cryptographic algorithm means to transfer private information and data in an encrypted form so that its not easily readable, and its done to maintain a secure communication.
Cryptyographic algorithm are basically divided into 3 types :
* Cipher : It means encryption or decryption that is a way of changing the message and keeping it as a secret .
It work as such assigning A-->F and B-->G and maintaining the text in some consistent pattern .
Cipher is a combination of both key and algorithm . A key is a variable that is combined in some way or the other with the eb=ncrypted text whereas a n algorithm is a formula for combining the key with the text .Mostly we use block ciphers that is used to break message into samll chunks and combines a key with each chunk . The most commonly used cipher suites use RSA algorithm(key exchange)
*Cryptographic Hash Functions :A hash function usually means a function which take a long input but it produces a fix output and the ouput is much shorter than the input . Some of the examples of this are : MD5, MD4, SHA-1,SHA-2
*Public key cryptography : Twoseperate keys but they are linked with the algorithm used .
SSL uses both symmetric and asymmetric algorithms for encryption . Symmetric algorithms use the same key that is there is a single key which is used to encrypt and decrypt data where as Asymmetric keys contain 2 keys one is the public key and the other is private key.Data encypted by one key can only be decryted by the other key .Asymmetric algorithms are generally secure because as one of the key is kept private. Symmetric keys are faster to transfer the data .
So the question which arises here is how SSL work ?
SSL works with a method of Encryption and Identification . Inorder to take the advantage of both Symmetric key and Asymmetric key the SSL is used in such a way that it encloses a symmetric key which is randomly selected eachtime in a message and which is encrypted by using a asymmetric key. So when a client needs a secure page it sends an HTTPS request .The server responds to this request by sending its public key and certificate .Then the client verifies by checking whether the certificate is from a trusted certificate Authority. Client uses the public key to encrypt a random symmetric encryption and sends it to the server with the encrypted URL as well as HTTP data.The server decrypts the symmetric encryption key using its private key and uses the symmetric key to decrypt the URL and HTTP data. Server sends back the request that are encrypted by the symmetric key .Client uses the same symmetric key and displays the HTML and HTTP data.
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