HTTPS

Introduction to HTTPS

HTTPS (Hypertext Transfer Protocol Secure) is a network communication protocol that protects the security of data transmission through encryption and authentication. It is an extension based on the HTTP protocol. It establishes an encrypted connection by using the SSL (Secure Sockets Layer) or TLS (Transport Layer Security) protocol to ensure the confidentiality and integrity of data during transmission.

Advantages of HTTPS:

• Data transmission security: Prevent data from being stolen or tampered with by encrypting data.
• Authentication: Verify the identity of the server through SSL certificate to prevent man-in-the-middle attacks .
• Support SEO: Search engines are more likely to include websites that use HTTPS.
• Improve user trust: HTTPS marks the security of the website and increases user trust in the website.

HTTPS is a network communication protocol that secures data transmission, ensuring data confidentiality and integrity through encryption and authentication. In today's Internet environment, the use of HTTPS has become an important means to protect user privacy and data security.

HTTP pain points

1. "Stateless" : The HTTP protocol is stateless, that is, the server does not save the client's status information. Each request is independent, and the server has no way of knowing whether the two previous requests are from the same client. This results in the need for additional mechanisms to maintain state information when dealing with application scenarios that need to maintain state (such as user login status), increasing the complexity of development and maintenance.
2. "Clear text transmission" : The HTTP protocol uses plain text transmission by default, and data is easily eavesdropped and tampered with during the transmission process. This is unsafe for the transmission of some sensitive information and requires additional encryption mechanisms to ensure data security.
3. "Performance issues" : The HTTP protocol has some performance issues during the transmission process. For example, each request requires establishing and closing a TCP connection, which brings significant overhead. At the same time, in the request-response mode of the HTTP protocol, the client needs to actively initiate a request before the server can respond. This one-way communication method may cause some delays.
4. "Scalability" : The HTTP protocol was not designed with the scale and complexity of the modern Internet in mind. With the development of the Internet, a large number of expansion requirements have emerged, such as supporting multimedia content, supporting real-time communication, etc. These requirements exceed the original design scope of the HTTP protocol and need to be implemented through various extension mechanisms, resulting in complexity and inconsistency of the protocol.

Although the HTTP protocol is widely used in Internet applications, there are still some pain points that need to be solved. In order to solve these problems, some new protocols and technologies have emerged, such as HTTPS, SPDY, HTTP/2, etc., to improve security, performance and scalability.

How HTTPS works

1. The client initiates an HTTPS request and connects to port 443 of the server.
2. The server sends its own SSL certificate to the client.
3. The client verifies whether the server's certificate is trusted and, if so, generates a random symmetric key .
4. The client encrypts the symmetric key using the server's public key and sends it to the server.
5. The server uses the private key to decrypt the symmetric key sent by the client.
6. The client and server use symmetric keys for encryption and decryption to ensure the security of data transmission.

encryption

Introduction to encryption

Encryption refers to the process of converting original data into unreadable ciphertext through a certain algorithm and key. Encryption protects the confidentiality of data and prevents unauthorized persons from gaining access to sensitive information. Common encryption algorithms include symmetric encryption and asymmetric encryption .

Symmetric encryption refers to an encryption algorithm that uses the same key for encryption and decryption. Common symmetric encryption algorithms include DES, AES, etc. In symmetric encryption, the sender uses a key to encrypt the original data into ciphertext, and the receiver uses the same key to decrypt the ciphertext back to the original data.

Asymmetric encryption refers to an encryption algorithm that uses different keys for encryption and decryption. Common asymmetric encryption algorithms include RSA, ECC, etc. In asymmetric encryption, the sender uses the public key to encrypt the original data into ciphertext, and the receiver uses the private key to decrypt the ciphertext and restore it to the original data.

The security of an encryption algorithm depends on the confidentiality of the key and the complexity of the algorithm . In order to enhance the security of encryption, technologies such as Message Authentication Code (MAC) and digital signatures are often used to verify the integrity and authenticity of the data.

Encryption is an important information security technology that can effectively protect the confidentiality and security of data by using appropriate encryption algorithms and key management methods.

Hash

Hash is an algorithm that maps arbitrary length data to fixed length data. The hash function can convert the input data into a fixed-length hash value, which is usually a number or a string. Hash functions have the following characteristics:

1. Given the same data as input, the hash function will produce the same hash value.
2. With different input data, the hash function will produce different hash values.
3. The output length of the hash function is fixed and is not affected by the length of the input data.

Hash functions are widely used in cryptography, data verification, data indexing and other fields. Common hash functions include MD5, SHA-1, SHA-256, etc.

Applications of hash functions include:

• Data integrity check: By comparing the hash value of the data, you can determine whether the data has been tampered with.
• Data index: Use the hash value of the data as an index to quickly find and compare data.
• Password storage: Storing hashes of user passwords in the database can increase password security.

The mathematical representation of the hash function is:, where represents the hash value, represents the hash function, and represents the input data.

Symmetric encryption

Introduction to symmetric encryption

Symmetric encryption is an encryption algorithm that uses the same key to encrypt and decrypt data. In symmetric encryption, the sender and receiver use the same key to encrypt and decrypt data. The advantage of this encryption algorithm is that it is fast and suitable for encrypting and decrypting large amounts of data. Common symmetric encryption algorithms include DES, AES, etc.

The process of symmetric encryption is as follows:

1. The sender uses the key to encrypt the plain text and generate cipher text.
2. The sender sends the ciphertext to the receiver.
3. The receiver uses the same key to decrypt the ciphertext and restore it to plaintext.

The advantage of symmetric encryption is that it is fast and suitable for encrypting and decrypting large amounts of data. However, the disadvantage of symmetric encryption is that the keys are less secure since both the sender and receiver need to share the same key. If the key is compromised, an attacker can easily decrypt the ciphertext.

In practical applications, symmetric encryption is often used in conjunction with asymmetric encryption. Asymmetric encryption is used for the secure transmission of keys, while symmetric encryption is used for the actual data encryption and decryption process. This balances speed and security.

Mathematical calculations involved in symmetric encryption

Symmetric encryption is an encryption algorithm that uses the same key for encryption and decryption. The mathematical calculations it involves mainly include the following aspects:

1. Substitution and permutation: Symmetric encryption algorithms usually use substitution and permutation operations to change the order and structure of the plaintext to increase the complexity of encryption. These operations can be achieved through mathematical operations, such as substitution and substitution using substitution tables or S-boxes.
2. XOR operation: A commonly used operation in symmetric encryption algorithms is the XOR operation. During the encryption process, the plaintext and the key are XORed to generate ciphertext; during the decryption process, the ciphertext and the key are XORed to recover the plaintext. The XOR operation is a simple binary operation that can be implemented through mathematical operations.
3. Modular arithmetic: Commonly used mathematical operations in symmetric encryption algorithms also include modular arithmetic. Modulo operation is a remainder operation that can be used to limit the range of encryption results to ensure that the encrypted data is within the specified range.
4. Linear algebra operations: Some symmetric encryption algorithms (such as AES) use linear algebra operations. These operations include matrix multiplication, matrix inversion, etc., used to confuse and diffuse plaintext information.

The mathematical calculations involved in symmetric encryption include substitution and permutation, XOR operations, modular operations, and possibly linear algebra operations. The purpose of these mathematical calculations is to increase the complexity of encryption and make the ciphertext difficult to crack.

DES algorithm

DES ( Data Encryption Standard ) is a symmetric encryption algorithm used to protect the confidentiality of data. It is a block cipher algorithm that divides plaintext data into fixed-length data blocks and converts plaintext into ciphertext through a series of encryption operations.

The main steps of the DES algorithm include initial permutation, 16-round Feistel network, inverse initial permutation and key generation. In the initial replacement stage, the plaintext data undergoes a series of replacement and selection operations to obtain the initial replacement data. Next, the initial permuted data is subjected to multiple rounds of encryption operations through the 16-round Feistel network. Each round of encryption operations includes subkey generation, extended permutation, S-box replacement, P-box permutation and round key addition operations. Finally, the data after 16 rounds of encryption operations is converted into ciphertext through inverse initial permutation.

The security of the DES algorithm mainly depends on the length of the key and the confidentiality of the key. The DES algorithm uses a 56-bit key, but due to the short key length, it is no longer secure. Therefore, commonly used encryption algorithms have shifted to using longer key lengths, such as the AES algorithm.

The encryption process of the DES algorithm can be expressed by the following formula:

Among them, represents the ciphertext, represents the encryption operation using the key, and represents the plaintext.

The decryption process of the DES algorithm can be expressed by the following formula:

Among them, represents the plain text, represents the decryption operation using the key, and represents the cipher text.

The DES algorithm is a classic symmetric encryption algorithm that converts plaintext into ciphertext through a series of encryption operations. At the same time, it can also perform decryption operations using the same key to restore ciphertext to plaintext. However, due to the short key length of the DES algorithm, it is no longer secure. Now commonly used encryption algorithms have shifted to using longer key lengths.

asymmetric encryption

Introduction to asymmetric encryption

Asymmetric encryption is an encryption algorithm that uses two keys: public key and private key. The public key is used to encrypt data and the private key is used to decrypt data. The two keys are related, but the private key cannot be deduced from the public key.

Asymmetric encryption works as follows:

1. The sender encrypts the data using the receiver's public key.
2. The recipient uses its own private key to decrypt the encrypted data.

The advantage of asymmetric encryption is high security because the private key is known only to the recipient and no one else can decrypt the data. At the same time, asymmetric encryption can also be used for digital signatures to verify the integrity and authenticity of data.

Common asymmetric encryption algorithms include RSA, Diffie-Hellman, and Elliptic Curve Cryptography (ECC).

The following is the formula of the RSA algorithm:

Public key: Private key:

encrypt and decode:

Among them, is the plaintext, is the ciphertext, is the public key index, is the private key index, and is the modulus.

Asymmetric encryption plays an important role in protecting the security of data transmission and storage, and is widely used in fields such as network communications, e-commerce, and digital certificates.

RSA algorithm

The RSA algorithm is an asymmetric encryption algorithm that consists of three main steps: key generation, encryption, and decryption.

1. Key generation: The RSA algorithm uses two large prime numbers p and q to generate public and private keys. First, choose two different prime numbers p and q, and calculate their product n=p*q. Then, calculate the Euler function φ(n)=(p-1)*(q-1). Next, choose an integer e such that 1<e<φ(n) and e and φ(n) are relatively prime. Finally, calculate the modular inverse element d of e, that is, the integer d that satisfies (e*d) mod φ(n) = 1. The public key is (n, e) and the private key is (n, d).
2. Encryption: To encrypt a message m, use the public key (n, e) for encryption. Convert message m to integer M, satisfying 0<=M<n. Then, calculate the ciphertext c = M^e mod n.
3. Decryption: To decrypt the ciphertext c, use the private key (n, d) to decrypt. Calculate the plaintext m = c^d mod n.

The security of the RSA algorithm is based on the difficulty of decomposing large numbers, that is, the difficulty of decomposing a large number into its prime factors. Therefore, the RSA algorithm is widely used in fields such as encrypted communications and digital signatures to protect the confidentiality and integrity of data.

The encryption and decryption process of the RSA algorithm can be expressed by the following formula:

Encryption: c = M^e mod n

Decryption: m = c^d mod n

Among them, M is the plaintext, c is the ciphertext, e is the public key index, n is the modulus, and d is the private key index.

digital certificate

digital signature

Digital signature is a technology used to verify data integrity and identity authentication. It uses an asymmetric encryption algorithm by encrypting and decrypting data.

The process of digital signature is as follows:

1. The sender uses the private key to encrypt the data to be sent and generate a digital signature.
2. The sender sends the original data to the receiver along with the digital signature.
3. The receiver uses the sender's public key to decrypt the digital signature and obtains the decrypted data.
4. The receiver uses the same encryption algorithm to encrypt the original data and obtains the encrypted data.
5. The receiver compares the decrypted data and the encrypted data to see if they are consistent. If they are consistent, it means that the data integrity has not been tampered with and the identity of the sender has been verified.

The purpose of a digital signature is to ensure that the data has not been tampered with during transmission and to verify the identity of the sender. It is widely used in e-commerce, network communications and other fields.

digital certificate

A digital certificate is a security tool used to verify and confirm identity in network communications. It is issued by an authoritative digital certificate authority (CA) and is used to prove the identity and validity of the public key of an entity (such as a website, individual or organization).

Digital certificates typically contain the following information:

• Subject information: name, email address, etc. of the certificate holder.
• Public key information: The certificate holder’s public key, used to encrypt and decrypt data.
• Certificate authority information: The name and public key of the CA that issued the certificate.
• Validity period: The effective date and expiration date of the certificate.
• Digital signature: The CA uses its own private key to sign the certificate to ensure the integrity and authenticity of the certificate.

The verification process of a digital certificate is by using the CA's public key to verify the digital signature of the certificate. If the digital signature verification is successful, the authenticity and integrity of the certificate can be confirmed. This allows users to trust the identity of the certificate holder and use their public key to communicate securely.

In network communications, digital certificates are widely used in SSL/TLS protocols to protect the security of data transmission between websites and users. By using digital certificates, websites can prove their identity and encrypt communications between users and servers to prevent data from being stolen or tampered with.

A digital certificate is a security tool used to verify and confirm identity in network communications. It is issued by a CA and contains subject information, public key information, certificate authority information, validity period, digital signature, etc. It plays an important role in securing data transmission between the website and the user.

Summarize

HTTPS is a protocol for secure communication over computer networks. It adds SSL/TLS protocol on the basis of HTTP to ensure communication security.

The implementation principle of HTTPS is as follows:

1. The client initiates an HTTPS request: The client establishes a secure connection by sending an HTTPS request to the server.
2. Server sends certificate: The server will send its own digital certificate to the client. The certificate contains the server's public key and other related information.
3. Client verification certificate: The client will verify the certificate sent by the server. Verification includes checking the legality, validity period, etc. of the certificate. If the verification passes, the client will continue to the next step.
4. The client generates a random key: The client generates a random symmetric key for subsequent encrypted communications.
5. The client uses the server's public key to encrypt the key: The client uses the server's public key to encrypt the generated random key, and then sends the encrypted key to the server.
6. The server uses the private key to decrypt the key: The server uses its own private key to decrypt the received encryption key and obtain the random key generated by the client.
7. Establish a secure connection: The client and server use this random key to encrypt and decrypt subsequent communication content to ensure communication security.

HTTPS implements encryption and authentication of communication content, ensuring data security and integrity. At the same time, HTTPS can also prevent security threats such as man-in-the-middle attacks and data tampering.

The SSL/TLS protocol is a protocol used to protect the security of network communications. It is built on top of the transport layer and provides security and data integrity to the application layer.

The SSL/TLS protocol achieves communication security by using encryption algorithms and certificates. It uses a combination of symmetric encryption algorithms and asymmetric encryption algorithms to protect the confidentiality and integrity of data. At the beginning of communication, a handshake process occurs between the client and server to negotiate encryption algorithms and keys, which are then used to encrypt and decrypt the communication data.

The SSL/TLS protocol also provides authentication functions by using digital certificates to verify the identity of the server. A digital certificate is issued by a trusted Certificate Authority and contains the server's public key and other related information. Clients can use certificates to verify the server's identity and ensure a secure connection to a legitimate server.

The SSL/TLS protocol protects the security of network communications and data integrity through encryption and authentication mechanisms. It is widely used for secure communication between web browsers and servers, as well as other application scenarios where data security needs to be protected.