• Digest Algorithm • Symmetric Encryption Algorithm • Asymmetric Encryption Algorithm • Digital Signature • Digital Certificate Digital abstract achieve • Abstract arbitrarily-length plaintext into a fixed-length string with a one-way hash function. Hash (plaintext) --> Fixed length summary Features • The computed summary length is always fixed regardless of the length of the plaintext. The length of the sum of hash('a') and hash('aaaaaaaaaaa') is the same. • The digests are different for different plaintexts. That is, the same plaintext, the calculated digest is the same, and the digests formed by different plaintexts are generally not the same (good hash functions do not collide) Digital abstract algorithm • md5 Md5 • Make a md5 calculation of the string to be encrypted to form a 128-bit (32-bit hexadecimal) digest. String: jiajun md5 Abstract: a51c0678c060ae4c4630d930fe83102c SHA-1 • Synthesize the 160-bit (40-bit hexadecimal) digest by performing a SHA calculation on the string to be encrypted. String: jiajun SHA-1 Abstract: 26352d75496932fd05e65724610ce1aaadf9259c Base64 is not an encryption algorithm but an encoding algorithm • Coding binary data into ascll code. For example, we upload the image to the server in the form of json, then we can convert the image binary data to binary through base64 encoding. Rainbow table crack hash algorithm • The two digital summarization algorithms md5 and sha-1 mentioned above are all irreversible algorithms. How to crack it? Rainbow table is a way to crack. Symmetric encryption achieve • The sender and receiver agree on a key and generate an encrypted ciphertext transmission. After the receiver accepts it, it uses the same key and inverse algorithm of the encryption algorithm to decrypt it. In general, I wrote a love letter for the floret, and then put it in a small locker box, after many people, and finally reached the floret. The floret opened the box with the same key. But if the key is picked up on the way, the love letter is made public. Symmetry refers to encryption and decryption using the same encryption key. Features • The algorithm is public and the encryption speed is fast. Symmetric encryption algorithm • DES algorithm, 64-bit key • AES algorithm, with 128,192,256 key lengths, and higher encryption strength. Application Analysis • A sends a secret file to B. At this time, a symmetric encryption algorithm can be used. Without a key, the file cannot be decrypted. Asymmetric encryption achieve • A sends a message to B. B first generates a public and private key, then exposes the public key, and A obtains the public key. Features • Asymmetric encryption is more complex, so encryption and decryption speeds are not as fast as symmetric encryption, but they are also more secure. Asymmetric encryption algorithm • RSA algorithm Application Analysis • Even if someone intercepts files in the middle, because there is no private key and the encryption algorithm is complex, decryption is difficult. digital signature achieve • A sends a message to B. A generates a public and private key and exposes the public key. Digital signature algorithm • MD5withRSA algorithm • SHA1withRSA algorithm Application Analysis • B receives A's file, and B wants to confirm that A sent it, then according to the digital signature method, according to A's public key to decrypt and compare, because A's private key is unlisted, so that the match can be confirmed A sent. Digital certificate achieve • A sends a message to B, and A generates a public and private key. Application Analysis • Send a digital certificate based on the digital signature. In this case, the receiver does not need to maintain a public key database. After CA authentication, the digital certificate is extracted and the public key is obtained. The open frame industrial monitor that we offer are a range of monitors without front bezel--all kits: TFT LCD panel (touchscreen), LCD controller board, inverter and cables mounting into a back enclosure. It is low profile design, suit for self-mounting into kiosks, cabinets, consoles, machines and control panels. This monitor is ideal for integrators and OEMs for special mounting applications. open frame monitor,open frame lcd monitors,open frame touch screen,open frame touch monitor,open frame displays,open frame lcd display Shenzhen Hengstar Technology Co., Ltd. , https://www.angeltondal.com
• Only forward message digests can be made. In other words, the plaintext cannot be restored from the message digest.
• sha
• Compared to md5, the summary information is longer, the calculation process is more complex, and the speed is slower, but it is also relatively safer.
• base64 is reversible and can be recovered as binary data by a decoding algorithm, so it cannot be encrypted at all. 
• The rainbow table cracking method searches through such a table. For example, an attacker obtains a user password ciphertext that is encrypted by the md5 algorithm. Then he can query such a table to find the plaintext of the password. .
• The rainbow table is a constant accumulation process. The content of the table is continuously enriched, and the probability of cracking gradually increases.
• If the user's password is a common password, such as a birthday, the attacker knows that some users will use birthdays as passwords. The attacker can calculate these birthday combinations in advance and record them in advance. Then the query in the rainbow table can be quickly queried to the password clear text. If the password is more complicated, if the ciphertext is leaked, it is difficult to find the rainbow table according to the generated ciphertext (because the table does not). This is why we have reduced the cracking rate for the use of salt.
• Once the key is compromised, it can be easily decrypted because the algorithm is public.
• If the key is compromised then the file can be decrypted, and as the technology evolves, it is also possible to use brute force brute force decryption.
• If A sends a secret file to many people, multiple appointments are required.
• Then use the public key for encryption and send the ciphertext to B.
• B is decrypted with the private key.
• If A sends a secret file to more than one person, then he does not need to make multiple appointments, and encrypts from the public key repository based on the recipient's public key.
• A performs a digital digest algorithm on the sent message and then encrypts it with the private key.
• A sends the encrypted ciphertext and text to B
• After receiving B, it decrypts the ciphertext using the public key to obtain the string C, and then uses the original text to perform the digest algorithm to obtain the string D, and then compares the CD. This will confirm the identity of A.
• Digital signature: The result of digesting the plaintext and then encrypting it with the private key
• A sends the public key, public key holder, signature algorithm, expiration date, and other information to CA (Digital Certificate Authority)
• After the CA approves the information, it signs it with the CA's private key, and the digital certificate is generated.
• Then A sends the plaintext, clear digital signature, and digital certificate to B
• After B receives it, it decrypts it using the CA's public key, performs the first verification, and verifies the digital certificate.
• After successful verification, a second check is performed to extract the public key in the digital certificate and decrypt the ciphertext.