Golang crypto 包详解

Golang的crypto包提供了加密算法的功能，包括散列、加密、签名等。以下是一些常用功能的示例代码：

1. 使用crypto/md5进行MD5散列：

import (
    "crypto/md5"
    "fmt"
)
 
func main() {
    data := []byte("hello world")
    hasher := md5.New()
    hasher.Write(data)
    md5Sum := hasher.Sum(nil)
    fmt.Println(md5Sum)
}

2. 使用crypto/sha256进行SHA256散列：

import (
    "crypto/sha256"
    "fmt"
)
 
func main() {
    data := []byte("hello world")
    hash := sha256.Sum256(data)
    fmt.Println(hash)
}

3. 使用crypto/rand生成随机数：

import (
    "crypto/rand"
    "fmt"
    "io"
)
 
func main() {
    b := make([]byte, 16)
    _, err := io.ReadFull(rand.Reader, b)
    if err != nil {
        fmt.Println("Error generating random bytes:", err)
        return
    }
    fmt.Printf("%x\n", b)
}

4. 使用crypto/aes进行AES加密和解密：

import (
    "crypto/aes"
    "crypto/cipher"
    "crypto/rand"
    "io"
    "log"
)
 
func encrypt(plaintext []byte) ([]byte, error) {
    key := make([]byte, 32) // AES-256 key
    _, err := io.ReadFull(rand.Reader, key)
    if err != nil {
        return nil, err
    }
 
    block, err := aes.NewCipher(key)
    if err != nil {
        return nil, err
    }
 
    gcm, err := cipher.NewGCM(block)
    if err != nil {
        return nil, err
    }
 
    nonce := make([]byte, gcm.NonceSize())
    _, err = io.ReadFull(rand.Reader, nonce)
    if err != nil {
        return nil, err
    }
 
    ciphertext := gcm.Seal(nonce, nonce, plaintext, nil)
    return ciphertext, nil
}
 
func decrypt(ciphertext []byte) ([]byte, error) {
    key := []byte(/* AES-256 key */)
 
    block, err := aes.NewCipher(key)
    if err != nil {
        return nil, err
    }
 
    gcm, err := cipher.NewGCM(block)
    if err != nil {
        return nil, err
    }
 
    if len(ciphertext) < gcm.NonceSize() {
        return nil, "ciphertext too short"
    }
 
    nonce, ciphertext := ciphertext[:gcm.NonceSize()], ciphertext[gcm.NonceSize():]
    plaintext, err := gcm.Open(nil, nonce, ciphertext, nil)
    if err != nil {
        return nil, err
    }
 
    return plaintext, nil
}
 
func main() {
    data := []byte("hello world")
    encrypted, err := encrypt(data)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Printf("Encrypted: %x\n", encrypted)
 
    decrypted, err := decrypt(encrypted)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Printf("Decrypted: %s\n", decrypt