openssl GCM 加密 add 说明
时间: 2023-11-08 07:28:11 浏览: 29
OpenSSL库中的GCM加密模式是一种高效的加密算法,可以在保证信息安全的前提下,将加密过程大大简化。在使用GCM加密模式时,需要调用openssl库中提供的GCM加密函数,并设置相应的参数和密钥。其中,add参数是指要加密的明文数据,可以通过多次调用add函数来添加多个数据块;而最终加密出来的密文数据,则需通过调用finalize函数来完成。在使用openssl库进行GCM加密时,需要注意使用安全的随机数生成器,以增强加密的安全性。
相关问题
openssl GCM
OpenSSL is a widely-used open-source cryptographic library that provides support for various cryptographic algorithms, including the GCM (Galois/Counter Mode) encryption mode.
GCM is an authenticated encryption mode that provides both confidentiality and integrity. It combines the Counter (CTR) mode of encryption with a universal hash function called Galois Message Authentication Code (GMAC). GCM is commonly used for secure communication protocols like TLS.
To use GCM with OpenSSL, you can utilize the EVP (Envelope) API provided by OpenSSL. Here's an example of how you can use OpenSSL to perform GCM encryption and decryption:
```c
#include <openssl/evp.h>
void encrypt_decrypt_gcm(const unsigned char* key, const unsigned char* iv, const unsigned char* aad,
const unsigned char* ciphertext, int ciphertext_len, unsigned char* tag,
unsigned char* plaintext) {
EVP_CIPHER_CTX* ctx;
int len;
int plaintext_len;
// Create and initialize the context
ctx = EVP_CIPHER_CTX_new();
EVP_EncryptInit_ex(ctx, EVP_aes_256_gcm(), NULL, NULL, NULL);
// Set the key and IV
EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_KEY_LEN, 256, NULL);
EVP_EncryptInit_ex(ctx, NULL, NULL, key, iv);
// Set the AAD (Additional Authenticated Data)
EVP_EncryptUpdate(ctx, NULL, &len, aad, sizeof(aad));
// Perform the encryption
EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext, plaintext_len);
// Finalize the encryption (generates the authentication tag)
EVP_EncryptFinal_ex(ctx, ciphertext + len, &len);
EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, 16, tag);
// Cleanup
EVP_CIPHER_CTX_free(ctx);
}
int main() {
unsigned char key[32]; // 256-bit key
unsigned char iv[12]; // 96-bit IV
unsigned char aad[16]; // Additional Authenticated Data
unsigned char ciphertext[128];
unsigned char tag[16];
unsigned char plaintext[128];
// Initialize the key, IV, AAD, and plaintext
encrypt_decrypt_gcm(key, iv, aad, ciphertext, sizeof(ciphertext), tag, plaintext);
return 0;
}
```
In this example, you would need to replace the placeholders for the key, IV, AAD, ciphertext, and plaintext with the actual data you want to use. Additionally, make sure to include the necessary OpenSSL headers and link against the OpenSSL library when compiling.
This is just a basic example and it's important to use proper cryptographic practices and ensure the security of your implementation. It's recommended to refer to the OpenSSL documentation and consult cryptographic experts for more guidance on using GCM with OpenSSL.
openssl公钥加密
OpenSSL是一个开源的加密库,提供了各种密码学功能,包括公钥加密。公钥加密是一种使用非对称密钥算法的加密方式,其中包括公钥和私钥两个密钥。公钥用于加密数据,私钥用于解密数据。
在OpenSSL中,使用RSA算法进行公钥加密。下面是使用OpenSSL进行公钥加密的步骤:
1. 生成密钥对:首先需要生成一对公钥和私钥。可以使用OpenSSL提供的命令行工具或者编程接口来生成密钥对。
2. 加载公钥:将生成的公钥加载到程序中,可以从文件中读取或者直接使用内存中的公钥。
3. 加密数据:使用加载的公钥对需要加密的数据进行加密操作。在OpenSSL中,可以使用RSA_public_encrypt函数来进行加密。
4. 解密数据:使用私钥对加密后的数据进行解密操作。在OpenSSL中,可以使用RSA_private_decrypt函数来进行解密。
需要注意的是,公钥加密适用于加密小块数据,通常用于加密对称密钥或者数字签名。如果需要加密大块数据,可以使用对称密钥算法进行加密,然后再使用公钥加密对称密钥。