[英]linux kernel crypto API for ECB AES
我正在尝试编写一个使用 linux 内核加密用户空间界面的示例代码。
多亏了 nibrunie,我确实发现了一个对我帮助很大的例子:
#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <linux/if_alg.h>
#include <linux/socket.h>
#include <string.h>
#ifndef SOL_ALG
#define SOL_ALG 279
#endif
int main(void)
{
int opfd;
int tfmfd;
struct sockaddr_alg sa = {
.salg_family = AF_ALG,
.salg_type = "skcipher",
.salg_name = "cbc(aes)"
};
struct msghdr msg = {};
struct cmsghdr *cmsg;
char cbuf[CMSG_SPACE(4) + CMSG_SPACE(20)] = {0};
char buf[16];
struct af_alg_iv *iv;
struct iovec iov;
int i;
tfmfd = socket(AF_ALG, SOCK_SEQPACKET, 0);
bind(tfmfd, (struct sockaddr *)&sa, sizeof(sa));
setsockopt(tfmfd, SOL_ALG, ALG_SET_KEY,
"\x06\xa9\x21\x40\x36\xb8\xa1\x5b"
"\x51\x2e\x03\xd5\x34\x12\x00\x06", 16);
opfd = accept(tfmfd, NULL, 0);
msg.msg_control = cbuf;
msg.msg_controllen = sizeof(cbuf);
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_level = SOL_ALG;
cmsg->cmsg_type = ALG_SET_OP;
cmsg->cmsg_len = CMSG_LEN(4);
*(__u32 *)CMSG_DATA(cmsg) = ALG_OP_ENCRYPT;
cmsg = CMSG_NXTHDR(&msg, cmsg);
cmsg->cmsg_level = SOL_ALG;
cmsg->cmsg_type = ALG_SET_IV;
cmsg->cmsg_len = CMSG_LEN(20);
iv = (void *)CMSG_DATA(cmsg);
iv->ivlen = 16;
memcpy(iv->iv, "\x3d\xaf\xba\x42\x9d\x9e\xb4\x30"
"\xb4\x22\xda\x80\x2c\x9f\xac\x41", 16);
iov.iov_base = "Single block msg";
iov.iov_len = 16;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
sendmsg(opfd, &msg, 0);
read(opfd, buf, 16);
for (i = 0; i < 16; i++) {
printf("%02x", (unsigned char)buf[i]);
}
printf("\n");
close(opfd);
close(tfmfd);
return 0;
}
这对 CBC AES 非常有用,但对 ECB AES 则不然。
据我了解,变量 iov 用于纯文本,iv 用于初始化 Vector,并调用ALG_SET_KEY作为密钥。
要获得 ECB AES 结果,我必须将 iv 设置为 16 bit 0 ,并且一次只进行一次加密; 然后我可以获得与 ECB AES 相同的 CBC AES 结果。
我曾尝试将 .salg_name 更改为“ecb(aes)”并注释 iv 部分,但在执行 read(opfd, buf, 16) 函数后程序将卡住。
请告诉我正确的做法。 我搜索了整个互联网,几乎找不到这个简单任务的例子。
编辑:感谢 gby,我得到了以下示例代码:
将 .salg_name 更改为“ecb(aes)”
删除初始化向量部分
不要忘记调整 cbuf (msg.msg_control) 的大小以只适合第一个标题
这是有效的 ECB AES 示例代码:
#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <linux/if_alg.h>
#include <linux/socket.h>
#include <string.h>
#ifndef SOL_ALG
#define SOL_ALG 279
#endif
int main(void)
{
int opfd;
int tfmfd;
struct sockaddr_alg sa = {
.salg_family = AF_ALG,
.salg_type = "skcipher",
.salg_name = "ecb(aes)"
};
struct msghdr msg = {};
struct cmsghdr *cmsg;
char cbuf[CMSG_SPACE(4)] = {0};
char buf[16];
struct iovec iov;
int i;
tfmfd = socket(AF_ALG, SOCK_SEQPACKET, 0);
bind(tfmfd, (struct sockaddr *)&sa, sizeof(sa));
setsockopt(tfmfd, SOL_ALG, ALG_SET_KEY,
"\x06\xa9\x21\x40\x36\xb8\xa1\x5b"
"\x51\x2e\x03\xd5\x34\x12\x00\x06", 16);
opfd = accept(tfmfd, NULL, 0);
msg.msg_control = cbuf;
msg.msg_controllen = sizeof(cbuf);
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_level = SOL_ALG;
cmsg->cmsg_type = ALG_SET_OP;
cmsg->cmsg_len = CMSG_LEN(4);
*(__u32 *)CMSG_DATA(cmsg) = ALG_OP_ENCRYPT;
iov.iov_base = "Single block msg";
iov.iov_len = 16;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
sendmsg(opfd, &msg, 0);
read(opfd, buf, 16);
for (i = 0; i < 16; i++) {
printf("%02x", (unsigned char)buf[i]);
}
printf("\n");
close(opfd);
close(tfmfd);
return 0;
}
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