内核非对称加密中的crypto_akcipher_set_pub_key总是返回错误
我正在研究一个内核模块，它使用内核crypto api的非对称密码，内核版本为4.8.0。 我通过openssl生成非对称密钥对，将它们转换为DER格式（我知道它是BER的一个子集），并将代码编入我的模块。 私钥工作得很好，但是公钥在crypto_akcipher_set_pub_key中总是失败，即使我尝试了更多其他密钥对。 dmesg只是打印：
[16891.604718] next_op: pc=0/10 dp=0/161 C=0 J=0 [16891.604721] - match? 30 30 00 [16891.604724] - TAG: 30 158 CONS [16891.604726] next_op: pc=2/10 dp=3/161 C=1 J=0 [16891.604727] - match? 30 02 32 [16891.604729] ASN1: Unexpected tag [m=2 d=4 ot=02 t=30 l=158] [16891.604730] set key error! -74,,,,,0 这是我的问题：
A）dmesg是否意味着公钥是错误的？ 如何生成内核加密兼容密钥对？
B）我找不到内核非对称密码的可用rsa密钥对，即使在Linux / crypto / testmgr.h或libkcapi / test / test.sh中也没有，你能帮帮我吗？
谢谢！
这是我的模块：
#include #include #include #include #include #include #include #include #include #include #include #include #include const char *priv_key = "\x30\x82\x02\x5d\x02\x01\x00\x02\x81\x81\x00\xd0" "\xb4\x5a\xc1\x9e\x2e\x4d\xae\xbd\x51\x39\xcc\x4b" "\x12\xf5\x76\x30\xcf\x39\x97\xf1\xd3\x0d\xaa\x37" "\x70\x2d\x2f\x01\xc9\x69\x09\xe3\x4e\xd5\x90\x68" "\xfe\xbf\x7c\x8b\x86\xdf\xf3\x14\xb3\x96\xcf\x1b" "\x39\xe3\xe6\x8a\x77\x6d\xe4\x89\xef\xdb\xba\x4a" "\x40\x6d\xa9\xec\x21\x62\x00\xa4\xc3\x45\xcc\xdd" "\x56\xb2\x77\x59\x46\x17\x27\x0e\x2c\xfe\x85\x53" "\x72\x26\x9b\xdc\x24\x83\xd1\x67\xa7\x4c\x88\x70" "\x78\x3f\x1c\x60\xd4\x95\x14\x57\xfc\xdb\x15\xaa" "\xab\x31\x32\xb2\x44\x72\xdd\xb0\x0b\x13\x62\x03" "\x50\x1d\xd4\x6a\xf6\xb2\x23\x02\x03\x01\x00\x01" "\x02\x81\x80\x7b\x83\x10\xe6\xde\xf7\x26\x30\x10" "\x88\x3e\x7d\x61\xbc\xa1\x99\xc5\xbf\x0d\xa5\x97" "\x8e\xc0\xda\x88\x9e\x91\x8e\xed\x2e\xc6\x43\xfc" "\xcb\x0d\xe6\xbd\xcc\x6d\x84\x86\x8a\x56\x84\xe4" "\x2e\x78\x44\xaf\x27\x2e\x71\xa4\x66\x93\x99\x99" "\xec\x62\x8c\x38\x1f\x33\x06\x37\xc1\x9d\x17\x6b" "\xad\xfb\x8e\x44\xd3\x11\xcb\x74\xa4\x01\x78\xb0" "\x9c\x64\xd3\x0d\x63\x99\x65\xe3\xca\xae\x11\xb2" "\xc4\x00\x36\xc2\xfc\x4b\x7b\x6f\x9e\x84\xb6\x97" "\x00\x56\x5b\x09\xa1\x28\xf5\x28\x8d\xc7\x93\x45" "\xba\xc0\x6b\xa9\x2d\xeb\x02\xcd\xde\x1e\x29\x02" "\x41\x00\xf6\x0e\x41\xbc\xfa\x40\x82\xba\xa0\x6a" "\xa5\x75\x5c\xcd\xfe\xa8\x11\xa6\xef\xbc\xad\x5f" "\x86\x40\xb4\x5a\x65\xc1\x7b\x5e\x89\xc2\x60\x38" "\x0e\x8b\x7d\x7d\x99\x30\x01\xf1\xea\x1e\x3e\x46" "\xf4\xd2\xd9\x80\xaf\x3a\x4b\x2f\xbb\x91\xbb\xb7" "\x22\x2d\x6a\x0f\x4e\x6f\x02\x41\x00\xd9\x23\xa7" "\x98\x0c\x58\xe1\x5d\xa7\x15\x05\xc6\xd9\x7b\xc5" "\x7b\xd3\x01\x8b\x1e\xf1\x2e\x99\xc5\xac\x41\xf1" "\x92\x88\xd9\x8e\x50\x86\xf9\x2f\x66\x42\xeb\xf9" "\x80\x78\xfa\xc7\xea\x63\x35\x7e\x6f\xc5\x35\x36" "\x6b\xa1\x8a\xa3\x49\x97\xbc\xa6\x9b\x5c\x6e\xf1" "\x8d\x02\x40\x44\x70\xa0\xbe\x64\xc9\x4e\xd3\x84" "\x4d\x45\xaa\x88\x5e\xcf\xe7\x85\xc9\x6e\x43\x87" "\xe1\xdb\x20\xe2\x49\x86\xa6\x33\x9f\x8f\x27\xde" "\xc5\x98\xde\x19\xd0\xb6\xac\x50\xce\x2e\x35\xad" "\x52\xe5\x44\x44\xb5\x73\x87\xfe\x63\xcf\x83\x70" "\xb8\x36\xac\x75\x24\xbe\xc7\x02\x41\x00\x87\xd2" "\x97\xa8\xb2\x40\x7e\x67\xf8\x75\x5b\xf1\xb0\x64" "\x8d\x79\x10\xd9\xec\x4d\xe4\x8b\x43\xc0\xb4\x29" "\x63\x94\x47\x69\xde\x6d\x5c\xa0\x4e\x17\xe7\x50" "\x77\xf6\xf6\xb5\xd7\x8b\x33\x97\x68\x89\x3d\x90" "\x35\x84\x49\xbd\xd0\xb9\xdd\xe2\x31\x4d\x09\x1a" "\x94\x99\x02\x41\x00\xc9\x12\xec\x64\xe9\x01\x27" "\x10\x6c\xad\xc5\x83\x8a\x26\x39\xe0\x05\xde\xde" "\xf9\x1a\x5d\xf6\xcb\xe8\xd2\x9b\x40\xd5\x11\xc8" "\x9a\x6d\x29\xb6\x15\x36\x9a\xee\x45\xe2\x51\x14" "\xa8\x2d\xab\x57\x86\x80\x87\x0a\x02\xaf\xfa\xda" "\x5e\x7d\xfb\x84\xd1\x3a\xe0\xed\x57"; const int priv_key_len = 609; const char *pub_key = "\x30\x81\x9e\x30\x0d\x06\x09\x2a\x86\x48\x86\xf7" "\x0d\x01\x01\x01\x05\x00\x03\x81\x8c\x00\x30\x81" "\x88\x02\x81\x80\x6d\x4d\xaf\xf5\x32\x98\xfa\x33" "\xf2\x4a\xb0\x50\x27\x6f\x50\x0b\x28\xca\x5f\x6e" "\xde\xec\x7b\xae\xeb\xd1\x89\xdf\xcf\x8d\x12\x6c" "\x0d\xf2\x32\x65\xb7\x04\xf2\xb8\x76\x67\xe9\x28" "\xc3\x12\x6b\x4a\x52\x09\xd6\x61\x9b\x21\x25\x04" "\xe0\x9a\xec\xbc\x25\x3f\xfc\x6f\x1a\x98\xa8\x02" "\xa8\x2e\x89\x91\x20\xcf\xf0\xd1\x9d\x09\x35\xac" "\x95\xe2\xe4\x8e\x5b\x7c\x34\x93\x39\x4f\x33\xbd" "\x6e\xe7\xc5\xbb\x2a\x28\x32\x13\x62\x39\x37\x87" "\x40\xe7\x59\xf8\x94\xad\xc4\x2e\xaf\x23\xf4\x98" "\xcd\x90\x27\x96\x41\xc6\x4a\xcd\x6d\x56\xfd\x5b" "\x02\x03\x01\x00\x01"; const int pub_key_len = 161; const char *msg = "\x54\x85\x9b\x34\x2c\x49\xea\x2a"; const int msg_len = 8; char *crypted = NULL; int crypted_len = 0; struct tcrypt_result { struct completion completion; int err; }; struct akcipher_testvec { unsigned char *key; unsigned char *msg; unsigned int key_size; unsigned int msg_size; }; static inline void hexdump(unsigned char *buf,unsigned int len) { while(len--) printk("%02x",*buf++); printk("\n"); } static void tcrypt_complete(struct crypto_async_request *req, int err) { struct tcrypt_result *res = req->data; if (err == -EINPROGRESS) return; res->err = err; complete(&res->completion); } static int wait_async_op(struct tcrypt_result *tr, int ret) { if (ret == -EINPROGRESS || ret == -EBUSY) { wait_for_completion(&tr->completion); reinit_completion(&tr->completion); ret = tr->err; } return ret; } static int uf_akcrypto(struct crypto_akcipher *tfm, void *data, int datalen, int phase) { void *xbuf = NULL; struct akcipher_request *req; void *outbuf = NULL; struct tcrypt_result result; unsigned int out_len_max = 0; struct scatterlist src, dst; int err = -ENOMEM; xbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!xbuf) return err; req = akcipher_request_alloc(tfm, GFP_KERNEL); if (!req) goto free_xbuf; init_completion(&result.completion); if (!phase) //test err = crypto_akcipher_set_pub_key(tfm, pub_key, pub_key_len); else err = crypto_akcipher_set_priv_key(tfm, priv_key, priv_key_len); // err = crypto_akcipher_set_priv_key(tfm, priv_key, priv_key_len); if (err){ printk("set key error! %d,,,,,%d\n", err,phase); goto free_req; } err = -ENOMEM; out_len_max = crypto_akcipher_maxsize(tfm); outbuf = kzalloc(out_len_max, GFP_KERNEL); if (!outbuf) goto free_req; if (WARN_ON(datalen > PAGE_SIZE)) goto free_all; memcpy(xbuf, data, datalen); sg_init_one(&src, xbuf, datalen); sg_init_one(&dst, outbuf, out_len_max); akcipher_request_set_crypt(req, &src, &dst, datalen, out_len_max); akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, tcrypt_complete, &result); if (phase){ err = wait_async_op(&result, crypto_akcipher_encrypt(req)); if (err) { pr_err("alg: akcipher: encrypt test failed. err %d\n", err); goto free_all; } memcpy(crypted,outbuf,out_len_max); crypted_len = out_len_max; hexdump(crypted, out_len_max); }else{ err = wait_async_op(&result, crypto_akcipher_decrypt(req)); if (err) { pr_err("alg: akcipher: decrypt test failed. err %d\n", err); goto free_all; } hexdump(outbuf, out_len_max); } free_all: kfree(outbuf); free_req: akcipher_request_free(req); free_xbuf: kfree(xbuf); return err; } static int userfaultfd_akcrypto(void *data, int datalen, int phase) { struct crypto_akcipher *tfm; int err = 0; tfm = crypto_alloc_akcipher("rsa", CRYPTO_ALG_INTERNAL, 0); if (IS_ERR(tfm)) { pr_err("alg: akcipher: Failed to load tfm for rsa: %ld\n", PTR_ERR(tfm)); return PTR_ERR(tfm); } err = uf_akcrypto(tfm,data,datalen,phase); crypto_free_akcipher(tfm); return err; } static int __init test_init(void) { crypted = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!crypted){ printk("crypted kmalloc error\n"); return -1; } userfaultfd_akcrypto(msg,msg_len,1); userfaultfd_akcrypto(crypted,crypted_len,0); kfree(crypted); } static void __exit test_exit(void) { } module_init(test_init); module_exit(test_exit); MODULE_LICENSE("GPL");
我自己已经弄明白了。
事实是openssl生成的公钥是正确的，但它包含更多的信息，这是内核加密api所不需要的。 使用额外的数据，内核ctypto api无法正确解析公钥结构，这就是“ASN1：Unexpected tag”的原因。
看一下内核兼容的公钥，它只包含以下元素：
{ total size integer size and value integer size and value }
以下命令将显示openssl生成的公共密钥的结构：
openssl asn1parse -in public_key.der -inform DER
输出如下：
0:d=0 hl=3 l= 159 cons: SEQUENCE 3:d=1 hl=2 l= 13 cons: SEQUENCE 5:d=2 hl=2 l= 9 prim: OBJECT :rsaEncryption 16:d=2 hl=2 l= 0 prim: NULL 18:d=1 hl=3 l= 141 prim: BIT STRING
真实数据在BIT STRING中。 它的偏移量为18.因此从偏移18到结束是您想要的数据。
您可以通过键入以下命令来读取BIT STRING内部结构：
openssl asn1parse -in public_key.der -inform DER -strparse 18
输出如：
0:d=0 hl=3 l= 137 cons: SEQUENCE 3:d=1 hl=3 l= 129 prim: INTEGER :D0B45AC19E2E4DA .... 135:d=1 hl=2 l= 3 prim: INTEGER :010001
就像与内核兼容的公钥一样。