關(guān)于Linux Kernel非對(duì)稱密碼算法的實(shí)現(xiàn)

作者簡(jiǎn)介:

baron (csdn:代碼改變世界ctw)，九年手機(jī)安全/SOC底層安全開發(fā)經(jīng)驗(yàn)。擅長(zhǎng)trustzone/tee安全產(chǎn)品的設(shè)計(jì)和開發(fā)。

在默認(rèn)情況下，本文講述的都是ARMV8-aarch64架構(gòu)，linux kernel 5.14

目錄

1、RSA 開關(guān)

2、RSA 實(shí)現(xiàn)

3、其它非對(duì)稱密碼

4、非對(duì)稱密碼算法的使用示例

5、總結(jié)

1、RSA 開關(guān)

RSA的實(shí)現(xiàn)由 CONFIG_CRYPTO_RSA 宏控制，該宏依賴于：

CONFIG_CRYPTO_AKCIPHER

CONFIG_CRYPTO_MANAGER

CONFIG_MPILIB

CONFIG_ASN1

(linux/crypto/Kconfig)
config CRYPTO_RSA  tristate "RSA algorithm"  select CRYPTO_AKCIPHER  select CRYPTO_MANAGER  select MPILIB  select ASN1  helpGenericimplementationoftheRSApublickeyalgorithm.

2、RSA 實(shí)現(xiàn)

(linux/crypto/rsa.c)
static struct akcipher_alg rsa = {  .encrypt = rsa_enc,  .decrypt = rsa_dec,  .set_priv_key = rsa_set_priv_key,  .set_pub_key = rsa_set_pub_key,  .max_size = rsa_max_size,  .exit = rsa_exit_tfm,  .base = {    .cra_name = "rsa",    .cra_driver_name = "rsa-generic",    .cra_priority = 100,    .cra_module = THIS_MODULE,    .cra_ctxsize = sizeof(struct rsa_mpi_key),  },};

主要實(shí)現(xiàn)了4個(gè)功能：

rsasetpriv_key

rsasetpub_key

rsa_enc

rsa_dec

其中 rsa_set_priv_key和 rsa_set_pub_key的實(shí)現(xiàn)，主要就是接受raw格式的密鑰(DER格密鑰)，將其轉(zhuǎn)換成nddpq等因子填充到密碼學(xué)結(jié)構(gòu)體中。rsa_enc和 rsa_dec ，主要就是 公鑰加密、私鑰解密的這種用法。

此類密碼學(xué)具體算法的實(shí)現(xiàn)，都是由 linux/lib/mpi 第三方libary實(shí)現(xiàn)的，是一種C語言的實(shí)現(xiàn)方式。

3、其它非對(duì)稱密碼

(1)、實(shí)現(xiàn)了3個(gè)ecdsa的密碼算法

ecdsanistp192

ecdsanistp256

ecdsanistp384

以為ecdsanistp192 為例：

(linux/crypto/ecdsa.c)
static struct akcipher_alg ecdsa_nist_p192 = {  .verify = ecdsa_verify,  .set_pub_key = ecdsa_set_pub_key,  .max_size = ecdsa_max_size,  .init = ecdsa_nist_p192_init_tfm,  .exit = ecdsa_exit_tfm,  .base = {    .cra_name = "ecdsa-nist-p192",    .cra_driver_name = "ecdsa-nist-p192-generic",    .cra_priority = 100,    .cra_module = THIS_MODULE,    .cra_ctxsize = sizeof(struct ecc_ctx),  },};

僅僅實(shí)現(xiàn)了兩個(gè)接口函數(shù):

ecdsa_verify : 公鑰驗(yàn)簽

ecdsasetpub_key ：導(dǎo)入公鑰

(2)、實(shí)現(xiàn)了1個(gè)sm2的密碼算法

(linux/crypto/sm2.c)
static struct akcipher_alg sm2 = {  .verify = sm2_verify,  .set_pub_key = sm2_set_pub_key,  .max_size = sm2_max_size,  .init = sm2_init_tfm,  .exit = sm2_exit_tfm,  .base = {    .cra_name = "sm2",    .cra_driver_name = "sm2-generic",    .cra_priority = 100,    .cra_module = THIS_MODULE,    .cra_ctxsize = sizeof(struct mpi_ec_ctx),  },};

僅僅實(shí)現(xiàn)了兩個(gè)接口函數(shù):

sm2_verify : 公鑰驗(yàn)簽

sm2setpub_key ：導(dǎo)入公鑰

(3)、實(shí)現(xiàn)了1個(gè)ecr的密碼算法

(linux/crypto/ecrdsa.c)
static struct akcipher_alg ecrdsa_alg = {  .verify    = ecrdsa_verify,  .set_pub_key  = ecrdsa_set_pub_key,  .max_size  = ecrdsa_max_size,  .exit    = ecrdsa_exit_tfm,  .base = {    .cra_name   = "ecrdsa",    .cra_driver_name = "ecrdsa-generic",    .cra_priority   = 100,    .cra_module   = THIS_MODULE,    .cra_ctxsize   = sizeof(struct ecrdsa_ctx),  },};

僅僅實(shí)現(xiàn)了兩個(gè)接口函數(shù):

ecrdsa_verify : 公鑰驗(yàn)簽

ecrdsasetpub_key ：導(dǎo)入公鑰

4、非對(duì)稱密碼算法的使用示例

如下所示，實(shí)現(xiàn)了 public_key_verify_signature(key,signature), 這個(gè)函數(shù)的實(shí)現(xiàn)，也被export出來，相當(dāng)于又封裝了一層。另外其它模塊如果有對(duì)非對(duì)稱密碼學(xué)算法的需求，也可以直接調(diào)用非對(duì)稱密碼學(xué)算法的API，例如直接調(diào)用如下這樣的函數(shù)：

crypto_akcipher_verify()

crypto_akcipher_set_pub_key()

如下是 public_key_verify_signature(key,signature)的實(shí)現(xiàn)，也可以當(dāng)作非對(duì)稱密碼學(xué)算法的使用示例：

(linux/crypto/asymmetric_keys/public_key.c)


/* * Verify a signature using a public key. */int public_key_verify_signature(const struct public_key *pkey,        const struct public_key_signature *sig){  struct crypto_wait cwait;  struct crypto_akcipher *tfm;  struct akcipher_request *req;  struct scatterlist src_sg[2];  char alg_name[CRYPTO_MAX_ALG_NAME];  char *key, *ptr;  int ret;
  pr_devel("==>%s()
", __func__);
  BUG_ON(!pkey);  BUG_ON(!sig);  BUG_ON(!sig->s);
  ret = software_key_determine_akcipher(sig->encoding,                sig->hash_algo,                pkey, alg_name);  if (ret < 0)    return ret;
  tfm = crypto_alloc_akcipher(alg_name, 0, 0);  if (IS_ERR(tfm))    return PTR_ERR(tfm);
  ret = -ENOMEM;  req = akcipher_request_alloc(tfm, GFP_KERNEL);  if (!req)    goto error_free_tfm;
  key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,          GFP_KERNEL);  if (!key)    goto error_free_req;
  memcpy(key, pkey->key, pkey->keylen);  ptr = key + pkey->keylen;  ptr = pkey_pack_u32(ptr, pkey->algo);  ptr = pkey_pack_u32(ptr, pkey->paramlen);  memcpy(ptr, pkey->params, pkey->paramlen);
  if (pkey->key_is_private)    ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);  else    ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);  if (ret)    goto error_free_key;
  if (sig->pkey_algo && strcmp(sig->pkey_algo, "sm2") == 0 &&      sig->data_size) {    ret = cert_sig_digest_update(sig, tfm);    if (ret)      goto error_free_key;  }
  sg_init_table(src_sg, 2);  sg_set_buf(&src_sg[0], sig->s, sig->s_size);  sg_set_buf(&src_sg[1], sig->digest, sig->digest_size);  akcipher_request_set_crypt(req, src_sg, NULL, sig->s_size,           sig->digest_size);  crypto_init_wait(&cwait);  akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |              CRYPTO_TFM_REQ_MAY_SLEEP,              crypto_req_done, &cwait);  ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
error_free_key:  kfree(key);error_free_req:  akcipher_request_free(req);error_free_tfm:  crypto_free_akcipher(tfm);  pr_devel("<==%s() = %d
", __func__, ret);  if (WARN_ON_ONCE(ret > 0))    ret = -EINVAL;  return ret;}EXPORT_SYMBOL_GPL(public_key_verify_signature);

5、總結(jié)

Linux Kernel非對(duì)稱密碼算法的實(shí)現(xiàn)總結(jié)如下：

實(shí)現(xiàn)了RSA的：“導(dǎo)入公鑰、導(dǎo)入私鑰、公鑰加密私鑰解密” 功能

實(shí)現(xiàn)了ecdsa的：”導(dǎo)入公鑰、公鑰驗(yàn)簽” 功能

實(shí)現(xiàn)了sm2的：”導(dǎo)入公鑰、公鑰驗(yàn)簽” 功能

實(shí)現(xiàn)了ecr的：”導(dǎo)入公鑰、公鑰驗(yàn)簽” 功能

原文標(biāo)題：Linux Kernel中非對(duì)稱密碼算法的實(shí)現(xiàn)

文章出處：【微信公眾號(hào)：Linux閱碼場(chǎng)】歡迎添加關(guān)注！文章轉(zhuǎn)載請(qǐng)注明出處。