openssl evp RSA 加密解密

openssl evp RSA 加密解密

可以直接使用RSA.h 提供的接口

如下测试使用EVP提供的RSA接口

1. EVP提供的RSA 加密解密

主要接口：

int EVP_PKEY_encrypt_init(EVP_PKEY_CTX *ctx);
int EVP_PKEY_encrypt(EVP_PKEY_CTX *ctx,
                     unsigned char *out, size_t *outlen,
                     const unsigned char *in, size_t inlen);
int EVP_PKEY_decrypt_init(EVP_PKEY_CTX *ctx);
int EVP_PKEY_decrypt(EVP_PKEY_CTX *ctx,
                     unsigned char *out, size_t *outlen,
                     const unsigned char *in, size_t inlen);

测试代码

先生成 EVP_KEY

    //生成密钥对
    RSA *r = RSA_new();
    int bits = ;
    BIGNUM *e = BN_new();
    BN_set_word(e, );
    RSA_generate_key_ex(r, bits, e, NULL);

    EVP_PKEY *key;
    key = EVP_PKEY_new();
    EVP_PKEY_set1_RSA(key, r);

测试加密解密

    //默认使用的是 RSA_PKCS1_PADDING，即这里最大加密块为64-11=53,大量数组需要分组处理
    char *srcStr = "";
    //char *srcStr = "hello world";
    int enclen = ;
    char encData[] = {};
    char decData[] = {};
    int declen = ;
    printf("src=%s\n",srcStr);

    //加密
    EVP_PKEY_CTX *ectx;
    ectx = EVP_PKEY_CTX_new(key, NULL);
    EVP_PKEY_encrypt_init(ectx);
    EVP_PKEY_encrypt(ectx, encData, &enclen, srcStr, strlen(srcStr));

    //解密
    EVP_PKEY_CTX *dctx;
    dctx = EVP_PKEY_CTX_new(key, NULL);
    EVP_PKEY_decrypt_init(dctx);
    EVP_PKEY_decrypt(dctx, decData, &declen, encData, enclen);
    printf("dec=%s\n",decData);

    EVP_PKEY_CTX_free(ectx);
    EVP_PKEY_CTX_free(dctx);

    EVP_PKEY_free(key);
    BN_free(e);
    RSA_free(r);

执行结果：

src=
dec=
Program ended with exit code: 

上述测试也是RSA的分组加密，如果加密数据比较长的时候，需要多次调用；

补位方式：RSA_PKCS1_PADDING 则，最大分组真为RSA_size(r) -11

2. 另外evp提供的签名与验签接口还有

int EVP_PKEY_sign_init(EVP_PKEY_CTX *ctx);
int EVP_PKEY_sign(EVP_PKEY_CTX *ctx,
                  unsigned char *sig, size_t *siglen,
                  const unsigned char *tbs, size_t tbslen);
int EVP_PKEY_verify_init(EVP_PKEY_CTX *ctx);
int EVP_PKEY_verify(EVP_PKEY_CTX *ctx,
                    const unsigned char *sig, size_t siglen,
                    const unsigned char *tbs, size_t tbslen);
int EVP_PKEY_verify_recover_init(EVP_PKEY_CTX *ctx);
int EVP_PKEY_verify_recover(EVP_PKEY_CTX *ctx,
                            unsigned char *rout, size_t *routlen,
                            const unsigned char *sig, size_t siglen);

3.  关于数字信封，签名信封，打开信封接口

__owur int EVP_OpenInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                        const unsigned char *ek, int ekl,
                        const unsigned char *iv, EVP_PKEY *priv);
__owur int EVP_OpenFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);

__owur int EVP_SealInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                        unsigned char **ek, int *ekl, unsigned char *iv,
                        EVP_PKEY **pubk, int npubk);
__owur int EVP_SealFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);

参考：https://www.openssl.org/docs/man1.1.0/crypto/EVP_PKEY_encrypt.html

https://www.openssl.org/docs/man1.1.0/crypto/EVP_PKEY_verify.html