openssl evp RSA 加密解密

2022-11-16 09:32:31

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

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