harmony 鸿蒙Generating an MD Using MD5 (C/C++)

2025-06-12
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Generating an MD Using MD5 (C/C++)

For details about the algorithm specifications, see Supported Algorithms and Specifications.

Adding the Dynamic Library in the CMake Script

target_link_libraries(entry PUBLIC libohcrypto.so)

How to Develop

During the MD operation, you can pass in all the data at a time or pass in data by segment. For the same piece of data, the result will be the same no matter how the data is passed. Use the appropriate method based on the data size.

The following provides examples of MD operations with different data passing methods.

Generating an MD by Passing In Full Data

Call OH_CryptoDigest_Create with the MD algorithm MD5 to generate an MD operation instance (OH_CryptoDigest).
Call OH_CryptoDigest_Update to pass in the data for generating an MD. The amount of data to be passed in by a single Md.update() call is not limited.
Call OH_CryptoDigest_Final to generate an MD.
Call OH_CryptoDigest_GetLength to obtain the MD length, in bytes.
Call OH_DigestCrypto_Destroy to destroy the OH_CryptoDigest instance.

Example

#include "CryptoArchitectureKit/crypto_common.h"
#include "CryptoArchitectureKit/crypto_digest.h"
#include <string.h>

static OH_Crypto_ErrCode doTestMd()
{
    OH_Crypto_ErrCode ret;
    OH_CryptoDigest *ctx = nullptr;
    char *testData = const_cast<char *>("0123456789");
    Crypto_DataBlob in = {.data = (uint8_t *)(testData), .len = strlen(testData)};
    Crypto_DataBlob out = {.data = nullptr, .len = 0};
    int mdLen = 0;
    ret = OH_CryptoDigest_Create("MD5", &ctx);
    if (ret != CRYPTO_SUCCESS) {
        return ret;
    }
    do {
        ret = OH_CryptoDigest_Update(ctx, &in);
        if (ret != CRYPTO_SUCCESS) {
            break;
        }
        ret = OH_CryptoDigest_Final(ctx, &out);
        if (ret != CRYPTO_SUCCESS) {
            break;
        }
        mdLen = OH_CryptoDigest_GetLength(ctx);
    } while (0);
    OH_Crypto_FreeDataBlob(&out);
    OH_DigestCrypto_Destroy(ctx);
    return ret;
}

Generating an MD by Passing In Data by Segment

Call OH_CryptoDigest_Create with the MD algorithm MD5 to generate an MD operation instance (OH_CryptoDigest).
Call OH_CryptoDigest_Update multiple times to pass in 20 bytes each time.
Call OH_CryptoDigest_Final to generate an MD.
Call OH_CryptoDigest_GetLength to obtain the MD length, in bytes.
Call OH_DigestCrypto_Destroy to destroy the OH_CryptoDigest instance.

Example

#include <stdlib.h>
#include "CryptoArchitectureKit/crypto_common.h"
#include "CryptoArchitectureKit/crypto_digest.h"
#define OH_CRYPTO_DIGEST_DATA_MAX (1024 * 1024 * 100)

static OH_Crypto_ErrCode doLoopMd()
{
    OH_Crypto_ErrCode ret;
    OH_CryptoDigest *ctx = nullptr;
    uint8_t *testData = (uint8_t *)malloc(OH_CRYPTO_DIGEST_DATA_MAX);
    Crypto_DataBlob out = {.data = nullptr, .len = 0};
    int mdLen = 0;
    int isBlockSize = 20;
    int offset = 0;

    ret = OH_CryptoDigest_Create("MD5", &ctx);
    if (ret != CRYPTO_SUCCESS) {
        return ret;
    }
    do {
        for (int i = 0; i < 640 / isBlockSize; i++) {
            Crypto_DataBlob in = {.data = reinterpret_cast<uint8_t *>(testData + offset),
                                .len = static_cast<size_t>(isBlockSize)};
            ret = OH_CryptoDigest_Update(ctx, &in);
            if (ret != CRYPTO_SUCCESS) {
                break;
            }
            offset += isBlockSize;
        }
        ret = OH_CryptoDigest_Final(ctx, &out);
        if (ret != CRYPTO_SUCCESS) {
            break;
        }
        mdLen = OH_CryptoDigest_GetLength(ctx);
    } while (0);
    OH_Crypto_FreeDataBlob(&out);
    OH_DigestCrypto_Destroy(ctx);
    return ret;
}