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1# Converting Binary Data into an Asymmetric Key Pair (C/C++)
2
3
4This topic uses RSA, ECC, and SM2 as an example to describe how to convert binary data into an asymmetric key pair (**OH_CryptoKeyPair**). That is, convert a piece of external or internal binary data into a **KeyPair** object for subsequent operations, such as encryption and decryption.
5
6> **NOTE**
7>
8> The asymmetric key conversion must comply with the following requirements:
9>
10> - The public key must use the ASN.1 syntax and DER encoding format and comply with X.509 specifications.
11>
12> - The private key must use the ASN.1 syntax and DER encoding format and comply with PKCS\#8 specifications.
13
14## Adding the Dynamic Library in the CMake Script
15```txt
16target_link_libraries(entry PUBLIC libohcrypto.so)
17```
18
19## Converting Binary Data into an RSA Key Pair
20
21For details about the algorithm specifications, see [RSA](crypto-asym-key-generation-conversion-spec.md#rsa).
22
231. Obtain the binary data of the RSA public key or private key and encapsulates the data into [Crypto_DataBlob](../../reference/apis-crypto-architecture-kit/_crypto_common_api.md#crypto_datablob).
24
25   Either the public key or private key can be passed in. In this example, the public key is passed in.
26
272. Call [OH_CryptoAsymKeyGenerator_Create](../../reference/apis-crypto-architecture-kit/_crypto_asym_key_api.md#oh_cryptoasymkeygenerator_create) with the string parameter **'RSA1024'** to create an asymmetric key generator (**OH_CryptoAsymKeyGenerator**) object for a 1024-bit RSA key with two primes.
28
29   The default number of primes for creating an RSA asymmetric key is **2**. The **PRIMES_2** parameter is omitted in the string parameter here.
30
313. Call [OH_CryptoAsymKeyGenerator_Convert](../../reference/apis-crypto-architecture-kit/_crypto_asym_key_api.md#oh_cryptoasymkeygenerator_convert) to convert the binary data into an asymmetric key pair (**OH_CryptoKeyPair**).
32
33Example: Convert binary data into an RSA key pair.
34
35```c++
36#include "CryptoArchitectureKit/crypto_common.h"
37#include "CryptoArchitectureKit/crypto_asym_key.h"
38
39static OH_Crypto_ErrCode doTestDataCovertAsymKey()
40{
41   OH_CryptoAsymKeyGenerator *ctx = nullptr;
42   OH_Crypto_ErrCode ret;
43
44   ret = OH_CryptoAsymKeyGenerator_Create("RSA1024|PRIMES_2", &ctx);
45   if (ret != CRYPTO_SUCCESS) {
46      return ret;
47   }
48
49   uint8_t rsaDatablob[] = { 48,129,159,48,13,6,9,42,134,72,134,247,13,1,1,1,5,0,3,129,141,0,
50   48,129,137,2,129,129,0,235,184,151,247,130,216,140,187,64,124,219,137,140,184,53,137,216,105,
51   156,141,137,165,30,80,232,55,96,46,23,237,197,123,121,27,240,190,14,111,237,172,67,42,47,164,
52   226,248,211,157,213,194,131,109,181,41,173,217,127,252,121,126,26,130,55,4,134,104,73,5,132,
53   91,214,146,232,64,99,87,33,222,155,159,9,59,212,144,46,183,83,89,220,189,148,13,176,5,139,156,
54   230,143,16,152,79,36,8,112,40,174,35,83,82,57,137,87,123,215,99,199,66,131,150,31,143,56,252,2,
55   73,41,70,159,2,3,1,0,1 };
56   Crypto_DataBlob retBlob = { .data = rsaDatablob, .len = sizeof(rsaDatablob) };
57
58   OH_CryptoKeyPair *dupKeyPair = nullptr;
59   ret = OH_CryptoAsymKeyGenerator_Convert(ctx, CRYPTO_DER, &retBlob, nullptr, &dupKeyPair);
60   if (ret != CRYPTO_SUCCESS) {
61         OH_CryptoAsymKeyGenerator_Destroy(ctx);
62         return ret;
63   }
64
65
66   OH_CryptoAsymKeyGenerator_Destroy(ctx);
67   OH_CryptoKeyPair_Destroy(dupKeyPair);
68   return ret;
69}
70```
71
72## Converting Binary Data into an ECC Key Pair
73
74For details about the algorithm specifications, see [ECC](crypto-asym-key-generation-conversion-spec.md#ecc).
75
761. Obtain the binary data of the ECC public key or private key and encapsulates the data into [Crypto_DataBlob](../../reference/apis-crypto-architecture-kit/_crypto_common_api.md#crypto_datablob).
77
78   Either the public key or private key can be passed in. In the following example, the public key and private key are passed in separately.
79
802. Call [OH_CryptoAsymKeyGenerator_Create](../../reference/apis-crypto-architecture-kit/_crypto_asym_key_api.md#oh_cryptoasymkeygenerator_create) with the string parameter **'ECC256'** to create an asymmetric key generator (**OH_CryptoAsymKeyGenerator**) object for a 256-bit ECC key pair.
81
823. Call [OH_CryptoAsymKeyGenerator_Convert](../../reference/apis-crypto-architecture-kit/_crypto_asym_key_api.md#oh_cryptoasymkeygenerator_convert) to convert the binary data into an asymmetric key pair (**OH_CryptoKeyPair**).
83
84Example: Convert binary data into an ECC key pair.
85
86```c++
87#include "CryptoArchitectureKit/crypto_common.h"
88#include "CryptoArchitectureKit/crypto_asym_key.h"
89
90static OH_Crypto_ErrCode doAsymEccCovert()
91{
92   OH_CryptoAsymKeyGenerator *ctx = nullptr;
93   OH_Crypto_ErrCode ret;
94
95   ret = OH_CryptoAsymKeyGenerator_Create("ECC256", &ctx);
96   if (ret != CRYPTO_SUCCESS) {
97      return ret;
98   }
99
100   uint8_t ecc224PubKeyBlobData[] = {
101      48,89,48,19,6,7,42,134,72,206,61,2,1,6,8,42,134, 72,206,61,3,1,7,3,66,0,4,157,58,248,
102      205,95,171,229,33,116,44,192,12,115,119,84,156,128,56,180,246,84,43,33,244,224,221,181,
103      154,155,222,157,124,131,217,214,134,199,155,61,196,203,107,13,227,121,57,199,109,220,
104      103,55,78,148,185,226,212,162,31,66,201,50,129,1,156
105   };
106
107   uint8_t ecc224PriKeyBlobData[] = {
108      48,49,2,1,1,4,32,255,121,33,196,188,159,112,149,146,107,243,78,152,214,12,119,87,199,
109      207,57,116,64,150,240,121,22,88,138,196,71,70,222,160,10,6,8,42,134,72,206,61,3,1,7
110   };
111   Crypto_DataBlob pubBlob = { .data = ecc224PubKeyBlobData, .len = sizeof(ecc224PubKeyBlobData) };
112   Crypto_DataBlob priBlob = { .data = ecc224PriKeyBlobData, .len = sizeof(ecc224PriKeyBlobData) };
113
114   OH_CryptoKeyPair *dupKeyPair = nullptr;
115   ret = OH_CryptoAsymKeyGenerator_Convert(ctx, CRYPTO_DER, &pubBlob, &priBlob, &dupKeyPair);
116   if (ret != CRYPTO_SUCCESS) {
117      OH_CryptoAsymKeyGenerator_Destroy(ctx);
118      return ret;
119   }
120
121   OH_CryptoAsymKeyGenerator_Destroy(ctx);
122   OH_CryptoKeyPair_Destroy(dupKeyPair);
123   return ret;
124}
125```
126
127## Converting Binary Data into an SM2 Key Pair
128
129For details about the algorithm specifications, see [SM2](crypto-asym-key-generation-conversion-spec.md#sm2).
130
1311. Obtain the binary data of the SM2 public key or private key and encapsulate the data into [Crypto_DataBlob](../../reference/apis-crypto-architecture-kit/_crypto_common_api.md#crypto_datablob).
132
133   Either the public key or private key can be passed in. In the following example, the public key and private key are passed in separately.
134
1352. Call [OH_CryptoAsymKeyGenerator_Create](../../reference/apis-crypto-architecture-kit/_crypto_asym_key_api.md#oh_cryptoasymkeygenerator_create) with the string parameter **'SM2_256'** to create an asymmetric key generator (**OH_CryptoAsymKeyGenerator**) object for a 256-bit SM2 key pair.
136
1373. Call [OH_CryptoAsymKeyGenerator_Convert](../../reference/apis-crypto-architecture-kit/_crypto_asym_key_api.md#oh_cryptoasymkeygenerator_convert) to convert the binary data into an asymmetric key pair (**OH_CryptoKeyPair**).
138
139Example: Convert binary data into an SM2 key pair.
140```c++
141#include "CryptoArchitectureKit/crypto_common.h"
142#include "CryptoArchitectureKit/crypto_asym_key.h"
143
144static OH_Crypto_ErrCode doAsymSm2Covert()
145{
146   OH_CryptoAsymKeyGenerator *ctx = nullptr;
147   OH_CryptoKeyPair *dupKeyPair = nullptr;
148   OH_Crypto_ErrCode ret;
149
150   ret = OH_CryptoAsymKeyGenerator_Create("SM2_256", &ctx);
151   if (ret != CRYPTO_SUCCESS) {
152      return ret;
153   }
154
155   uint8_t sm2PubKeyBlobData[] = { 48,89,48,19,6,7,42,134,72,206,61,2,1,6,8,42,134,
156      72,206,61,3,1,7,3,66,0,4,157,58,248,205,95,171,229,33,116,44,192,12,115,119,84,156,128,
157      56,180,246,84,43,33,244,224,221,181,154,155,222,157,124,131,217,214,134,199,155,61,196,
158      203,107,13,227,121,57,199,109,220,103,55,78,148,185,226,212,162,31,66,201,50,129,1,156 };
159
160   uint8_t sm2PriKeyBlobData[] = { 48,49,2,1,1,4,32,255,121,33,196,188,159,112,149,146,
161      107,243,78,152,214,12,119,87,199,207,57,116,64,150,240,121,22,88,138,196,71,70,222,160,
162      10,6,8,42,134,72,206,61,3,1,7 };
163   Crypto_DataBlob pubBlob = { .data = sm2PubKeyBlobData, .len = sizeof(sm2PubKeyBlobData) };
164   Crypto_DataBlob priBlob = { .data = sm2PriKeyBlobData, .len = sizeof(sm2PriKeyBlobData) };
165   ret = OH_CryptoAsymKeyGenerator_Convert(ctx, CRYPTO_DER, &pubBlob, &priBlob, &dupKeyPair);
166   if (ret != CRYPTO_SUCCESS) {
167      OH_CryptoAsymKeyGenerator_Destroy(ctx);
168      return ret;
169   }
170
171   OH_CryptoAsymKeyGenerator_Destroy(ctx);
172   OH_CryptoKeyPair_Destroy(dupKeyPair);
173   return ret;
174}
175```
176