1# Signature Verification with an RSA Key Pair (PSS Mode) (C/C++)
2
3
4For details about the algorithm specifications, see [RSA](crypto-sign-sig-verify-overview.md#rsa).
5
6
7## Adding the Dynamic Library in the CMake Script
8```txt
9   target_link_libraries(entry PUBLIC libohcrypto.so)
10```
11
12## How to Develop
13
14
151. Use [OH_CryptoVerify_Create](../../reference/apis-crypto-architecture-kit/_crypto_signature_api.md#oh_cryptoverify_create) with the string parameter **'RSA2048|PSS|SHA256|MGF1_SHA256'** to create a **Verify** instance. As indicated by the string parameter, the asymmetric key type is **RSA2048**, the padding mode is **PSS**, the MD algorithm is **SHA256**, and mask algorithm is **MGF1_SHA256**.
16
172. Use [OH_CryptoVerify_SetParam](../../reference/apis-crypto-architecture-kit/_crypto_signature_api.md#oh_cryptoverify_setparam) to set parameters. The parameter values must be the same as those set for signing.
18
193. Use [OH_CryptoVerify_Init](../../reference/apis-crypto-architecture-kit/_crypto_signature_api.md#oh_cryptoverify_init) to initialize the **Verify** instance by using the public key (**OH_CryptoPubKey**).
20
214. Use [OH_CryptoVerify_Update](../../reference/apis-crypto-architecture-kit/_crypto_signature_api.md#oh_cryptoverify_update) to pass in the data to be verified.
22
23   Currently, the amount of data to be passed in by a single **OH_CryptoVerify_Update** is not limited. You can determine how to pass in data based on the data volume. If a small amount of data is to be verified, you can directly call **OH_CryptoVerify_Final** after **OH_CryptoVerify_Init()**.
24
255. Use [OH_CryptoVerify_Final](../../reference/apis-crypto-architecture-kit/_crypto_signature_api.md#oh_cryptoverify_final) to verify the signature.
26
27**Example**
28
29
30```c++
31#include "CryptoArchitectureKit/crypto_common.h"
32#include "CryptoArchitectureKit/crypto_signature.h"
33#include "CryptoArchitectureKit/crypto_asym_key.h"
34
35static bool doTestRsaPssSignatureSeg()
36{
37   OH_CryptoAsymKeyGenerator *keyCtx = nullptr;
38   OH_CryptoKeyPair *keyPair = nullptr;
39   OH_CryptoVerify *verify = nullptr;
40
41   uint8_t plainText[] = {
42      0x13, 0xa7, 0x73, 0xe8, 0xb8, 0x22, 0x99, 0x72, 0x98, 0x29, 0xae, 0x74, 0xa8, 0x4a, 0xea, 0xa9,
43   };
44   Crypto_DataBlob msgBlob = {
45      .data = reinterpret_cast<uint8_t *>(plainText),
46      .len = sizeof(plainText)
47   };
48
49   uint8_t pubKeyText[] = {
50      0x2d, 0x2d, 0x2d, 0x2d, 0x2d, 0x42, 0x45, 0x47, 0x49, 0x4e, 0x20, 0x52, 0x53, 0x41, 0x20, 0x50,
51      0x55, 0x42, 0x4c, 0x49, 0x43, 0x20, 0x4b, 0x45, 0x59, 0x2d, 0x2d, 0x2d, 0x2d, 0x2d, 0x0a, 0x4d,
52      0x49, 0x49, 0x42, 0x43, 0x67, 0x4b, 0x43, 0x41, 0x51, 0x45, 0x41, 0x76, 0x6a, 0x6c, 0x59, 0x35,
53      0x53, 0x72, 0x54, 0x57, 0x32, 0x43, 0x78, 0x74, 0x47, 0x32, 0x54, 0x67, 0x54, 0x54, 0x39, 0x39,
54      0x78, 0x71, 0x37, 0x62, 0x4e, 0x41, 0x6b, 0x54, 0x2b, 0x65, 0x6a, 0x75, 0x65, 0x7a, 0x37, 0x39,
55      0x37, 0x2f, 0x65, 0x63, 0x56, 0x4b, 0x34, 0x78, 0x37, 0x58, 0x41, 0x4d, 0x6d, 0x73, 0x4a, 0x0a,
56      0x4a, 0x63, 0x66, 0x49, 0x36, 0x73, 0x54, 0x4d, 0x4e, 0x68, 0x45, 0x6b, 0x70, 0x79, 0x63, 0x31,
57      0x4b, 0x32, 0x46, 0x6e, 0x30, 0x74, 0x59, 0x47, 0x2f, 0x6d, 0x4d, 0x37, 0x72, 0x71, 0x6d, 0x6a,
58      0x6c, 0x6b, 0x75, 0x72, 0x34, 0x72, 0x74, 0x6a, 0x4a, 0x4a, 0x75, 0x66, 0x34, 0x35, 0x45, 0x42,
59      0x30, 0x79, 0x6c, 0x55, 0x65, 0x47, 0x61, 0x39, 0x6d, 0x44, 0x4a, 0x57, 0x76, 0x62, 0x2b, 0x73,
60      0x0a, 0x41, 0x4a, 0x78, 0x33, 0x41, 0x44, 0x78, 0x70, 0x50, 0x31, 0x59, 0x36, 0x46, 0x61, 0x71,
61      0x54, 0x44, 0x6e, 0x64, 0x47, 0x41, 0x6e, 0x6b, 0x65, 0x4d, 0x53, 0x2f, 0x56, 0x71, 0x53, 0x45,
62      0x65, 0x75, 0x43, 0x36, 0x4d, 0x42, 0x38, 0x52, 0x53, 0x65, 0x6f, 0x31, 0x4f, 0x59, 0x4c, 0x53,
63      0x73, 0x7a, 0x36, 0x43, 0x76, 0x38, 0x34, 0x76, 0x76, 0x53, 0x69, 0x32, 0x37, 0x32, 0x51, 0x44,
64      0x6e, 0x0a, 0x6f, 0x4b, 0x4f, 0x4d, 0x34, 0x43, 0x78, 0x6d, 0x6e, 0x32, 0x31, 0x58, 0x5a, 0x43,
65      0x5a, 0x2f, 0x59, 0x50, 0x32, 0x35, 0x67, 0x5a, 0x6e, 0x57, 0x4f, 0x61, 0x42, 0x4c, 0x50, 0x57,
66      0x79, 0x6f, 0x48, 0x46, 0x65, 0x49, 0x55, 0x42, 0x48, 0x4c, 0x50, 0x69, 0x4a, 0x2b, 0x72, 0x58,
67      0x48, 0x4e, 0x65, 0x4f, 0x38, 0x2b, 0x70, 0x6c, 0x37, 0x49, 0x42, 0x74, 0x66, 0x35, 0x67, 0x70,
68      0x4a, 0x76, 0x0a, 0x31, 0x6e, 0x78, 0x72, 0x45, 0x4b, 0x73, 0x75, 0x2b, 0x6e, 0x64, 0x48, 0x43,
69      0x6e, 0x46, 0x64, 0x6f, 0x38, 0x2f, 0x49, 0x46, 0x46, 0x4a, 0x6a, 0x70, 0x36, 0x73, 0x6f, 0x55,
70      0x4a, 0x4f, 0x5a, 0x52, 0x4b, 0x6e, 0x6f, 0x41, 0x4b, 0x34, 0x67, 0x6a, 0x34, 0x48, 0x30, 0x50,
71      0x76, 0x49, 0x79, 0x4d, 0x67, 0x4b, 0x61, 0x43, 0x43, 0x41, 0x55, 0x57, 0x70, 0x4a, 0x65, 0x76,
72      0x35, 0x42, 0x52, 0x0a, 0x42, 0x4f, 0x56, 0x38, 0x4f, 0x59, 0x34, 0x48, 0x48, 0x6f, 0x42, 0x6b,
73      0x47, 0x4d, 0x6e, 0x32, 0x71, 0x6a, 0x4d, 0x48, 0x78, 0x49, 0x6c, 0x71, 0x48, 0x50, 0x67, 0x59,
74      0x70, 0x41, 0x53, 0x50, 0x51, 0x77, 0x49, 0x44, 0x41, 0x51, 0x41, 0x42, 0x0a, 0x2d, 0x2d, 0x2d,
75      0x2d, 0x2d, 0x45, 0x4e, 0x44, 0x20, 0x52, 0x53, 0x41, 0x20, 0x50, 0x55, 0x42, 0x4c, 0x49, 0x43,
76      0x20, 0x4b, 0x45, 0x59, 0x2d, 0x2d, 0x2d, 0x2d, 0x2d, 0x0a,
77   };
78
79   Crypto_DataBlob keyBlob = {
80      .data = reinterpret_cast<uint8_t *>(pubKeyText),
81      .len = sizeof(pubKeyText)
82   };
83
84   uint8_t signText[] = {
85      0xac, 0x2b, 0x12, 0x56, 0x1c, 0xe1, 0x60, 0x49, 0xc2, 0xd9, 0x87, 0x89, 0xfb, 0xa3, 0xc5, 0x41,
86      0x64, 0x7f, 0x6f, 0x80, 0xc8, 0xdb, 0xb3, 0xdf, 0x25, 0x76, 0x4b, 0x1e, 0x51, 0xaa, 0x0a, 0x6d,
87      0x83, 0x49, 0xae, 0x00, 0x7a, 0x99, 0xf4, 0xc8, 0x98, 0x45, 0x71, 0xfc, 0x5e, 0xdb, 0xed, 0x31,
88      0xad, 0xf2, 0x35, 0x05, 0xe2, 0x3e, 0xf1, 0xcb, 0x96, 0xb2, 0xb9, 0x59, 0xaf, 0x30, 0x25, 0xb0,
89      0xda, 0x83, 0x18, 0x2b, 0x11, 0xa4, 0x93, 0x2d, 0x9e, 0x93, 0x99, 0x62, 0xdd, 0xea, 0x1b, 0xfa,
90      0x60, 0xb8, 0xea, 0x9c, 0xef, 0x4f, 0x2b, 0x9d, 0xd1, 0x3e, 0xe1, 0x6b, 0x24, 0x98, 0x9d, 0x32,
91      0xa3, 0x1e, 0x9d, 0x45, 0xe7, 0x3d, 0x51, 0x7e, 0x3b, 0x0c, 0xee, 0x3f, 0xca, 0x29, 0xd9, 0x02,
92      0xe5, 0xb8, 0xf5, 0x89, 0x06, 0xf4, 0xfe, 0x27, 0x44, 0xff, 0x38, 0xed, 0x5a, 0x0e, 0x89, 0x16,
93      0x15, 0x26, 0xf0, 0xb2, 0x4c, 0x95, 0xee, 0x0a, 0xd3, 0x61, 0xc7, 0xb2, 0x4b, 0xfd, 0x20, 0xb9,
94      0x83, 0x25, 0x43, 0x4d, 0xa0, 0x3d, 0xaa, 0x40, 0x7b, 0xac, 0x01, 0x48, 0x8e, 0x2a, 0x96, 0x11,
95      0xc0, 0x31, 0x51, 0x5b, 0xaf, 0xeb, 0x8b, 0xaf, 0xb5, 0x88, 0xcb, 0xe0, 0x97, 0x45, 0x36, 0xe9,
96      0x6e, 0x6e, 0xe0, 0x55, 0xea, 0xf4, 0xd2, 0x88, 0xbb, 0xc9, 0x85, 0x94, 0xd5, 0x65, 0xeb, 0xa3,
97      0x1c, 0xd1, 0xd6, 0xf5, 0x22, 0x29, 0xf1, 0x16, 0xa5, 0x53, 0x1b, 0xd0, 0x6c, 0xf6, 0x0d, 0xa8,
98      0xd4, 0xe4, 0xb2, 0x0a, 0x92, 0x64, 0x7a, 0x6d, 0xf2, 0x76, 0xf3, 0xb0, 0x08, 0x44, 0x31, 0x31,
99      0x90, 0x48, 0x9e, 0x2e, 0x03, 0xc7, 0xab, 0x5d, 0x7a, 0x07, 0x1f, 0x1d, 0x10, 0x21, 0x54, 0x60,
100      0x0d, 0x26, 0xe4, 0x1c, 0xc7, 0x82, 0x03, 0x65, 0x64, 0x70, 0x41, 0x68, 0x0f, 0xfa, 0x64, 0x3c,
101   };
102
103   Crypto_DataBlob signBlob = {
104      .data = reinterpret_cast<uint8_t *>(signText),
105      .len = sizeof(signText)
106   };
107
108   // keypair
109   OH_Crypto_ErrCode ret = CRYPTO_SUCCESS;
110   ret = OH_CryptoAsymKeyGenerator_Create((const char *)"RSA2048", &keyCtx);
111   if (ret != CRYPTO_SUCCESS) {
112      return false;
113   }
114   ret = OH_CryptoAsymKeyGenerator_Convert(keyCtx, CRYPTO_PEM, &keyBlob, nullptr, &keyPair);
115   if (ret != CRYPTO_SUCCESS) {
116      OH_CryptoAsymKeyGenerator_Destroy(keyCtx);
117      return false;
118   }
119   OH_CryptoPubKey *pubKey = OH_CryptoKeyPair_GetPubKey(keyPair);
120   // verify
121   ret = OH_CryptoVerify_Create((const char *)"RSA2048|PSS|SHA256|MGF1_SHA256", &verify);
122   if (ret != CRYPTO_SUCCESS) {
123      OH_CryptoVerify_Destroy(verify);
124      OH_CryptoAsymKeyGenerator_Destroy(keyCtx);
125      return false;
126   }
127   ret = OH_CryptoVerify_Init(verify, pubKey);
128   if (ret != CRYPTO_SUCCESS) {
129      OH_CryptoVerify_Destroy(verify);
130      OH_CryptoAsymKeyGenerator_Destroy(keyCtx);
131      return false;
132   }
133   bool res = OH_CryptoVerify_Final(verify, &msgBlob, &signBlob);
134   if (res != true) {
135      OH_CryptoVerify_Destroy(verify);
136      OH_CryptoAsymKeyGenerator_Destroy(keyCtx);
137      return false;
138   }
139
140   OH_CryptoVerify_Destroy(verify);
141   OH_CryptoAsymKeyGenerator_Destroy(keyCtx);
142   OH_CryptoKeyPair_Destroy(keyPair);
143   return res;
144}
145```
146