OpenSSL RSA加解密代碼片段

在RSA使用過程中，公鑰加密一般用來協商密鑰；私鑰加密一般用來簽名。
Ø n：模數
Ø e：公鑰指數
Ø d：私鑰指數
n+e可以組成公鑰
n+d可以組成私鑰

代碼包括
1。生成RSA的數據結構
2。用指定的n,e,d生成RSA的數據結構
3。用私鑰加密
4。用公鑰解密
5。SHA256報文摘要

1. #include <stdio.h>
2. #include <stdlib.h>
3. #include <string.h>
4. #include <openssl/sha.h>
5. #include <openssl/rsa.h>
6. void testRSAGen(){
7. RSA *r;
8. int bits=512,ret;
9. unsigned long e=RSA_3;
10. BIGNUM *bne;
11. r=RSA_generate_key(bits,e,NULL,NULL);
12. RSA_print_fp(stdout,r,11);
13. printf("--------------------------------/n");
14. RSA_free(r);
15. bne=BN_new();
16. ret=BN_set_word(bne,e);
17. r=RSA_new();
18. ret=RSA_generate_key_ex(r,bits,bne,NULL);
19. if(ret!=1)
20. {
21. printf("RSA_generate_key_ex err!/n");
22. return -1;
23. }
24. //RSA_print_fp(stdout,r,11);
25. RSA_free(r);
27. }
28. void testRSA(){
29. RSA *r;
30. BIGNUM *bne,*bnn,*bnd;
32. int bits = 1024, ret, len, flen, padding, i;
34. unsigned char *key, *p;
35. BIO *b;
36. //要加密的明文
37. unsigned char *in = "abcef";
38. unsigned char *encData,*decData,*tmpData;//加密後的數據/解密後的數據/臨時指針
40. //使用的密匙數據
41. unsigned long e = 75011;
42. const char *MODULUS="9EC7D9A2DC5B095F8E5F90295121F41262FAEFBE9AF57B772A71F1F9D9635F8769CB78DA2BCFE9B27FC1F3AD4A3D178F8C61981225EF5DEACBDC5665F12E691AA13DDD321A59CFCF376F002036612FF3C5E057A3007FF675AFA3EDE34DC23A1A2637294870EBE823F76B5CE21E25F3FA5137F5DE12437DE0118245B927B28221";
43. const char *PRIVATE="8B26E30ECA6E8F3668F6FA78B0C55FB75A4A3FAD0667B152933A4991D7A815D1498F5E1EF44ACEF6CDF252E56F367DED5BA024DF6B267B7E36BD35552DFA0A4CC1E9D0A4BC8E7C76F98D4971441D6693745A0A76E175571BD160E4B1536A6EFF5A08EDA45236E96E7A4748CF4D031CA8B2F4CCE9F2E1286F432DE6495A535E43";
45. //構建RSA數據結構
46. bne = BN_new();
47. bnd = BN_new();
48. bnn = BN_new();
49. ret = BN_set_word(bne, e);
50. BN_hex2bn(&bnd, PRIVATE);
51. BN_hex2bn(&bnn, MODULUS);
53. r = RSA_new();
54. r->e=bne;
55. r->d=bnd;
56. r->n=bnn;
57. RSA_print_fp(stdout, r, 5);
59. //准備輸出的加密數據結構
60. flen = RSA_size(r);// - 11;
61. encData = (unsigned char *)malloc(flen);
62. bzero(encData, flen);//memset(encData, 0, flen);
64. printf("Begin RSA_private_encrypt .../n");
65. ret = RSA_private_encrypt(flen, in, encData, r, RSA_NO_PADDING);
66. if(ret < 0){
67. printf("Encrypt failed!/n");
68. return;
69. }
70. printf("Size:%d/n", ret);
71. printf("ClearText:%s/n", in);
72. printf("CipherText(Hex):/n");
73. tmpData=encData;
74. for (i=0; i<ret; i++){
75. printf("0x%02x, ", *tmpData);
76. tmpData++;
77. }
78. printf("end private encrypt /n");
79. printf("------------------------/n");
82. //准備輸出的解密數據結構
83. flen = RSA_size(r);// - 11;
84. decData = (unsigned char *)malloc(flen);
85. bzero(decData, flen);//memset(encData, 0, flen);
87. printf("Begin RSA_public_decrypt .../n");
88. ret = RSA_public_decrypt(flen, encData, decData, r, RSA_NO_PADDING);
89. if(ret < 0){
90. printf("RSA_public_decrypt failed!/n");
91. return;
92. }
93. printf("Size:%d/n", ret);
94. printf("ClearText:%s/n", decData);
96. free(encData);
97. free(decData);
98. RSA_free(r);
100. }
101. void testSHA256(){
102. unsigned char in[]="asdfwerqrewrasfaser";
103. unsigned char out[32];
105. size_t n;
106. int i;
108. n=strlen((const char*)in);
110. SHA256(in,n,out);
111. printf("/n/nSHA256 digest result:/n");
113. printf("%d/n",sizeof(out));
115. for(i=0;i<32;i++)
116. printf("%d",out[i]);
117. printf("/n");
119. }
120. int main(void) {
121. puts("!!!Hello World!!!"); /* prints !!!Hello World!!! */
122. testSHA256();
123. testRSA();
124. return EXIT_SUCCESS;
125. }