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I am creating a little tool for encrypt and decrypt using a pair keys (public and private keys). I export public and private key on my computer and I can encrypt and decrypt files without problems. I have problem when I try decrypt files in other machine with the same public key. 

// initializing CSP HCRYPTPROV hProv; HCRYPTKEY hKey;

if(!CryptAcquireContext(hProv, NULL, NULL, PROV_RSA_FULL, 0)){  if(GetLastError() == NTE_BAD_KEYSET){       if (!CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, CRYPT_NEWKEYSET)){          return FALSE;       }   } }

// create a pair keys if (!CryptGenKey(hProv, AT_KEYEXCHANGE,  CRYPT_ARCHIVABLE, &hKey))    return FALSE;

// public key if (!CryptExportKey(hKey, 0, PUBLICKEYBLOB, 0, NULL, sizePublicKey))  return FALSE;

*publicKey = (BYTE *) LocalAlloc(LPTR, *sizePublicKey * sizeof(DWORD)); if(*publicKey == NULL)  return FALSE;

if (!CryptExportKey(hKey, 0, PUBLICKEYBLOB, 0, *publicKey, sizePublicKey))  return FALSE; // save public key on file

// private key if (!CryptExportKey(hKey, 0, PRIVATEKEYBLOB, 0, NULL, sizePrivateKey))   return FALSE;

*privateKey = (BYTE *) LocalAlloc(LPTR, *sizePrivateKey * sizeof(DWORD)); if(*publicKey == NULL)    return FALSE;

if (!CryptExportKey(hKey, 0, PRIVATEKEYBLOB, 0, *privateKey, sizePrivateKey))   return FALSE;

PrivateKey.key = (BYTE *) LocalAlloc(LPTR, *sizePrivateKey * sizeof(DWORD)); if(*publicKey == NULL)     return FALSE; // save private key on file


//I encrypt file using  if(!CryptEncrypt(hKey, 0, TRUE, 0, cache, &sizeCache, BLOCK_SIZE_ENCRYPT)){
                free(cache);
                return FALSE;           }

//To decrypt file //First import public key

CryptImportKey(hProv, publicKey, sizePublicKey, 0, 0, &hKey)

//To decrypt:           if (!CryptDecrypt(hKey, 0, TRUE, 0, cache, &sizeCache)){
                free(cache);
                return FALSE;           }

In the same computer that key ware created the application encrypt and decrypt correctly but if I try decrypt files in other computer the CryptDecrypt() failed with error 80090003 (error got by GetLastError()) Any idea? what am I doing wrong...? How to I can export the public key to other computer? Thanks!

Michael W
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Virkof
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  • Did you google for `cryptdecrypt 80090003`? If yes, why don't you mention what that error means so that other people don't have to look it up themselves? – us2012 Jan 17 '13 at 02:47
  • Your question seems to indicate some level of confusion about how RSA encryption works. You do not give your public key to the recipient of your message so that they can decrypt it. You use *their* public key to encrypt the message, and they use their private key to decrypt it. – JBentley Jan 17 '13 at 02:59

1 Answers1

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Probably you are not exporting the key, just using the CSP containing the key, while you are in the same computer, the key is stored in the container where you "link" by using the cryptoapi. Once you go to other computer the container is not present, so you can not use the key.

Make sure that the Private Key is exportable.

DaniRG
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