Chee Yee
87 lines
2.5 KiB
C
87 lines
2.5 KiB
C
#include "crypt.h"
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int openssl_encrypt(unsigned char *plaintext, int plaintext_len, unsigned char *key,
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unsigned char *iv, unsigned char *ciphertext, int *ciphertext_len)
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{
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EVP_CIPHER_CTX *ctx;
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int len;
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/* Create and initialise the context */
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if (!(ctx = EVP_CIPHER_CTX_new()))
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return 0;
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/*
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* Initialise the encryption operation. IMPORTANT - ensure you use a key
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* and IV size appropriate for your cipher
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* In this example we are using 256 bit AES (i.e. a 256 bit key). The
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* IV size for *most* modes is the same as the block size. For AES this
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* is 128 bits
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*/
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if (1 != EVP_EncryptInit_ex(ctx, EVP_aes_256_cbc(), NULL, key, iv))
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return 0;
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/*
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* Provide the message to be encrypted, and obtain the encrypted output.
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* EVP_EncryptUpdate can be called multiple times if necessary
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*/
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if (1 != EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext, plaintext_len))
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return 0;
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*ciphertext_len = len;
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/*
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* Finalise the encryption. Further ciphertext bytes may be written at
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* this stage.
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*/
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if (1 != EVP_EncryptFinal_ex(ctx, ciphertext + len, &len))
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return 0;
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*ciphertext_len += len;
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/* Clean up */
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EVP_CIPHER_CTX_free(ctx);
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return 1;
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}
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int openssl_decrypt(unsigned char *ciphertext, int ciphertext_len, unsigned char *key,
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unsigned char *iv, unsigned char *plaintext, int *plaintext_len)
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{
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EVP_CIPHER_CTX *ctx;
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int len;
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/* Create and initialise the context */
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if (!(ctx = EVP_CIPHER_CTX_new()))
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return 0;
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/*
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* Initialise the decryption operation. IMPORTANT - ensure you use a key
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* and IV size appropriate for your cipher
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* In this example we are using 256 bit AES (i.e. a 256 bit key). The
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* IV size for *most* modes is the same as the block size. For AES this
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* is 128 bits
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*/
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if (1 != EVP_DecryptInit_ex(ctx, EVP_aes_256_cbc(), NULL, key, iv))
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return 0;
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/*
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* Provide the message to be decrypted, and obtain the plaintext output.
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* EVP_DecryptUpdate can be called multiple times if necessary.
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*/
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if (1 != EVP_DecryptUpdate(ctx, plaintext, &len, ciphertext, ciphertext_len))
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return 0;
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*plaintext_len = len;
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/*
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* Finalise the decryption. Further plaintext bytes may be written at
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* this stage.
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*/
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if (1 != EVP_DecryptFinal_ex(ctx, plaintext + len, &len))
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return 0;
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*plaintext_len += len;
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/* Clean up */
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EVP_CIPHER_CTX_free(ctx);
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return 1;
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} |