我需要在 GCM 模式下使用 AES 加密对一些数据进行加密/解密，但显然这无法通过 CommonCrypto API 完成。之前here 已经问过这个问题，但接受的答案不是我想要的，因为我需要使用这个特定的算法。
有什么想法吗？我应该使用 OpenSSL 吗？因为我听说在iOS中使用它时会出现一些错误。
我正在 Swift 中寻找答案，但 Objective-C 也可以。
【问题讨论】：
标签： ios swift cryptography commoncrypto
CommonCryptorSPI.h 中有一些 GCM crypt 函数，它们还没有公开。 但是，如果将它们添加到桥接头中，则可以使用它们。
#include <CommonCrypto/CommonCryptor.h>
CCCryptorStatus CCCryptorGCM(
CCOperation op, /* kCCEncrypt, kCCDecrypt */
CCAlgorithm alg,
const void *key, /* raw key material */
size_t keyLength,
const void *iv,
size_t ivLen,
const void *aData,
size_t aDataLen,
const void *dataIn,
size_t dataInLength,
void *dataOut,
const void *tag,
size_t *tagLength);
或者你可以试试SwCrypt库。
【讨论】：
从 iOS 13 开始，我们有了 CryptoKit，它非常强大，并且在您掌握要点时相对容易。今天我创建了一个演示 AES-GCM 256 加密和解密的游乐场。我不是密码学专家，但操场演示了使用此算法的两种可能方法。请随意克隆我的 Playground 存储库并使用 CryptoKit Playground：
import Foundation
import CryptoKit
let key = SymmetricKey(size: .bits256)
let plain = """
{"data":{"id":"7fab123e96","created_at":"2020-01-21T14:16:41Z","name":"John","age":18,"sex":"male"}}
"""
/// Encrypt: Using plain text only • nonce & tag are randomly created
/// Decrypt: Specify all 3 parameters: nonce + cipher text + tag
func cryptoDemoCipherText() {
// Encrypt
let sealedBox = try! AES.GCM.seal(plain.data(using: .utf8)!, using: key)
// Decrypt
let sealedBoxRestored = try! AES.GCM.SealedBox(nonce: sealedBox.nonce, ciphertext: sealedBox.ciphertext, tag: sealedBox.tag)
let decrypted = try! AES.GCM.open(sealedBoxRestored, using: key)
print("Crypto Demo I\n••••••••••••••••••••••••••••••••••••••••••••••••••\n")
print("Combined:\n\(sealedBox.combined!.base64EncodedString())\n")
print("Cipher:\n\(sealedBox.ciphertext.base64EncodedString())\n")
print("Nonce:\n\(sealedBox.nonce.withUnsafeBytes { Data(Array($0)).base64EncodedString() })\n")
print("Tag:\n\(sealedBox.tag.base64EncodedString())\n")
print("Decrypted:\n\(String(data: decrypted, encoding: .utf8)!)\n")
}
/// Encrypt: Specify all 3 parameters yourself: nonce + cipher text + tag
/// Decrypt: Using combined data (nonce + cipher text + tag) and tag to open
func cryptoDemoCombinedData() {
let nonce = try! AES.GCM.Nonce(data: Data(base64Encoded: "fv1nixTVoYpSvpdA")!)
let tag = Data(base64Encoded: "e1eIgoB4+lA/j3KDHhY4BQ==")!
// Encrypt
let sealedBox = try! AES.GCM.seal(plain.data(using: .utf8)!, using: key, nonce: nonce, authenticating: tag)
// Decrypt
let sealedBoxRestored = try! AES.GCM.SealedBox(combined: sealedBox.combined!)
let decrypted = try! AES.GCM.open(sealedBoxRestored, using: key, authenticating: tag)
print("Crypto Demo II\n••••••••••••••••••••••••••••••••••••••••••••••••••\n")
print("Combined:\n\(sealedBox.combined!.base64EncodedString())\n")
print("Cipher:\n\(sealedBox.ciphertext.base64EncodedString())\n")
print("Nonce:\n\(nonce.withUnsafeBytes { Data(Array($0)).base64EncodedString() })\n")
print("Tag:\n\(tag.base64EncodedString())\n")
print("Decrypted:\n\(String(data: decrypted, encoding: .utf8)!)\n")
}
print("Key32:\n\(key.withUnsafeBytes { Data(Array($0)).base64EncodedString() })\n")
cryptoDemoCombinedData()
cryptoDemoCipherText()
https://github.com/Blackjacx/Playgrounds/blob/master/playgrounds/CryptoKit.playground/Contents.swift
希望它对你们中的一些人有所帮助:-)
【讨论】：
虽然这个问题已经回答了，但我想补充一下我的贡献。
前段时间，我回复了a question very similar to this one。总而言之，我还需要使用 AES GCM 加密一些数据，但 Apple 没有任何可用的公共功能（显然，他们没有这样做的任何意图）。所以我开发了自己的库，可以在GitHub 找到。
下面有一个使用示例：
#import <CommonCrypto/CommonCrypto.h>
#import "IAGAesGcm.h"
// Define an Encryption Key
u_char keyBytes[kCCKeySizeAES128] = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10};
NSData *key = [NSData dataWithBytes:keyBytes length:sizeof(keyBytes)];
// Define an Initialization Vector
// GCM recommends a IV size of 96 bits (12 bytes), but you are free
// to use other sizes
u_char ivBytes[12] = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C};
NSData *iv = [NSData dataWithBytes:ivBytes length:sizeof(ivBytes)];
// Define an Additional Authenticated Data
NSData *aad = [@"AdditionalAuthenticatedData" dataUsingEncoding:NSUTF8StringEncoding];
// Now, we are ready to encrypt some plain data
NSData *expectedPlainData = [@"PlainData" dataUsingEncoding:NSUTF8StringEncoding];
// The returned ciphered data is a simple class with 2 properties: the actual encrypted data and the authentication tag.
// The authentication tag can have multiple sizes and it is up to you to set one, in this case the size is 128 bits
// (16 bytes)
IAGCipheredData *cipheredData = [IAGAesGcm cipheredDataByAuthenticatedEncryptingPlainData:expectedPlainData
withAdditionalAuthenticatedData:aad
authenticationTagLength:IAGAuthenticationTagLength128
initializationVector:iv
key:key
error:nil];
// And now, de-cypher the encrypted data to see if the returned plain data
// is as expected
NSData *plainData = [IAGAesGcm plainDataByAuthenticatedDecryptingCipheredData:cipheredData
withAdditionalAuthenticatedData:aad
initializationVector:iv
key:key
error:nil];
XCTAssertEqualObjects(expectedPlainData, plainData);
【讨论】：
#import "CommonCryptorSPI.h"
/*!
* @brief Generates AES GCM ciphertext, tag (MAC) and IV of a input data
* @param dataIn the data to be encrypted
* @param ivLenghtInBits the desired length for the initialization vector (iv)
* @param symmetricKey the symmetric key
* @param aad the additional authentication data
* @param encryptOrDecrypt the operation type kCCEncrypt or kCCDecrypt
* @param error NSError pointer
* @return a NSDictionary with the cyphertext ('cyphertext' key) tag ('tag' key) and the iv ('iv' key)
*/
+ (NSDictionary *)dataEncryption:(NSData *)dataIn ivLengthInBits:(int)ivLenghtInBits key:(NSData *)symmetricKey aad:(NSData *)aad context:(CCOperation)encryptOrDecrypt error:(NSError **)error
{
CCCryptorStatus ccStatus = kCCSuccess;
NSData *iv = [self randomKeyDataGeneratorWithNumberBits:ivLenghtInBits];
NSMutableData *dataOut = [NSMutableData dataWithLength:dataIn.length];
NSMutableData *tag = [NSMutableData dataWithLength:kCCBlockSizeAES128];
size_t tagLength = kCCBlockSizeAES128;
ccStatus = CCCryptorGCM(encryptOrDecrypt,
kCCAlgorithmAES,
symmetricKey.bytes,
kCCKeySizeAES256,
iv.bytes,
iv.length,
aad.bytes,
aad.length,
dataIn.bytes,
dataIn.length,
dataOut.mutableBytes,
tag.bytes,
&tagLength);
if (ccStatus == kCCSuccess) {
return [NSDictionary dictionaryWithObjectsAndKeys:dataOut,@"cyphertext",tag,@"tag",iv,@"iv",nil];
} else {
if (error) {
*error = [NSError errorWithDomain:@"kEncryptionError"
code:ccStatus
userInfo:nil];
}
return nil;
}
}
/*!
* @brief Generates NSData from a randomly generated byte array with a specific number of bits
* @param numberOfBits the number of bits the generated data must have
* @return the randomly generated NSData
*/
- (NSData *)randomKeyDataGeneratorWithNumberBits:(int)numberOfBits {
int numberOfBytes = numberOfBits/8;
uint8_t randomBytes[numberOfBytes];
int result = SecRandomCopyBytes(kSecRandomDefault, numberOfBytes, randomBytes);
if(result == 0) {
return [NSData dataWithBytes:randomBytes length:numberOfBytes];
} else {
return nil;
}
}
如果你没有CommonCryptorSPI.h，这里是：
/*
* Copyright (c) 2010 Apple Inc. All Rights Reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this
* file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_LICENSE_HEADER_END@
*/
#ifndef _CC_CryptorSPI_H_
#define _CC_CryptorSPI_H_
#include <sys/types.h>
#include <sys/param.h>
#include <stdint.h>
#include <string.h>
#ifdef KERNEL
#include <machine/limits.h>
#else
#include <limits.h>
#include <stdlib.h>
#endif /* KERNEL */
#include <Availability.h>
#ifdef __cplusplus
extern "C" {
#endif
/*
This is an SPI header. It includes some work in progress implementation notes that
will be removed when this is promoted to an API set.
*/
/*
Private Ciphers
*/
/* Lion SPI name for no padding. Defining for compatibility. Is now
ccNoPadding in CommonCryptor.h
*/
enum {
ccDefaultPadding = 0,
};
enum {
kCCAlgorithmAES128NoHardware = 20,
kCCAlgorithmAES128WithHardware = 21
};
/*
Private Modes
*/
enum {
kCCModeGCM = 11,
kCCModeCCM = 12,
};
/*
Private Paddings
*/
enum {
ccCBCCTS1 = 10,
ccCBCCTS2 = 11,
ccCBCCTS3 = 12,
};
/*
Private Cryptor direction (op)
*/
enum {
kCCBoth = 3,
};
/*
Supports a mode call of
int mode_setup(int cipher, const unsigned char *IV, const unsigned char *key, int keylen,
const unsigned char *tweak, int tweaklen, int num_rounds, int options, mode_context *ctx);
*/
/* User supplied space for the CryptorRef */
CCCryptorStatus CCCryptorCreateFromDataWithMode(
CCOperation op, /* kCCEncrypt, kCCEncrypt, kCCBoth (default for BlockMode) */
CCMode mode,
CCAlgorithm alg,
CCPadding padding,
const void *iv, /* optional initialization vector */
const void *key, /* raw key material */
size_t keyLength,
const void *tweak, /* raw tweak material */
size_t tweakLength,
int numRounds,
CCModeOptions options,
const void *data, /* caller-supplied memory */
size_t dataLength, /* length of data in bytes */
CCCryptorRef *cryptorRef, /* RETURNED */
size_t *dataUsed) /* optional, RETURNED */
__OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_5_0);
/*
Assuming we can use existing CCCryptorCreateFromData for all modes serviced by these:
int mode_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, mode_context *ctx);
int mode_decrypt(const unsigned char *ct, unsigned char *pt, unsigned long len, mode_context *ctx);
*/
/*
Block mode encrypt and decrypt interfaces for IV tweaked blocks (XTS and CBC)
int mode_encrypt_tweaked(const unsigned char *pt, unsigned long len, unsigned char *ct, const unsigned char *tweak, mode_context *ctx);
int mode_decrypt_tweaked(const unsigned char *ct, unsigned long len, unsigned char *pt, const unsigned char *tweak, mode_context *ctx);
*/
CCCryptorStatus CCCryptorEncryptDataBlock(
CCCryptorRef cryptorRef,
const void *iv,
const void *dataIn,
size_t dataInLength,
void *dataOut)
__OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_5_0);
CCCryptorStatus CCCryptorDecryptDataBlock(
CCCryptorRef cryptorRef,
const void *iv,
const void *dataIn,
size_t dataInLength,
void *dataOut)
__OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_5_0);
/*
Assuming we can use the existing CCCryptorRelease() interface for
int mode_done(mode_context *ctx);
*/
/*
Not surfacing these other than with CCCryptorReset()
int mode_setiv(const unsigned char *IV, unsigned long len, mode_context *ctx);
int mode_getiv(const unsigned char *IV, unsigned long *len, mode_context *ctx);
*/
/*
DES key utilities
*/
CCCryptorStatus CCDesIsWeakKey(
void *key,
size_t Length)
__OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_5_0);
void CCDesSetOddParity(
void *key,
size_t Length)
__OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_5_0);
uint32_t CCDesCBCCksum(void *input, void *output,
size_t length, void *key, size_t keylen,
void *ivec)
__OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_5_0);
/*
* returns a cipher blocksize length iv in the provided iv buffer.
*/
CCCryptorStatus
CCCryptorGetIV(CCCryptorRef cryptorRef, void *iv)
__OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_5_0);
/*
GCM Support Interfaces
Use CCCryptorCreateWithMode() with the kCCModeGCM selector to initialize
a CryptoRef. Only kCCAlgorithmAES128 can be used with GCM and these
functions. IV Setting etc will be ignored from CCCryptorCreateWithMode().
Use the CCCryptorGCMAddIV() routine below for IV setup.
*/
/*
This adds the initial vector octets from iv of length ivLen to the GCM
CCCryptorRef. You can call this function as many times as required to
process the entire IV.
*/
CCCryptorStatus
CCCryptorGCMAddIV(CCCryptorRef cryptorRef,
const void *iv,
size_t ivLen)
__OSX_AVAILABLE_STARTING(__MAC_10_8, __IPHONE_5_0);
/*
Additional Authentication Data
After the entire IV has been processed, the additional authentication
data can be processed. Unlike the IV, a packet/session does not require
additional authentication data (AAD) for security. The AAD is meant to
be used as side–channel data you want to be authenticated with the packet.
Note: once you begin adding AAD to the GCM CCCryptorRef you cannot return
to adding IV data until the state has been reset.
*/
CCCryptorStatus
CCCryptorGCMAddAAD(CCCryptorRef cryptorRef,
const void *aData,
size_t aDataLen)
__OSX_AVAILABLE_STARTING(__MAC_10_8, __IPHONE_6_0);
// Maintain the old symbol with incorrect camel-case for now.
CCCryptorStatus
CCCryptorGCMaddAAD(CCCryptorRef cryptorRef,
const void *aData,
size_t aDataLen)
__OSX_AVAILABLE_STARTING(__MAC_10_8, __IPHONE_6_0);
// This is for old iOS5 clients
CCCryptorStatus
CCCryptorGCMAddADD(CCCryptorRef cryptorRef,
const void *aData,
size_t aDataLen)
__OSX_AVAILABLE_STARTING(__MAC_10_8, __IPHONE_5_0);
CCCryptorStatus CCCryptorGCMEncrypt(
CCCryptorRef cryptorRef,
const void *dataIn,
size_t dataInLength,
void *dataOut)
__OSX_AVAILABLE_STARTING(__MAC_10_8, __IPHONE_5_0);
CCCryptorStatus CCCryptorGCMDecrypt(
CCCryptorRef cryptorRef,
const void *dataIn,
size_t dataInLength,
void *dataOut)
__OSX_AVAILABLE_STARTING(__MAC_10_8, __IPHONE_5_0);
/*
This terminates the GCM state gcm and stores the tag in tag of length
taglen octets.
*/
CCCryptorStatus CCCryptorGCMFinal(
CCCryptorRef cryptorRef,
const void *tag,
size_t *tagLength)
__OSX_AVAILABLE_STARTING(__MAC_10_8, __IPHONE_5_0);
/*
This will reset the GCM CCCryptorRef to the state that CCCryptorCreateWithMode()
left it. The user would then call CCCryptorGCMAddIV(), CCCryptorGCMaddAAD(), etc.
*/
CCCryptorStatus CCCryptorGCMReset(
CCCryptorRef cryptorRef)
__OSX_AVAILABLE_STARTING(__MAC_10_8, __IPHONE_5_0);
/*
This will initialize the GCM state with the given key, IV and AAD value
then proceed to encrypt or decrypt the message text and store the final
message tag. The definition of the variables is the same as it is for all
the manual functions. If you are processing many packets under the same
key you shouldn’t use this function as it invokes the pre–computation
with each call.
*/
CCCryptorStatus CCCryptorGCM(
CCOperation op, /* kCCEncrypt, kCCDecrypt */
CCAlgorithm alg,
const void *key, /* raw key material */
size_t keyLength,
const void *iv,
size_t ivLen,
const void *aData,
size_t aDataLen,
const void *dataIn,
size_t dataInLength,
void *dataOut,
const void *tag,
size_t *tagLength)
__OSX_AVAILABLE_STARTING(__MAC_10_8, __IPHONE_5_0);
void CC_RC4_set_key(void *ctx, int len, const unsigned char *data)
__OSX_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_5_0);
void CC_RC4(void *ctx, unsigned long len, const unsigned char *indata,
unsigned char *outdata)
__OSX_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_5_0);
/*
GCM interface can then be easily bolt on the rest of standard CCCryptor interface; typically following sequence can be used:
CCCryptorCreateWithMode(mode = kCCModeGCM)
0..Nx: CCCryptorAddParameter(kCCParameterIV, iv)
0..Nx: CCCryptorAddParameter(kCCParameterAuthData, data)
0..Nx: CCCryptorUpdate(inData, outData)
0..1: CCCryptorFinal(outData)
0..1: CCCryptorGetParameter(kCCParameterAuthTag, tag)
CCCryptorRelease()
*/
enum {
/*
Initialization vector - cryptor input parameter, typically
needs to have the same length as block size, but in some cases
(GCM) it can be arbitrarily long and even might be called
multiple times.
*/
kCCParameterIV,
/*
Authentication data - cryptor input parameter, input for
authenticating encryption modes like GCM. If supported, can
be called multiple times before encryption starts.
*/
kCCParameterAuthData,
/*
Mac Size - cryptor input parameter, input for
authenticating encryption modes like CCM. Specifies the size of
the AuthTag the algorithm is expected to produce.
*/
kCCMacSize,
/*
Data Size - cryptor input parameter, input for
authenticating encryption modes like CCM. Specifies the amount of
data the algorithm is expected to process.
*/
kCCDataSize,
/*
Authentication tag - cryptor output parameter, output from
authenticating encryption modes like GCM. If supported,
should be retrieved after the encryption finishes.
*/
kCCParameterAuthTag,
};
typedef uint32_t CCParameter;
/*
Sets or adds some other cryptor input parameter. According to the
cryptor type and state, parameter can be either accepted or
refused with kCCUnimplemented (when given parameter is not
supported for this type of cryptor at all) or kCCParamError (bad
data length or format).
*/
CCCryptorStatus CCCryptorAddParameter(
CCCryptorRef cryptorRef,
CCParameter parameter,
const void *data,
size_t dataSize);
/*
Gets value of output cryptor parameter. According to the cryptor
type state, the request can be either accepted or refused with
kCCUnimplemented (when given parameteris not supported for this
type of cryptor) or kCCBufferTooSmall (in this case, *dataSize
argument is set to the requested size of data).
*/
CCCryptorStatus CCCryptorGetParameter(
CCCryptorRef cryptorRef,
CCParameter parameter,
void *data,
size_t *dataSize);
#ifdef __cplusplus
}
#endif
#endif /* _CC_CryptorSPI_H_ */
请记住，AES GCM 要求密钥和 IV 具有特定数量的位，因此我建议获取您要使用的任何密钥的 SHA-256 哈希，然后像这样调用函数：
NSError *error;
NSDictionary *AESGCMEncrypted = [self dataEncryption:data ivLengthInBits:96 key:YourSHA256BitsKey aad:aadData context:kCCEncrypt error:&error];
【讨论】：
以下代码（从这个 C code 修改）应该在 iOS 中运行良好。它启用 AES-GCM 文件加密和解密。该标签包含在加密文件中，将在解密操作期间被提取和验证。
#include "openssl/evp.h"
typedef struct _cipher_params_t{
unsigned char *key;
unsigned char *iv;
unsigned char *tag;
char *aad;
unsigned int iv_len;
unsigned int aad_len;
unsigned int encrypt;
const EVP_CIPHER *cipher_type;
}cipher_params_t;
+(int) file_enc_dec_aes_gcm: (cipher_params_t*) params inPath: (const char*) inPath outPath: (const char*) outPath {
FILE *ifp = fopen(inPath, "rb");
if (!ifp) {
/* Unable to open file for reading */
fprintf(stderr, "ERROR: fopen error: %s\n", strerror(errno));
return errno;
}
/* Open and truncate file to zero length or create ciphertext file for writing */
FILE *ofp = fopen(outPath, "wb");
if (!ofp) {
/* Unable to open file for writing */
fprintf(stderr, "ERROR: fopen error: %s\n", strerror(errno));
return errno;
}
/* Allow enough space in output buffer for additional block */
int cipher_block_size = EVP_CIPHER_block_size(params->cipher_type);
unsigned char in_buf[BUFSIZE], out_buf[BUFSIZE + cipher_block_size];
int num_bytes_read, out_len;
EVP_CIPHER_CTX *ctx;
ctx = EVP_CIPHER_CTX_new();
if(ctx == NULL){
fprintf(stderr, "ERROR: EVP_CIPHER_CTX_new failed. OpenSSL error: %s\n", ERR_error_string(ERR_get_error(), NULL));
cleanup(params, ifp, ofp, ERR_EVP_CTX_NEW);
}
/* Don't set key or IV right away; we want to check lengths */
if(!EVP_CipherInit_ex(ctx, params->cipher_type, NULL, NULL, NULL, params->encrypt)){
fprintf(stderr, "ERROR: EVP_CipherInit_ex failed. OpenSSL error: %s\n", ERR_error_string(ERR_get_error(), NULL));
cleanup(params, ifp, ofp, ERR_EVP_CIPHER_INIT);
}
//EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, 12, NULL);
OPENSSL_assert(EVP_CIPHER_CTX_key_length(ctx) == AES_256_KEY_SIZE);
//OPENSSL_assert(EVP_CIPHER_CTX_iv_length(ctx) == AES_BLOCK_SIZE);
/* Now we can set key and IV */
if(!EVP_CipherInit_ex(ctx, NULL, NULL, params->key, params->iv, params->encrypt)){
fprintf(stderr, "ERROR: EVP_CipherInit_ex failed. OpenSSL error: %s\n", ERR_error_string(ERR_get_error(), NULL));
EVP_CIPHER_CTX_cleanup(ctx);
cleanup(params, ifp, ofp, ERR_EVP_CIPHER_INIT);
}
std::cout << "AAD len = " << strlen(params->aad) << std::endl;
if(!EVP_EncryptUpdate (ctx, NULL, &out_len, (const unsigned char *)params->aad, strlen(params->aad))){
fprintf(stderr, "ERROR: EVP_CipherUpdate AAD failed. OpenSSL error: %s\n", ERR_error_string(ERR_get_error(), NULL));
EVP_CIPHER_CTX_cleanup(ctx);
cleanup(params, ifp, ofp, ERR_EVP_CIPHER_INIT);
}
//std::cout <<"aad out len = " << out_len << std::endl;
unsigned char tag[AES_BLOCK_SIZE] = {0};
if(!params->encrypt)
{
//retrieve tag
fread(tag, sizeof(unsigned char), AES_BLOCK_SIZE, ifp);
params->tag = tag;
}
else{
fseek(ofp, AES_BLOCK_SIZE, SEEK_SET); //16 is tag len only done during encryption
}
while(1){
// Read in data in blocks until EOF. Update the ciphering with each read.
num_bytes_read = fread(in_buf, sizeof(unsigned char), BUFSIZE, ifp);
if (ferror(ifp)){
fprintf(stderr, "ERROR: fread error: %s\n", strerror(errno));
EVP_CIPHER_CTX_cleanup(ctx);
cleanup(params, ifp, ofp, errno);
}
if(!EVP_CipherUpdate(ctx, out_buf, &out_len, in_buf, num_bytes_read)){
fprintf(stderr, "ERROR: EVP_CipherUpdate failed. OpenSSL error: %s\n", ERR_error_string(ERR_get_error(), NULL));
EVP_CIPHER_CTX_cleanup(ctx);
cleanup(params, ifp, ofp, ERR_EVP_CIPHER_UPDATE);
}
//std::cout <<"enc/dec out len = " << out_len << std::endl;
fwrite(out_buf, sizeof(unsigned char), out_len, ofp);
if (ferror(ofp)) {
fprintf(stderr, "ERROR: fwrite error: %s\n", strerror(errno));
EVP_CIPHER_CTX_cleanup(ctx);
cleanup(params, ifp, ofp, errno);
}
if (num_bytes_read < BUFSIZE) {
/* Reached End of file */
break;
}
}
/* Now cipher the final block and write it out to file */
if(params->encrypt && !EVP_CipherFinal_ex(ctx, out_buf, &out_len)){
fprintf(stderr, "ERROR: EVP_CipherFinal_ex failed. OpenSSL error: %s\n", ERR_error_string(ERR_get_error(), NULL));
EVP_CIPHER_CTX_cleanup(ctx);
cleanup(params, ifp, ofp, ERR_EVP_CIPHER_FINAL);
}
/* Get the tag */
if(params->encrypt && 1 != EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, 16, params->tag))
{
//handleErrors();
fprintf(stderr, "ERROR: Tag gen failed. OpenSSL error: %s\n", ERR_error_string(ERR_get_error(), NULL));
EVP_CIPHER_CTX_cleanup(ctx);
cleanup(params, ifp, ofp, ERR_EVP_CIPHER_FINAL);
}
else if(params->encrypt)
{
fwrite(out_buf, sizeof(unsigned char), out_len, ofp);
printf("Successful encryption and tag generation...\n");
BIO_dump_fp(stdout, (const char*)params->tag, 16);
fseek(ofp, 0, SEEK_SET);
fwrite(params->tag, sizeof(char), AES_BLOCK_SIZE, ofp);
}
/* verify the tag */
if(!params->encrypt && !EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, 16,params->tag))
{
//handleErrors();
fprintf(stderr, "ERROR: Tag error. OpenSSL error: %s\n", ERR_error_string(ERR_get_error(), NULL));
EVP_CIPHER_CTX_cleanup(ctx);
cleanup(params, ifp, ofp, ERR_EVP_CIPHER_FINAL);
}
int ret = -1;
if(!params->encrypt){
ret = EVP_CipherFinal_ex(ctx, out_buf, &out_len);
if(ret > 0){
fwrite(out_buf, sizeof(unsigned char), out_len, ofp);
printf("tag verification and decryption success \n");
}else{
fprintf(stderr, "ERROR: EVP_CipherFinal_ex failed. Tag verification failed...OpenSSL error: %s\n", ERR_error_string(ERR_get_error(), NULL));
EVP_CIPHER_CTX_cleanup(ctx);
cleanup(params, ifp, ofp, ERR_EVP_CIPHER_FINAL);
}
}
if (ferror(ofp)) {
fprintf(stderr, "ERROR: fwrite error: %s\n", strerror(errno));
EVP_CIPHER_CTX_cleanup(ctx);
cleanup(params, ifp, ofp, errno);
}
fclose(ifp);
fclose(ofp);
EVP_CIPHER_CTX_cleanup(ctx);
return ret;
}
void cleanup(cipher_params_t *params, std::ifstream& ifp, std::ofstream& ofp, int rc){
free(params);
ifp.close();
ofp.close();
exit(rc);
}
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