如何在iOS上使用AES GCM进行encryption？
我需要在GCM模式下使用AESencryption来encryption/解密一些数据，但显然这不能用CommonCrypto API来完成。 这已经在这里被问过，但接受的答案不是我正在寻找，因为我需要使用这个特定的algorithm。
有任何想法吗？ 我应该使用OpenSSL吗？ 因为我听说在iOS中使用它有一些错误。
我在Swift中寻找答案，但是Objective-C也可以。
CommonCryptorSPI.h中有一些GCM crypt函数，它们尚未公开。 但是，如果将它们添加到桥接标头，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); 或者您可以尝试SwCrypt库。
虽然这个问题已经回答了，但我想补充一下我的贡献。
前一段时间，我回答了一个和这个非常相似的问题 。 总之，我还需要用AES GCMencryption一些数据，但是苹果没有任何公共function可用（显然，他们没有这个意图）。 所以我开发了我自己的库在GitHub中可用 。
下面是一个使用的例子：
#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);
#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Keys和IV具有特定的位数，因此我build议您获取您想要使用的任何密钥的SHA-256哈希，然后调用如下所示的函数：
NSError *error; NSDictionary *AESGCMEncrypted = [self dataEncryption:data ivLengthInBits:96 key:YourSHA256BitsKey aad:aadData context:kCCEncrypt error:&error];