在前面的文章中我有說過AES和RSA這兩種加密方式，正好在前段時間再項目中有使用到，在這里再把這兩種加密方式綜合在一起寫一下，具體到他們的使用，以及RSA各種加密文件的生成。
一： RSA各種加密相關文件生成
1、首先生成私鑰（1024）
$ openssl genrsa -out private_key.pem 1024
上面是生成了一個名為 private_key 的pem文件，也就是我們的私鑰文件，他其實就是一個簡單的txt文本文件而已。
2、生成證書請求文件
$ openssl req -new -key private_key.pem -out rsacert.csr
上面命令中的 private_key.pem 就是我們的私鑰文件，你會根據它生成一份名為 rsacert 的 csr 文件，當然這個名字是由你定義的。回車之后他會提示你輸入國家、省份、mail等信息，當然你也可以什么都不填全部回車。大致是下面圖的信息：
通過上面的命令你有了一份 rsacert.csr 文件。
3、生成證書並且簽名，我們設置有效期為10年，當然這個時間也是你自己定義的
$ openssl x509 -req -days 3650 -in rsacert.csr -signkey private_key.pem -out rsacert.crt
4、生成iOS要是用的公鑰文件，文件格式為der格式，文件為 public_key.der （名字自己定義）
$ openssl x509 -outform der -in rsacert.crt -out public_key.der
5、生成iOS要使用的私鑰，為p12格式（名字寫了p.p12 這個自己定義）
$ openssl pkcs12 -export -out p.p12 -inkey private_key.pem -in rsacert.crt
這里我們需要自己注意的點：這一步會提示給私鑰文件設置密碼，直接輸入想要設置密碼即可，然后敲回車，然后再驗證剛才設置的密碼，再次輸入密碼，然后敲回車，就可以驗證了，設置密碼是因為在解密時，private_key.p12文件需要和這里設置的密碼配合使用，因此需要牢記此密碼。具體的使用砸下面的代碼中我們會展示出來怎么使用。
6、要是單單的iOS加密所需要的文件我們在這里也就已經設置OK了，但安卓一般在使用公鑰的使用會用pem格式的公鑰，所以這里我們還是需要再處理一下，在前面我們生成的公鑰是der格式的，我們在生成一份pem格式的：
$ openssl rsa -in private_key.pem -out rsa_public_key.pem -pubout
7、安卓或者Java的同學肯定也需要私鑰驗證配合我們加解密數據的進行相互驗證的，但他們需要的私鑰都是PKCS8格式的， 所以我們還需要把我們pem格式的私鑰轉成PKCS8格式的：
$ openssl pkcs8 -topk8 -in private_key.pem -out pkcs8_private_key.pem -nocrypt
通過上面的這么多步，我們需要的各種格式的文件我們就都創建完成了。大概如下圖所示：
注意：你要查看這幾個文件的內容是不同的，比如你查看rsa_public_key.pem 和 rascert.der的內容是不相同的，格式不一樣內容肯定不一樣，所以要驗證還是以結果為主。
二：准備完成、解釋一下為什么要配合使用
說說為什么要他們配合使用：
補充：它們倆之間配合使用也和它們加密的優缺點有關系，AES加密速度比較快，但安全等級沒有RSA高，RSA加密運算比較復雜，但速度相對比較慢。所以讓它只加密Key的話比較合適，量比較少。就不會有性能問題。
要是我們單純的使用AES，AES都知道是對稱性加密，對稱性的意思就是說加密和解密用的是同一個Key，當我們移動端把數據加密完的時候我們把數據傳給后端，這時候后端要想解開這個加密的數據就需要知道你是用什么Key加密的，這時候可能有同學會想，那我們和后端定義相同的Key不就OK了嗎，嗯....那后端的Key就保存在哎服務器，移動端的呢？寫在本地還是去服務端請求？都不可以。因為用過這兩種方式那安全性就沒辦法保證了。你寫在本地的可以反編譯你的代碼，要是去服務端請求那就能被人劫持，只要知道了這個Key那你的加密就變得毫無意義！但至少我們知道了一點，這個Key很重要！
很重要那我們該怎么處理呢，這時候就回到我們前面說的正題，AES和RSA配合使用，這個Key的安全性就通過我們的RSA非對對稱性加密保證，對稱性就是加密解密要使用同一個Key，非對稱性可肯定就是加密和解密不能使用同一個Key了，那就是我們的公鑰和私鑰，公鑰加密私鑰解密，把我們的Key通過公鑰加密之后上傳服務器，服務端拿到之后通過私鑰解密就拿到了Key，再去解密我們的AES數據，有同學會想，前面說我們的AES的Key可能會被劫持，那加了密被劫持呢，放心被劫持到的也是我們通過公鑰加密的，想要得知真正的Key就得知道我們的私鑰，可私鑰在我們服務端要想拿到除非有了間諜，不然是沒法解開真正的Key。
三：解釋完成，該上代碼了
我們先看RSA加密的代碼，代碼具體的都有注釋，使用時候需要我們注意的我們在下面說，下面是這個.m文件的代碼：
注意：RSA加密相同的字符串每一次的結果都是不相同的，所以不能以兩端加密同一樣的字符串要結果相同進行驗證加密是否正確，要以解密出來的東西是否相同為標准判斷！
#import "RSAEncryptor.h"
#import <Security/Security.h>
@implementation RSAEncryptor
static NSString *base64_encode_data(NSData *data){
data = [data base64EncodedDataWithOptions:0];
NSString *ret = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
return ret;
}
static NSData *base64_decode(NSString *str){
NSData *data = [[NSData alloc] initWithBase64EncodedString:str options:NSDataBase64DecodingIgnoreUnknownCharacters];
return data;
}
#pragma mark - 使用'.der'公鑰文件加密
//加密
+ (NSString *)encryptString:(NSString *)str publicKeyWithContentsOfFile:(NSString *)path{
if (!str || !path) return nil;
return [self encryptString:str publicKeyRef:[self getPublicKeyRefWithContentsOfFile:path]];
}
//獲取公鑰
+ (SecKeyRef)getPublicKeyRefWithContentsOfFile:(NSString *)filePath{
NSData *certData = [NSData dataWithContentsOfFile:filePath];
if (!certData) {
return nil;
}
SecCertificateRef cert = SecCertificateCreateWithData(NULL, (CFDataRef)certData);
SecKeyRef key = NULL;
SecTrustRef trust = NULL;
SecPolicyRef policy = NULL;
if (cert != NULL) {
policy = SecPolicyCreateBasicX509();
if (policy) {
if (SecTrustCreateWithCertificates((CFTypeRef)cert, policy, &trust) == noErr) {
SecTrustResultType result;
if (SecTrustEvaluate(trust, &result) == noErr) {
key = SecTrustCopyPublicKey(trust);
}
}
}
}
if (policy) CFRelease(policy);
if (trust) CFRelease(trust);
if (cert) CFRelease(cert);
return key;
}
+ (NSString *)encryptString:(NSString *)str publicKeyRef:(SecKeyRef)publicKeyRef{
if(![str dataUsingEncoding:NSUTF8StringEncoding]){
return nil;
}
if(!publicKeyRef){
return nil;
}
NSData *data = [self encryptData:[str dataUsingEncoding:NSUTF8StringEncoding] withKeyRef:publicKeyRef];
NSString *ret = base64_encode_data(data);
return ret;
}
#pragma mark - 使用'.12'私鑰文件解密
//解密
+ (NSString *)decryptString:(NSString *)str privateKeyWithContentsOfFile:(NSString *)path password:(NSString *)password{
if (!str || !path) return nil;
if (!password) password = @"";
return [self decryptString:str privateKeyRef:[self getPrivateKeyRefWithContentsOfFile:path password:password]];
}
//獲取私鑰
+ (SecKeyRef)getPrivateKeyRefWithContentsOfFile:(NSString *)filePath password:(NSString*)password{
NSData *p12Data = [NSData dataWithContentsOfFile:filePath];
if (!p12Data) {
return nil;
}
SecKeyRef privateKeyRef = NULL;
NSMutableDictionary * options = [[NSMutableDictionary alloc] init];
[options setObject: password forKey:(__bridge id)kSecImportExportPassphrase];
CFArrayRef items = CFArrayCreate(NULL, 0, 0, NULL);
OSStatus securityError = SecPKCS12Import((__bridge CFDataRef) p12Data, (__bridge CFDictionaryRef)options, &items);
if (securityError == noErr && CFArrayGetCount(items) > 0) {
CFDictionaryRef identityDict = CFArrayGetValueAtIndex(items, 0);
SecIdentityRef identityApp = (SecIdentityRef)CFDictionaryGetValue(identityDict, kSecImportItemIdentity);
securityError = SecIdentityCopyPrivateKey(identityApp, &privateKeyRef);
if (securityError != noErr) {
privateKeyRef = NULL;
}
}
CFRelease(items);
return privateKeyRef;
}
+ (NSString *)decryptString:(NSString *)str privateKeyRef:(SecKeyRef)privKeyRef{
NSData *data = [[NSData alloc] initWithBase64EncodedString:str options:NSDataBase64DecodingIgnoreUnknownCharacters];
if (!privKeyRef) {
return nil;
}
data = [self decryptData:data withKeyRef:privKeyRef];
NSString *ret = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
return ret;
}
#pragma mark - 使用公鑰字符串加密
/* START: Encryption with RSA public key */
//使用公鑰字符串加密
+ (NSString *)encryptString:(NSString *)str publicKey:(NSString *)pubKey{
NSData *data = [self encryptData:[str dataUsingEncoding:NSUTF8StringEncoding] publicKey:pubKey];
NSString *ret = base64_encode_data(data);
return ret;
}
+ (NSData *)encryptData:(NSData *)data publicKey:(NSString *)pubKey{
if(!data || !pubKey){
return nil;
}
SecKeyRef keyRef = [self addPublicKey:pubKey];
if(!keyRef){
return nil;
}
return [self encryptData:data withKeyRef:keyRef];
}
+ (SecKeyRef)addPublicKey:(NSString *)key{
NSRange spos = [key rangeOfString:@"-----BEGIN PUBLIC KEY-----"];
NSRange epos = [key rangeOfString:@"-----END PUBLIC KEY-----"];
if(spos.location != NSNotFound && epos.location != NSNotFound){
NSUInteger s = spos.location + spos.length;
NSUInteger e = epos.location;
NSRange range = NSMakeRange(s, e-s);
key = [key substringWithRange:range];
}
key = [key stringByReplacingOccurrencesOfString:@"\r" withString:@""];
key = [key stringByReplacingOccurrencesOfString:@"\n" withString:@""];
key = [key stringByReplacingOccurrencesOfString:@"\t" withString:@""];
key = [key stringByReplacingOccurrencesOfString:@" " withString:@""];
// This will be base64 encoded, decode it.
NSData *data = base64_decode(key);
data = [self stripPublicKeyHeader:data];
if(!data){
return nil;
}
//a tag to read/write keychain storage
NSString *tag = @"RSAUtil_PubKey";
NSData *d_tag = [NSData dataWithBytes:[tag UTF8String] length:[tag length]];
// Delete any old lingering key with the same tag
NSMutableDictionary *publicKey = [[NSMutableDictionary alloc] init];
[publicKey setObject:(__bridge id) kSecClassKey forKey:(__bridge id)kSecClass];
[publicKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
[publicKey setObject:d_tag forKey:(__bridge id)kSecAttrApplicationTag];
SecItemDelete((__bridge CFDictionaryRef)publicKey);
// Add persistent version of the key to system keychain
[publicKey setObject:data forKey:(__bridge id)kSecValueData];
[publicKey setObject:(__bridge id) kSecAttrKeyClassPublic forKey:(__bridge id)
kSecAttrKeyClass];
[publicKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)
kSecReturnPersistentRef];
CFTypeRef persistKey = nil;
OSStatus status = SecItemAdd((__bridge CFDictionaryRef)publicKey, &persistKey);
if (persistKey != nil){
CFRelease(persistKey);
}
if ((status != noErr) && (status != errSecDuplicateItem)) {
return nil;
}
[publicKey removeObjectForKey:(__bridge id)kSecValueData];
[publicKey removeObjectForKey:(__bridge id)kSecReturnPersistentRef];
[publicKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecReturnRef];
[publicKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
// Now fetch the SecKeyRef version of the key
SecKeyRef keyRef = nil;
status = SecItemCopyMatching((__bridge CFDictionaryRef)publicKey, (CFTypeRef *)&keyRef);
if(status != noErr){
return nil;
}
return keyRef;
}
+ (NSData *)stripPublicKeyHeader:(NSData *)d_key{
// Skip ASN.1 public key header
if (d_key == nil) return(nil);
unsigned long len = [d_key length];
if (!len) return(nil);
unsigned char *c_key = (unsigned char *)[d_key bytes];
unsigned int idx = 0;
if (c_key[idx++] != 0x30) return(nil);
if (c_key[idx] > 0x80) idx += c_key[idx] - 0x80 + 1;
else idx++;
// PKCS #1 rsaEncryption szOID_RSA_RSA
static unsigned char seqiod[] =
{ 0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01,
0x01, 0x05, 0x00 };
if (memcmp(&c_key[idx], seqiod, 15)) return(nil);
idx += 15;
if (c_key[idx++] != 0x03) return(nil);
if (c_key[idx] > 0x80) idx += c_key[idx] - 0x80 + 1;
else idx++;
if (c_key[idx++] != '\0') return(nil);
// Now make a new NSData from this buffer
return ([NSData dataWithBytes:&c_key[idx] length:len - idx]);
}
+ (NSData *)encryptData:(NSData *)data withKeyRef:(SecKeyRef) keyRef{
const uint8_t *srcbuf = (const uint8_t *)[data bytes];
size_t srclen = (size_t)data.length;
size_t block_size = SecKeyGetBlockSize(keyRef) * sizeof(uint8_t);
void *outbuf = malloc(block_size);
size_t src_block_size = block_size - 11;
NSMutableData *ret = [[NSMutableData alloc] init];
for(int idx=0; idx<srclen; idx+=src_block_size){
//NSLog(@"%d/%d block_size: %d", idx, (int)srclen, (int)block_size);
size_t data_len = srclen - idx;
if(data_len > src_block_size){
data_len = src_block_size;
}
size_t outlen = block_size;
OSStatus status = noErr;
status = SecKeyEncrypt(keyRef,
kSecPaddingPKCS1,
srcbuf + idx,
data_len,
outbuf,
&outlen
);
if (status != 0) {
NSLog(@"SecKeyEncrypt fail. Error Code: %d", status);
ret = nil;
break;
}else{
[ret appendBytes:outbuf length:outlen];
}
}
free(outbuf);
CFRelease(keyRef);
return ret;
}
/* END: Encryption with RSA public key */
#pragma mark - 使用私鑰字符串解密
/* START: Decryption with RSA private key */
//使用私鑰字符串解密
+ (NSString *)decryptString:(NSString *)str privateKey:(NSString *)privKey{
if (!str) return nil;
NSData *data = [[NSData alloc] initWithBase64EncodedString:str options:NSDataBase64DecodingIgnoreUnknownCharacters];
data = [self decryptData:data privateKey:privKey];
NSString *ret = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
return ret;
}
+ (NSData *)decryptData:(NSData *)data privateKey:(NSString *)privKey{
if(!data || !privKey){
return nil;
}
SecKeyRef keyRef = [self addPrivateKey:privKey];
if(!keyRef){
return nil;
}
return [self decryptData:data withKeyRef:keyRef];
}
+ (SecKeyRef)addPrivateKey:(NSString *)key{
NSRange spos = [key rangeOfString:@"-----BEGIN RSA PRIVATE KEY-----"];
NSRange epos = [key rangeOfString:@"-----END RSA PRIVATE KEY-----"];
if(spos.location != NSNotFound && epos.location != NSNotFound){
NSUInteger s = spos.location + spos.length;
NSUInteger e = epos.location;
NSRange range = NSMakeRange(s, e-s);
key = [key substringWithRange:range];
}
key = [key stringByReplacingOccurrencesOfString:@"\r" withString:@""];
key = [key stringByReplacingOccurrencesOfString:@"\n" withString:@""];
key = [key stringByReplacingOccurrencesOfString:@"\t" withString:@""];
key = [key stringByReplacingOccurrencesOfString:@" " withString:@""];
// This will be base64 encoded, decode it.
NSData *data = base64_decode(key);
data = [self stripPrivateKeyHeader:data];
if(!data){
return nil;
}
//a tag to read/write keychain storage
NSString *tag = @"RSAUtil_PrivKey";
NSData *d_tag = [NSData dataWithBytes:[tag UTF8String] length:[tag length]];
// Delete any old lingering key with the same tag
NSMutableDictionary *privateKey = [[NSMutableDictionary alloc] init];
[privateKey setObject:(__bridge id) kSecClassKey forKey:(__bridge id)kSecClass];
[privateKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
[privateKey setObject:d_tag forKey:(__bridge id)kSecAttrApplicationTag];
SecItemDelete((__bridge CFDictionaryRef)privateKey);
// Add persistent version of the key to system keychain
[privateKey setObject:data forKey:(__bridge id)kSecValueData];
[privateKey setObject:(__bridge id) kSecAttrKeyClassPrivate forKey:(__bridge id)
kSecAttrKeyClass];
[privateKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)
kSecReturnPersistentRef];
CFTypeRef persistKey = nil;
OSStatus status = SecItemAdd((__bridge CFDictionaryRef)privateKey, &persistKey);
if (persistKey != nil){
CFRelease(persistKey);
}
if ((status != noErr) && (status != errSecDuplicateItem)) {
return nil;
}
[privateKey removeObjectForKey:(__bridge id)kSecValueData];
[privateKey removeObjectForKey:(__bridge id)kSecReturnPersistentRef];
[privateKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecReturnRef];
[privateKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
// Now fetch the SecKeyRef version of the key
SecKeyRef keyRef = nil;
status = SecItemCopyMatching((__bridge CFDictionaryRef)privateKey, (CFTypeRef *)&keyRef);
if(status != noErr){
return nil;
}
return keyRef;
}
+ (NSData *)stripPrivateKeyHeader:(NSData *)d_key{
// Skip ASN.1 private key header
if (d_key == nil) return(nil);
unsigned long len = [d_key length];
if (!len) return(nil);
unsigned char *c_key = (unsigned char *)[d_key bytes];
unsigned int idx = 22; //magic byte at offset 22
if (0x04 != c_key[idx++]) return nil;
//calculate length of the key
unsigned int c_len = c_key[idx++];
int det = c_len & 0x80;
if (!det) {
c_len = c_len & 0x7f;
} else {
int byteCount = c_len & 0x7f;
if (byteCount + idx > len) {
//rsa length field longer than buffer
return nil;
}
unsigned int accum = 0;
unsigned char *ptr = &c_key[idx];
idx += byteCount;
while (byteCount) {
accum = (accum << 8) + *ptr;
ptr++;
byteCount--;
}
c_len = accum;
}
// Now make a new NSData from this buffer
return [d_key subdataWithRange:NSMakeRange(idx, c_len)];
}
+ (NSData *)decryptData:(NSData *)data withKeyRef:(SecKeyRef) keyRef{
const uint8_t *srcbuf = (const uint8_t *)[data bytes];
size_t srclen = (size_t)data.length;
size_t block_size = SecKeyGetBlockSize(keyRef) * sizeof(uint8_t);
UInt8 *outbuf = malloc(block_size);
size_t src_block_size = block_size;
NSMutableData *ret = [[NSMutableData alloc] init];
for(int idx=0; idx<srclen; idx+=src_block_size){
//NSLog(@"%d/%d block_size: %d", idx, (int)srclen, (int)block_size);
size_t data_len = srclen - idx;
if(data_len > src_block_size){
data_len = src_block_size;
}
size_t outlen = block_size;
OSStatus status = noErr;
status = SecKeyDecrypt(keyRef,
kSecPaddingNone,
srcbuf + idx,
data_len,
outbuf,
&outlen
);
if (status != 0) {
NSLog(@"SecKeyEncrypt fail. Error Code: %d", status);
ret = nil;
break;
}else{
//the actual decrypted data is in the middle, locate it!
int idxFirstZero = -1;
int idxNextZero = (int)outlen;
for ( int i = 0; i < outlen; i++ ) {
if ( outbuf[i] == 0 ) {
if ( idxFirstZero < 0 ) {
idxFirstZero = i;
} else {
idxNextZero = i;
break;
}
}
}
[ret appendBytes:&outbuf[idxFirstZero+1] length:idxNextZero-idxFirstZero-1];
}
}
free(outbuf);
CFRelease(keyRef);
return ret;
}
/* END: Decryption with RSA private key */
@end
注意： 在我們使用RSA的p12文件解密的時候 也就是使用下面這個方法的時候：
+ (NSString *)decryptString:(NSString *)str privateKeyWithContentsOfFile:(NSString *)path password:(NSString *)password
使用到的 password 的這個參數就是我們給 p12文件設置的密碼。這也是為什么前面我們說的你的記住這個密碼的原因，不然你只能重新生成了。當然服務端解密的時候是不需要的。
path 這個參數就是你的p12文件在你本地的路徑，這個就自己寫了。
四：AES呢
首先的說說AES我們需要注意的幾個點：
1、加密位數 128還是256的這個得幾個端統一不能說你用256的服務端解的時候用128的。
2、IV 初始向量 這個也得統一，一般128的加密位數使用16位的初始向量
3、具體的AES加密代碼的注釋我在前面的博客中有寫，它里面參數的含義是什么都有說明，這里就簡單的看一下128加密代碼，要是想看這個加密方法的具體說明，找一下以前的博客。
4、string的加密解密還是歸結到data的加密解密了，先看data的加密解密：
#import "NSData+AES.h"
static NSString * const AES_IV = @"自己定義";
@implementation NSData (AES)
- (NSData *)aes128_encrypt:(NSString *)key //加密
{
// kCCKeySizeAES256是加密位數
/*
enum {
kCCKeySizeAES128 = 16,
kCCKeySizeAES192 = 24,
kCCKeySizeAES256 = 32,
kCCKeySizeDES = 8,
kCCKeySize3DES = 24,
kCCKeySizeMinCAST = 5,
kCCKeySizeMaxCAST = 16,
kCCKeySizeMinRC4 = 1,
kCCKeySizeMaxRC4 = 512,
kCCKeySizeMinRC2 = 1,
kCCKeySizeMaxRC2 = 128,
kCCKeySizeMinBlowfish = 8,
kCCKeySizeMaxBlowfish = 56,
};
*/
char keyPtr[kCCKeySizeAES128+1];
bzero(keyPtr, sizeof(keyPtr));
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [self length];
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void * buffer = malloc(bufferSize);
size_t numBytesEncrypted = 0;
//
CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128,
kCCOptionPKCS7Padding,
keyPtr, kCCBlockSizeAES128,
[AES_IV UTF8String],
[self bytes], dataLength,
buffer, bufferSize,
&numBytesEncrypted);
if (cryptStatus == kCCSuccess) {
return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
}
free(buffer);
return nil;
}
- (NSData *)aes128_decrypt:(NSString *)key //解密
{
char keyPtr[kCCKeySizeAES128+1];
bzero(keyPtr, sizeof(keyPtr));
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [self length];
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);
size_t numBytesDecrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128,
kCCOptionPKCS7Padding ,
keyPtr, kCCBlockSizeAES128,
[AES_IV UTF8String],
[self bytes], dataLength,
buffer, bufferSize,
&numBytesDecrypted);
if (cryptStatus == kCCSuccess) {
return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
}
free(buffer);
return nil;
}
5、String的加密解密 128 位的代碼如下：
// 利用Key加密字符串
-(NSString *) aes_encrypt:(NSString *)key{
const char *cstr = [self cStringUsingEncoding:NSUTF8StringEncoding];
NSData *data = [NSData dataWithBytes:cstr length:self.length];
//對數據進行加密
NSData *result = [data aes128_encrypt:key];
//轉換為2進制字符串
if (result && result.length > 0) {
Byte *datas = (Byte*)[result bytes];
NSMutableString *output = [NSMutableString stringWithCapacity:result.length * 2];
for(int i = 0; i < result.length; i++){
[output appendFormat:@"%02x", datas[i]];
}
return output;
}
return nil;
}
//利用Key解密字符串
-(NSString *) aes_decrypt:(NSString *)key{
//轉換為2進制Data
NSMutableData *data = [NSMutableData dataWithCapacity:self.length / 2];
unsigned char whole_byte;
char byte_chars[3] = {'\0','\0','\0'};
int i;
for (i=0; i < [self length] / 2; i++) {
byte_chars[0] = [self characterAtIndex:i*2];
byte_chars[1] = [self characterAtIndex:i*2+1];
whole_byte = strtol(byte_chars, NULL, 16);
[data appendBytes:&whole_byte length:1];
}
//對數據進行解密
NSData* result = [data aes128_decrypt:key];
if (result && result.length > 0) {
return [[NSString alloc] initWithData:result encoding:NSUTF8StringEncoding];
}
return nil;
}