[iOS]AES加密在iOS上面的实现

Encryption.h文件

 

 

#import <Foundation/Foundation.h>
 
@class NSString;
 
@interface NSData (Encryption)
 
- (NSData *)AES256EncryptWithKey:(NSString *)key;   //加密
- (NSData *)AES256DecryptWithKey:(NSString *)key;   //解密
- (NSString *)newStringInBase64FromData;            //追加64编码
+ (NSString*)base64encode:(NSString*)str;           //同上64编码
 
@end

 

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Encryption.m文件

 

#import "Encryption.h"
#import <CommonCrypto/CommonCryptor.h>
 
 
static char base64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 
@implementation NSData (Encryption)
 
- (NSData *)AES256EncryptWithKey:(NSString *)key   //加密
{
    char keyPtr[kCCKeySizeAES256+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 | kCCOptionECBMode,
                                          keyPtr, kCCBlockSizeAES128,
                                          NULL,
                                          [self bytes], dataLength,
                                          buffer, bufferSize,
                                          &numBytesEncrypted);
    if (cryptStatus == kCCSuccess) {
        return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
    }
    free(buffer);
    return nil;
}
 
 
- (NSData *)AES256DecryptWithKey:(NSString *)key   //解密
{
    char keyPtr[kCCKeySizeAES256+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 | kCCOptionECBMode,
                                          keyPtr, kCCBlockSizeAES128,
                                          NULL,
                                          [self bytes], dataLength,
                                          buffer, bufferSize,
                                          &numBytesDecrypted);
    if (cryptStatus == kCCSuccess) {
        return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
    }
    free(buffer);
    return nil;
}
 
 
- (NSString *)newStringInBase64FromData            //追加64编码
{
    NSMutableString *dest = [[NSMutableString alloc] initWithString:@""];
    unsigned char * working = (unsigned char *)[self bytes];
    int srcLen = [self length];
    for (int i=0; i<srcLen; i += 3) {
        for (int nib=0; nib<4; nib++) {
            int byt = (nib == 0)?0:nib-1;
            int ix = (nib+1)*2;
            if (i+byt >= srcLen) break;
            unsigned char curr = ((working[i+byt] << (8-ix)) & 0x3F);
            if (i+nib < srcLen) curr |= ((working[i+nib] >> ix) & 0x3F);
            [dest appendFormat:@"%c", base64[curr]];
        }
    }
    return dest;
}
 
+ (NSString*)base64encode:(NSString*)str
{
    if ([str length] == 0)
        return @"";
    const char *source = [str UTF8String];
    int strlength  = strlen(source);
    char *characters = malloc(((strlength + 2) / 3) * 4);
    if (characters == NULL)
        return nil;
    NSUInteger length = 0;
    NSUInteger i = 0;
    while (i < strlength) {
        char buffer[3] = {0,0,0};
        short bufferLength = 0;
        while (bufferLength < 3 && i < strlength)
            buffer[bufferLength++] = source[i++];
        characters[length++] = base64[(buffer[0] & 0xFC) >> 2];
        characters[length++] = base64[((buffer[0] & 0x03) << 4) | ((buffer[1] & 0xF0) >> 4)];
        if (bufferLength > 1)
            characters[length++] = base64[((buffer[1] & 0x0F) << 2) | ((buffer[2] & 0xC0) >> 6)];
        else characters[length++] = '=';
        if (bufferLength > 2)
            characters[length++] = base64[buffer[2] & 0x3F];
        else characters[length++] = '=';
    }
    NSString *g = [[[NSString alloc] initWithBytesNoCopy:characters length:lengthencoding:NSASCIIStringEncoding freeWhenDone:YES] autorelease];
    return g;
}
 
 
@end
 
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测试代码
 
 
#import "Encryption.h"
 
 
 
 
    NSString *key = @"my password";
    NSString *secret = @"text to encrypt";
    //加密
    NSData *plain = [secret dataUsingEncoding:NSUTF8StringEncoding];
    NSData *cipher = [plain AES256EncryptWithKey:key];
    NSLog(@"%@",[[cipher newStringInBase64FromData] autorelease]);
    printf("%s\n", [[cipher description] UTF8String]);
    NSLog(@"%@", [[[NSString alloc] initWithData:cipher encoding:NSUTF8StringEncoding] autorelease]);//打印出null,这是因为没有解密。
    //解密
    plain = [cipher AES256DecryptWithKey:key];
    printf("%s\n", [[plain description] UTF8String]);
    NSLog(@"%@", [[[NSString alloc] initWithData:plain encoding:NSUTF8StringEncoding] autorelease]);
    //打印出secret的内容,用密码解密过了。如果使用错误的密码，则打印null