iPhone-NSDataを公開鍵で暗号化し、秘密鍵で復号化する方法
UIImageをNSDataに変換しています。次に、公開鍵を使用してそのNSDataを暗号化する必要があり、秘密鍵を使用して復号化する必要があります。ステップバイステップの手順を提供してください。どのアルゴリズムを使用する必要がありますか？暗号化と復号化に適したライブラリはありますか？暗号化と復号化のためのコードスニペットも提供します。
私はRSString Encryption for Decryption for NSStringを試しましたが、それを変更してNSDataで機能させることもできます
プロジェクトバンドルにSecurity.Frameworkを追加します。
ViewController.hのコードは次のとおりです：
#import <UIKit/UIKit.h>
#import <Security/Security.h>
@interface ViewController : UIViewController
{
SecKeyRef publicKey;
SecKeyRef privateKey;
NSData *publicTag;
NSData *privateTag;
}
- (void)encryptWithPublicKey:(uint8_t *)plainBuffer cipherBuffer:(uint8_t *)cipherBuffer;
- (void)decryptWithPrivateKey:(uint8_t *)cipherBuffer plainBuffer:(uint8_t *)plainBuffer;
- (SecKeyRef)getPublicKeyRef;
- (SecKeyRef)getPrivateKeyRef;
- (void)testAsymmetricEncryptionAndDecryption;
- (void)generateKeyPair:(NSUInteger)keySize;
@end
ViewController.mファイルのコードは次のとおりです：
#import "ViewController.h"
const size_t BUFFER_SIZE = 64;
const size_t CIPHER_BUFFER_SIZE = 1024;
const uint32_t PADDING = kSecPaddingNone;
static const UInt8 publicKeyIdentifier[] = "com.Apple.sample.publickey";
static const UInt8 privateKeyIdentifier[] = "com.Apple.sample.privatekey";
@implementation ViewController
-(SecKeyRef)getPublicKeyRef {
OSStatus sanityCheck = noErr;
SecKeyRef publicKeyReference = NULL;
if (publicKeyReference == NULL) {
[self generateKeyPair:512];
NSMutableDictionary *queryPublicKey = [[NSMutableDictionary alloc] init];
// Set the public key query dictionary.
[queryPublicKey setObject:(__bridge id)kSecClassKey forKey:(__bridge id)kSecClass];
[queryPublicKey setObject:publicTag forKey:(__bridge id)kSecAttrApplicationTag];
[queryPublicKey setObject:(__bridge id)kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
[queryPublicKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecReturnRef];
// Get the key.
sanityCheck = SecItemCopyMatching((__bridge CFDictionaryRef)queryPublicKey, (CFTypeRef *)&publicKeyReference);
if (sanityCheck != noErr)
{
publicKeyReference = NULL;
}
// [queryPublicKey release];
} else { publicKeyReference = publicKey; }
return publicKeyReference; }
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
- (void)testAsymmetricEncryptionAndDecryption {
uint8_t *plainBuffer;
uint8_t *cipherBuffer;
uint8_t *decryptedBuffer;
const char inputString[] = "How to Encrypt data with public key and Decrypt data with private key";
int len = strlen(inputString);
// TODO: this is a hack since i know inputString length will be less than BUFFER_SIZE
if (len > BUFFER_SIZE) len = BUFFER_SIZE-1;
plainBuffer = (uint8_t *)calloc(BUFFER_SIZE, sizeof(uint8_t));
cipherBuffer = (uint8_t *)calloc(CIPHER_BUFFER_SIZE, sizeof(uint8_t));
decryptedBuffer = (uint8_t *)calloc(BUFFER_SIZE, sizeof(uint8_t));
strncpy( (char *)plainBuffer, inputString, len);
NSLog(@"init() plainBuffer: %s", plainBuffer);
//NSLog(@"init(): sizeof(plainBuffer): %d", sizeof(plainBuffer));
[self encryptWithPublicKey:(UInt8 *)plainBuffer cipherBuffer:cipherBuffer];
NSLog(@"encrypted data: %s", cipherBuffer);
//NSLog(@"init(): sizeof(cipherBuffer): %d", sizeof(cipherBuffer));
[self decryptWithPrivateKey:cipherBuffer plainBuffer:decryptedBuffer];
NSLog(@"decrypted data: %s", decryptedBuffer);
//NSLog(@"init(): sizeof(decryptedBuffer): %d", sizeof(decryptedBuffer));
NSLog(@"====== /second test =======================================");
free(plainBuffer);
free(cipherBuffer);
free(decryptedBuffer);
}
/* Borrowed from:
* https://developer.Apple.com/library/mac/#documentation/security/conceptual/CertKeyTrustProgGuide/iPhone_Tasks/iPhone_Tasks.html
*/
- (void)encryptWithPublicKey:(uint8_t *)plainBuffer cipherBuffer:(uint8_t *)cipherBuffer
{
NSLog(@"== encryptWithPublicKey()");
OSStatus status = noErr;
NSLog(@"** original plain text 0: %s", plainBuffer);
size_t plainBufferSize = strlen((char *)plainBuffer);
size_t cipherBufferSize = CIPHER_BUFFER_SIZE;
NSLog(@"SecKeyGetBlockSize() public = %lu", SecKeyGetBlockSize([self getPublicKeyRef]));
// Error handling
// Encrypt using the public.
status = SecKeyEncrypt([self getPublicKeyRef],
PADDING,
plainBuffer,
plainBufferSize,
&cipherBuffer[0],
&cipherBufferSize
);
NSLog(@"encryption result code: %ld (size: %lu)", status, cipherBufferSize);
NSLog(@"encrypted text: %s", cipherBuffer);
}
- (void)decryptWithPrivateKey:(uint8_t *)cipherBuffer plainBuffer:(uint8_t *)plainBuffer
{
OSStatus status = noErr;
size_t cipherBufferSize = strlen((char *)cipherBuffer);
NSLog(@"decryptWithPrivateKey: length of buffer: %lu", BUFFER_SIZE);
NSLog(@"decryptWithPrivateKey: length of input: %lu", cipherBufferSize);
// DECRYPTION
size_t plainBufferSize = BUFFER_SIZE;
// Error handling
status = SecKeyDecrypt([self getPrivateKeyRef],
PADDING,
&cipherBuffer[0],
cipherBufferSize,
&plainBuffer[0],
&plainBufferSize
);
NSLog(@"decryption result code: %ld (size: %lu)", status, plainBufferSize);
NSLog(@"FINAL decrypted text: %s", plainBuffer);
}
- (SecKeyRef)getPrivateKeyRef {
OSStatus resultCode = noErr;
SecKeyRef privateKeyReference = NULL;
// NSData *privateTag = [NSData dataWithBytes:@"ABCD" length:strlen((const char *)@"ABCD")];
// if(privateKey == NULL) {
[self generateKeyPair:512];
NSMutableDictionary * queryPrivateKey = [[NSMutableDictionary alloc] init];
// Set the private key query dictionary.
[queryPrivateKey setObject:(__bridge id)kSecClassKey forKey:(__bridge id)kSecClass];
[queryPrivateKey setObject:privateTag forKey:(__bridge id)kSecAttrApplicationTag];
[queryPrivateKey setObject:(__bridge id)kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
[queryPrivateKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecReturnRef];
// Get the key.
resultCode = SecItemCopyMatching((__bridge CFDictionaryRef)queryPrivateKey, (CFTypeRef *)&privateKeyReference);
NSLog(@"getPrivateKey: result code: %ld", resultCode);
if(resultCode != noErr)
{
privateKeyReference = NULL;
}
// [queryPrivateKey release];
// } else {
// privateKeyReference = privateKey;
// }
return privateKeyReference;
}
#pragma mark - View lifecycle
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
privateTag = [[NSData alloc] initWithBytes:privateKeyIdentifier length:sizeof(privateKeyIdentifier)];
publicTag = [[NSData alloc] initWithBytes:publicKeyIdentifier length:sizeof(publicKeyIdentifier)];
[self testAsymmetricEncryptionAndDecryption];
}
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
}
- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
}
- (void)viewDidDisappear:(BOOL)animated
{
[super viewDidDisappear:animated];
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
} else {
return YES;
}
}
- (void)generateKeyPair:(NSUInteger)keySize {
OSStatus sanityCheck = noErr;
publicKey = NULL;
privateKey = NULL;
// LOGGING_FACILITY1( keySize == 512 || keySize == 1024 || keySize == 2048, @"%d is an invalid and unsupported key size.", keySize );
// First delete current keys.
// [self deleteAsymmetricKeys];
// Container dictionaries.
NSMutableDictionary * privateKeyAttr = [[NSMutableDictionary alloc] init];
NSMutableDictionary * publicKeyAttr = [[NSMutableDictionary alloc] init];
NSMutableDictionary * keyPairAttr = [[NSMutableDictionary alloc] init];
// Set top level dictionary for the keypair.
[keyPairAttr setObject:(__bridge id)kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
[keyPairAttr setObject:[NSNumber numberWithUnsignedInteger:keySize] forKey:(__bridge id)kSecAttrKeySizeInBits];
// Set the private key dictionary.
[privateKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecAttrIsPermanent];
[privateKeyAttr setObject:privateTag forKey:(__bridge id)kSecAttrApplicationTag];
// See SecKey.h to set other flag values.
// Set the public key dictionary.
[publicKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecAttrIsPermanent];
[publicKeyAttr setObject:publicTag forKey:(__bridge id)kSecAttrApplicationTag];
// See SecKey.h to set other flag values.
// Set attributes to top level dictionary.
[keyPairAttr setObject:privateKeyAttr forKey:(__bridge id)kSecPrivateKeyAttrs];
[keyPairAttr setObject:publicKeyAttr forKey:(__bridge id)kSecPublicKeyAttrs];
// SecKeyGeneratePair returns the SecKeyRefs just for educational purposes.
sanityCheck = SecKeyGeneratePair((__bridge CFDictionaryRef)keyPairAttr, &publicKey, &privateKey);
// LOGGING_FACILITY( sanityCheck == noErr && publicKey != NULL && privateKey != NULL, @"Something really bad went wrong with generating the key pair." );
if(sanityCheck == noErr && publicKey != NULL && privateKey != NULL)
{
NSLog(@"Successful");
}
// [privateKeyAttr release];
// [publicKeyAttr release];
// [keyPairAttr release];
}
@end
さらにサポートが必要な場合はお知らせください。
お役に立てれば。
NSData + AESCrypt.h
#import <Foundation/Foundation.h>
@interface NSData (AESCrypt)
- (NSData *)AES256EncryptWithKey:(NSString *)key;
- (NSData *)AES256DecryptWithKey:(NSString *)key;
+ (NSData *)dataWithBase64EncodedString:(NSString *)string;
- (id)initWithBase64EncodedString:(NSString *)string;
- (NSString *)base64Encoding;
- (NSString *)base64EncodingWithLineLength:(NSUInteger)lineLength;
- (BOOL)hasPrefixBytes:(const void *)prefix length:(NSUInteger)length;
- (BOOL)hasSuffixBytes:(const void *)suffix length:(NSUInteger)length;
NSData + AESCrypt.m
#import "NSData+AESCrypt.h"
#import <CommonCrypto/CommonCryptor.h>
static char encodingTable[64] =
{
'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P',
'Q','R','S','T','U','V','W','X','Y','Z','a','b','c','d','e','f',
'g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v',
'w','x','y','z','0','1','2','3','4','5','6','7','8','9','+','/'
};
@implementation NSData (AESCrypt)
- (NSData *)AES256EncryptWithKey:(NSString *)key{
// 'key' should be 32 bytes for AES256, will be null-padded otherwise
char keyPtr[kCCKeySizeAES256 + 1]; // room for terminator (unused)
bzero( keyPtr, sizeof( keyPtr ) ); // fill with zeroes (for padding)
// fetch key data
[key getCString:keyPtr maxLength:sizeof( keyPtr ) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [self length];
//See the doc: For block ciphers, the output size will always be less than or
//equal to the input size plus the size of one block.
//That's why we need to add the size of one block here
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc( bufferSize );
size_t numBytesEncrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt( kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
keyPtr, kCCKeySizeAES256,
NULL /* initialization vector (optional) */,
[self bytes], dataLength, /* input */
buffer, bufferSize, /* output */
&numBytesEncrypted );
if( cryptStatus == kCCSuccess )
{
//the returned NSData takes ownership of the buffer and will free it on deallocation
return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
}
free( buffer ); //free the buffer
return nil;
}
- (NSData *)AES256DecryptWithKey:(NSString *)key{
// 'key' should be 32 bytes for AES256, will be null-padded otherwise
char keyPtr[kCCKeySizeAES256+1]; // room for terminator (unused)
bzero( keyPtr, sizeof( keyPtr ) ); // fill with zeroes (for padding)
// fetch key data
[key getCString:keyPtr maxLength:sizeof( keyPtr ) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [self length];
//See the doc: For block ciphers, the output size will always be less than or
//equal to the input size plus the size of one block.
//That's why we need to add the size of one block here
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc( bufferSize );
size_t numBytesDecrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt( kCCDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
keyPtr, kCCKeySizeAES256,
NULL /* initialization vector (optional) */,
[self bytes], dataLength, /* input */
buffer, bufferSize, /* output */
&numBytesDecrypted );
if( cryptStatus == kCCSuccess )
{
//the returned NSData takes ownership of the buffer and will free it on deallocation
return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
}
free( buffer ); //free the buffer
return nil;
}
#pragma mark -
+ (NSData *)dataWithBase64EncodedString:(NSString *)string
{
return [[[NSData allocWithZone:nil] initWithBase64EncodedString:string] autorelease];
}
- (id)initWithBase64EncodedString:(NSString *)string
{
NSMutableData *mutableData = nil;
if( string )
{
unsigned long ixtext = 0;
unsigned long lentext = 0;
unsigned char ch = 0;
unsigned char inbuf[4], outbuf[3];
short i = 0, ixinbuf = 0;
BOOL flignore = NO;
BOOL flendtext = NO;
NSData *base64Data = nil;
const unsigned char *base64Bytes = nil;
// Convert the string to ASCII data.
base64Data = [string dataUsingEncoding:NSASCIIStringEncoding];
base64Bytes = [base64Data bytes];
mutableData = [NSMutableData dataWithCapacity:base64Data.length];
lentext = base64Data.length;
while( YES )
{
if( ixtext >= lentext ) break;
ch = base64Bytes[ixtext++];
flignore = NO;
if( ( ch >= 'A' ) && ( ch <= 'Z' ) ) ch = ch - 'A';
else if( ( ch >= 'a' ) && ( ch <= 'z' ) ) ch = ch - 'a' + 26;
else if( ( ch >= '0' ) && ( ch <= '9' ) ) ch = ch - '0' + 52;
else if( ch == '+' ) ch = 62;
else if( ch == '=' ) flendtext = YES;
else if( ch == '/' ) ch = 63;
else flignore = YES;
if( ! flignore )
{
short ctcharsinbuf = 3;
BOOL flbreak = NO;
if( flendtext )
{
if( ! ixinbuf ) break;
if( ( ixinbuf == 1 ) || ( ixinbuf == 2 ) ) ctcharsinbuf = 1;
else ctcharsinbuf = 2;
ixinbuf = 3;
flbreak = YES;
}
inbuf [ixinbuf++] = ch;
if( ixinbuf == 4 )
{
ixinbuf = 0;
outbuf [0] = ( inbuf[0] << 2 ) | ( ( inbuf[1] & 0x30) >> 4 );
outbuf [1] = ( ( inbuf[1] & 0x0F ) << 4 ) | ( ( inbuf[2] & 0x3C ) >> 2 );
outbuf [2] = ( ( inbuf[2] & 0x03 ) << 6 ) | ( inbuf[3] & 0x3F );
for( i = 0; i < ctcharsinbuf; i++ )
[mutableData appendBytes:&outbuf[i] length:1];
}
if( flbreak ) break;
}
}
}
self = [self initWithData:mutableData];
return self;
}
#pragma mark -
- (NSString *)base64Encoding
{
return [self base64EncodingWithLineLength:0];
}
- (NSString *)base64EncodingWithLineLength:(NSUInteger)lineLength
{
const unsigned char *bytes = [self bytes];
NSMutableString *result = [NSMutableString stringWithCapacity:self.length];
unsigned long ixtext = 0;
unsigned long lentext = self.length;
long ctremaining = 0;
unsigned char inbuf[3], outbuf[4];
unsigned short i = 0;
unsigned short charsonline = 0, ctcopy = 0;
unsigned long ix = 0;
while( YES )
{
ctremaining = lentext - ixtext;
if( ctremaining <= 0 ) break;
for( i = 0; i < 3; i++ )
{
ix = ixtext + i;
if( ix < lentext ) inbuf[i] = bytes[ix];
else inbuf [i] = 0;
}
outbuf [0] = (inbuf [0] & 0xFC) >> 2;
outbuf [1] = ((inbuf [0] & 0x03) << 4) | ((inbuf [1] & 0xF0) >> 4);
outbuf [2] = ((inbuf [1] & 0x0F) << 2) | ((inbuf [2] & 0xC0) >> 6);
outbuf [3] = inbuf [2] & 0x3F;
ctcopy = 4;
switch( ctremaining )
{
case 1:
ctcopy = 2;
break;
case 2:
ctcopy = 3;
break;
}
for( i = 0; i < ctcopy; i++ )
[result appendFormat:@"%c", encodingTable[outbuf[i]]];
for( i = ctcopy; i < 4; i++ )
[result appendString:@"="];
ixtext += 3;
charsonline += 4;
if( lineLength > 0 )
{
if( charsonline >= lineLength )
{
charsonline = 0;
[result appendString:@"\n"];
}
}
}
return [NSString stringWithString:result];
}
#pragma mark -
- (BOOL)hasPrefixBytes:(const void *)prefix length:(NSUInteger)length
{
if( ! prefix || ! length || self.length < length ) return NO;
return ( memcmp( [self bytes], prefix, length ) == 0 );
}
- (BOOL)hasSuffixBytes:(const void *)suffix length:(NSUInteger)length
{
if( ! suffix || ! length || self.length < length ) return NO;
return ( memcmp( ((const char *)[self bytes] + (self.length - length)), suffix, length ) == 0 );
}
次のコードを使用できます。
NSData *encryptedData = [UIImagePNGRepresentation(/*your image*/) AES256EncryptWithKey:/*your enc key*/];
NSData *plainData = [encryptedData AES256DecryptWithKey:/*your enc key*/];
UIImage *img =[UIImage imageWithData:plainData];